Lessons from a life-long commitment to seabird research

Transcription

1 Lessons from a life-long commitment to seabird research Mike Harris Centre for Ecology & Hydrology, Edinburgh

2 The Welsh years

3 The Galapagos years

4 Isle of May years the present St Kilda Isle of May Isle of May Isle of May chosen because: Puffin numbers increasing in contrast to St Kilda where numbers had declined Easy to get to, easy to work

5 Isle of May long-term studies Intensive fieldwork on puffins Puffin work scaled down to monitoring level and studies on guillemots the focus 1982 present Data rich: Demographic, behavioural and diet data collected annually Anke Addy

6 Lessons learned over the years 1. Think very carefully before stopping anything Ageing puffins Collecting food samples Correction values for guillemot counts Puffin chick weights 2. Keep an open mind 3. Archive data 4. Publish your results 5. Know your study species

7 Monitoring the breeding population Puffin numbers increasing up to 2003 Counts Population counts

8 Monitoring the breeding population Population crashed by 30% Why??????? Counts Population counts

9 Survival of breeding adults Liz Mackley Photo Liz Mackley

10 Survival of breeding adults Survival Year

11 Post-fledging survival Ian Fisher

12 Following the survival of these chicks chicks marked Mist-netting of up to 2,500 birds per year 556 recaptures Also 33 recoveries of birds dead away from the island

13 Immature survival model Live and dead encounters (Burnham model) Starting model only agespecific (5 classes) GOF: c-hat (median c-hat approach) = 1.08 Model selection: Strong time-dependence in adult survival None in survival (adult or juvenile)

14 Immature survival at other colonies Area Cohorts Survival to 5 years Adult survival Fidelity to natal colony Isle of May This study Hornøya c. 1.0 Sandvik et al Gulf of Maine Breton et al. 2005, 2006

15 Population model Annual values for adult survival and breeding success Mean survival for immatures from cohorts Start breeding when 6 years old Liz Mackley

16 Output of basic model Modelled population Basic model Counts Population counts

17 Immature survival set at 0.7, Modelled population Basic model Adjusted model Counts Population counts

18 Proportions of adults and immatures Adult Bill curved, 2 or more grooves Immature Bill pointed, < 2 grooves Photo Liz Mackley

19 The missing years.. 40 Percentage immature in early July 30 % Year

20 Lessons learned over the years 1. Think very carefully before stopping anything Ageing puffins Collecting puffin food samples Correction values for guillemot counts Puffin chick weights 2. Keep an open mind 3. Archive data 4. Publish your results 5. Know your study species

21 Food samples Sprats Sandeels Sheila Russell Akinori Takahashi

22 Long-term changes in diet Proportion of chick diet by weight Proportion Sandeels Sprat

23 Changes in 0-group sandeel length Length (mm) % decline in energy value Akinori Takahashi

24 Data before stomach.. 0 group sandeels Older sandeels

25 Lessons learned over the years 1. Think very carefully before stopping anything Ageing puffins Collecting puffin food samples Correction values for guillemot counts Puffin chick weights 2. Keep an open mind 3. Archive data 4. Publish your results 5. Know your study species

26 Guillemot counts converting birds to pairs 1.0 Correction factor = pairs/birds Year Birds Individuals or pairs Year Pairs

27 Adults with chicks at 12:00 hr 50 Percentage 40 Two adults No adult

28 Lessons learned over the years 1. Think very carefully before stopping anything Ageing puffins Collecting puffin food samples Correction values for guillemot counts Puffin chick weights 2. Keep an open mind 3. Archive data 4. Publish your results 5. Know your study species

29 Puffin chick weights declining Weight (g) Peak weight Fledging weight

30 2. Keep an open mind! Up to ring recoveries from Isle of May and Farne Islands This and studies of levels of pollutants and heavy metals suggested that birds spent the whole year in the North Sea

31 Results using geolocators Confirmed that some birds stayed in the North Sea

32 Results using geolocators But others migrated well into the Atlantic

33 Wintering areas in Adult survival Normally = = 0.69 Isle of May

34 Survival in relation to wintering area Survival 0.69 ( ) Survival 0.91 ( ) Puffins spent even longer in the Atlantic when overwinter survival normal

35 3. Archive your data!!

36 4. Publish results (or make data available) Importance of good collaborators

37 5. Know your study species

38 Thanks to the many people who have helped with fieldwork in particular Sarah Wanless, Mark Newell, Stuart Murray and Sheila Russell. Morten Frederiksen and Francis Daunt helped with analyses, Scottish Natural Heritage allowed us to work on the Isle of May and JNCC contributed funding Akinori Takahashi