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Seabirds maintain offspring provisioning rate despite fluctuations in prey abundance: a multi-species functional response for guillemots in the North Sea
Smout, S., Rindorf, A., Wanless, S., Daunt, F., Harris, M.P. & Matthiopoulos, J. (2013) Journal of Applied Ecology 50(4):1071-1079
- Seabirds that consume more than one prey type may adjust their foraging to maintain provisioning rates for their chicks. How energetically
effective are these strategies, and what are the implications for the management of seabirds and their marine habitat?
- A multi-species functional response links consumption rates to the availability of multiple prey types, but fitting multi-species functional
responses to field data can be difficult, requiring consumption measurements over a range of different prey abundances. Such detailed data may be
especially difficult to obtain in marine ecosystems.
- We used annual time-series data on chick provisioning for the common guillemot Uria aalge together with abundance indices for its two main prey
(lesser sandeel Ammodytes marinus and sprat Sprattus sprattus) to parameterize a multi-species functional response for parents provisioning chicks
at a major North Sea colony from 1992 to 2005.
- The fitted model reproduced changes in diet and consumption rate which were consistent with changes in local prey abundance including a
long-term decline in sandeels.
- The model predicted that energy intake by chicks would be more sensitive to changes in sprat abundance than sandeel abundance. Guillemots
appeared able to adjust their foraging tactics over a wide range of prey abundances to maintain a consistent energetic intake rate for chicks.
- Synthesis and applications. Our results suggest guillemot chicks obtain adequate calorific intake from their parents despite fluctuating prey
abundances, conferring some resilience in the face of environmental variation. The parameterized multi-species functional response model can be
used to estimate levels of severe prey shortage that compromise provisioning. It also enables us to interpret predator consumption rates so that
these can be used as a metric of prey availability. Further, quantifying trophic links between marine prey and apex predators is needed to support
the development of multi-species models in which the predators can be included. Such models are needed as tools to effectively manage the marine
ecosystem, taking into account the objectives of fishing, conservation and the need to maintain Good Environmental Status.
Keywords: Ammodytes marinus, chick provisioning, generalist, Good Environmental Status, indicator species, MCMC, predator–prey interactions,
seabird diet, Sprattus sprattus, Uria aalge
Links at this site
- Common Guillemot (Uria aalge)
- Lesser Sandeel (Ammodytes marinus)
- Sprat (Sprattus sprattus)
- chick provisioning
- Good Environmental Status
- indicator species
- Markov chain Monte Carlo
- predator-prey interactions
- seabird diet
Harris, M.P. &
- Isle of May
- Firth of Forth
- North Sea
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