Bardsey's Wildlife 2021

MANX SHEARWATER CENSUS

5.1 DISCUSSION

5.1.1 POPULATION INCREASE

Results from the 2021 survey of the northern part of the East Side (Area C) showed an increase of 11.89%
(1222) in the total number of burrows (AOBs and unoccupied burrows combined) compared with the
previous census in 2015. However, some areas from this 2021 census may be re-counted in 2023, as based
on results from the other areas that have been surveyed during the current census, this increase is lower
than anticipated.

The total number of burrows in Area C has risen from 7424 in 2009 to 10,279 in 2015 (+45.27%) and 11,501
in 2021. This is an increase of 54.92% since 2009 (Table 2).

The number of AOBs showed a similar percentage increase to that of the total number of burrows, rising
from 6625 in 2009 to 9624 in 2015 (+45.27%), and then by 10.42% in 2021 to 10,627 AOBs.

Table 3: Comparison of Areas A+B+C in the 2019-21, 2014-16 and 2008-10 surveys

Area A+B+C 2019-21 2014-16 2008-10 % change +27.21%
23,583 18,539 14,755 2014-16 – 2019-21 +25.65%
Number of 2008-10 – 2014-16 +59.84%
burrows 2008-10 – 2019-21

AOBs 21,674 17,276 12,870 2014-16 – 2019-21 +25.46%
2008-10 – 2014-16 +34.23%
2008-10 – 2019-21 +68.41%

If we combine the 2019 and 2020 results (Areas A + B) from the current census, there have been 12,082
burrows counted in total, 46.11% greater than the total for the same areas in the previous 2014-2016
census. Similarly, the total number of AOBs increased by 48.22%, from 7453 in the same area in the 2014-
2016 census to 11,047 in the current census.

Adding the northern half of the East Side (Area C), counted in 2021, to the 2019 and 2020 totals from
Areas A and B, there have been 23,583 burrows counted in total during the current census so far. This is
an increase of 27.21% (5044) burrows compared to the previous census using data from Areas A, B and
C, and an increase of 59.83% (8828) in burrows since the 2008-10 census. The increase in Apparently-
Occupied Burrows in the same areas since the 2014-2016 census was 25.46% (4398 AOBs), and since the
2008-10 census there has been an increase of 68.41% (8804 AOBs).

These results show that the total number of burrows, and those that are Apparently-Occupied, are
increasing at a similar rate since the 2014-2016 survey (27.21% and 25.46%), perhaps suggesting that
prospecting and excavating birds are returning to take up residency and breed.

These data also suggest that the carrying capacity for breeding Manx Shearwaters on Bardsey has not
yet been reached, although the percentage increase on the northern section of the East Side of the
island (Area C) of 11.89% (all burrows) and 10.42% (AOBs) was lower than the increase for Areas A and B
of the survey on the western side of the island at 46.11% (all burrows) and 48.22% (AOBs), which could
suggest that the East Side is nearing capacity.

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5.1.2 OCCUPANCY RATES

5.1.2.1 OCCUPANCY RATES 2021 CENSUS (AREA C)

Burrow occupancy rate is broadly similar across the three survey periods for Area C, between 89.20%
and 93.63%; however, there was a slight decrease in the occupancy rate of the 2021 census area
compared to the previous census. In the 2015 census, 93.63% of burrows were apparently occupied,
compared to 92.40% in 2021. This decrease in occupancy rate suggests that more prospecting birds are
digging burrows.

Table 4: Occupancy rates during the 2021 census (Area C) compared to 2015 and 2009.

Area C total 2021 2015 2009 % change
% of burrows 92.40 93.63 89.20 2015 – 2021 -1.31%
2009 – 2015 +4.97%
occupied 2009 – 2021 +3.59%

5.1.2.2 OCCUPANCY RATES 2021 CENSUS (AREAS A+B+C)

Looking at the three areas (A, B and C) surveyed so far in this current census and comparing to the 2008-
2010 and the 2014-2016 censuses we see that the occupancy rate has fallen slightly (-1.39%) from the
2014-16 survey but is still higher (+5.38%) than the 2008-10 survey.

Table 5: Occupancy rates of Areas A, B and C in 2019-21 compared to 2014-16 and 2008-10

Area A+B+C 2019-21 2014-16 2008-10 % change -1.39%
91.91 93.19 87.22 2014-16 – 2019-21 +6.84%
% of burrows 2008-10 – 2014-16 +5.38%
occupied 2008-10 – 2019-21

5.1.3 RESPONSE RATES

The number of birds that responded to voice playback in the 2021 census was much lower than in 2019
and 2020, but more in line with the rates experienced in 2014-2016. From the 10,627 burrows, responses
were elicited from 1438 (13.53%).

Table 6: 2019 -2021 Manx Shearwater surveys on Bardsey with x2.39 correction factor
applied .

Number of AOBs % of Playback % of Responses x
burrows burrows responses responses correction
occupied from AOBs factor (2.39)
(from
Area A 3550 3078 86.70 AOBs) 46.52 3422
Area B 8532 7969 93.40 1432 31.32 5965
Area C 11,501 10,627 92.40 2496 13.53 3437
Areas A+B+C 23,583 21,674 91.91 1438 24.76 12,825
5366

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5.1.4 CORRECTION FACTOR

5.1.4.1 METHOD

In 2020, a sample of 39 burrows known to be occupied were visited to elicit a response from the
occupant using voice playback on five separate occasions (Prettyman 2020). The average response
rate from these five visits was then used to calculate a correction factor, which could then be applied
to all the voice playback results in order to estimate the total number of occupied burrows.

5.1.4.2 RESULTS

The response rates from 39 burrows varied from 35.9% to 61.54%, with an average of 43.82%. The
correction factor across each of the five visits varied from 1.63 to 2.79, with an average of 2.39 which has
been used as the correction factor.

5.1.5 IMPROVED AUDIO QUALITY AND DUAL-SEX CALLS

It is well documented that male Manx Shearwaters have a response rate of 93-98% to calls of other males
during the breeding season and that females respond less than 1% of the time to the call of a male
(Perkins et al. 2017). As mentioned previously, dual-sex calls were used in the 2019 to 2021 voice playback
surveys on Bardsey as a direct result of a study by Perkins et al. (2017) which found that females respond
at higher rates to calls of another female compared to male-only calls. The response rate of AOBs
decreased significantly from 46.52% in Area A in 2019, to 31.32% in 2020 for Area B, and even more so to
13.53% for Area C in 2021 despite the same equipment being used. There appears to be no obvious
reason for birds on the eastern side of the island not to respond at the same rate as birds on the western
side. However, the response rate in Area C in 2021 of 13.53% was very similar to a sample in the same
area in 2015 (12.11%).

During 2015 and 2016 a test was carried out using the iLuv speakers and iPods to try and elicit responses
from incubating birds in 30 study burrows. Over a 14-day period, each burrow was surveyed four times
following the same voice playback methodology as used in the 2008 and 2014 censuses (25 seconds of
playback using male-only calls, followed by a 25 second listening period). Given that the process
occurred over a 14-day period, both males and females should have been incubating eggs in burrows
at different times during that period and so a response rate of ~50% was expected. Consequently, it was
surprising to find that the response rates varied from c15-25% (pers obs./Stansfield and Leatherbee -
unpublished data).

As previously stated, the 2021 results saw a slight increase in responses compared with 2015, presumably
due to the methodology (dual-sex playback) along with the equipment used. The new EasyAcc Mini
Bluetooth Speaker and digital MP3 dual-sex recording of Manx Shearwaters produced a much better
sound quality at a greater volume; the improvement in sound quality alone could be expected to
improve the likelihood of a bird calling back to it. It is unclear, however, as to why the response rate wass
much lower than in 2019 and 2020.

5.1.6 OTHER OBSERVATIONS AND CONSIDERATIONS

The results of the 2019 to 2021 surveys suggest that Bardsey’s Manx Shearwater population is still rapidly
expanding and that the island’s carrying capacity for nesting Manx Shearwaters has not yet been
reached.

It can be assumed that the population of shearwaters nesting in the southern half of the East Side (Area
D), which is due to be surveyed in 2022, will not have fallen in number since the 3025 AOBs that were

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counted in 2014-2016. If this figure is added to the 21,674 AOBs counted so far, a total of 24,699 is arrived
at.

Assuming that the increase in Area D will be similar to Area C, and we add 10.42% to that figure, we get
an estimated 3340 AOBs in Area D. Adding this estimate to the known figure of 21,674 there will be an
estimated 25,014 AOBs.

The productivity rate for Manx Shearwaters was 65% in 2021, meaning that a minimum of 16,259 chicks
could have hatched. If we add this to the estimated 50,028 breeding adults, then there may have been
as many as 66,287 Manx Shearwaters on the island during the summer months (excluding non-breeders).

6 SUMMARY

The results from the 2021 survey suggest that the population of Manx Shearwaters on Bardsey has rapidly
increased in this section of the island. A total of 11,501 burrows (occupied and unoccupied) were
counted across the 2021 study area. Of these, 10,627 (92.40%) were deemed to be Apparently-
Occupied, and voice playback elicited responses from 1438 (13.53%) of these.

Combining the 2019-2021 census results, the overall number of burrows counted is 23,583, 27.21% above
the total for the same areas in the previous census. Likewise, the total number of AOBs has increased by
25.46%, from 17,276 in the 2014-2016 census to 21,674 in the current census.

If we assume that the southern East Side populations remain unchanged since the last census, Bardsey
now has a minimum of 24,699 AOBs. However, if we assume that the rate of increase on the southern
East Side (Area D) is the same as the rest of the East Side (Area C) and apply a 10.42% increase, the total
number of AOBs, is projected to be 25,014.

The island’s population is now estimated at 25,000 pairs.

7 ACKNOWLEDGEMENTS

Thanks are due to Sam Prettyman, Megan Hollywood-Harry, Stuart Cossey and Ed Betteridge for
undertaking the fieldwork, and to Emma Stansfield and Patrick Davies for commenting on drafts of this
paper.

8 REFERENCES

Booker, H., Price, D., Slader, P. Frayling, T., Williams, T., & Bolton, M. 2019. Seabird recovery on Lundy
British Birds 112: 217-230

Brooke, M. 2013. The Manx Shearwater. T&AD Poyser, London.
Dykes, B. & Stansfield. S. 2019. Breeding birds: a summary of the breeding season on Bardsey and

Ynysoedd Gwylan in 2018. 2018 Bardsey’s Wildlife. Rep. Bardsey Bird Fld. Obs. 62:134-159.
Hooper, L., Hewitt, J., & Stansfield, S. 2020. Manx Shearwater Population Census 2019-2022 year 1. 2019

Bardsey’s Wildlife. Rep. Bardsey Bird Fld. Obs. 63: 178-187.
Murray, S., Shewry, M.C., Mudge, G.P. & Spray, S. 2003. A survey of Manx Shearwaters Puffinus puffinus

on Rum, Inner Hebrides in 2001. Atlantic seabirds, 5: 89-100.
Perkins, A.J., Douse, A., Morgan, G., Cooper, A. & Bolton, M. 2017. Using dual-sex

calls improves the playback census method for a nocturnal burrow-nesting seabird, the Manx
Shearwater Puffinus puffinus. Bird Study, 64:146-158.
Perrins, C.M., Wood, M.J., Garroway, C.J., Boyle, D., Oakes, N., Revera, R., Collins, P. & Taylor, C. 2012.
A whole-island census of the Manx Shearwaters Puffinus puffinus breeding on Skomer Island in
2011. Seabird, 25:1-13.

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MANX SHEARWATER CENSUS

Prettyman, S. Manx Shearwater Population Census 2019-2022 year 1. 2020 Bardsey’s Wildlife. Rep.
Bardsey Bird Fld. Obs. 64: 182-191

Stansfield, S., & Carter, M. 2017. Manx Shearwater studies: Manx Shearwater 2014-2016 population
census. 2016 Bardsey’s Wildlife. Rep. Bardsey Bird Fld. Obs. 60: 152-158.

Walsh, P.M., Halley, D.J., Harris, M.P., Del Nevo, A., Sim, I.M.W. & Tasker, M.L. 1995. Seabird monitoring
handbook for Britain and Ireland: a compilation of methods for survey and monitoring of
breeding seabirds. JNCC/RSPB/ITE/Seabird Group.
Group.

Fig. 8 Manx Shearwaters ashore at night © Steven Stansfield 197

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MANX SHEARWATER
A pilot tracking project
Line Cordes & Steven Stansfield

Manx Shearwater REP. BARDSEY BIRD FLD OBS.

© Ed Betteridge

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1 INTRODUCTION

In 2021, a pilot study using novel accelerometer/GPS tags fitted to Manx Shearwaters Puffinus puffinus
was undertaken by Bangor University and BBFO to attempt to quantify the energetic costs of flying under
different wind conditions while moving between foraging areas during early incubation; to generate
cost-space maps depicting the energyscapes of foraging Manx shearwaters and determine whether
birds choose the path of least resistance, and finally to predict the future energetic costs for Manx
Shearwaters from the two colonies to reach the Irish Sea Front Special Protection Area (SPA) under
different climate change scenarios

For the majority of animals, movement is essential for finding food, but is also very energetically
expensive. Optimal foraging theory states that animals should move in a way that minimizes energy
expenditure and maximizes energy gain. However, in order to understand what represents an efficient
movement strategy, one must take into account characteristics of the environment that the animal is
moving through (e.g. incline, vegetation, current).

Marine animals that return to specific areas, such as resting and breeding sites, are of particular interest
as they depend on patchy and widely distributed resources. To reach these foraging areas they have
to navigate ever-changing fluid energy landscapes of either air or water (e.g. changes in wind speed
and direction). Animals from different locations may therefore experience very different conditions and
subsequent energetic costs in reaching key prey fields. In this study, GPS and accelerometer tags were
deployed on Manx Shearwaters from two different colonies in the Irish Sea (Bardsey and Copeland
Island), strategically selected around the Irish Sea Front SPA.

Manx Shearwaters are adept fliers, which intermittently flap and glide, making them an excellent study
species. Novel accelerometer tags were deployed on Manx Shearwaters in order to estimate the overall
dynamic body acceleration in response to wind and wave patterns (as air moving over waves creates
updrafts aiding flight of this low flying species). Manx Shearwaters breeding in this region frequently visit
rich foraging grounds in the northwest Irish Sea, where a large tidal front forms each spring, and which
has been designated as a Special Protection Area for Manx Shearwaters. Birds from different colonies
will likely experience different wind and wave patterns in reaching this important foraging area, resulting
in colony-specific energetic cost of foraging.

2 AIMS

The goals of this project are to assess whether Manx Shearwaters choose the path of least resistance or
incur added costs in trying to reach specific foraging hot spots.

This research is particularly interesting as climate change is predicted to alter the wind conditions to
which seabirds have adapted, potentially altering the energetic costs of breeding birds that are
provisioning for chicks and thereby impacting the dynamics of procellariform populations.

• Objective 1: Quantify the energetic costs of flying under different wind and wave
conditions for birds from the two colonies.

• Objective 2: Generate cost-space maps depicting the energyscapes of foraging
Manx Shearwaters and determine whether birds choose the path of least resistance.

• Objective 3: Predict the future energetic costs for Manx Shearwaters from the two
colonies to reach the Irish Sea Front SPA under different climate change scenarios.

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3 METHODS

During the incubation period of the Manx Shearwater (mid-late May), a total of 16 nests was located on
Bardsey and nine on Copeland that were easily accessible, and the adult birds could be removed from
the nest chamber.

The tags used in this study are TechnoSmart Axy-Depth Fig. 1 TechnoSmart Axy-Depth
accelerometer/GPS tags (fig 1.). Each tag weighs 8g, accelerometer/GPS tag © Steph Harris
with battery power to last up to 10 days. They recorded
a GPS location every 5 minutes (fig. 5), while
continuously recording acceleration (50Hz), pressure
(1hz) and temperature (1hz). The tags were attached
to the back feathers of the bird using TESA™ Tape (a
strong adhesive marine durable cloth tape). Three
narrow strips of tape were placed around the feathers
and the tag holding it firmly in position. The research
was conducted under a special methods licence
issued by the British Trust for Ornithology

The birds were then processed, with a number of Fig. 2 TechnoSmart Axy-Depth
biometrical data being logged, including wing length, accelerometer/GPS tag attached to
wingspan, wing area and body mass. The birds were Manx Shearwater© Steph Harris
then placed back into the nest and left to venture out
to sea. The nests were checked daily to ascertain if the
birds had left, and to also see when they had returned.
The tags, once switched on, went into a low-power
mode until the inbuilt accelerometer recorded
movement above a pre-set threshold when it then
began to record data. Upon the birds’ return the tags
were carefully removed from the feathers. The data
from the tags were downloaded and stored on a
number of computers and also transferred off the
island to the University at Bangor.

Fig. 3 Manx Shearwater at sea © Steven Stansfield 201

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4 PRELIMINARY TRACKING RESULTS

4.1.MOVEMENTS

Further detailed analysis of the tracking, accelerometer, pressure and temperature data that were
collected will be undertaken as part of an expansion of the project which will run over the summers of
2022 and 2023.

Visualisation of the tracking data suggests that birds may use favourable winds to reach foraging sites,
which may result in increased costs on the return journey as they are constrained to fly under the
prevailing conditions.

Tracks from birds from Bardsey revealed high levels of activity in the area of the Irish Sea Front see Fig. 4.

Only one of the birds headed to the south of the island, with only one individual going into Cardigan Bay
as far east as Criccieth. Two birds did not venture beyond Caernarfon Bay, with three moving into
Liverpool Bay and foraging off the coastline between North Wales and Lancashire. The furthest track of
any individual (fig 4) saw one bird venture as far north as the Isle of Whithorn on the North Solway coast
at 54o43’26.64”N 4o19’18.92”W having spent time foraging in Liverpool Bay. Interestingly the bird returned
south to Bardsey on the same route by which it went north.

Manx Shearwaters at sea © Ed Betteridge

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MANX SHEARWATER TRACKING

Fig. 4 Tracks from all Fig. 5 Longest track of Fig. 6 Track with data points
Bardsey birds a bird to the Solway at five minute intervals

5 ACKNOWLEDGMENTS

We would like to thank National Geographic for funding this pilot project. The staff of Bardsey Bird and
Field Observatory deserve our thanks for their help during the field season. Dr Steph Harris made
constructive comments on an earlier draft of this note.

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CHOUGH

A summary of the 2021 breeding season
Steven Stansfield

Chough REP. BARDSEY BIRD FLD OBS.

© Steven Stansfield

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1 INTRODUCTION

Choughs Pyrrhocorax pyrrhocorax breed across much of central Asia, southern and eastern Europe and
Morocco, with small outlying populations in the Canary Islands, Ethiopia and Sudan. Historically, Choughs
bred around much of the UK’s coastline and some parts of inland Scotland. However, due to persecution
and changes in livestock management, the UK population underwent a steep decline and range
contraction during the late 1800s, leaving the only remaining breeding birds in their current strongholds
today (Bullock et al., 1983). In the early 20th century, Chough populations in England and Scotland
continued their downward trajectory, whilst those in Wales and on the Isle of Man showed some signs of
recovery.

The most recent national census of Choughs in the UK and the Isle of Man took place in 2014, and
estimated the population to be 394 breeding pairs, with the majority found in Wales (59%) and the Isle of
Man (30%; Hayhow et al., 2018). Overall, numbers of Choughs in the UK and the Isle of Man have fallen
very slightly between this survey and the previous one in 2002 which estimated 399 pairs. These
population trends exhibit some geographical variation, with increases in Wales, the Isle of Man, Cornwall
and south Wales, contrasting with a 25% decline in Scotland, and smaller declines in parts of north and
mid-Wales.

Choughs are comprehensively protected in the UK and Europe since they are listed under Schedule 1 of
the Wildlife and Countryside Act 1981, as well as Annex 1 of the EC Conservation of Wild Birds Directive
1979. The Bardsey population is further protected as they are a feature of the Ynys Enlli Glannau
Aberdaron Special Protection Area (SPA) and Bardsey Island Site of Special Scientific Interest (SSSI), in
addition to being listed in Gwynedd’s Local Biodiversity Action Plan.

STATUS AND LEGAL PROTECTION SUMMARY

• Listed as a protected species under Annex I of the EC Conservation of Wild Birds Directive 1979
(2009/147/EC)

• Protected under Schedule 1 of the Wildlife and Countryside Act 1981
• A designated feature of the Ynys Enlli SSSI
• Feature of the Ynys Enlli and Glannau Aberdaron SPA
• Listed in the Gwynedd Biodiversity Action Plan

Number of pairs 10
9
8
7
6
5
4
3
2
1
0

1953
1955
1957
1959
1961
1963
1965
1967
1969
1971
1973
1975
1977
1979
1981
1983
1985
1987
1989
1991
1993
1995
1997
1999
2001
2003
2005
2007
2009
2011
2013
2015
2017
2019
2021

Year Mean 4.60 ±s.d.2.25
Number of pairs

Fig. 1 Bardsey Chough breeding population 1953-2021

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CHOUGHS

The Chough population on Bardsey has increased substantially since the Observatory began monitoring
them in 1953. Prior to the start of this century, an average of four pairs nested each year, but since 2001
this has increased to around seven pairs annually. Seven pairs bred on Bardsey in both 2019 and 2020,
which is less than in each of the two preceding years. In 2021 six pairs nested (with another prospecting),
30.94% greater than the mean number of pairs for 1953-2021 (4.58 ±s.d.2.24).

Table 1. Breeding data 1953-2021. The average number of breeding pairs, average number
of chicks fledged and average productivity 1953-2021.

1953-2021 Average number Average number Average productivity:
1953-1970 of breeding pairs (±s.d.) of chicks fledged (±s.d.) chicks/pair (±s.e.)
1973-2000 2.64 ±0.13
2001-2010 4.58 ±2.24 11.41 ±5.97 3.27 ±0.29
2012-2021 2.11 ±0.96 6.24 ±3.03 2.48 ±0.18
4.29 ±1.24 2.79 ±0.28
6.00 ±0.67 10.89 ±5.03 1.99 ±0.15
8.00 ± 1.05 16.90 ±6.30
15.90 ±4.23

5.00 30

4.00 25
20

3.00
15

2.00
10

1.00 5

0.00 0
Productivity
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021

Number of Pairs and Young

Year

Pairs Productivity young

Fig. 2 Number of Chough pairs, their chicks and productivity rates 1998 – 2021.

2 AIMS

Choughs are a designated feature of the Bardsey Island SSSI and NNR. As such, the Welsh government
has a statutory obligation to monitor the population. This is done through the countryside agency, Natural
Resources Wales (NRW), who in turn contract BBFO to undertake the work through Section 16 of the
Wildlife and Countryside Act Management Agreement.

3 METHODS

Choughs were observed during the early part of the nesting season and their nests located. Each pair
was observed for up to two hours per visit to confirm breeding and other activity. Chicks in all of the
accessible nests were fitted with a single metal and three plastic colour rings in a unique combination
that allows them to be individually identified in the field, post-fledging. All nest visits and ringing were
conducted under the appropriate licences from NRW and the British Trust for Ornithology (BTO). Once
the chicks fledged, they were monitored until they left the island.

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4 RESULTS

Fourteen traditional nest sites were checked and monitored during the 2021 breeding season, with six
pairs attempting to breed and another prospecting in early spring. This was fewer than in 2019 and 2020.
Four of the six pairs were confirmed to successfully fledge young, with a total of 12 chicks fledging (1 x 2
chicks, 2 x 3 chicks and 1 x 4 chicks).

The number of fledged chicks in 2021 is 24.53% lower than the ten-year mean (15.90±s.d.4.23), and 20.00%
lower than in 2020. Productivity was 6.67% lower than in 2020.

Table 2. Breeding data 2012-2021

Year 2012 2013 2014 2015 2016 2017 2018 2019 2020 2021
№ of pairs 9 9 8 9 8 9 8 7 7 6
№ of young 15 13 24 18 14 22 15 11 15 12
Productivity
1.67 1.44 3.00 2.00 1.75 2.44 1.88 1.57 2.14 2.00

Fig. 3. Chough near the Pen Cristin nest site © Steven Stansfield

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CHOUGHS

4.1 NEST DETAILS OF CHOUGHS ON BARDSEY IN 2021

4.1.1 NORTH WEST CORNER

Date Start Finish Nesting activity

01/04/2021 No sign of any activity
15/04/2021 No sign of any activity
01/05/2021 No sign of any activity

Summary – no activity

4.1.2 OGOF MORLAS

Date Start Finish Nesting activity
No sign of any activity
30/03/2021 No sign of any activity
15/05/2021 No sign of any activity
01/06/2021

4.1.3 BLACK ANVIL Summary – no activity

Bird Ring number Right Left combination
combination
Female Un-ringed ORANGE/ ORANGE
Male ASH/METAL ASH/ METAL
EX08750 GREEN/WHITE ASH/ METAL
Chick 1 EX08748 GREEN/ ORANGE ASH/ METAL
Chick 2 EX08749 GREEN/ RED
Chick 3

Date Start Finish Nesting activity
24/03/2021 10:15 12:15
Pair seen feeding around nest site and came to sit by nest
21/04/2021 13:00 13:15 entrance for ~5 mins before flying south along the East Side.
14:00 15:30 Pair was seen feeding on the slope above Bae Felen at 13:00.
17/05/2021 Pair entered nest site together at 15:00 and after ~2 minutes the
04/06/2021 15:00 15:30 male left and flew south.
17/06/2021 10:00 11:00 Nest visited; three small chicks present < 1 week old.
16:00 17:30
Three chicks ringed.

Adults seen with the three ringed chicks, led them into the Ogof
Morlas site where identity of the juveniles was confirmed.
Parents left chicks but came back to site and flew north with
the juveniles.

Summary – three young fledged

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4.1.4 THE PINK TRYWN

Date Start Finish Nesting activity
24/03/2021 10:15 12:15
21/04/2021 14:00 15:30 No sign of any activity
17/05/2021 15:00 15:30 No sign of any activity
No sign of any activity

Summary – no activity

4.1.5 CARREG LLEWYDION

Date Start Finish Nesting activity
24/03/2021 10:15 12:15 No sign of any activity
21/04/2021 14:00 15:30 No sign of any activity
17/05/2021 15:00 15:30 No sign of any activity

Summary – no activity

4.1.6 BAE FELEN

Bird Ring number Right combination Left combination
Female Un-ringed BLUE/#2J GREEN/METAL

Male

Date Start Finish Nesting activity
04/04/2021 12:00 13:00
Pair visited the Bae Felen site together at 12:15 and left after c5
21/04/2021 10:00 12:00 minutes, rings were read, and the pair left together and flew
north out of site.
02/05/2021 10:00 12:00 The male was seen entering the Bae Felen site at c10:30 but then
17/05/2021 14:30 16:00 flew south and entered the Zawn nest site and shortly after flew
up to the slope above the Zawn and began to feed with un-
ringed partner.

Pair seen entering Zawn and Bae Felen site.

No activity, nest site visited and nothing found.

Summary – prospecting pair – same as Zawn

Fig. 4. Chough on East Side near Bae Felen © Steven Stansfield

210 REP. BARDSEY BIRD FLD OBS.

CHOUGHS

4.1.7 THE ZAWN

Bird Ring number Right combination Left combination
Female Un-ringed BLUE/#2J GREEN/METAL

Male

Date Start Finish Nesting activity
21/04/2021 10:00 12:00
Pair visiting nest frequently during the monitoring session (every
02/05/2021 10:00 12:00 ~20 minutes), also feeding around the site on the slope above
17/05/2021 14:30 16:00 the nest.
Pair seen visiting nest together from north, exiting ~five minutes
later and sitting on slope for 30 seconds before flying north.
Male bird feeding and ‘umbrellaing’ on the grass above the
nest site, indicating its sex which was previously unknown. Bird
then entered the nest and left a few minutes later and flew
north.

Summary – prospecting pair - same as Bae Felen

4.1.8 SEAL CAVE

Bird Ring number Right combination Left combination
Male #H0/ METAL WHITE/WHITE
Female LIME/ METAL
ORANGE /RED

Date Start Finish Nesting activity
04/04/2021 10:00 12:00 Pair same as in 2020 entered nest site with nest material (mainly
wool) and stayed around the nest site for ~5 minutes at 10:45.
21/04/2021 11:00 11:30 Observers visited the nest and 2 eggs were in the nest, the pair
was calling, the pair visited the nest after ~5 minutes.
17/05/2021 11:00 12:00 Nest visited, one egg and three very young chicks present.
28/05/2021 13:30 14:00
Nest visited and empty, so perhaps failed during late May
storms. Nest material still intact though.

Summary – failed at young stage

4.1.9 OGOF BRAICH Y FWYAF

Bird Ring number Right combination Left combination
Female Unringed
Unringed
Male

Date Start Finish Nesting activity
27/03/2021 11:00 12:50 Pair visited the nest site with nest material at 11:00 (mainly twigs
and vegetation) twice in 40 minutes.
04/04/2021 12:15 13:40
21/04/2021 09:30 10:50 Pair carried nest material to site at 13:00.
Pair entered nest site together for ~5 minutes, left together and
02/05/2021 10:00 10:30 flew north shortly after.

No sign of any activity.

Summary – failed at nest building stage

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4.1.10 TORNADO LEDGE

Date Start Finish Nesting activity
27/03/2021 11:00 12:50 No sign of any activity
04/04/2021 12:15 13:40 No sign of any activity
21/04/2021 09:30 10:50 No sign of any activity
02/05/2021 10:00 10:30 No sign of any activity
27/03/2021 11:00 12:50 No sign of any activity

Summary – no activity

4.1.11 OGOF BARCUT

Bird Ring number Right combination Left combination
Female Un-ringed
Un-ringed
Male

Date Start Finish Nesting activity
27/03/2021 11:30 12:30
Pair flew out of Ogof Braich y Fwyaf and into Ogof Barcut.
21/04/2021 09:00 09:30 Nest site visited but nothing found. Un-ringed pair was entering
28/05/2021 09:00 10:00 Ogof Braich y Fwyaf.
No activity, nothing in nest site.

Summary – no activity

4.1.12 PEN CRISTIN

Bird Ring number Right combination Left combination
Female METAL WHITE/WHITE
METAL
Male YELLOW/BLACK

Date Start Finish Nesting activity
17/03/2021 14:00 15:00 Male visited nest site three times carrying nest material.
01/04/2021 10:00 11:00
Pair feeding on slope near nest site, flew south, did not enter
17/04/2021 09:00 10:00 nest.
Male entered nest site at 09:15; and female came out and sat
06/06/2021 08:30 09:30 outside nest site, male flew north and female flew to nest.
17/06/2021 11:00 12:30 Observer went to nest and could feel one large chick.

Two chicks seen flying close to nest site with parents. Parent
would fly away for ~20 mins at a time and return to chicks
outside the nest.
Chicks were seen regularly around Pen Cistin for ~2 weeks
subsequently.

Summary – two young fledged

4.1.13 OGOF DIBAN

Bird Ring number Right combination Left combination
Female ORANGE/# “0F” LIME/METAL
METAL
Male GREEN/GREEN

212 REP. BARDSEY BIRD FLD OBS.

CHOUGHS

Chick 1 EX04736 BLACK/ YELLOW ASH/METAL
Chick 2 EX04737 BLACK/ ORANGE ASH/METAL
Chick 3 EX04738 ASH/METAL
Chick 4 EX04739 BLACK/ RED ASH/METAL
BLACK/ LIME

Date Start Finish Nesting activity
18/03/2021 07:00 08:00 Pair feeding on South End together.
23/03/2021 07:00 08:00
25/03/2021 09:00 10:00 Nest building, collecting wool and taking it to nest site.
01/04/2021 07:00 08:00
03/04/2021 13:00 15:00 Collecting wool on Narrows and flew south.
15:40
09/04/2021 13:40 Pair feeding on South End.
11:00
04/06/2021 10:00 1530 Pair visited site at 13:15 and sat outside nest for ten minutes; flew
05/2021 1500 north together and did not return.
Female visited at 14:11 and stood calling from outside nest and
10/06/2021 walked into nest hole after 3 minutes. 14:30 male flew down to
entrance and female came out of nest hole and both bill-
stropped for ~2 minutes and male flew away north then came
back into nest hole. 14:37 male flew out of nest and female
followed; both stayed around the nest site bill-stropping for 3
minutes then both flew away.

Three chicks ringed.
Seen regularly through May during daily census.

Two chicks (BLACK/ RED and BLACK/ LIME) seen outside the nest
hole.

BLACK/ ORANGE was found dead after fledging

Summary – three young fledged

4.1.14 OGOF TRWYN-YR-HWCH BACH (WEST COAST)

Bird Ring number Right combination Left combination
Female GREEN/ #“3T”, GREEN/METAL
EX04740 ASH/METAL BLUE
Male EX04741 BLACK/GREEN ASH/METAL
Chick 1 EX04742 BLACK/BLUE ASH/METAL
Chick 2 EX04743 BLACK/ BLACK ASH/METAL
Chick 3 BLACK/BROWN ASH/METAL
Chick 4

Date Start Finish Nesting activity
17/03/2021 07:30 08:30 Usual pair visiting nest site and bill-stropping but not seen
carrying nest material.
10/04/2021 16:00 16:40 Male entered nest site, left with female and pair sat outside nest
site.
20/04/2021 10:00 11:00 Feeding on the East Side together.
05/2021
14:00 15:00 Seen regularly through May during daily census.
14/05/2021 18:00 18:30 Four chicks ringed.
12/06/2021 Four chicks seen with adults flying around the West Coast.

Summary – four young fledged

.

65: 204-219 213

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5 DISCUSSION

Chough numbers on Bardsey have fluctuated dramatically since monitoring began in 1953. However,
the trend clearly shows an increase in the breeding population, with a minimum of nine pairs attempting
to breed in four of the last ten years. The population trend also suggests that Choughs are responding
positively to the management of the island, where grazing by both sheep and cattle is creating an
abundance of short sward semi-natural vegetation.

The number of Chough pairs breeding on Bardsey this year was one fewer than last year and was two
pairs (25.00%) fewer than the ten-year average (8.00±s.d.1.05). Breeding success was lower than last
year, with three fewer chicks fledging from six (one fewer) pairs. Of the six active pairs, two failed to rear
young: one failed at the nest-building stage and one at early-chick rearing stage. Whether this was due
to predation is unclear; however storms in the spring could also have been the cause of the failures. From
the four nests that were successful 12 young fledged, the overall productivity from six pairs was 2.00,
slightly lower than last year and slightly higher than the ten-year mean of 1.99±s.e.0.15.

Choughs on Bardsey will be affected by wider environmental variables such as changes in climate or
population fluctuations elsewhere. However, on a local level, specific management on the island is likely
to have a significant impact, particularly on the extent of suitable feeding habitat. The fact that the
population is stable goes some way to indicate that the management of the island for Choughs is
successful. By grazing both sheep and cattle, the island maintains an appropriate amount of short
grassland areas as favoured feeding areas for Choughs.

Fig. 5. Chough on Solfach seaweed in October © Steven Stansfield

214 REP. BARDSEY BIRD FLD OBS.

CHOUGHS

5.1 MANAGEMENT STATEMENTS AND SPECIES TARGETS

Although now outdated, the latest management statement for Choughs on Bardsey (2010-2015) from
the 2010 Conservation Management Plan Supplement (Moralee 2010) states:

To contribute to the maintenance of the internationally important population
(1% or more of the Great Britain population) of breeding and non-breeding
season Chough within the Glannau Aberdaron and Ynys Enlli SPA.

The species’ targets as listed in the 2010 Management Plan Supplement are:

• The breeding population of Chough is at least four pairs
• The wintering population of Chough is at least ten individuals
• Sufficient suitable habitat is present to support the populations
• Breeding population is stable or increasing
• Productivity is stable
• Breeding and non-breeding birds use Ynys Enlli for feeding

throughout the year
• Chough feeding habitats are themselves in a favourable conservation

status and that the specified and operational limits and grazing
prescriptions for these habitats incorporate Chough feeding
requirements (i.e. sward height and bare ground)
• Disturbance of breeding and feeding Chough is minimal
• The factors affecting the feature are under control

In the Guide for land managers: Summary of Island Management Plan 2002-2006, Wilkinson
(2004) gives a ‘Vision’ for the Feature:

‘VISION’ FOR THE FEATURE

Size of breeding population is stable or increasing as far as availability of nest
sites will allow (min 1% UK population) and non-breeding individuals are
present and utilising the island for feeding and social interaction.

65: 204-219 215

STANSFIELD

Further to the Wilkinson plan (2004), Moralee (2010) refined the grazing prescriptions for many of the areas
which are managed for, amongst other things, Chough feeding. Most areas within the SPA and SAC
have very similar, if not identical, sward height objectives within the plan.

Fig. 6. Choughs near Solfach in October © Steven Stansfield
5.2 BREEDING AND PRODUCTIVITY

The Management Plan for Ynys Enlli (Wilkinson 2004) stated that the acceptable minimum limit for nesting
pairs of Choughs is five pairs in three of any consecutive five-year period. The number of pairs has now
been five or more for the last 20 years and should therefore be seen as being in a favourable condition.

Productivity in 2021 was 2.00 chicks per pair. This is 6.67% lower than the 2020 productivity rate of 2.14
and is 20.00% below the acceptable minimum of 2.50 chicks per pair set in the Management Plan. The
supplement to the Management Plan (Moralee 2010) targets ‘stable productivity’, but this target has not
been met since 2014. The last time productivity was greater than the minimum set out as ‘acceptable’
was in 2014 when 3.00 chicks per pair were raised from eight pairs which fledged 24 young.

The mean productivity over the last decade is 1.99 (±s.e.0.15) with fluctuations as low as 1.44 in 2012 and
reaching a peak of 3.00 in 2014; the 2021 productivity rate of 2.00 was 0.53% lower than the ten-year
mean and also 24.24% lower than the long-term 1953-2021 mean (2.64 ±s.e.0.13). Wilkinson (2004) stated
that one of the indicators of the ‘health of the feature’ would be the production of >2.5 chicks per pair
each year. However, Fig. 7. shows that a productivity figure of >2.5 chicks per pair has been achieved in
only one of the past ten years. Based on this alone, the feature would not be in a favourable condition.
However, productivity is calculated by dividing the number of young fledged by the total number of
pairs breeding or attempting to breed and does not take into account the age structure or experience
of the birds within that population. A larger population with a high proportion of young, inexperienced
birds, as is currently on the island, will inevitably lead to lower productivity than from a smaller population
made up of experienced pairs. Therefore, the productivity of Bardsey’s Choughs is expected to increase
over the coming years as the current young birds gain experience.

216 REP. BARDSEY BIRD FLD OBS.

CHOUGHS

Productivity 5.0
4.5
4.0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0.0

1953
1955
1957
1959
1961
1963
1965
1967
1969
1971
1973
1975
1977
1979
1981
1983
1985
1987
1989
1991
1993
1995
1997
1999
2001
2003
2005
2007
2009
2011
2013
2015
2017
2019
2021

Year

Productivity Mean 1953-2021 2.64 ±s.e.0.13

Fig. 7. Chough productivity (chicks per pair) 1953-2021.

4.0

3.5

3.0

Productivity 2.5

2.0

1.5

1.0

0.5

0.0 2013 2014 2015 2016 2017 2018 2019 2020 2021
2012

Year Mean 1.99 ±s.e.0.15
Productivity

Fig. 8 Productivity (chicks per pair) 2012-2021.

Over the past decade 159 young have been produced, with the lowest total of 11 in 2019 and the
highest in 2013 (24), which was the year that saw the highest productivity of the last decade. The ten-
year mean is 1.99, 20.40% below the proposed target productivity of 2.5 chicks per pair.

30
25

Number of Young 20
15

10
5

0 2013 2014 2015 2016 2017 2018 2019 2020 2021
2012 217

Year

Young Mean 11.41 ±s.d.5.97

Fig. 9 Number of young produced per annum 2012-2021.

65: 204-219

STANSFIELD

5.3 WINTERING AND NON-BREEDING CHOUGHS

No staff were present on the island during the first two months of the year. By March, when staff had
arrived, pairs had started to form and some were nest building, meaning that there were no flocks of
significant size. There were very few notable arrivals from mainland breeding birds until October, when
numbers peaked at 53. As usual, Solfach was almost exclusively where Choughs were seen feeding in
flocks. This feeding behaviour began in late September/early October and from this point on, it was not
uncommon to see 20-30 Choughs feeding on Solfach and the immediate surrounding grass.

Fig. 10 Non-resident Choughs on Solfach in autumn ©

60Daily count of birds

50

40

30

20

10

0
J FM A M J J A S O N D

Fig. 11 Maximum daily counts for Choughs on Bardsey in 2021.

218 REP. BARDSEY BIRD FLD OBS.

CHOUGHS

6 SUMMARY

2021 was another reasonable breeding season for Choughs on Bardsey, though slightly poorer than in
2020. Despite this, it has proved to be another year that Chough have not met the proposed productivity
rate.

During 2021, six pairs attempted to breed (25% below the ten-year mean 8.00 ±s.d.1.05), and of these,
four successfully fledged young. The other two pairs failed during the nest-building and early chick-
rearing stages.

The resulting 2.00 chicks per pair is 0.53% greater the ten-year mean (1.99±s.e.0.15). The number of young
fledged (12) is 24.53% below the ten-year mean (15.90±s.d.4.23). These figures are outside the
acceptable limits set out for the management of the NNR, SPA and SAC. However, looking long-term,
the population is 30.94% greater than the long-term (1953-2021) mean (4.58±s.d.2.24), with the
productivity being 24.24% lower than the long-term mean (2.64 ±s.e.0.13).

7 REFERENCES

Baillie, S.R. 1990. Integrated population monitoring of breeding birds in Britain and Ireland. Ibis, 132: 151-
166.

Bullock, I., Drewett, D. & Mickleburg, S. 1983. The Chough in Britain and Ireland. British Birds, 76: 377–401.
Hayhow, D.B., Johnstone, I., Thorpe, R., Moore, A. and Finney, S. 2007. Breeding status of Choughs

Pyrrhocorax pyrrhocorax in the UK and Isle of Man in 2002. Bird Study, 54: 23-34.
Hayhow, B.D et al. 2018. Status of breeding Chough Pyrrhocorax pyrrhocorax in the UK and Isle of Man

2014. Bird Study 65: 458-470.
Hewitt, K. & Wilkinson, H. 2003. Ynys Enlli NNR Conservation Management Plan. Countryside Council for

Wales.
Loxton, R.G. and Jones, P.H. 1995. The breeding birds of Bardsey, Skomer, Skokholm and the Calf of

Man.Part1: Introduction and species accounts. Rep. Bardsey Bird Fld Obs. 38: 84-159.
Loxton, R.G., Kittle, T. and Jones, P.H. 1999. Atlas of recoveries of birds ringed by Bardsey Bird and Field

Observatory 1953-1996. BBFO, Bethesda, Gwynedd.
McCanch, N. 2000. The relationship between Chough Pyrrhocorax pyrrhocorax breeding populations

and grazing pressure on the Calf of Man. Bird Study, 47: 295-303.
Moralee, A. 2010. Ynys Enlli Nature Conservation Management Plan drafted on behalf of the Bardsey

Island Trust by RSPB. Unpublished. Natural Resources Wales.
Perfect, E. 2018. Chough breeding studies update. Rep. Bardsey Bird Fld. Obs. 61: 208-219.
Reid, J. M., Bignal, E. M., Bignal, S., McCracken, D. I. and Monaghan, P. 2003. Environmental variability,

life-history covariation and cohort effects in the Red-billed Chough Pyrrhocorax pyrrhocorax.
Journal of Animal Ecology 72: 36-46
Reid, J. M., Bignal, E. M., Bignal, S., Bogdanova, M. I., Monaghan, P. and McCracken, D. I. 2011.
Diagnosing the timing of demographic bottlenecks: sub-adult survival in red-billed choughs.
Journal of Applied Ecology 48: 797-805
Roberts, P. 1983. Feeding habitats of Choughs on Bardsey Island. Bird Study, 30: 67-73.
Roberts, P. 1985. The Choughs of Bardsey. British Birds 78: 217-232.
Stansfield, S.D. 1999. Chough breeding success and choice of feeding habitat on Ynys Enlli in 1998. Rep
Bardsey Bird Fld Obs. 42: 59-64
Stansfield, S.D. 2003. Breeding success of the Chough Pyrrhocorax pyrrhocorax on Ynys Enlli in 2002.
Unpublished Report to NRW for Grant-aided work in 2002.
Stansfield, S.D. & Carter, M. 2017. Chough breeding studies update. Rep. Bardsey Bird Fld. Obs. 60: 170-
180.
Wilkinson, H. 2004. Guide for Land Managers, Summary of island management plan 2002-2006 Volume
1: background & designated features. Countryside Council for Wales.

65: 204-219 219

BIRD RINGING The purpose of ringing birds is to collect data to monitor survival rates
and movements, amongst other things. This provides a fundamental
Birds ringed on Bardsey in 2021 contribution to conservation as it helps scientists to understand the
Stuart Cossey, Ed Betteridge and Ollie King causes of changes in population sizes over time, and therefore how to
prevent and reverse declines. The data collected from ringing can be
analysed and used to inform decision making by governments,
conservation bodies and economic developers.

All naturally-occurring wild birds in the UK are protected from
persecution under the Wildlife and Countryside Act (1981). It is illegal
to kill, injure or ‘take’ any wild bird, or to take or damage the nest of
any wild bird whilst in use or being built. The eggs of all wild birds are
also protected. It is an offence to have in your possession any live wild
birds. As a result, all bird ringing in the UK requires a special licence,
and follows specific regulations.

The British and Irish Ringing Scheme is run and administered by the

British Trust for Ornithology (BTO)
www.bto.org

The BTO issues ringing licences on behalf of the UK and Irish
Governments. A licence to ring birds is issued only after initial approval,
followed by a lengthy training process by an authorised instructor.
Qualified ringers catch birds using mist nets, Heligoland traps, spring
traps and other methods; a small, uniquely-numbered metal ring is
then carefully placed around the bird’s leg providing a reliable and
harmless method of identifying the birds as individuals.

Licensed ringing at Bardsey Bird Observatory operates to a high
standard and ringing training is also available. In line with BTO
regulations, all of the ringing data that Bardsey Bird Observatory has
collected since 1953 has been submitted to the BTO and has been
incorporated into their national database, as well as being held in our
own databases.

The BTO is one of the world’s leading impartial scientific
research organisations specialising in knowledge about wild
birds. The BTO is interested in changes to populations in
relation to their ecology and the habitats on which they
depend. Their information base includes long-term datasets,
such as ours, that have been in place for at least 50 years.

220 REP. BARDSEY BIRD FLD OBS.

65: 220-241 221

COSSEY, BETTERIDGE & KING

1 INTRODUCTION

Each year birds migrate along their flyways all over the world in spring and autumn; many, as can be
seen in the systematic list earlier in this report, are endangered. One of the ways we can understand
more about them is to collect scientific data to support conservation; ringing forms part of the important
research necessary to help protect species that are declining. Ornithologists around the world have
been ringing for over 100 years and much of our current knowledge about migration and populations
has come from ringing birds.

Bardsey Bird Observatory started ringing when it was established in 1953 and has an ongoing program
of ringing. Up to the end of 2021 there have been 303,162 birds of 196 species ringed on the island.

2 METHODS

Birds are trapped by licenced ringers in a variety of ways, such as in mist nets, Helgoland traps, spring
traps, by woosh-netting, dazzling and a number of other methods. A small metal ring is then placed on
the bird’s leg using specialised pliers and rings; data is recorded about each individual bird.

A summary of the ringing that was undertaken during the 2021 season is presented below, broken down
monthly from mid-March, when ringing began, to late October, followed by a table showing the totals
of each species ringed during the year.

3 RESULTS

A total of 4010 birds were ringed in 2021, 1179 birds fewer than last year’s total of 5189 and 11.59% lower
than the 1953-2021 mean (4535.25±s.d.1912.72). Full-grown birds made up 3349 and the total number of
pulli ringed in 2021 was 657.

A total of 61 species was ringed this year, 20 fewer than last year with Red-eyed Vireo being the only
unusual species ringed.

The increase in the number of seabird pulli ringed was due being able to travel to the Gwylan Islands to
ring seabirds. Both spring and autumn saw several good days of warbler passage, with good numbers of
Blackcaps, Chiffchaffs and Willow Warblers. This can be seen in the ringing totals, as this year 664 Willow
Warblers and 288 Blackcaps were ringed, compared with last year’s totals of 540 and 378 respectively.

This year 175 Razorbills and 57 Guillemots were ringed, compared to last year’s totals of 30 and nine
respectively. Herring Gull pulli totals were also up on last year, 169 were ringed compared with 80. Fewer
Lesser Black-backed Gulls were ringed, with ten being caught compared to last year’s 18. On Ynys
Gwylan Fawr 22 Great Black-backed Gulls were ringed. There were 77 Shag chicks ringed between
Bardsey and Ynys Gwylan Fawr. There were also five Cormorant chicks ringed on Ynys Gwylan Fawr.

Manx Shearwater was once again the most numerous species to be ringed in 2021. A total of 861 birds
was ringed, comprising 723 full-grown birds and 138 pulli.

Previously, House Martins have only ever been caught occasionally, and in low numbers; this year,
however, an astonishing total of 89 was ringed, 66 of which were trapped in a single net. This is more than
double the overall total ever ringed on the island; the previous-highest annual total was six. Also of note
were the 92 Linnets ringed, the highest annual total since 1988.

222 REP. BARDSEY BIRD FLD OBS.

BIRD RINGING

3.1 MONTHLY SUMMARIES

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Total

Number Ringed 0 0 227 750 232 954 390 542 658 257 0 0 4010
Number of Species
0 0 17 21 22 26 26 31 28 16 0 0 61

MARCH

Drag-netting in the first week produced a Snipe trapped on 17th. Mist-netting began on 18th when the
first nets were erected at Cristin; migrants were around in reasonable numbers throughout the month,
and 35 Blackcaps, 52 Chiffchaffs and 37 Willow Warblers were similar totals to 2020. Goldcrests were the
most plentiful with 66 ringed; these were accompanied by two Firecrests. A Moorhen was also trapped
in the Heligoland trap on 31st. 17 species were ringed this month, compared to 24 last year.

APRIL

The first full month of ringing resulted in a total of 750 birds of 21 species ringed. Spring warbler passage
on Bardsey peaks in April; this month’s Willow Warbler totals were higher than last April’s with 234 ringed,
compared to 199 last year, a 17.59% increase. Only 167 Blackcaps were ringed, 36.26% lower than last
year’s total of 262 in April and 86 Chiffchaffs were ringed. The only Greenfinch of the year was caught,
as were the first Grasshopper Warbler, the first four Whitethroats, the first Reed Warbler and the first eight
Sedge Warblers. A Siberian Chiffchaff (P. c. tristis) was trapped at Cristin on 26th. Finches moved through
in good numbers resulting in 98 Goldfinches, 67 Lesser Redpolls and 35 Siskins being ringed. Other finches
ringed included seven Chaffinches and two Bullfinches. Dazzling began this month, resulting in a Purple
Sandpiper ringed on 27th.

Siberian Chiffchaff P.c.tristis © Steve Stansfield 223
65: 220-241

COSSEY, BETTERIDGE & KING

MAY

The month’s tally decreased by 36.95% compared to last year; 232 birds of 22 species were ringed. The
low ringing totals were due to poor weather with frequently high winds and rain. Surprisingly, Sedge
Warblers were the most numerous species with 44 ringed. Chiffchaffs outnumbered Willow Warblers, with
32 of the former and 20 of the latter being ringed.

A further 24 Blackcaps, seven Whitethroats and two Reed Warblers were ringed, along with the year’s
first Lesser Whitethroat. Spotted Flycatchers began passing through in May, with a total of 13 ringed. The
first and only Pied Flycatcher of the spring was caught at Nant on 14th. Finches were trapped in low
numbers: eight Goldfinches, two Siskins and 19 Lesser Redpolls were caught. The first juvenile Blackbirds,
Dunnocks and Stonechats fledged this month with two, ten and two ringed respectively. Eight Chough
pulli were ringed, four each from two nest sites. A trip to the East Side to survey seabirds resulted in a
single Puffin ringed, and dazzlng produced one Ringed Plover.

JUNE

Migration had all but come to a standstill by the time June arrived. Seven Blackcaps, 16 Chiffchaffs, two
Willow Warblers, 15 Lesser Redpolls and three Siskins were the only signs of movement.

871 birds of the total 950 ringed were seabirds. This month, 164 Herring Gulls, nine Lesser Black-backed
Gulls, 26 Great Black-backed Gulls, two Kittiwakes, 77 Shags, five Cormorants, seven Puffins, 30 Guillemots
and 167 Razorbills were ringed. This was the best month for ringing Manx Shearwaters with 387 ringed.
The first two Oystercatcher chicks were also ringed along with another brood of three Choughs.

JULY

Four Pied Wagtail pulli and 16 Swallow pulli were ringed. Four Rock Pipit pulli ringed on 29th were the first
since 2017, and were also fitted with Darvic rings. The breeding pair of Ringed Plovers successfully fledged
two young and these pulli were the first to be ringed since 2011.

A few nights of Storm Petrel ringing were undertaken at Bae y Rhigol with 47 new birds, and a further
eight retraps. A total of 194 Manx Shearwaters was ringed including the first eight pulli. A trip around the
East Side produced 27 Guillemots, eight Razorbills, five Herring Gulls and a Lesser Black-backed Gull.

Five Wheatears were ringed, having been caught in spring traps. Warbler totals were still low with 12
Willow Warblers, also two Blackcaps and five Sedge Warblers which had fledged on Bardsey. The first
Redstart, a fresh juvenile, was ringed, however this was not a bird from the island. Other scarce breeders
fledged young, with five Great Tits and two Goldfinches being caught and ringed. The Helgoland at
Cristin was working well with 11 fledged Stonechats and two juvenile Swallows trapped.

AUGUST

This month 542 birds of 31 species were ringed, the highest species diversity for any month this year. The
month began with more Storm Petrels and Manx Shearwaters being ringed.

Autumn Willow Warbler passage was building, and 150 new birds were ringed alongside 19 Blackcaps,
two Garden Warblers and 11 Sedge Warblers. Other migrants ringed included one Reed Warbler, three
Grasshopper Warblers, nine Whitethroats, two Garden Warblers, one Pied Flycatcher and two Spotted
Flycatchers. A Wood Warbler ringed at Cristin on 9th was the first since 2018. The ringing site at the
sacrificial crop of sunflowers and barley at Rhedynogoch was established again this year; the crop was

224 REP. BARDSEY BIRD FLD OBS.

BIRD RINGING

Sunflowers and Linnets at Tŷ Pellaf © Steve Stansfield

planted by Gareth Roberts, earlier in the year, to provide a food source for birds in the autumn. A total
of 74 Linnets was ringed this month, 167.15% larger than the annual mean from 1953 to 2021.

Juvenile Stonechats were still moving through the garden at Cristin with another 15 trapped in the
Heligoland trap. A juvenile Woodpigeon was also ringed in Tŷ Pellaf Withy on 4th.

As expected, wader passage increased further, so effort was put into dazzling on nights when the
weather was favourable and this led to one Ringed Plover and three Dunlins being ringed.

SEPTEMBER

Warbler passage reached a peak this month, a month later than in 2020, with 19 Blackcaps, 78
Chiffchaffs and 209 Willow Warblers. The last Reed Warbler and Grasshopper Warbler were ringed as well
as the final 11 Whitethroats and two Sedge Warblers of the year. The total of Sedge Warblers was 74,
higher than last year’s figure of 49.

Other migrants also began moving through, with 18 Goldcrests, two Firecrests, eight Spotted Flycatchers,
nine Pied Flycatchers and two Tree Pipits ringed. The first Great Spotted Woodpecker of the year was
ringed. This month was also good for hirundines with 21 Swallows and 77 House Martins attracted to tape
lures at Cristin; the annual means from 1953 to 2021 are 31.57±s.d.27.65 and 1.9±s.d.10.89. The last three
Stonechats were ringed, taking the year’s total to 33, the highest since 38 in 1967.

Night-time ringing excursions saw the final 112 Manx Shearwaters of the year being ringed, these were
mostly juveniles picked up at night as they were making their way to the coast before setting off for South
America for the winter; a total of 861were ringed this year. A Storm Petrel brought the year’s total to 74.

OCTOBER

This month, 257 birds of 16 species were ringed, well below last year’s total of 860 birds. Ringing was
particularly difficult during this month with both rain and wind preventing ringing. However, warblers were
still on the move with 31 Blackcaps, 20 Chiffchaffs and two Yellow-browed Warblers ringed. It was also
the peak month for Goldcrests with 121 ringed.

Finch passage was near non-existent, Chaffinches were the most abundant with 19 ringed, closely
followed by six Goldfinches, and four Siskins; the total number of Siskins ringed this year was 47, the most
ever in a year. The only Redwings of the year were ringed with 11 trapped at Cristin during the month.
Another four Great Spotted Woodpeckers took the year’s total to five. The best bird to be ringed in the
year was caught at Cristin on 2nd, the second Red-eyed Vireo to be ringed on Bardsey after an individual
was ringed on 15 October 1985. It was also re-trapped on 4th. It appeared to be feeding well, having
gained 1.2g in two days.

65: 220-241 225

COSSEY, BETTERIDGE & KING

3.2 TOTALS TABLE

Table 1. Number of birds ringed in 2021, a comparison with the 2020 totals and with the 1953-2021
mean, number of birds ringed from 1953-2021, the annual maxima, and the 1953-2021 mean

∑ compares 2021 total with 2020 total, x̄ compares 2021 total with 1953-2021 mean, ↑ = Up on, = = Equal to, ↓ = Down on, FG = Full Grown

Species 2021 2021 2021 ∑ x̄ 53-2021 53-2021 53-2021 Annual 53-2021
Pullus FG Total Pullus FG Total Maxima Mean
Quail
Shelduck 2 1 =↓ 2 5 5 1 0.07
Mallard 1 =↓ 28 8 10 3 0.15
Teal 1 =↓ 17 45 6 0.67
Nightjar 26 1 =↓ 1 9 9 2 0.13
Swift 169 3 =↓ 1 3 3 1 0.04
Cuckoo =↓ 44 29 29 6 0.43
Rock Dove 10 3 =↓ 87 88 8 1.31
Stock Dove 48 1 =↓ 53 1 2 2 0.03
Woodpigeon 145 =↓ 705 1 1 0.01
Turtle Dove 1 1 =↓ 149 137 1 12 2.70
Collared Dove 4 =↓ 37 181 9 0.55
Water Rail 2 ↓↓ 27 58 37 6 0.87
Corncrake =↓ 2 221 58 17 3.31
Sora 9 =↓ 3 15 221 5 0.22
Moorhen 30 =↓ 1 15 1 0.01
Little Grebe 1 =↓ 1,037 400 37 6.76
Oystercatcher 4 =↓ 1,114 3 1 2 0.04
Lapwing 3 ↓↓ 10,372 165 453 54 12.99
Golden Plover =↓ 2,583 10 26 2.37
Grey Plover =↓ 1,883 4 3 1 0.06
Ringed Plover ↓↓ 4,973 4 870 1 0.06
Dotterel 4 ↓↑ 190 159 16 3.24
Whimbrel =↓ 2 2 1 0.03
Curlew ↓↓ 656 123 4 26 1.87
Bar-tailed Godwit ↓↓ 113 4 22 1.73
Turnstone ↓↓ 44 217 6 0.66
Knot ↓↓ 320 2 31 4.78
Curlew Sandpiper ↓↓ 76 125 18 1.13
Sanderling =↓ 6 116 3 0.09
Dunlin =↓ 20 44 4 0.30
Purple Sandpiper 3 ↓↓ 596 320 45 8.90
Baird's Sandpiper 1 ↓↓ 74 76 17 1.10
Little Stint =↓ 1 6 1 0.01
Pectoral Sandpiper =↓ 8 20 1 0.12
Woodcock =↓ 2 596 1 0.03
Jack Snipe =↓ 58 74 12 0.87
Snipe ↓↓ 40 1 6 0.63
Grey Phalarope 1 ↑↑ 56 8 8 0.84
Common Sandpiper =↓ 4 2 1 0.06
Spotted Sandpiper ↓↓ 67 58 9 1.00
Redshank =↓ 1 40 1 0.01
Greenshank ↓↓ 137 56 11 2.04
Kittiwake =↓ 3 4 1 0.04
Sabine's Gull 2 =↓ 193 67 144 18.36
Black-headed Gull =↓ 2 1 1 0.03
Great Black-backed Gull =↓ 1 137 1 0.01
Herring Gull 26 ↑ ↑ 13 3 88 16.82
Lesser Black-backed Gull 169 ↑ ↑ 130 1,230 768 156.75
Little Tern 10 ↓ ↓ 211 2 237 41.70
Guillemot =↓ 1 1 1 0.01
Razorbill 57 ↑ ↑ 264 1,127 272 32.04
Black Guillemot 175 ↑ ↑ 1,324 10,502 325 94.01
Puffin =↓ 2,794 2 0.03
8 ↑↓ 762 1 85 21.16
226 2,147
6,297
2
1,418

REP. BARDSEY BIRD FLD OBS.

BIRD RINGING

Species 2021 2021 2021 ∑ x̄ 53-2021 53-2021 53-2021 Annual 53-2021
Pullus FG Total Pullus FG Total Maxima Mean
Storm Petrel
Leach's Petrel 138 74 74 ↓ ↑ 19 1,417 1,436 321 21.43
Fulmar 77 723 =↓ 105 35 35 4 0.52
Manx Shearwater =↓ 8,023 51 156 21 2.33
Gannet 5 1 4,705 701.87
Shag 861 ↓ ↑ 1,324 38,906 46,929 2243 0.04
Cormorant 11 5 =↓ 3 3 1 71.45
Bittern 11 19.94
Grey Heron 16 1 77 ↑ ↑ 82 4,787 243 0.01
Sparrowhawk 1 5 ↑↓ 45 12 1,336 128 0.10
Hen Harrier =↓ 1 1.81
Barn Owl 8 ↓↓ 1 1 1 0.01
Little Owl 1 =↓ 24 7 7 2 0.13
Long-eared Owl 35 =↓ 56 110 121 9 1.43
Hoopoe 89 ↓↓ 1 1 1 0.36
Kingfisher =↓ 270 9 9 2 0.04
Wryneck 1 =↓ 525 51 96 8 0.01
Great Spotted Woodpecker 2 =↓ 156 23 24 4 0.52
Green Woodpecker 664 =↓ 335 3 3 1 0.69
Kestrel 285 =↓ 66 1 1 1 0.01
Merlin 74 5 ↓↑ 35 35 4 0.64
Peregrine 5 =↓ 2 46 46 7 0.15
Ring-necked Parakeet ↓↓ 24 1 1 1 0.84
Red-backed Shrike ↓↓ 19 43 4 0.01
Isabelline Shrike =↓ 15 10 10 2 0.13
Great Grey Shrike =↓ 1,261 56 4 0.01
Woodchat Shrike =↓ 1 1 1 0.01
Red-eyed Vireo =↓ 3 9 9 2 0.18
Golden Oriole =↓ 1 1 1 0.03
Jay =↓ 6 1 1 1 0.31
Magpie 1 ↑↑ 1 12 12 2 0.06
Chough =↓ 2 2 1 6.01
Jackdaw =↓ 5 21 21 4 8.57
Carrion Crow 1 ↓↓ 4 4 2 5.04
Raven 133 403 29 5.13
Coal Tit 11 ↑ ↑ 49 574 31 0.99
Willow Tit =↓ 182 338 67 5.94
Blue Tit =↓ 9 344 16 0.01
Great Tit =↓ 66 8 15.36
Penduline Tit ↓↓ 398 398 57 9.88
Woodlark =↓ 1 1 1 0.01
Skylark ↓↓ 1,029 266 0.01
Sand Martin 1,027 662 62 8.72
Swallow 8 ↓↓ 638 1 1 0.33
House Martin =↓ 1 1 1 31.57
Cetti's Warbler =↓ 1 584 119 1.90
Long-tailed Tit =↓ 569 22 6 0.01
Wood Warbler =↓ 22 2,115 137 5.24
Western Bonelli's Warbler 854 127 6 1.63
Yellow-browed Warbler 51 ↑ ↑ 124 1 1 0.12
Pallas's Warbler 89 ↑ ↑ 1 351 53 1.64
Radde's Warbler 351 109 7 0.25
Dusky Warbler =↓ 109 8 2 0.06
Willow Warbler =↓ 8 110 14 0.03
Chiffchaff 1 ↑↓ 110 17 3 822.12
Greenish Warbler =↓ 17 4 1 287.42
Arctic Warbler 2 ↓↑ 4 2 1 0.19
Great Reed Warbler =↓ 2 55,082 2789 0.01
Sedge Warbler =↓ 19,257 859 0.03
Paddyfield Warbler =↓ 55,076 13 3 169.33
Blyth's Reed Warbler 664 ↑ ↓ 19,256 1 1 0.01
Reed Warbler 285 ↑ ↓ 2 1 0.06
Marsh Warbler ↓↓ 13 11,345 644 2.67
Booted Warbler =↓ 1 1 1 0.13
=↓ 2 4 2 0.03
74 ↑ ↓ 179 10
=↓ 11,340 9 1
=↓ 1 2 1
5 ↑↑ 4
↓↓
=↓ 179
9
2

65: 220-241 227

COSSEY, BETTERIDGE & KING

Species 2021 2021 2021 ∑ x̄ 53-2021 53-2021 53-2021 Annual 53-2021
Pullus FG Total Pullus FG Total Maxima Mean
Melodious Warbler
Icterine Warbler 4 5 =↓ 1 86 86 9 1.28
Lanceolated Warbler 4 288 =↓ 1 37 37 3 0.55
Grasshopper Warbler 1 =↓ 1 0.03
Blackcap 7 5 ↓↓ 19 2 2 197 26.52
Garden Warbler 1 288 ↓ ↑ 1,776 1,777 728 117.30
Barred Warbler 32 7 ↑↓ 48 7,858 7,859 112 23.55
Lesser Whitethroat 4 =↓ 1,578 1,578 3 0.27
Western Orphean Warbler 233 1 =↓ 36 19 2.75
Whitethroat 108 =↓ 15 18 18 1 0.01
Subalpine Warbler 32 ↑ ↓ 284 184 184 489 97.70
Firecrest 6 =↓ 2 0.30
Goldcrest 11 4 ↓↓ 73 1 1 20 4.30
Wren 26 233 ↓ ↓ 6,527 6,546 2566 478.04
Nuthatch 108 ↓ ↑ 104 166 70.85
Treecreeper 23 =↓ 589 20 20 1 0.04
Rosy Starling 49 =↓ 288 288 3 0.78
Starling =↓ 2 32,028 32,028 1 0.01
Grey-cheeked Thrush 11 ↓↓ 60 4,698 4,746 812 82.82
Song Thrush 2 =↓ 256 1 0.03
Mistle Thrush 33 6 ↓↓ 341 3 3 156 50.55
Redwing 8 =↓ 150 52 52 2 0.19
Blackbird 11 ↓ ↓ 25 554 79.64
Eyebrowed Thrush 40 26 ↓ ↓ 1 1 550 151.01
Fieldfare =↓ 51 5,507 5,543 1 0.01
Ring Ouzel 2 =↓ 1 16 2.75
Spotted Flycatcher 16 =↓ 2 2 13 1.75
Robin 2 23 ↑ ↓ 16 3,362 3,377 264 57.34
Bluethroat 16 49 ↓ ↓ 167 71.94
Nightingale 27 =↓ 13 13 1 0.03
Red-flanked Bluetail =↓ 5,311 5,311 5 0.43
Red-breasted Flycatcher 2 =↓ 9,807 10,091 1 0.01
Pied Flycatcher 1 =↓ 4 0.72
Black Redstart 92 11 ↑ ↓ 1 1 84 15.93
Redstart 102 ↓↓ 183 183 6 1.19
Whinchat 2 ↑↓ 117 117 55 9.85
Stonechat 131 =↓ 3,842 3,842 15 1.99
Wheatear 47 33 ↑ ↑ 4,743 4,816 54 14.54
Isabelline Wheatear 8 ↓↓ 197 29.94
House Sparrow =↓ 2 2 1 0.01
Tree Sparrow ↓↓ 29 29 75 7.24
Dunnock ↓↓ 3 0.18
Yellow Wagtail 40 ↓ ↑ 1 1 95 29.93
Grey Wagtail =↓ 48 48 8 0.21
Pied/White Wagtail ↓↓ 1,067 1,067 15 0.45
Richard's Pipit 6 ↓↓ 80 80 48 13.33
Meadow Pipit =↓ 660 660 1 0.01
Tree Pipit 16 ↓ ↓ 133 133 168 35.46
Water Pipit 2 ↓↓ 866 970 12 2.07
Rock Pipit =↓ 1,417 2,006 1 0.01
Chaffinch 20 ↓ ↓ 95 23.52
Brambling 27 ↓ ↓ 1 1 957 214.72
Hawfinch ↓↓ 483 485 326 10.49
Bullfinch =↓ 1 0.09
Common Rosefinch 2 ↑↑ 12 12 7 1.06
Greenfinch ↓↓ 1,942 2,002 3 0.45
Twite 1 =↓ 233 38.37
Linnet =↓ 14 14 1 0.01
Common Redpoll 92 ↑ ↑ 30 30 105 27.70
Lesser Redpoll =↓ 637 893 3 0.25
Redpoll Sp. 102 ↓ ↑ 108 18.61
Crossbill =↓ 1 1 45 1.57
Goldfinch =↓ 2,034 2,375 1 0.03
Siskin 132 ↓ ↑ 404 34.24
47 ↑ ↑ 139 139 26 6.16
228 1 1

1,426 1,576
14,359 14,384

703 703
6 6
71 71

30 30
2,568 2,568

1 1
1,804 1,855

17 17
1,244 1,245

105 105
2 2

2,278 2,294
413 413

REP. BARDSEY BIRD FLD OBS.

BIRD RINGING

Species 2021 2021 2021 ∑ x̄ 53-2021 53-2021 53-2021 Annual 53-2021
Pullus FG Total Pullus FG Total Maxima Mean
Lapland Bunting =↓
Snow Bunting =↓ 3 9 9 2 0.13
Yellowhammer =↓ 1 1 1 0.01
Ortolan Bunting =↓ 9 78 81 11 1.21
Little Bunting =↓ 4 4 2 0.06
Yellow-breasted Bunting =↓ 7 7 2 0.10
Black-headed Bunting =↓ 1 1 1 0.01
Reed Bunting ↓↓ 3 3 1 0.04
Song Sparrow =↓ 266 275 27 4.10
White-throated Sparrow =↓ 1 1 1 0.01
Dark-eyed Junco =↓ 1 1 1 0.01
Blackpoll Warbler =↓ 1 1 1 0.01
Summer Tanager =↓ 2 2 1 0.03
Rose-breasted Grosbeak =↓ 1 1 1 0.01
Red-headed Bunting =↓ 1 1 1 0.01
1 1 1 0.01
Totals
661 3,349 4,010 42,701 260,465 303,166
Number of Species 63 192 196
16 55 61

Red-eyed Vireo, 2 October 2021 © Steve Stansfield 229
65: 220-241

COSSEY, BETTERIDGE & KING
Grasshopper Warbler (top) Sparrowhawk (bottom) © Steven Stansfield

230 REP. BARDSEY BIRD FLD OBS.

BIRD RINGING
Whitethroat (top) Sedge Warbler (bottom) © Steven Stansfield

65: 220-241 231

COSSEY, BETTERIDGE & KING

RECOVERIES, RETRAPS & CONTROLS

1 INTRODUCTION

Capturing birds which already have rings on, or finding a dead bird wearing a ring enables the collection
of data about birds’ movements around the world, as well as knowing how long they live. When a bird
with a ring on is re-captured, the number on the ring can be matched up to its original ringing details,
along with any subsequent information collected, thus helping build up a picture of the bird’s travels,
history and lifecycle. The more information that is collected, the more accurate an assessment of
species’ behaviour and longevity can be made.

2 METHODS

Bird rings are made to fit different species of birds and are therefore produced in various sizes; each ring
size is assigned to a species according to the diameter of their tarsus (leg bone) and each ring is stamped
with a unique number. When a bird is caught, the appropriate ring size is carefully fitted by licenced
ringers, and details are recorded about the bird such as the length of the wing, its weight, the name of
the ringer, time, date etc. before releasing the bird back into its natural habitat. Additionally, some
species (e.g. Choughs, Rock Pipits, Whimbrels, Shags and large gulls on Bardsey) are fitted with
individually identifiable plastic (Darvic PVC) rings with a unique code inscribed on them that can be
easily feen in the field, or a combination of plain plastic rings identifying them as individuals. When birds
are subsequently trapped, resighted (usually colour ringed birds) or found dead, they fall into one of the
following three categories:

Retrap - a bird that has been both ringed and re-captured
at the same site - in this case Bardsey

Recovery - a bird that was ringed on Bardsey and
subsequently found either at a different site (i.e. away from
Bardsey) or dead at the same site; in this case Bardsey

Control - a bird found to be wearing a ring which was fitted
at a different site - i.e. away from Bardsey

Data from controls are collected by Observatory staff and sent to the British Trust for Ornithology
(BTO) who process them and send back details of the history of the bird with its original ringing details.
They also send back information about recoveries of birds that were ringed on Bardsey and re-captured
elsewhere.

232 REP. BARDSEY BIRD FLD OBS.

BIRD RINGING

Kittiwake DAF ringed in 2007 as an adult on Puffin Island is now nesting successfully on Bardsey © Steve Stansfield

65: 220-241 233

COSSEY, BETTERIDGE & KING

3 RESULTS

This season we received 87 recovery/control reports from the BTO with details relating to birds either
ringed on Bardsey and recovered elsewhere, or birds that were ringed elsewhere and controlled on
Bardsey. We were also notified about a number of our own colour-ringed birds directly from the
observers.

Below are a selection of some of the most interesting retraps, recoveries and controls from the year.

3.1 KEY TO CODES

Age/ Sex codes
1 pullus (nestling or chick)
2 fully grown, year of hatching quite unknown
3 hatched during calendar year of ringing
4 hatched prior to calendar year of ringing, exact year unknown
5 hatched during previous calendar year
6 hatched prior to previous calendar year, exact year unknown
7 definitely hatched two calendar years before ringing
8 hatched more than two calendar years before year of ringing
M male
F female

Condition at recovery
+ intentionally killed by man
X found dead
XF found freshly dead or dying
XL found long dead
V alive, probably healthy; caught and released but not by a ringer
VV alive, probably healthy; ring/colour mark read in field but not by a ringer
R caught and released by a ringer
B caught and released by a ringer – nesting
RR alive, probably healthy; ring or colour mark read in field by a ringer
S found injured, not known to have been released
Sx found moribund (sick or injured, eventually died)
Sr found sick or injured, released after rehabilitation with ring
A alive, probably healthy - fate unknown
AC alive, probably healthy – now captive
/ / condition on finding wholly unknown

234 REP. BARDSEY BIRD FLD OBS.

BIRD RINGING

3.2 RECOVERIES AND CONTROLS

O Y S T E R C A T C H E R Haematopus ostralegus Pioden y Mor

FB35344 1 14.06.2011 Bardsey
R 13.10.2021 Whiteford Sands, Gower, Swansea
128 km 164˚SSE
3784 days

D U N L I N Calidris alpina Pibydd Mawn

BB08881 3 16.08.2017 Bardsey
R 02.05.2021 Busturia, Vizcaya, SPAIN
1055 km 172˚S
1355 days

P U R P L E S A N D P I P E R Calidris maritima Pibydd Du

8B92406 1 05.08.2021 Mandal, Vest-Agder, NORWAY
RED CZV RR 23.09.2021 Bardsey
Metal
48 days 964 km 239˚SW

Norwegian-ringed Purple Sandpiper © Ed Betteridge

This Purple Sandpiper was wearing a yellow leg flag inscribed CZV on its tibia, allowing the bird to be
individually identified in the field.

K I T T I W A K E Rissa tridactyla Gwylan Goesddu
80 km 220˚SW
EL48437 1 08.07.2007 Puffin Island, Isle of Anglesey
DAF RR 27.07.2021 Bardsey
45133 days

This Kittiwake was nesting on Bardsey, see image on page 233.

65: 220-241 235

COSSEY, BETTERIDGE & KING

G R E A T B L A C K - B A C K E D G U L L Larus marinus Gwylan Gefnddu Fwyaf

MA47648 1 28.06.2019 Dalkey Island, Dublin, IRELAND
489:D RR 09.10.2021 Bardsey

833 days Lambay Island, Dublin, IRELAND 104 km 123˚SE
22.06.2021 Bardsey
MA55565 1 10.10.2021
S51:D RR Walney Island
110 days Bardsey
20.07.2021 116 km 134˚SE
09.10.2021
HT69249 1
N:4G7 RR 81 days

178 km 215˚ SW

MA24969 19.06.2019 1 - Ynys Gwylan Fawr 123 km 192˚SSW
B:160 RR 09.10.2019 2 - Gann Estuary, Dale, Pembrokeshire 123 km 197˚SW
14.10.2019 3 - Skomer Island, Pembrokeshire 529 km 179˚S
14.02.2020 4 - Plogoff, Bretagne, Finistère, FRANCE 123 km
05.10.2020 5 - Gann Estuary, Dale, Pembrokeshire 85.5 km 192˚ SSW
14.10.2020 6 - Nevern Estuary, Newport, Pembrokshire 85.5 km 136˚SE
08.04.2021 7 - Nevern Estuary, Newport, Pembrokshire 123 km 136˚SE
26.11.2021 8 - Gann Estuary, Dale, Pembrokeshire
192˚SSW
891 days

This well-travelled gull B:160 moved from Ynys Gwylan Fawr to Pembrokeshire in October 2019, where
it was first seen on the Gann Estuary (See Map 1 #2), then on Skomer (#3) before heading to France
(#4) in February 2020. It then returned to the Gann in October 2020 (#5) and then up to Nevern
Estuary, Newport nine days later (#6). It was reported again from Nevern in April 2021 (#7) and then
back on the Gann (#8) in November of that year. This tracking of a single bird through colour rings
shows the real scientific value of adding a fairly inexpensive plastic ring to the birds’ legs. Since
starting to fit Darvic rings on gulls on Bardsey the recovery rate has increased to over 10%.

Great Black-backed Gull B:160 in 2019 on Skomer island, Pembrokeshire. Site #3 © Sylwia Zbijewska/Skomer Warden

236 REP. BARDSEY BIRD FLD OBS.

BIRD RINGING

1

6&7
3
2, 5 & 8

4

Map 1. Site numbers refer to the numbers in the table opposite for GBBG B:160 starting on Ynys
Gwylan Fawr in 2019, before heading to Pembrokeshire, then France and back to Pembrokeshire.

Great Black-backed Gull B:160 in 2020 at Plogoff, Bretagne, Finistère, France, © Stéphane Guerin 237
65: 220-241

COSSEY, BETTERIDGE & KING

H E R R I N G G U L L Larus argentatus Gwylan y Penwaig

GV85101 1 01.06.2020 Bardsey 123 km 240˚WSW
VV 23.08.2021 Carne, Wexford, IRELAND
121 km 119˚SE
GV88034 1 448 days Tailaght Hospital, Dublin, IRELAND
J09:D RR 06.07.2021 Bardsey
10.09.2021
GV56944 1 Bardsey
GN62866 R 66 days Bryncroes, Gwynedd
19.06.2005
29.06.2021 13 km 45˚NE
5854 days

M E D I T E R R A N E A N G U L L Ichthyaetus melanocephalus Gwylan Mor y Canoldir

IA191136 1 11.06.2019 Rehbach Gravel Pit, Leipzig, GERMANY
AZNN RR 17.10.2020 Bardsey

3652241 1 494 days 1178 km 279˚W
313J RR 30.06.2017 Den Bommel, Goeree-Overflakkee, THE NETHERLANDS 281˚WNW
17.10.2020 Bardsey
1205 days
619 km

Mediterranean Gull 313J in 2020 on Solfach © Jeff Wragg

G U I L L E M O T Uria aalge Gwylog

R52177 1 30.06.2007 Sumburgh, Shetland

R 05.07.2021 Bardsey

5119 days 816km 196˚SSW
Llurs
R A Z O R B I L L Alca torda

K00097 1 30.06.2009 Sanda Island, Kintyre 282km 169˚S
K42232 R 15.06.2021 Bardsey 581km 171˚S
K37266 4368 days 162km 74˚ENE
6 25.06.2018 Carnach Mhor, Western Isles
M468823 R 03.08.2021 Bardsey
1135 days
1 18.05.1985 Bardsey
X 04.08.2021 Middlewich, Cheshire (dead on lawn)
13196 days

S T O R M P E T R E L Hydrobates pelagicus Pedryn Drycin

2473756 4 19.07.2021 Hartland Point, Devon
R 03.08.2021 Bardsey

15 days 198 km 355˚N

238 REP. BARDSEY BIRD FLD OBS.

BIRD RINGING

2773036 4 07.07.2021 Bardsey 350˚N
2765879 R 25.07.2021 Sanda Island, Kintyre 347˚NNW
2738278
2765879 4 18 days 285 km 360˚N
2738263 R 09.08.2020 Bardsey 343˚NNW
17.07.2021 Copeland Bird Observatory, NORTHERN IRELAND 347˚NNW
4
R 342 days 219 km
14.07.2020 Bardsey
4 02.07.2021 Calf of Man, ISLE OF MAN
R
353 days 143 km
4 09.08.2020 Bardsey
R 24.08.2021 Madmans Window, NORTHERN IRELAND

380 days 256km
14.07.2020 Bardsey
14.07.2021 Mangarstadh, Western Isles

365 days 620km

M A N X S H E A R W A T E R Puffinus puffinus Aderyn-Drycin Manaw

FB37769 4 23.07.1996 Bardsey 7783 km 204˚SSW
FC30282 S 26.09.2021 Abais, Sergipe, BRAZIL
FB09490 9196 days 205 km 23˚NE
FB52191 4 12.05.1988 Bardsey
EJ99511 X 14.08.2021 St Bees, Cumbria 92 km 294˚WNW
FB18789 12147 days
FB18838 4 05.08.2002 Bardsey 143 km 0˚N
FC88194 X 26.04.2021 Kilcoole, Wicklow, IRELAND
6839 days 121 km 18˚NNE
4 14.08.2017 Bardsey
R Calf of Man, ISLE OF MAN 9971 km 206˚SSW
10.5.2021
1 1365 days Skomer Island, Pembrokeshire 9877km 206˚SSW
R 12.08.2015 Bardsey
12.07.2021
4 2161 days Bardsey
X 14.06.2005 Imbituba, Santa Catarina, BRAZIL
12.10.2021
4 5964 days Bardsey
R 30.07.2005 Praia Brava, BRAZIL
31.10.2021
4 5937 days Bardsey
R 10.08.1996 Skomer Island, Pembrokeshire
06.06.2021
9066 days 118km 197˚SSW

Bardsey is home to over 25,000 pairs of breeding Manx Shearwaters which begin to arrive in mid-March
and leave the island from mid-August, heading for Brazil. This year, two of our Manx Shearwaters were
recovered in Brazil. With the growing frequency of storms, it will be interesting to see whether the number
of recoveries of these birds increases. It is known through ringing that these birds make the long migration
between Bardsey and Brazil/Argentina and from previous recoveries it can be seen that they can be in
the south Atlantic in under three weeks.

S H A G Phalacrocorax aristotelis Mulfran Werdd

1469758 1 01.06.2020 Bardsey
30.01.2021 Marazion, Cornwall
BAJB . R
243 days
299 km 190˚S

H O U S E M A R T I N Delichon urbicum Gwennol y Bondo

ACL8390 1 27.07.2021 Bryncroes, Gwynedd 12km 231˚SW
R 01.09.2021 Bardsey
36 days

65: 220-241 239

COSSEY, BETTERIDGE & KING

R O C K P I P I T Anthus petrosus Corhedydd y Graig

ACL8390 4 26.08.2015 Bardsey
VV 13.12.2020 Ronde, DENMARK
1058km 69˚ENE
1936 days

W I L L O W W A R B L E R Phylloscopus trochilus Telor Helyg

RH4395 3 24.08.2019 Puenteceso, La Coruna, SPAIN 1104km 17˚NNE
R 10.09.2021 Bardsey 124 km 17˚NNE
748 days

KYP663 4 16.04.2020 Skokholm Island, Pembrokeshire
R 20.04.2021 Bardsey
369 days

C H I F F C H A F F Phylloscopus collybita Siff-saff

LDC654 4 01.06.2021 Calf of Man, ISLE OF MAN 143 km 180˚S
NAV870 R 06.06.2021 Bardsey 310 km 141˚SE

3 5 days Bardsey
R 13.10.2021 Durlston Country Park, Dorset
22.10.2021

9 days

S E D G E W A R B L E R Acrocephalus schoenobaenus Telor Hesg

AAN1638 4 01.05.2021 Bardsey
R 04.08.2021 Keyhaven Marshes, Hampshire

95 days 319 km 136˚SE

B L A C K C A P Sylvia atricapilla Telor Penddu

AZL5509 4 13.04.2021 Portland Bill, Dorset 298 km 328˚NNW
AXL5123 R 14.04.2021 Bardsey

3 1 day Nanjizal, Cornwall
R 31.08.2020 Bardsey
20.04.2021
307 km 12˚NNE
232 days

240 REP. BARDSEY BIRD FLD OBS.

BIRD RINGING

G O L D F I N C H Carduelis carduelis Nico

AYR0412 5 29.04.2021 Bardsey 79 km 172˚S
APH4610 R 12.06.2021 Llechryd, Ceredigion
AAN1715 355km 125˚SE
1 44 days Bardsey
R 19.04.2020 Hardham, West Sussex
22.01.2021
3 Bardsey
R 278 days Forest of Dean, Gloucestershire
14.10.2020
14.11.2021 188km 125˚SE

396 days

L E S S E R R E D P O L L Acanthis cabaret Llinos Bengoch Fechan

AAN1088 3 21.09.2020 Bardsey 362 km 93˚E
AYP9056 R 23.03.2021 Beechamwell, Swaffham, Norfolk
S738491 270 km 252˚WSW
AJL7689 3 183 days Hatfield Moor, South Yorkshire
R 23.10.2020 Bardsey 455 km 292˚WNW
15.04.2021
3 Sandwich Bay Estate, Kent
R 174 days Bardsey
23.11.2020
3 20.04.2021 Marston Sewage Works, Lincolnshire
R Bardsey
148 days
17.10.2020 277 km 266˚W
19.04.2021

184 days

3.2 RETRAPS

This year, 585 Manx Shearwaters were recaptured; of these, 30 were at least 20 years old and seven were
at least 30 years old, the oldest of these are shown below. The oldest Manx Shearwater caught this year
was ‘FR55865’, which was ringed in 1983, this bird was ringed as an adult so is at least 38 years old.

M A N X S H E A R W A T E R Puffinus puffinus Aderyn-Drycin Manaw
241
FC30182 4 11/06/1988 Bardsey
FB58384 S 02/08/1994 Bardsey
FR55865 R 11/06/2021 Bardsey
FB05591 12053 days
4 09/07/1983 Bardsey
FC62757 R 08/07/1999 Bardsey
FB18093 S 13/07/2020 Bardsey
S 09/06/2021 Bardsey
FR79480 13850 days
FB36617 4 09/07/1991 Bardsey
R 11/04/2005 Bardsey
FC48293 S 24/06/2010 Bardsey
FB58800 S 03/08/2021 Bardsey
FC30182 11013 days
FB58384 4 25/07/1985 Bardsey
R 11/06/2013 Bardsey
S 18/06/2021 Bardsey
13112 days
4 24/07/1990 Bardsey
R 12/07/2021 Bardsey
11311 days
4 11/06/1988 Bardsey
S 02/08/1994 Bardsey
R 11/06/2021 Bardsey
S 01/07/2021 Bardsey
12074 days

65: 220-241

STANSFIELD

Section 3

Non-avian
Sreecptoiornts3

Vagrant Emperor

Non-avian© Steven Stansfield
reports

Red Admiral
© Jeff Wragg

242 REP. BARDSEY BIRD FLD OBS