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Sex-specific foraging behaviour in a monomorphic seabird.
S Lewis1, S Benvenuti, L Dall'Antonia
1School of Biological and Biomedical Sciences, University of Durham, South Road, UK.
Proceedings. Biological Sciences
|September 3, 2002
Summary
Sexual differences in foraging behavior exist in seabirds, even in species without size differences. Female northern gannets exhibit distinct foraging strategies, including deeper dives and greater surface time, challenging size-based explanations.
Area of Science:
- Avian Ecology
- Behavioral Ecology
- Marine Biology
Background:
- Parental foraging behavior often shows sexual differences in size-dimorphic seabirds.
- These differences are typically attributed to variations in body size between sexes.
- The role of factors other than body size remains underexplored.
Purpose of the Study:
- To investigate sexual differences in foraging behavior within a sexually monomorphic seabird species, the northern gannet (Morus bassanus).
- To test the hypothesis that body size is the primary driver of sex-specific foraging strategies.
- To explore alternative explanations for observed sexual differences in foraging.
Main Methods:
- Utilized specially designed instruments for data collection.
- Employed radio telemetry to track foraging trips.
- Compared foraging trip directions, durations, dive depths, and sea surface times between male and female northern gannets.
Main Results:
- Both male and female northern gannets showed consistency in foraging trip directions and durations.
- Significant differences in foraging behavior were observed between sexes.
- Female gannets were more selective foragers, performed longer and deeper dives, and spent more time on the sea surface than males.
Conclusions:
- Sexual differences in foraging behavior can occur independently of body size differences in seabirds.
- The findings challenge the prevailing body size-mediated explanation for sex-specific foraging.
- Further research is needed to explore alternative theories, such as behavioral plasticity or ecological factors, driving these foraging differences.