Bardsey Bird and Field Observatory 2022 Report on work funded by Natural Resources Wales Section 16 Management Agreement
Front cover – Shag This species had an excellent breeding season on Bardsey and Ynysoedd Gwylan Frontispiece – House Martin This juvenile hatched at the Lighthouse on Bardsey BBFO would like to thank all the photographers and contributors to this report, especially Steven Stansfield (Director of Operations and Observatory Warden) for producing this report, Ed Betteridge, and Ollie King for undertaking fieldwork and producing sections of this report, Haf Meredydd for translating the Crynodeb to Cymraeg, and Emma Stansfield for editing the text and Andrew Lawrence for proof-reading the document
Contents 1. Crynodeb..............................................................................................................................................................................1 1. Abstract................................................................................................................................................................................5 2. Introduction ..................................................................................................................................................................10 2.1 Aims and objectives 11 2.2 Health and safety 12 3. Breeding success of the Chough...............................................................................................................15 3.1 Introduction 15 3.2 Methods 16 3.3 Results 17 3.3.1 Nesting activity of choughs on Bardsey in 2022 17 3.3.2 Clutch sizes and productivity (fledging success). 25 3.4 Discussion 25 3.4.1 Management statements and species’ targets 25 3.4.2 Breeding and productivity 27 3.4.3 Wintering population and non-breeding Choughs 29 3.5 Summary 29 3.6 References 30 4. Breeding birds on Bardsey and Ynysoedd Gwylan..................................................................33 4.1. Introduction 33 4.2. Methods 33 4.3. Results 39 4.4 Seabird Colour marking 68 4.5 Summary 68 4.6 References 70 5. Manx Shearwater population census – year 4...............................................................................73 5.1 Introduction 73 5.2 Methods 74 5.2.1 Count 1: The total number of burrows 78 5.2.2 Count 2: Number of apparently-occupied burrows 78 5.2.3 Count 3: Response to the voice playback 79 5.2.4 Survey effort 80 5.3 Results 80 5.3.1 Discussion 82 5.3.1.1 Population increase 82 5.3.1.2 Occupancy rates 84 5.3.1.3 Response rates 84 5.3.1.4 Correction factor 85 5.3.1.4.1 Method 85 5.3.1.4.2 Results 85 5.3.1.5 Improved audio quality and dual-sex calls 85 5.3.1.6 Other observations and considerations 87 5.4 Summary 87 5.5 Acknowledgments 88 5.6 References 88
6. Productivity monitoring and ringing of Manx Shearwaters..............................................91 6.1 Introduction 91 6.2 Aims 91 6.3 Methods 92 6.3.1 Productivity monitoring 92 6.3.2 Ringing 93 6.3.2.1 Ringing adult birds 93 6.3.2.2 Ringing young birds 93 6.3.3 Growth rate of chicks 93 6.3.4 Re-trapping adult and young birds 94 6.4 Results 94 6.4.1 Productivity 94 6.4.2 Ringing new birds 96 6.4.3 Re-capturing ringed birds 96 6.4.4 Chick growth rates 97 6.4.5 Wing lengths 97 6.4.6 Weights 100 6.4.7 Fledging 103 6.5 Discussion 104 6.6 Summary 105 6.7 Acknowledgments 106 6.8 References and selected bibliography 106 7. Disturbance of Grey Seals on Bardsey............................................................................................... 109 7.1 Introduction 109 7.2 Methods 109 7.3 Suggestions for reducing disturbance 110 7.3.1 Education about disturbance 110 7.4 Data collection 111 7.4.1 Seal numbers 111 7.4.2 Disturbance 114 7.5 Results and observations 114 7.6 Breeding Grey Seals 122 8. Other funded projects ......................................................................................................................................129 8.1. Public outreach - educational talks and walks 129 8.1.1. Moth mornings 130 8.1.2. Educational presentations 130 8.1.3 Sample Slides from the presentation 132 8.1.4 Audio-visual interpretation media 135 9 Conclusions/recommendations ...............................................................................................................139 10 Appendices...............................................................................................................................................................140 Appendix 1 – Sample breeding bird census maps.......................................................................140 11 Acknowledgments...............................................................................................................................................145
1 1. Crynodeb Yn ystod tymor 2022, bu staff Gwylfa Adar a Maes Ynys Enlli yn cyflawni gwaith maes ar nifer o brojectau gyda chymorth ariannol Cyfoeth Naturiol Cymru yn unol â Chytundeb Adran 16. Y projectau oedd: 1) Monitro llwyddiant nythu a chynhyrchedd y Frân Goesgoch. 2) Monitro a mapio yr holl rywogaethau o adar môr sy’n nythu ar Enlli ac Ynysoedd Gwylan. 3) Monitro a mapio yr holl adar tir sy’n nythu ar Enlli. 4) Cyfrifiad o Adar Drycin Manaw yn ne ddwyrain Enlli. 5) Cynhyrchedd Adar Drycin Manaw mewn sampl o safleoedd nythu. 6) Monitro ymyrraeth â’r Morloi Llwyd gan ymwelwyr a chychod sy’n galw draw. 7) Sgyrsiau a theithiau addysgiadol i ymwelwyr â’r ynys. Cafodd y Frân Goesgoch flwyddyn gweddol dda a 2022 oedd y flwyddyn gyntaf ers 2014 lle atebwyd targed y raddfa gynhyrchedd o 2.50. Yn ystod 2022, rhoddodd chwe phâr gynnig ar fagu, 22.08% yn is na’r cymedr deng-mlynedd, gyda phum pâr yn llwyddo i fagu cywion. Methodd y pâr arall yn ystod y cyfnod bwydo cywion pan olchwyd y nyth i’r môr yn ystod stormydd. O ganlyniad, mae’r nifer o 2.50 cyw fesul pâr 20.77%, yn uwch na’r cymedr deng-mlynedd. Mae’r nifer o gywion a hedfanodd y nyth (15) 5.66% yn is na’r cymedr deng-mlynedd. Felly, er bod y cyfyngiadau derbyniol a nodwyd ar gyfer rheolaeth y WNG (Gwarchodfa Natur Genedlaethol), AGA (Ardal Gwarchodaeth Arbennig) ac ACA (Ardal Cadwraeth Arbennig) ar gyfer cynhyrchedd wedi eu hateb; mae’r lleihad yn y nifer o barau sy’n magu ers 2017 wedi golygu nifer is-na’r-cyfartaledd o gywion dros y ddegawd ddiwethaf. Fodd bynnag, o ystyried y tymor hir, mae’r boblogaeth o chwe phâr 30.35% yn fwy na’r cymedr tymor hir (1953-2022), a’r cynhyrchedd 5.30% yn is na’r cymedr tymor hir. Cafodd poblogaethau o adar sy’n magu eithaf llwyddiant yn 2022. Drwyddo draw, dangosodd y nifer o barau a gofnodwyd eleni ochr yn ochr â’r cynhyrchedd ar gyfer pob rhywogaeth o adar môr nad oedd Ffliw Adar (H5N1) wedi effeithio ar boblogaethau magu ar Enlli nag ar Ynysoedd Gwylan. Cynyddodd y nifer o Llursod yn sylweddol eleni gyda 1298 pâr, 37.00% yn uwch na’r cymedr deng-mlynedd, a gwelwyd y cynnydd cyntaf o ran nifer ers 2018, pan gofnodwyd uchafswm o 1321 pâr. Cafodd Gwylogod eu blwyddyn orau a gofnodwyd gyda 2193 SCA. Parhaodd ffigur cynhyrchedd o 0.37 yn gyson gyda’r cymedr deng-mlynedd. Prinhaodd nifer y Palod yn y nythfa am y tro cyntaf ers 2012, gan mai cyfrif TCA eleni oedd 160. Efallai mai’r rheswm am hyn oedd cynnydd mawr yn y nifer TCA ar Ynys Gwylan Fawr. Parhaodd y nifer o Wylanod Coesddu i gynyddu o ran nifer eleni gyda chofnod o 230 pâr, y cyfanswm uchaf ers 346 yn 2007. Roedd 65 o nythod Mulfrain Gwyrdd ar Enlli, chwech yn fwy nag yn 2021, a chafwyd 146 o gywion gan roi cynhyrchedd o 2.25. Roedd cyfanswm o 378 NCA Gwylanod y Penwaig 1.34% yn uwch na chymedr 2013-2022, tra bod 159 o NCA Gwylan Gefnddu Leiaf 11.96% yn is na’r cymedr deng-mlynedd. Amrywiodd y cynhyrchedd ar gyfer y ddwy rywogaeth: mewn sampl o 124 NCA Gwylan y Penwaig yn nythfa Talcen Mynydd cafwyd 78 cyw gan roi ffigur cynhyrchedd o 0.63. O ran yr Wylan Gefnddu Leiaf, mewn sampl o 117 NCA yn Nhalcen Mynydd, llwyddodd o leiaf 40 cyw i hedfan y nyth. Nythodd pedwar pâr o Wylanod Cefnddu Mwyaf. Cynhaliodd Adar Drycin y Graig 35 SafCA, y cyfrif uchaf ers 2006 gyda ffigur cynhyrchedd o 0.63 wedi ei ddyfalu. Cynhyrchedd Adar Drycin
2 Manaw oedd 0.77 cyw fesul pâr oedd yn magu, 13.77% yn uwch na’r cymedr dengmlynedd. O ganlyniad i deithiau â chwch i Ynys Gwylan Fawr ar 15, 21 a 23 Mehefin, a thaith i Ynys Gwylan Bach ar 23 Mehefin, llwyddwyd i arolygu’r poblogaethau magu ar yr ynysoedd. Cofnodwyd pedwar cyw Llurs ac ŵy, yn ogystal â 31 SCA. Cofnodwyd cyfanswm o 90 Gwylog ar SCA yn ogystal â 55 cyw, gan roi cynhyrchedd o 0.61, 92.31% yn uwch na’r cymedr deng-mlynedd. Nifer TCA y Pâl oedd 741, 13.33% yn uwch na’r cyfartaledd deng-mlynedd. Cwympodd niferoedd yr Wylan Gefnddu Fwyaf o 10 o’u cymharu â’r llynedd wedi i’r boblogaeth ymddangos yn bur sefydlog, gydag amcangyfrif o 41 NCA yn cael eu cofnodi; 30.21% yn is na’r cymedr deng-mlynedd. Cwympodd y nifer o Wylanod y Penwaig hefyd yn unol â’r tueddiad negyddol a nodwyd, gan mai dim ond 42 NCA a gofnodwyd. Cofnodwyd pum NCA y Fulfran, gydag un ar Ynys Gwylan Bach. Dyma’r ail flwyddyn yn olynol iddyn nhw fagu ers 2013. Cofnodwyd y dystiolaeth gyntaf o Bedryn Drycin yn magu ar Ynys Gwylan Fawr gan fod galwadau wedi eu clywed ar 21 Mehefin. O ran adar daearol, doedd dim arwydd bod y Gog wedi nythu eleni. Cofnodwyd naw nythaid o Hwyaid Gwylltion, 20.35% yn is na chymedr 2013-2022. O’r rhain, dim ond pedwar o gywion a lwyddodd i oroesi. Roedd 2 yn llai o barau o Ieir Dŵr eleni o’i gymharu â 2021. Cynyddodd y nifer o Biod Môr i 73 pâr, 8.98% yn is na’r cymedr dengmlynedd. Nythodd Cwtiaid Torchog am yr ail flwyddyn yn olynol wedi absenoldeb o saith mlynedd, gan gynhyrchu nythaid o dri chyw ac ail nythaid gydag un cyw – cyfanswm o bedwar cyw yn goroesi. Llwyddodd y pâr o Hebogiaid Tramor i fagu un cyw o’i gymharu â dau y llynedd. Nythodd dau bâr o Gigfrain unwaith eto, gydag un pâr yn llwyddo i fagu pedwar cyw a’r llall un cyw. Doedd dim tystiolaeth o ymdrechion magu gan y Titw Mawr, y Siff-siaff, na’r Llinos Bengoch Leiaf eleni. Nythodd dau bâr o Delorion yr Helyg a goroesodd cyfanswm o bum cyw. Cafodd Telorion yr Hesg flwyddyn dda arall a chofnodwyd naw pâr. Roedd nifer y Llwydfron a’r Telor Penddu yr un fath â’r llynedd, gyda phedwar pâr o’r cyntaf a thri phâr o’r ail a enwyd. Cynyddodd y nifer o Drywod oedd yn nythu o 30 pâr o 2021, 4.89% yn uwch na’r cymedr deng-mlynedd. Cwympodd nifer y parau o Fronfreithod i un, a daliwyd pedair tiriogaeth gan Robinod Coch eto eleni, sydd yn dal 23.08% yn is na’r cymedr deng-mlynedd. Cofnodwyd y cyfrif uchaf o barau o Glochdar Cerrig gydag 20 ledled yr ynys, y rhan fwyaf yn magu o fewn yr eithin. Roedd y nifer y parau o Dinwen y Garn yn ateb y cyfartaledd dengmlynedd o 28 pâr, a chynhyrchwyd 44 o gywion, 8.70% yn is na’r cymedr dengmlynedd. Cofnodwyd chwech yn fwy o diriogaethau Llwyd y Gwrych eleni o’i gymharu â 2021. Nodwyd cwymp yn y nifer o barau o’r Siglen Fraith gan mai dim ond saith pâr a gofnodwyd. Cwympodd y nifer o Gorhedyddion y Graig rhywfaint gyda dau bâr yn llai na’r llynedd. Mae hi’n ymddangos bod nifer Corhedyddion y Waun yn amrywio’n fawr, gyda’r 87 pâr yn gynnydd o 36 o gyfanswm 2021. Cynyddodd y nifer o barau o Linosiaid ychydig gyda 22 wedi eu cofnodi, er bod 52 o gywion wedi rhoi cynhyrchedd o 2.36 cyw fesul pâr, 8.33% yn is na’r cymedr deng-mlynedd. Nythodd tri phâr o Nico unwaith eto, gan fagu cyfanswm o wyth cyw. Mae canlyniadau arolwg Adar Drycin Manaw 2022 yn awgrymu bod poblogaeth Enlli wedi cynyddu’n gyflym yn yr adran hon o’r ynys. Cyfrifwyd cyfanswm o 5,301 twll (efo adar a heb adar) ledled ardal astudiaeth 2022. O’r rhain, tybiwyd bod 4,749 (89.59%)
3 yn Cynnal Adar, ac wrth chwarae tâp o’u galwadau cafwyd ymateb o 1714 (36.09%) o’r rhain. Wrth gyfuno canlyniadau cyfrifiadau 2019-2021, mae’r nifer o dyllau drwyddo draw yn 28,884, 55.80% uwchben cyfanswm y cyfrifiad blaenorol. Yn yr un modd, mae cyfanswm y nifer o TCA wedi cynyddu o 52.95%, o 17,276 yng nghyfrifiad 2014-2016 i 26,423 yn y cyfrifiad cyfredol. Amcangyfrifir bod poblogaeth yr ynys bellach yn 26,423 pâr. Llwyddwyd i fonitro 124 o dyllau Adar Drycin Manaw oedd ag adar yn eistedd ar wyau hyd at gwblhau’r cylch nythu. Dyfalwyd y cynhyrchedd a llwyddodd 80 o gywion i adael y twll. Rhoddodd hyn gynhyrchedd o 0.65 cyw fesul pâr, cwymp o 12.16% ar gynhyrchedd y llynedd (0.74), a 3.27% yn is na’r cymedr deng-mlynedd. Mae hyn 10.96% yn is na’r cymedr ers 1998 pan ddechreuodd Gwylfa Adar Enlli fonitro cynhyrchedd. Cafwyd llwyddiant unwaith eto gyda modrwyo ac ail-ddal Adar Drycin Manaw, gyda 1350 o adar unigol yn cael eu trin yn ystod y flwyddyn; roedd 723 yn adar newydd yn eu llawn dwf a fodrwywyd. Ail-ddaliwyd 538 o adar unigol eraill gyfanswm o 603 o weithiau. Roedd un unigolyn a ddaliwyd yn 2021 wedi ei fodrwyo’n wreiddiol ym 1985. Modrwywyd yr aderyn fel oedolyn, felly mae o leiaf 36 mlwydd oed, gan nad ydy adar ifanc yn dychwelyd i fagu hyd nes eu bod yn dair neu bedair oed. Yn ogystal â’r 723 o adar yn eu llawn dwf, modrwywyd 138 o adar ifanc eraill yn eu nythod, gan roi prif gyfanswm o 861 o adar wedi derbyn modrwyau newydd yn ystod y flwyddyn. Ni gafodd Adar Drycin Manaw ifanc eu pwyso a’u mesur hyd at eu hamser i adael y nyth eleni oherwydd cyfyngiadau monitro yn unol â HPA1. Dadansoddwyd data o’r saith mlynedd blaenorol yn holistaidd. Cymedr hyd adenydd y cywion rhwng 2015- 2021 oedd 228.48mm±s.d.13.36, a chymedr pwysau y cywion oedd 474.97g±s.d.43.09. Cymedr y colled mewn pwysau oedd 92.88g±s.d.46.43, gydag uchafswm colli pwysau o 234g o 684.2g i 450.2g yn 2020. Cyfrifwyd Morloi Llwyd bron yn ddyddiol ledled y tymor yn Rhonllwyn, Solfach ac ar Garreg y Rhona. Yn ogystal â’r tair ardal ganolbwyntio hyn, cofnodwyd yn rheolaidd hefyd y niferoedd llai sy’n dod i’r lan ar greigiau Pen Diban ac ar hyd gweddill arfordir yr ynys. Cafwyd y cyfrif uchaf eleni ym mis Awst pan gofnodwyd 262 o amgylch yr ynys ar y 18fed. Ychydig o ddigwyddiadau a gafwyd eleni o ran cychod yn peri aflonyddwch, a dim ond dau ddigwyddiad lle cafwyd cryn dipyn o ymyrraeth; ym mis Awst pan ddaeth saith jet-sgi yn agos i’r lan ar drai a pheri i’r Morloi ruthro’n wyllt i’r môr o Garreg y Rhona ac ym mis Medi pan aflonyddwyd ar nifer mawr o’r Morloi yn Rhonllwyn gan ddau gwch rib. Ym mis Awst, gosodwyd tri arwydd yn gofyn i bobl gadw draw o loi bach y Morloi – un wrth y Storws, lle mae ymwelwyr dydd yn dod i’r lan, un ger Porth Solfach, a’r olaf yn agos i Rhonllwyn lle ceir y nifer fwyaf o loi bach. O ddiwedd Awst hyd at ddechrau mis Tachwedd mae staff yr Wylfa yn cyfrif, yn monitro ac yn mapio safleoedd geni Morloi Llwyd Enlli. Yn 2022 cafwyd lleiafswm o 62 o loi eu geni ar yr ynys, yr un fath â 2021. Yn ystod tymor 2022 cynhaliwyd rhaglen mwy neu lai lawn o deithiau tywys a digwyddiadau lle’r oedd gwesteion yn gallu cymryd rhan unwaith eto. O ddiwedd y gwanwyn, fodd bynnag, roeddem yn cynnal teithiau fel arfer wedi i gyfyngiadau gael eu codi. Cafodd cyfanswm o 34 ‘digwyddiad’ eu harwain, gyda chyfanswm o 341 o ymwelwyr yn cael eu tywys ar deithiau bywyd gwyllt neu ar sesiynau Adar Drycin. Bu’n rhaid rhoi’r gorau i’r teithiau Adar Drycin wedi 4 Awst pan osodwyd cyfyngiadau gan CNC (Cyfoeth Naturiol Cymru) ar drin adar môr oherwydd y Ffliw Adar H5N1 (HPAI) hynod o bathogenig. Cynhaliwyd boreau gwyfynod ar 152 dyddiad yn ystod y
4 flwyddyn rhwng mis Mawrth a mis Hydref. Ni gyfrifwyd yr union nifer o westeion a fynychodd y rhain eleni, er bod hyd at 20 yn eu mynychu’n rheolaidd, gyda mwy ambell dro’n mynychu’n ystod cyfnodau prysuraf yr haf; byddai rhai gwesteion yn mynychu bob dydd yn ystod eu harhosiad. Yn ystod 2022, cynhaliwyd sawl cyflwyniad am yr ynys a gwaith yr Wylfa (GAMYE) fel rhan o’r GNG ayyb, ac i fynychwyr drwy gyfrwng Zoom. Rhoddwyd dau gyflwyniad drwy gyfrwng Zoom gyda chyfanswm o dros 100 o wylwyr. Ymysg y rhain roedd cymdeithasau byd natur yn Swydd Gaerhirfryn ac yn Norfolk, yn ogystal â sawl sgwrs i aelodau a chyfeillion (gwesteion rheolaidd â’r ynys) yr Wylfa ac Ymddiriedolaeth Ynys Enlli. Rhoddwyd un sgwrs i Glwb Adar Cley ar leoliad ym mis Rhagfyr 2022 gyda dros 90 aelod yn ei mynychu. Unwaith eto, casglwyd deunydd cyfryngau digidol a’u hymgorffori i’r cyflwyniad AV sy’n cael ei chwarae yn ystafell ddehongli’r Wylfa ar gyfer ymwelwyr dydd a’r sawl sy’n aros ar yr ynys. Gwyliodd llawer o westeion y cyflwyniad 20-munud o’r dechrau i’r diwedd, gyda rhai’n dychwelyd ymhellach ymlaen yn yr wythnos. Mynegai/Key AOLs – adults on ledges AOBs - apparently occupied burrows AONs - apparently occupied nests AOSs - apparently occupies sites AOLs - SCA (silffoedd o bosib yn cynnal adar) AOBs - TCA (tyllau o bosib yn cynnal adar) OANs - NCA (nythod o bosib yn cynnal adar) SafCA - (safleoedd o bosib yn cynnal adar) Looking south over Bardsey © Myles Jenks
5 1 . Abstract During the 2022 season, staff from the Bardsey Bird and Field Observatory carried out fieldwork for a number of projects with financial aid from Natural Resources Wales under the Section 16 Agreement. These were: 1) Monitoring the nesting success and productivity of the Chough. 2) Monitoring and mapping of all the breeding seabird species on Bardsey and Ynysoedd Gwylan. 3) Monitoring and mapping of all the land birds breeding on Bardsey. 4) A census of Manx Shearwaters from the Southeastern section of Bardsey. 5) Manx Shearwater productivity at a sample of nest sites. 6) Monitoring disturbance of Grey Seals by visitors and visiting boats. 7) Educational talks and walks for visitors on the island. Choughs had a fair year and 2022 was the first year since 2014 where the target productivity rate of 2.50 was met. During 2022, six pairs attempted to breed (22.08% below the ten-year mean with five pairs that successfully fledged young. The other pair failed during the chick rearing stage when the nest was washed out by the sea during storms. The resulting 2.50 chicks per pair is 20.77% greater than the ten-year mean. The number of young fledged (15) is 5.66% below the ten-year mean. Therefore, although the acceptable limits set out for the management of the NNR, SPA and SAC for productivity was met; the reduction in breeding pairs since 2017 resulted in a lowerthan-average number of chicks over the past decade. However, looking long-term, the population of six pairs is 30.35% greater than the long-term (1953-2022) mean, with the productivity being 5.30% lower than the long-term mean. Breeding bird populations did quite well in 2022. Overall, the numbers of pairs recorded this year alongside the productivity for all seabird species showed that Avian Influenza (H5N1) did not impact breeding populations on Bardsey or the Gwylan Islands. Razorbill numbers bounced back considerably this year with 1298 pairs, 37.00% higher than the ten-year mean, and saw the first increase in numbers since 2018, when a peak of 1321 pairs was recorded. Guillemots had their best year on record with 2193 AOL recorded. A productivity figure of 0.37 remained consistent with the ten-year mean. The Puffin colony decreased for the first time since 2012, as this year’s AOB count was 160. This may be due to a large increase in the AOB number on Ynys Gwylan Fawr. Kittiwakes continued to increase in numbers this year with 230 pairs recorded, the highest total since 346 in 2007. There were 65 Shag nests on Bardsey, six more than in 2021, and fledged 146 juveniles giving a productivity of 2.25. A total of 378 Herring Gull AONs was 1.34% higher than the 2013-2022 mean, whilst 159 Lesser Black-backed Gull AONs was 11.96% lower than that the ten-year mean. Productivity varied for both species: a sample of 124 Herring Gull AONs at the North End colony saw 78 fledge, giving a productivity figure of 0.63. For Lesser Black-backed Gulls, a sample of 117
6 AONs at the North End, a minimum of 40 juveniles fledged. Four pairs of Great Blackbacked Gulls nested. Fulmars: 35 held AOSs, the highest count since 2006 with a productivity figure of 0.63 calculated. Manx Shearwater productivity was 0.77 chicks per breeding pair, 13.77% higher than the ten-year mean. Boat trips to Ynys Gwylan Fawr on 15, 21 and 23 June, and a trip to Ynys Gwylan Bach on 23 June allowed coverage of the breeding populations on the islands. Four Razorbill chicks and an egg were recorded, alongside 31 AOLs. A total of 90 Guillemot AOLs were recorded alongside 55 chicks, giving a productivity of 0.61, 92.31% higher than the ten-year mean. The number of Puffin AOBs was 741, 13.33% higher than the ten-year average. Great Black-backed Gull numbers dropped by 10 compared to last year after the population seemed fairly stable, with an estimated 41 AONs recorded and was 30.21% lower than the ten-year mean. Herring Gull numbers also dropped in accordance with the observed negative trend, as only 42 AONs were logged. Five Cormorant AONs were recorded, with one present on Ynys Gwylan Bach. This is the second year in a row they have bred since 2013. The first evidence of Storm Petrels breeding on the Ynys Gwylan Fawr was recorded as calls were heard on 21 June. In terms of terrestrial birds, there was no sign of any breeding activity for Cuckoos this year. Nine Mallard broods were logged, 20.35% lower than the 2013-2022 mean. Of these, only four chicks successfully fledged. There were two fewer Moorhen pairs this year compared to 2021. Oystercatchers increased to 74 pairs, 8.98% lower than the ten-year mean. Ringed Plovers bred for the second year in a row after a seven-year absence, producing a brood of three and a second brood of one - fledging four chicks in total. Ringed Plover chick © Steven Stansfield
7 The pair of Peregrines fledged a single chick compared to two last year. Two pairs of Ravens bred again, with one pair successfully fledging a brood of four and the other fledging one chick. There was no evidence of breeding attempts by Great Tits, Chiffchaffs, and Lesser Redpolls this year. Two pairs of Willow Warblers bred fledging five young. Sedge Warblers had another good year with nine pairs recorded. Both Whitethroat and Blackcap numbers remained the same as last year, with four and three pairs respectively. Wrens increased by 30 pairs from 2021, 4.89% above the tenyear mean. Song Thrush pairs reduced to one, and Robins held four territories again this year, which is still 23.08% below the ten-year mean. The highest count of Stonechat pairs was recorded with 20 logged across the Island, most of which are found breeding within the gorse. Wheatear pairs matched the ten-year average of 28 pairs, and produced 44 young, 8.70% below the ten-year mean. There were six more Dunnock territories recorded this year compared to 2021. A dip in Pied Wagtail pairs was noted as only seven pairs were recorded. Rock Pipits decreased slightly with two fewer pairs than last year. Meadow Pipit numbers seem to continually fluctuate, with the 87 pairs an increase of 36 from the 2021 total. Linnet pairs slightly increased with 22 logged, though 52 juveniles gave a productivity of 2.36 young per pair, 8.33% below the ten-year mean. Three pairs of Goldfinches nested again, fledging eight young in total. The results from the 2022 Manx Shearwaters survey suggest that the population on Bardsey has rapidly increased in this section of the island. A total of 5,301 burrows (occupied and unoccupied) were counted across the 2022 study area. Of these, 4,749 (89.59%) were deemed to be Apparently-Occupied, and voice playback elicited responses from 1714 (36.09%) of these. Combining the 2019-2021 census results, the overall number of burrows counted is 28,884, 55.80% above the total in the previous census. Likewise, the total number of AOBs has increased by 52.95%, from 17,276 in the 2014-2016 census to 26,423 in the current census. The island’s population is now estimated at 26,423 pairs. In total 124 Manx Shearwater burrows containing birds incubating eggs were monitored to completion. Productivity was calculated and a total of 80 chicks fledged. This gave a productivity of 0.65 chicks per pair, a decrease of 12.16% on last year’s productivity (0.74), and 3.27% lower than the ten-year mean. This is 10.96% lower than the mean since 1998 when Bardsey Bird Observatory began monitoring productivity. Ringing and re-trapping Manx Shearwaters was again successful, with 1350 individual birds handled during the year; 723 were new full-grown birds that were ringed. A further 538 unique birds were recaptured a total of 603 times. One individual captured in 2021 was originally ringed in 1985. The bird was ringed as an adult, so it is at least 36 years old, since juvenile birds do not return to breed until they are three to four years old. In addition to the 723 full grown birds, a further 138 young birds were ringed in their nests, giving a grand total of 861 birds fitted with new rings during the year. No young shearwaters were weighed and measured to completion this year due to monitoring restrictions regarding HPAI. Data over the previous seven years was holistically analysed. The mean fledging wing-length from 2015-2021 was 228.48mm±s.d.13.36, whilst the mean fledging weight was
8 474.97g±s.d.43.09. The mean weight-loss was 92.88g±s.d.46.43, with a maximum loss of 234g from 684.2g to 450.2g in 2020. Grey Seals were counted almost daily throughout the season in Henllwyn, Solfach and on Carreg yr Honwy. In addition to these three focal areas, the smaller numbers that haul out around the South End and along the rest of the island’s coastline were also recorded on a regular basis. The peak counts this year came in August when 262 were recorded around the island on 18th. There were very few incidents noted this year of vessels causing disturbance, and only two incidents which caused a large amount of disturbance; in August when seven Jet-skis came close inshore at low water and caused a mass stampede from Carreg yr Honwy and in September when a two ribs disturbed a large number of seals in Henllwyn. In August, three signs were deployed asking people to keep away from the seal pups; one by the boathouse, where day visitors come ashore, one near Solfach, and the last hear Henllwyn where the densest rookery is. From late-August to early November Observatory staff count, monitor and map occurrences of pupping Grey Seals on Bardsey. In 2022 a minimum of 62 pups were born on the island, the same as in 2021. The 2022 season saw a near-full program of guided walks and events return with guests being allowed to participate. From late spring however, we were running walks at full strength once restrictions had been lifted. In total there were 34 ‘events’ led, with a total of 341 visitors being taken out on wildlife walks or on shearwater sessions. The shearwater walks had to be discontinued after 4 August when NRW restricted seabird handling due to Highly pathogenic Avian Influenza H5N1(HPAI). Moth mornings were run on 152 dates during the year from March to October. The actual number of guests attending was not counted this year, though there were regularly up to 20, and sometimes more guests attending during the busy summer periods, some guests would attend daily during their stay. During 2022, a number of presentations were given about the island and the work of BBFO regarding the NNR etc. and to attendees via Zoom. Two presentations were given via zoom and a total of over 100 viewers. These included natural history societies in Lancashire and in Norfolk, as well as several talks to members and friends (regular guests to the island) of both BBFO and BITL. One talk was given in person to the Cley Bird Club in December 2022 with over 90 members in attendance. Digital media was again collected and incorporated into the AV presentation that is played in the Observatory’s interpretation room for both day visitors and long-stay visitors. Many guests watched the 20-minute presentation from start to finish, with some returning later in the week.
9 Puffin © Ollie King
10 2. Introduction Bardsey, or Ynys Enlli, lies approximately 3km off the south-western tip of the Llŷn Peninsula in North Wales. With the exception of Anglesey (Ynys Môn), Bardsey is the largest island off the coast of Gwynedd. It is cut off from the mainland by the Bardsey Sound. The island is 2.3km in length and 1.0km at its widest (30m at its narrowest) and covers an area of 444 acres (178 ha). The maximum elevation is the summit of Mynydd Enlli at 167m. Bardsey can be considered at times as ‘two islands’; the northern section is roughly rectangular in shape and is bounded on the east side by ‘the mountain’, which rises steeply on the east face from the sea, creating an abundance of sea cliffs, caves and steep, vegetated slopes. It then forms a ‘humpback’ and falls westwards onto a sloping plain. The smaller ‘island’ is a low domed ridge reaching a maximum elevation of 15m and is connected by a narrow isthmus to the north part of Bardsey. Exposure to salt-laden, predominantly south-westerly winds, with fairly limited amounts of fresh water, intensive grazing by sheep and, until recently, Wild Rabbits Oryctolagus cuniculus, coupled with centuries of management by the human inhabitants, has produced an interesting mosaic of mainly herbaceous vegetation mixed with dwarf scrub communities and small amounts of maritime heath. The terrestrial flora and fauna of the island are diverse considering the size of Bardsey. The island supports nationally important numbers of Chough Pyrrhocorax pyrrhocorax, Manx Shearwater Puffinus puffinus and several globally scarce Lichens. In addition, the island is an important site for migrant birds as it lies on the east side of the Irish Sea migration route. The island is, therefore, of great conservation importance and carries the following international designations: • It is a National Nature Reserve (NNR). • Enlli is a Site of Special Scientific Interest (SSSI) for its biological features. • It is a Special Protection Area (SPA) for its breeding populations of Manx Shearwater and Chough (which also overwinter on the island). • It is part of the Llŷn Area of Outstanding Natural Beauty (AONB). • It also comes under the Pen Llŷn Heritage Coast and Environmentally Sensitive Area (ESA). • It forms part of the Clogwyni Pen Llŷn Special Area of Conservation (SAC) for its Atlantic seacliffs with maritime grassland and associated heaths. • The Intertidal parts of the island fall within the Pen Llŷn a’r Sarnau marine SAC where the North Atlantic Grey Seals are a feature of the marine SAC and use Bardsey’s boulder bays and rocky platforms as important summer haul-outs and breeding sites.
11 2.1 Aims and objectives Bardsey NNR supports a number of nationally and internationally important features of conservation interest. Bardsey is designated under both European and UK legislation and the legal responsibilities for management of the features of conservation importance are the responsibility of the landowners, the Bardsey Island Trust Limited (BITL). As an NNR, Bardsey is unusual in that it has never had a constant CCW/Natural Resources Wales (NRW) warden presence based on the reserve itself. The island is owned by the Bardsey Island Trust which is recognised under Section 35of the Wildlife & Countryside Act as an approved body for the management of the NNR. Looking North © Andy Purcell In recent years BITL has entrusted land management for conservation of the protected site features to a tenant farmer (with a farm manager resident on the island), with the site feature monitoring element of the conservation management divided between the Bardsey Bird and Field Observatory (BBFO) (most of the bird monitoring and Grey Seals) and a resident ecologist (mainly botanical monitoring) employed by RSPB. This monitoring is a crucial element of conservation of the protected site features. Through the means of the section 16 Management Agreement, the BBFO’s feature monitoring
12 work has been supported for many years by CCW and now Natural Resources Wales. This support recognises the expertise that the Observatory brings to this role but also the unique advantage of having a base on-site and being able to make a daily contribution to building the record of knowledge of the site’s ecology. The Objectives of the 2022-2024 Section 16 Management Agreement with BBFO are as follows: The management of the island shall be aimed at achieving the following objectives: • To support maintenance or enhancement of the protected habitats and species which the site supports (for which the site is designated) through the provision of appropriate monitoring, surveillance and other data to inform the management of the island. • To support management which enhances the general biodiversity of the National Nature Reserve. • To support management which enhances the public’s awareness, understanding and enjoyment of the National Nature Reserve. • To assist with the practical implementation of the Bardsey Management Plan. • To achieve all the above objectives while respecting the character of the island and the diversity of interests of other users of the island. This report summarises the work undertaken as part of the agreement, makes conservation suggestions and provides detailed accounts of the status of the features monitored by BBFO. 2.2 Health and safety Under the 1974 Health and Safety at Work Act, every employer has a legal obligation to undertake a full risk assessment for work carried out by their employees and to take all appropriate H&S measures to ensure the safety and well-being of said employees. During 1998 to 2000 a full risk assessment was undertaken on behalf of BBFO and BITL taking into account all works carried out by their staff during a full year on the island. These works included all types of monitoring and fieldwork carried out on the island such as night-time monitoring of shearwaters and ringing of seabirds in cliff colonies, lone working etc. The H&S manual is under constant revision and in 2023 is due to be completely overhauled. A full copy of the risk assessment and Health and Safety document is kept at the Observatory on the island and a copy is available on request from the secretary of BBFO.
13 3 Breeding success of the Chough
14
15 3. Breeding success of the Chough 3.1 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 only very slightly between this survey and the previous one in 2002 which estimated 399 pairs. However, these population trends exhibit some geographical variation, with increases in Wales, the Isle of Man, and the Cornwall and south Wales population, 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 Aberdaron Coast and Bardsey Island (Glannau Aberdaron ac Ynys Enlli) 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. Fig. 3.1 Bardsey Chough breeding population 1953-2022 0 1 2 3 4 5 6 7 8 9 10 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 Pairs Mean Number of pairs 4.60 ±s.d.2.24
16 The Chough population on Bardsey has increased substantially since the Observatory began monitoring them, with numbers gradually increasing from one pair 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, this fell to six pairs in 2021. In 2022 six pairs again nested 30.43% greater than the mean number of pairs for 1953-2022 (4.60 ±s.d.2.24). Table 3.1. Average number of breeding pairs, average number of chicks fledged and average productivity 1953-2022 Average number of breeding pairs (±s.d.) Average number of chicks fledged (±s.d.) Average productivity: chicks/pair (±s.e.) 1953-2022 4.60 ±2.24 11.46 ±5.95 2.64 ±0.13 1953-1970 2.11 ±0.96 6.24 ±3.03 3.27 ±0.29 1973-2000 4.29 ±1.24 10.89 ±5.03 2.48 ±0.18 2001-2010 6.00 ±0.67 16.90 ±6.30 2.79 ±0.28 2013-2022 7.70 ± 1.16 15.90 ±4.23 2.07 ±0.15 Fig. 3.2 Number of pairs, productivity and young 1998-2022 3.2 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. 0 5 10 15 20 25 30 0.00 0.50 1.00 1.50 2.00 2.50 3.00 3.50 4.00 4.50 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 Number of Pairs and Young Year Pairs Productivity Young Productivity
17 3.3 Results Fourteen traditional nest sites were checked and subsequently monitored during the 2022 breeding season, with six pairs attempting to breed. This was the same as 2021, however down on the seven pairs in 2020. Five of the six pairs were confirmed to successfully fledge young, with a total of 15 chicks fledging (1 x 1, chicks, 2 x 3 chicks and 2 x 4 chicks). The number of fledged chicks in 2022 is 5.66% lower than the ten-year mean (15.90±s.d.4.23), and 25.00% higher than in 2021. Productivity was 25.00% higher than in 2021. Table 3.2 Number of pairs, number of young and productivity 2013 -2022 Year 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 № of pairs 9 8 9 8 9 8 7 7 6 6 № of young 13 24 18 14 22 15 11 15 12 15 Productivity 1.44 3.00 2.00 1.75 2.44 1.88 1.57 2.14 2.00 2.50 Fig. 3.3. Male Chough near the Black Anvil nest site © Ed Betteridge 3 . 3.1 N esting activity of choughs on Bardsey in 2022 3.4.1 NORTH WEST CORNER – no activity Date Start Finish Nesting activity 29/4/2022 14:35 16:35 No activity 18/05/2022 09:30 11:30 No activity
18 3.4.2 OGOF MORLAS – no activity Date Start Finish Nesting activity 15/04/2022 11:10 12:30 No activity 05/05/2022 15:30 16:00 No activity 07/05/2022 15:00 15:15 No activity 14/05/2022 17:10 17:25 Nest site visited no sign of activity 3.4.3 BLACK ANVIL – three chicks fledged Bird Ring number Right combination Left combination Female Un-ringed Male ASH/METAL ORANGE/ ORANGE Chick 1 EX04835 ASH(1A)/METAL MUD/ MUD Chick 2 EX04836 ASH(1C)/METAL MUD/WHITE Chick 3 EX04837 ASH(1E)/METAL MUD/YELLOW Chick 4 EX04838 ASH(1F)/METAL MUD/ORANGE Date Start Finish Nesting activity 15/04/2022 11:10 12:30 Pair passed straight west at 11:20, presumably the same returned at 11:50 and flew to nest site. Both came out and were feeding above nest site and rings were read. Female went into nest site and did not leave. Male flew south where it approached other (Zawn?) pair; was seen on and off around the other pair/feeding (12:00-12:15) 05/05/2022 15:20 16:00 Bird flushed from nest site, male feeding high above (15:59) 07/05/2022 15:00 15:15 Bird flying above nest site 09/05/2022 15:00 15:15 Pair dropped in 19/05/2022 13:45 14:00 Pair dropped in together (13:52) then a single bird flew south (13:53) after being flushed by a Peregrine 29/05/2022 11:45 12:00 Nest site visited, four large chicks present (11:53) 31/05/2022 15:45 16:15 Nest site visited and 4 chicks ringed 22/06/2022 18:00 18:10 Pair seen flying above with two chicks 24/06/2022 14:00 14:15 Pair seen flying above with two chicks 11/07/2022 10:00 10:10 Chicks 1A, 1E and 1F seen together on the West Coast past Solfach
19 3.4.4 TRWYN PINC – no activity Date Start Finish Nesting activity 15/04/2022 11:10 12:30 No activity 05/05/2022 16:15 17:15 No activity 07/05/2022 15:15 17:15 No activity 19/05/2022 13:45 15:45 No activity 3.4.5 CARREG LLWYDION – no activity Date Start Finish Nesting activity 15/04/2022 11:10 12:30 No activity 05/05/2022 16:15 17:15 No activity 07/05/2022 15:15 17:15 No activity 19/05/2022 13:45 15:45 No activity 3.4.6 BAE FELEN – no activity Date Start Finish Nesting activity 15/04/2022 12:00 12:20 Pair seen feeding high above Bae Felen (1 unringed, 1 ?) before both flying down and straight in the Zawn site (12:18) 05/05/2022 16:20 17:15 Nest site visited, no sign of any activity 07/05/2022 15:15 17:15 No activity 14/05/2022 14:50 16:50 No activity 29/05/2022 12:15 12:30 No activity, nest site visited and nothing found 3.4.7 THE ZAWN – no activity Date Start Finish Nesting activity 15/04/2022 12:00 12:20 Pair seen feeding high above Bae Felen (1 unringed, 1?) before both flying down and straight in the Zawn site (12:18) 05/05/2022 16:20 17:15 Nest site visited, no sign of any activity 09/05/2022 09:30 10:00 Pair went in at (9:35) and pair in again (9:55) 14/05/2022 14:50 16:50 No activity
20 3.4.8 SEAL CAVE – three chicks fledged Date Start Finish Nesting activity 26/04/2022 15:45 16:45 Female was sat above nest site (15:47-16:10), then flew in, 2 flew out then mobbed another pair to the north (16:12) 08/05/2022 14:30 16:15 Female flushed from nest (14:25), nest site visited, 2 chicks and 2 eggs present (14:32). Both birds seen above nest site with both visiting the nest (14:51- 15:01) after leaving. Male then left female in nest before returning above nest 15:36 09/05/2022 10:30 10:35 Pair dropped in 14/05/2022 14:35 16:50 Bird flew out of nest site (14:45), bird in (15:31), pair flew out and fed for c2mins above the Zawn before flying west (15:43), bird visited again (16:37) 24/05/2022 15:00 16:30 Nest visited and 4 chicks ringed. Pair remained above nest site and revisited within 5 minutes of leaving 21/06/2022 15:00 16:30 3 chicks above nest with both parents plus a dead un-ringed chick in nest site – meaning there were five chicks hatched. Bird Ring number Right combination Left combination Female Un-ringed Male Unknown METAL WHITE/WHITE Chick 1 EX04831 GREEN/RED ASH/METAL Chick 2 EX04832 GREEN /LIME ASH/METAL Chick 3 EX04833 GREEN /GREEN ASH/METAL Chick 4 EX04834 GREEN /BLUE ASH/METAL
21 3.4.9 OGOF BRAICH Y FWYAF – no activity Date Start Finish Nesting activity 26/04/2022 15:00 17:00 No activity 08/05/2022 14:50 16:50 No activity 3.4.10 TORNADO LEDGE – no activity Date Start Finish Nesting activity 26/04/2022 15:00 17:00 No activity 08/05/2022 14:50 16:50 No activity Fig. 4 Chough on Solfach March © Ed Betteridge
22 3.4.11 OGOF BARCUT – four chicks fledged Date Start Finish Nesting activity 03/04/2022 16:30 17:45 No activity 13/04/2022 14:25 15:45 Pair arrived, one individual went straight into nest then another in and straight back out where it fed and preened above nest site for c5 mins (un-ringed) 26/04/2022 16:45 17:00 Un-ringed bird above nest (15:15) calling. Male called female off nest (15:23) and both were sat above the nest site until 15:26 02/05/2022 14:00 16:00 Un-ringed feeding high above nest site (14:33). Unringed again above the nest site (15:09). Bird flew into nest hole (15:10), pair past Barcut (15:13). Bird flew into nest site (15:29), pair above nest site (16:00) 14/05/2022 14:15 14:30 Nest site visited and no sign of any activity 15/05/2022 14:00 14:55 Pair seen flying above before dropping in, birds observed from a distance and were seen to enter nest hole. Nest site visited and found to have at least 3 chicks (14:20). Pair together above Pen Cristin (14:51) 25/05/2022 17:55 18:10 At least three chicks still present in nest (18:00) however, out of reach 29/06/2022 15:00 15:30 2 adults and 4 chicks feeding above the Zawn, presumed to be this pair as neither adults nor chicks were ringed. Bird Ring number Right combination Left combination Female Un-ringed Male Unknown
23 3.4.12 PEN CRISTIN – one chick thought to have fledged Date Start Finish Nesting activity 03/04/2022 16:30 17:45 No activity 13/04/2022 14:25 15:45 One arrived at 15:15 and went straight in and was shortly followed by another bird c1 min later that landed out of site then carried on south 26/04/2022 13:50 15:30 Un-ringed was above nest site (14:12) then flew south. Un-ringed then returned to nest site (14:25) for c2mins 02/05/2022 14:00 16:00 Pair in flight above nest site (14:06), male then alone to the south (14:09) then both south (14:10). Male back above nest (14:36), female goes into nest (14:39) then both south (14:41) One in (14:50), male flying above then feeding to the south (14:57). Pair flew south (15:06). Male back above nest (15:57) 14/05/2022 14:15 14:30 Bird seen visiting nest site 15/05/2022 14:00 14:55 Bird seen visiting nest site (13:34), then feeding above (13:38-13:50), pair above nest fighting Barcut pair (14:51) 23/05/2022 14:15 14:20 Pair in together (14:16) 23/06/2022 19:00 19:10 Pair with 1 chick above Pen Cristin thought to be this family Bird Ring number Right combination Left combination Female Un-ringed Male Unknown YELLOW/BLACK METAL
24 3.4.13 OGOF DIBAN – failed at chick stage Date Start Finish Nesting activity 22/04/2022 17:44 18:00 Male called female off nest and both flew off south (17:49) 10/05/2022 09:40 09:50 Pair seen feeding on South End just north of nest site 12/05/2022 14:20 14:45 Pair seen together just east of the nest site. Nest visited and 4 chicks present (14:27). Birds returned and visited the chicks almost immediately (14:31) 27/05/2022 19:45 20:00 Nest visited, 2 chicks dead just outside nest and nest empty Presumed killed by recent storms. Pair still around nest area 3.4.14 OGOF TRWYN-YR-HWCH BACH – four chicks fledged Date Start Finish Nesting activity 09/04/2022 08:15 08:25 Male sat above nest, called out the female and displayed 14/04/2022 17:25 17:30 Pair feeding together above nest site 15/04/2022 09:00 09:05 Male feeding alone above nest site 29/04/2022 14:25 14:30 Male feeding above nest site, flew down and called female off nest 23/05/2022 13:20 13:40 Pair circled above then were feeding to the east before dropping into nest site (13:37) 14/06/2022 09:50 10:00 Male and female and 4 young feeding on cliffs above nest 22/06/2022 09:30 10:00 4 young and 2 adults on Solfach 18/06/2022 09:30 09:30 Female with 4 young Bird Ring number Right combination Left combination Female ORANGE/# “0F” LIME/METAL Male Unknown METAL GREEN/GREEN
25 3 . 3 .2 Clutch sizes and productivity (fledging success). There was a minimum of 20 eggs laid this year. The six pairs fledged 15 young and the productivity was 2.50 chicks per pair. 3.4 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 three of the last ten years. The population trend 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 the same as last year and was 22.08% lower than the ten-year average (7.70±s.d.1.16). Breeding success was higher than last year, with three more chicks fledging from six pairs. Of the six active pairs, only one failed to rear young, failing at the chick rearing stage. The nest was visited and found to be clearly damaged by recent storms. The overall productivity in 2022 was 2.50, 25% higher than the previous year and 20.77% higher than the ten-year mean of 2.07±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. 3.4.1 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: Bird Ring number Right combination Left combination Female GREEN/ #“3T”, GREEN/METAL Male ASH/METAL BLUE
26 The species’ targets as listed in the 2010 Management Plan Supplement are: In the Guide for land managers: Summary of Island Management Plan 2002-2006, Wilkinson (2004) gives a ‘Vision’ for the Feature: Further to the Wilkinson plan (2004), Moralee (2010) refined the grazing prescriptions for many of the areas which are managed for Chough feeding (amongst other things). Most areas within the SPA and SAC have very similar, if not identical, sward height objectives within the plan. ‘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 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 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
27 3.4.2 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 fiveyear 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 2022 was 2.50 chicks per pair. This is 25% higher than the 2021 productivity rate of 2.00 and exactly the acceptable minimum of 2.50 chicks per pair set in the Management Plan. This makes 2022 the highest year for productivity since 2014. The supplement to the Management Plan (Moralee 2010) targets ‘stable productivity’, but this target has not been met since 2014 when productivity was 3.00. The mean productivity over the last decade is 2.07 (±s.e.0.15) with fluctuations as low as 1.44 in 2013 and reaching a peak of 3.00 in 2014; the 2022 productivity rate of 2.50 was 22.08% lower than the ten-year mean and also 5.30% lower than the long-term 1953-2022 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. 6. 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; this may be evident with productivity hitting the target 2.5 this year. Fig. 3.5 Choughs near Solfach in October © Ed Betteridge
28 Fig. 3.6 Productivity 1953-2022 Fig. 3.7 Productivity 2013-2022 Over the past decade 159 young have been produced, with the lowest total of 11 in 2019 and the highest being 24 in 2014 which was the year that saw the highest productivity of the last decade. The ten-year mean is 2.07, 17.20% below the proposed target productivity of 2.5 chicks per pair. Fig. 3.8 Number of young produced per annum 2013-2022 0.0 1.0 2.0 3.0 4.0 5.0 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 Productivity 2.64 ±s.e.0.13 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 Year Productivity Mean Productivity 2.07 ±s.e.0.15 0 5 10 15 20 25 30 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 Year Young Mean Number of Young 15.90 ±s.d.4.23
29 3.4.3 Wintering population and n o n -breeding C houghs Any flocks of significant size had departed the island by March when Observatory staff were present on the island, pairs had started to form, and some were nest building. Therefore, there were few notable arrivals of mainland breeding birds until 16 October when a flock of 40 were seen around the Narrows and the South End. Sightings of colour ringed individuals proved that many of these mainland breeding birds remained on the island until the end of the season, however, counts then never exceeded 20. Fig. 3.9 Maximum daily counts for Choughs on Bardsey in 2022 3.5 Summary 2022 was the first year since 2014 where the target productivity rate of 2.50 was met. During 2022, six pairs attempted to breed (22.08% below the ten-year mean (7.70±s.d.1.16) and of these, five successfully fledged young. The other pair failed during the chick rearing stage when the nest was washed out by the sea during storms. The resulting 2.50 chicks per pair is 20.77% greater than the ten-year mean (2.07±s.e.0.15). The number of young fledged (15) is 5.66% below the ten-year mean (15.90±s.d.4.23). Therefore, although the acceptable limits set out for the management of the NNR, SPA and SAC for productivity was met; the reduction in breeding pairs since 2017 resulted in a lower-than-average number of chicks over the past decade. However, looking long-term, the population of six pairs is 30.35% greater than the long-term (1953-2022) mean (4.6±s.d.2.24), with the productivity being 5.30% lower than the long-term mean (2.64 ±s.e.0.13). 0 5 10 15 20 25 30 35 40 45 J F M A M J J A S O N D Daily count of birds
30 3.6 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 Redbilled 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.
31 4 Breeding birds on Bardsey and Ynysoedd Gwylan
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33 4. Breeding birds on Bardsey and Ynysoedd Gwylan 4.1. Introduction Since 1953, Roberts (1985), Jones (1988), Leitch (1992), Loxton and Jones (1995) and Eagle (2012) have produced summaries of the breeding birds on Bardsey, in addition there are annual summaries of the previous year’s nesting season in the systematic list in each of the Observatory’s reports. Since 1998, however, increased effort has meant that more data has been collected systematically and a more comprehensive report has been produced each year with the aim of providing a quick reference of the breeding data from year to year, comparing the data for 2023 with that collected in the previous nine years and showing the number of pairs nesting, productivity figures (where available and relevant) and notes on successes or failures compared with previous years. From 2009 to date, the four-visit Breeding Bird Survey (BBS) method has also been used for breeding landbirds, the data from this survey help with the assessment of land management impacts on non-seabird species and inform conservation management reviews. The seabird data, as well as being used by Natural Resources Wales (NRW) to assess the island’s seabird populations and health, are fed into the Seabird Monitoring Programme (SMP). SMP is an ongoing annual monitoring programme, established in 1986, of 26 species of seabird that regularly breed in Britain and Ireland. It aims to ensure that sample data on breeding numbers and breeding success of seabirds are collected, both regionally and nationally, to enable their conservation status to be assessed. The SMP is led and co-ordinated by JNCC in partnership with others including NRW. In November 2009 all Partners signed a Statement of Intent that established the way forward for future data sharing and collaborative working. 4.2. Methods The Observatory was funded through the NRW management agreement to monitor the breeding landbirds and seabird sites as part of the NNR. As in previous years, the monitoring and mapping of seabirds followed the methods set out by Walsh et al. (1995) in the Seabird Monitoring Handbook. Mostly land-based counts were undertaken, but a boat trip on 15 June allowed sets of photographs to be taken of the larger cliff-nesting seabird colonies, with the number of birds counted on a computer monitor at a later date. As has been the case since 1998, the non-seabird species had their territories (usually singing males) mapped or, where nests and/or young were located, these were marked on maps which are kept at the Observatory. The maps were compiled by BBFO staff from data collected during their daily census of the island, along with specific routes covered to map species such as Oystercatcher, Rock Pipit, Meadow Pipit, Wren and Linnet. Additionally, four BBS visits
34 covering the whole island (spread over several mornings) were made during 15-17 April, 11-13 May, 31 May to June and 28-29 June. The data generated from this exercise will be helpful when comparing Bardsey with other sites. A full explanation of the methods employed for each species is given in the BBFO Report for 2009 (Brown and Stansfield, 2010). Table 4.1. Census units, method and registration points Mallard Census Unit Breeding females, female with young/female on nest. Method Check all known sites daily from early March to late June. Potential issues Failure to note a fail/relay/2nd clutch. Consider dates/timings to reduce problems Shelduck Census Unit Breeding females, female entering or leaving hole or same general area on more than one occasion Method Check all known sites daily from early March to late June. Potential issues Very secretive around nest burrow Peregrine Falcon Census Unit Occupied sites calling/displaying birds Method Check all known previous sites from April Potential issues Requires access to the east side of Mynydd Enlli Moorhen Census Unit Occupied territories bird with young or bird agitated and calling from suitable nesting area Method Check all previous known sites and other suitable sites from March. Potential issues Birds are skulky and sometimes call from feeding areas near compost piles in gardens Oystercatcher Census Unit Territorial pair Method Walk round the coastline in mid-late May and map all units. Find all nests possible and count number of eggs. Work out mean clutch size, hatching rate and estimate productivity from number of large young seen Potential issues Productivity estimate based on number of located nests with eggs, therefore missing early failures Wood Pigeon Census Unit Occupied territories, displaying or calling bird Method Check for evidence of occupied territories during daily census of the island from March onwards Potential issues Protracted breeding season and semi-colonial nesting.
35 Little Owl Census Unit Occupied territories, calling males Method Map calling birds from early March – visit all previously known nesting areas four times during season Potential issues Some pairs do not seem very vocal at all during breeding season Long-eared Owl Census Unit Occupied territories, calling males on more than one visit, or presence of young Method Check plantation on regular basis after dark. Ask visitors in northern trust houses to listen out for calls and follow up any reports. Potential issues Migrants have occasionally been heard calling. However, most years when birds have nested the adult birds have been silent Cuckoo Census Unit Small fledged young Method Located during daily census counts Potential issues Almost impossible to note any breeding attempt other than a successful one Sky Lark Census Unit Occupied territories singing bird on more than one visit. Method Map census units during daily census of the island. Potential issues Care should be taken that migrant birds taking up territory should not be counted Swallow Census Unit Occupied nest site Method Visit all buildings and outbuildings, pig sties, etc. and record all active nests Potential issues Frequently birds only partially build nests – these included as occupied nest sites House Martin Census Unit Occupied nest sites Method Check for evidence of occupied nest sites during daily census of the island Potential issues Frequently birds only partially build nests – these included as occupied nest sites Meadow Pipit Census Unit Singing male/nest building Method Carry out transects covering the whole island on four occasions during the specified periods. Transects should be 100 metres apart Potential issues Care should be taken not to double count birds with large territories, or to count migrant pipits. To be carried out at same time as Winter Wren census
36 Rock Pipit Census Unit Singing male/nest building Method Count all singing birds on suitable areas at same time as Oystercatcher survey Potential issues Consider earlier visits as attempts may fail prior to Oystercatcher survey Pied Wagtail Census Unit Occupied nest sites Method Visit all buildings and outbuildings, pig sties, etc. Potential issues Care should be taken not to count migrant birds. Very secretive around nest. Pairs frequently visit coast to feed Wren Census Unit Occupied territories (based on singing males) Method Carry out transects covering the whole island on four occasions during the specified periods Potential issues Census should be carried out before 0600. Transects should be 100 metres apart Dunnock Census Unit Occupied territories (based on singing males) Method Check for evidence of occupied territories during daily census of the island Potential issues Method selected due to small, widely dispersed population. Sizeable territories and more than one female possible Robin Census Unit Occupied territories (based on singing males) Method Check for evidence of occupied territories during daily census of the island Potential issues Method selected due to small, widely dispersed population Stonechat Census Unit Occupied territories (based on singing males) Method Check for evidence of occupied territories during daily census of the island Potential issues Method selected due to small, widely dispersed population Wheatear Census Unit Occupied territories (based on singing males) Method Check for evidence of occupied territories during daily census of the island Potential issues Method selected due to small, widely dispersed population. Care should be taken not to count migrant birds Blackbird Census Unit Occupied territories (based on singing males) Method Check for evidence of occupied territories during daily census of the island Potential issues Method selected due to small, widely dispersed population
37 All warbler species Census Unit Occupied territories (based on singing males) Method Check for evidence of occupied territories during daily census of the island Potential issues Method selected due to small, widely dispersed population. Migrant birds sing from areas traditionally used for breeding Magpie Census Unit Occupied territories (based on nests-building/territorial adult) Method Check for evidence of occupied territories during daily census of the island Potential issues Birds are often surprisingly elusive during nesting season Chough Census Unit Occupied site Method Two visits to all known nest sites. The first visits between 6 April and 6 May. The second visit should take place between 7 May and 15 June. It is not necessary to visit nests to complete the census, observations being made from nearby vantage points. Some sites are difficult to access from land and sites such as Pen Cristin are best viewed from the sea. However, to minimise the number of visits to sites and as part of ongoing studies of marked birds, some second visits should be combined with visits to nests to ring nestlings where possible. If results are inconclusive, additional visits can be undertaken Potential issues At least 1hr should be spent near each known or apparently suitable nest site – all previously known sites on Bardsey should be covered. Where possible, census visits will not take place during strong winds, persistent rain or poor visibility Carrion Crow Census Unit Occupied territories (based on nests-building/territorial adult) Method Check for evidence of occupied territories during daily census of the island in all suitable/previous sites Raven Census Unit Occupied territories (based on nests-building/territorial adult) Method Check for evidence of occupied territories during daily census of the island in all suitable/previous sites from late February onwards Potential issues Nests are often difficult to find on the east side of the island Chaffinch Census Unit Occupied territory (singing male/pair nest building) Method Check for evidence of occupied territories during daily census of the island Potential issues Ensure migrant birds are not counted
38 Linnet Census Unit Occupied territories (based on maximum number of individuals counted in a visit divided by 2) Method Carry out transects covering the whole island on four occasions during the specified periods. Transects should be 100 metres apart Potential issues Ensure migrant birds are not counted. Males may pair with multiple females Lesser Redpoll and Goldfinch Census Unit Occupied territories – (based on nests-building/territorial adult) Method Check for evidence of occupied territories during daily census of the island Potential issues Ensure migrant birds are not counted Guillemot © Ed Bedtteridge
39 4.3. Results The following systematic list summarises the nesting season for each species during 2020. The number of nesting pairs and productivity figures from 2020 are compared with data from 2011 to 2019. The number of nesting pairs and productivity estimates from 2011 to 2019 are shown in table format where sufficient data are available. Fig 4.1 Breeding categories: Opposite page Herring Gulls © Steven Stansfield STATUS DEFINITION Scarce 1-10 pairs breeding annually Uncommon 11-50 pairs breeding annually Fairly common 51-250 pairs breeding annually Common 251-1000 pairs breeding annually Abundant 1001+ pairs breeding annually KEY AOB Apparently Occupied Burrows AOS Apparently Occupied Sites AOL Adults On Ledges AON Adults On Nests
40
41 SHELDUCK Tadorna tadorna Scarce Four pairs were present during the spring, however only one brood of six chicks was seen for a single morning in April, and not seen since. The last time any chicks successfully fledged was in 2014. 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 № pairs with young 5 3 2 2 4 2 6 2 1 1 № of fledglings 13 2 0 0 0 0 0 0 0 0 MALLARD Anas platyrhynchos Scarce, population stable There was a total of nine broods in 2022, one higher than 2021 and 20.35% lower than the 2013-2022 mean (11.30±s.d.3.65), but 108.16% greater than the long-term average from 1953-2022 (4.32±s.d.3.76). Broods were found from April through to July with two on Pwll Gareth, two on the Twin Ponds, one on Pwll Cain, one on Nant Pond, one in Cristin Withy, and two on Tŷ Pellaf Pond. There was a minimum of 54 ducklings throughout the season, giving an average brood size of six. Duckling survival rates were low as they are often predated by Ravens, Carrion Crows and gulls. Most chicks were predated before reaching any considerable size, though four immature young were seen on Solfach on 23 July. 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 № of broods 6 12 11 17 10 16 15 9 8 9 0 1 2 3 4 5 6 7 1953 1958 1963 1968 1973 1978 1983 1988 1993 1998 2003 2008 2013 2018 Year Shelduck Mean Number of pairs 1.24 ±s.d.1.88 0 5 10 15 20 1953 1958 1963 1968 1973 1978 1983 1988 1993 1998 2003 2008 2013 2018 Year Mallard Mean Number of pairs 4.32 ±s.d.3.76
42 A female was flushed off a nest containing 11 eggs on Ynys Gwylan Bach on 23 June during a seabird monitoring trip. WOODPIGEON Columba palumbus Scarce, population stable In total, nine territories were located this year, the same as last year, and 18.92% below the ten-year mean (11.10±s.d.2.08), 37.67% greater than the long-term average from 1953-2022 (6.54 ±s.d.4.61). At least five juveniles were counted. 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 № of pairs 9 10 11 13 15 12 13 10 9 9 MOORHEN Gallinula chloropus Scarce/uncommon, population fluctuating Six pairs were recorded this year, two less than last year, which is 31.03% lower than the ten-year mean (8.70±s.d.3.23). It is also 20.16% lower than the long-term 1953-2022 mean (7.51±s.d.4.23). A total of seven broods containing 18 young were recorded, resulting in a productivity of 3.00, 56.41% higher than the ten-year mean (1.92±s.e.0.30). 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 № of pairs 4 7 12 12 12 13 7 6 8 6 № of young 8 21 9 17 13 15 7 19 21 18 Productivity 2.00 3.00 0.75 1.42 1.08 1.15 1.00 3.16 2.62 3.00 0 5 10 15 20 1953 1958 1963 1968 1973 1978 1983 1988 1993 1998 2003 2008 2013 2018 Year Woodpigeon Mean Number of pairs 6.54 ±s.d.4.61 0 5 10 15 20 25 1953 1958 1963 1968 1973 1978 1983 1988 1993 1998 2003 2008 2013 2018 Year Moorhen Mean Number of pairs 7.51 ±s.d.4.23
43 OYSTERCATCHER Haematopus ostralegus Fairly common, stable A total of 74 pairs nested this year: 58 pairs opted for the rocky coastline, whilst 16 pairs were found in grassland and amongst the gorse on the West Coast and South End. This total is 8.98% lower than the ten-year mean (81.30±s.d.13.41), and 14.39% higher than the long-term average from 1953-2022 (64.69 ±s.d.19.65. Of the 34 nests that were found, 73 eggs were counted, giving an average clutch size of 2.15. This is 12.92% below the ten-year mean (2.47±s.d.0.21). A minimum of 13 fledged young was counted in July, giving a productivity of just 0.18 chicks per pair. 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 № of pairs 87 101 98 82 84 84 72 77 54 74 Mean clutch 2.69 2.63 2.36 2.14 2.46 2.65 2.38 2.50 2.73 2.15 Productivity 0.78 0.38 0.07 0.46 0.31 0.39 0.40 - 0.26 0.18 RINGED PLOVER Charadrius hiaticula Scarce A pair was recorded breeding on the Narrows, just south of Solfach in June. A nest with four eggs was found on 8 June, with three young hatching and fledging on 24 June. A second brood was recorded in August with one juvenile recorded fledging, giving a productivity of 4.00. This is the second year in a row that this species has bred since 2014. Ringed Plover © Ollie King 0 20 40 60 80 100 120 1953 1958 1963 1968 1973 1978 1983 1988 1993 1998 2003 2008 2013 2018 Year Oystercatcher Mean Number of pairs 64.69 ±s.d.19.65
44 KITTIWAKE Rissa tridactyla Fairly common, population increasing This year saw 230 AONs, 49 (27.07%) more than last year and 76.52% greater the tenyear mean (130.30±s.d.46.98), the highest total since 2007. The number of AONs this year was 55.39% above the long-term 1953-2022 average (148.02 ±s.d.102.28). From the 230 nests, 158 large juveniles were counted and believed to have fledged, giving a productivity of 0.69, 2.38% lower than the ten-year mean (0.70±s.e.0.12). 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 № of pairs (AON (AON) (AON) 62 104 125 122 125 90 121 143 181 230 № of young 27* 20* 52* 27* 9* 36* 101 119 268 158 Productivity 0.71 0.21 0.84 0.41 0.11 0.92 0.84 0.83 1.48 0.69 *Only partial census carried out in these years; more birds may have fledged. Productivity calculated at study plots from a smaller number of AON. GREAT BLACK - BACKED GULL Larus marinus Scarce Four pairs bred this year, a 2.44% decrease from the ten-year mean (4.10±s.d.1.97) and 81.33% higher than the long-term 1953-2022 average (2.21 ±s.d.1.81). Seven juveniles were seen on the East Side in June, giving a minimum productivity of 1.75, 88.58% above the ten-year mean (0.93±s.e.0.17). 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 № of pairs 8 5 6 4 5 3 2 2 2 4 Productivity 0.63 0.20 1.83 1.00 0.20 0.67 1.00 1.00 1.00 1.75 0 50 100 150 200 250 300 350 400 1953 1958 1963 1968 1973 1978 1983 1988 1993 1998 2003 2008 2013 2018 Year Kittiwake Mean Number of pairs 148.02 ±s.d.102.56 0 2 4 6 8 10 1953 1958 1963 1968 1973 1978 1983 1988 1993 1998 2003 2008 2013 2018 Year Great Black Backed Gull Number of pairs 2.21 ±s.d.1.81
45 An estimated 39 pairs nested on Ynys Gwylan Fawr producing a minimum of 38 juveniles, and a further two AON with two juveniles were recorded on Ynys Gwylan Bach. This was 30.21% lower than the ten-year mean (58.75±s.d.19.94). The productivity figure calculated from numbers on Ynys Gwylan Fawr was 1.00 was 35.82% above the ten-year average (0.74±s.e.0.04). 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 № of pairs - 79 92 72 35 50 50 - 51 41 Productivity - 0.75 0.64 0.79 0.68 0.54 0.82 - 0.67 1.00 HERRING GULL Larus argentatus Common, population recovering A total of 378 pairs was counted, 41 (12.17%) greater than the 2021 total and 1.34% above the ten-year mean (373.00±s.d.36.86). This figure was 14.23% greater than the long-term 1953-2022 average (330.91±s.d.141.90). A sample of 124 AONs at the North End colony saw 78 fledge, giving a productivity figure of 0.63, 2.91% lower than the ten-year mean (0.65±s.e.0.03). 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 № of pairs 323 399 400 331 377 417 345 423 337 378 Productivity 0.64 0.69 0.54 0.84 0.64 0.77 0.71 0.54* 0.48* 0.63* * Productivity calculated from study plots. On 15 June, 42 AONs were counted on Ynys Gwylan Fawr, 53.59% below the ten-year mean (90.50±s.d.46.07). A minimum of 40 young was counted, giving a productivity figure of 0.95, 9.79% above the 2013-2022 mean (0.87±s.e.0.06). 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 № of pairs - 61 52 113 145 165 89 - 57 42 Productivity - 1.15 0.54 0.88 0.84 - 0.76 - 0.95 0.95 LESSER BLACK - BACKED GULL Larus fuscus Fairly common, population stable This year saw 159 AON, 57 (55.88%) higher than the 2021 total yet 11.96% lower than the ten-year mean (180.60±s.d.54.36). This figure is 14.96% lower than the long-term 1953-2022 mean (186.97±s.d.189.40). This total is up from last year’s 102 pairs, which 0 100 200 300 400 500 600 700 1953 1958 1963 1968 1973 1978 1983 1988 1993 1998 2003 2008 2013 2018 Year Herring Gull Mean Number of pairs 330.91 ±s.d.141.90