Seabird Group Conference

Presentation extrinsic drivers of individual foraging consistency at the International Seabird Group Conference, Edinburgh, September 2016. Here we show that predictability may favour consistent behaviour by foraging seabirds

Transcript

1. Does environmental predictability play a role in shaping individual foraging behaviour? Alice M Trevail, Jonathan A Green, Jonathan Sharples, Jeffrey Polton, John Arnould & Samantha C Patrick @AliceTrevail alice.trevail@Liverpool.ac.uk
2. Individual consistency Individual consistency in habitat selection • Ecological processes • Population dynamics • Potential for evolution • Marine management ` Ed Schneider The Telegraph Liam Quinn Anders Lundberg Antarctic connection aquaportail.com Antarctica.gov.au Joachim S Muller Robert OToole @AliceTrevail
3. Individual consistency Individual consistency in habitat selection Extrinsic e.g. environment • Ecological processes • Population dynamics • Potential for evolution • Marine management ` Ed Schneider The Telegraph Liam Quinn Anders Lundberg Antarctic connection aquaportail.com Antarctica.gov.au Joachim S Muller Robert OToole Intrinsic e.g. hereditary @AliceTrevail
4. Q : Do predictable resources lead to consistent behaviour? Static physical parameters as indicator: • Depth currents water column structure • Tidal stratification productivity Environmental predictability @AliceTrevail Latitude (°N) Longitude (°W) Tidal stratification log10 (m-2 s3) Depth (m) Tidal stratification Depth 54 53 52 6 5 4 3 250 200 150 100 50 0 54 53 52 6 5 4 3 7 6 5 4 3 2 1 0 8
5. Predictability at study colonies Skomer Puffin Island @AliceTrevail Skomer Puffin Is. Depth 52 51.8 51.6 5 5.2 5.4 5.6 0 160 Depth (m) 5 4 4.5 53.6 53.4 53.2 Depth Deeper & more variable Shallower & spatially homogenous Latitude (°N) Longitude (°W) Longitude (°W)
6. 0 8 Tidal stratificati on log10 (m-2 s3) 7 6 5 4 3 2 1 0 8 52 51.8 51.6 5 5.2 5.4 5.6 Tidal stratification Tidal stratification log10 (m-2 s3) 7 6 5 4 3 2 1 0 8 5 4 4.5 53.6 53.4 53.2 Tidal stratification Tidal stratification log10 (m-2 s3) Predictability at study colonies Skomer Puffin Island @AliceTrevail Skomer Puffin Is. Higher stratification index & more variable Vertically mixed & spatially homogenous Latitude (°N) Longitude (°W) Longitude (°W) More mixed More stratified
7. Predictability at study colonies Skomer Puffin Island @AliceTrevail Skomer Puffin Is. Vertically stratified & Spatially heterogeneous Predictable resource hotspots Vertically mixed & Spatially homogenous Unpredictable resource distribution
8. Methods: seabird tracking • Black-legged kittiwakes – Indicator species • iGotU 120 GPS logger Last 2 yrs: modified battery (13g) with increased recapture rate (2016: 78%) • Multiple trips per individual • Puffin Island: 505 trips, 59 individuals, 6 years • Skomer Island: 22 trips, 10 individuals, 1 year @AliceTrevail Latitude (°) 4.4 4.2 4 53.3 53.4 53.5 53.6 4.3 4.1 Puffin Island 52 51.9 51.8 51.7 Skomer Island 5.5 5.4 5.3 5.2 Longitude (°)
9. Trait expression Environment Population Methods: quantifying individual consistency @AliceTrevail
10. Trait expression Environment Population Trait expression Environment Individuals Methods: quantifying individual consistency @AliceTrevail
11. Trait expression Environment Population Trait expression Environment Individuals Methods: quantifying individual consistency @AliceTrevail Trait expression Environment Trips Individual variability
12. Methods: quantifying individual consistency Population variance in a trait Residual Individual behaviour Individual consistency @AliceTrevail • Variance in linear mixed effects model explained by bird random effect
13. Methods: quantifying individual consistency Population variance in a trait Residual Individual behaviour Individual consistency Residual Individual variability Within-trip consistency @AliceTrevail • Variance in linear mixed effects model explained by bird and trip as random effects
14. @AliceTrevail Methods: quantifying individual consistency 5.6 5.4 5.2 51.6 51.7 51.8 51.9 52 52.1 5.6 5.4 5.2 Latitude (°N) Longitude (°W) 7 6 5 4 3 2 1 Tidal stratification log10 (m-2 s3) Tidal stratification GPS tracks Stratification for GPS points Habitat use 5.6 5.4 5.2
15. 5.6 5.4 5.2 @AliceTrevail Methods: quantifying individual consistency 5.6 5.4 5.2 51.6 51.7 51.8 51.9 52 52.1 Latitude (°N) Resource Selection Function 7 6 5 4 3 2 1 Tidal stratification log10 (m-2 s3) Tidal stratification Stratification for random points = Available (0) 5.6 5.4 5.2 Stratification for GPS points = Used (1) Longitude (°W) • Binomial GL mixed effects model with used/available (1/0) as response variable
16. Foraging consistency: Habitat use 0.0 0.2 0.4 Unpredictable Puffin Is. Predictable Skomer 0.2 0.4 0.6 0.8 Unpredictable Puffin Is. Predictable Skomer Environment Consistency Individual consistency Within-trip consistency @AliceTrevail Depth Stratification
17. 0 20 40 60 80 100 120 0.00 0.02 0.04 @AliceTrevail Resource selection: Population Predictable = Skomer Island Available Used Density Unpredictable = Puffin Island Available Used 0.00 0.01 0.02 Depth (m)
18. @AliceTrevail Resource selection: Population Predictable = Skomer Island Available Used 0.0 0.4 0.8 1.2 Density 0 1 2 3 4 5 6 0.0 0.5 1.0 1.5 2.0 Unpredictable = Puffin Island Available Used Tidal stratification (log10 (m-2 s3))
19. @AliceTrevail Resource selection: Population Shallower Deeper Mixed Stratified Predictable = Skomer Island Unpredictable = Puffin Island
20. @AliceTrevail Next step: Individual resource selection Selection Available Used Predictable = Skomer Island Population Individuals Unpredictable = Puffin Island Population Individuals Environment Available Used Hypothesis:
21. Consistency higher within trips than between trips Use of temporally dynamic features @AliceTrevail Discussion ` Kent Smith
22. Consistency higher within trips than between trips Use of temporally dynamic features Predictable resources may favour consistency • Reduce competition at hotspots • Predictability -> increased opportunity to specialise • Individual learning @AliceTrevail Discussion Matt Doggett
23. Consistency higher within trips than between trips Use of temporally dynamic features Predictable resources may favour consistency • Reduce competition at hotspots • Predictability -> increased opportunity to specialise • Individual learning Resource selection stronger in unpredictable environment Less variation in individual behaviour ? @AliceTrevail Discussion
24. Consistency higher within trips than between trips Use of temporally dynamic features Predictable resources may favour consistency • Reduce competition at hotspots • Predictability -> increased opportunity to specialise • Individual learning Resource selection stronger in unpredictable environment Less variation in individual behaviour ? Individuals differ in resource selection strength Need more data to explore different environments @AliceTrevail Discussion
25. Questions? Thanks to Puffin Island field teams, including: Federico de Pascalis, Harriet Clarke, Ruth Dunn, Phil Collins & Louise Soanes As well as Skomer wardens, B and Ed, & Ros Green @AliceTrevail alice.trevail@Liverpool.ac.uk