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One meadow for two sparrows: resource partitioning in a high elevation habitat
Michaël Beaulieu1, Keith W Sockman
1Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA. mbeaulie@email.unc.edu
Oecologia
|April 25, 2012
Summary
Resource partitioning in sparrows changes with food availability. As resources increase, Lincoln
Area of Science:
- Ecology
- Animal Behavior
- Evolutionary Biology
Background:
- Resource partitioning is crucial for sympatric species coexistence.
- The influence of environmental variability, especially resource availability, on partitioning in free-ranging animals is not fully understood.
- Understanding these dynamics is key to predicting species interactions and community structure.
Purpose of the Study:
- To test the hypothesis that natural fluctuations in food resources impact resource partitioning between sympatric sparrow species.
- To investigate the dynamic relationship between environmental conditions and trophic segregation.
- To elucidate the mechanisms driving changes in feeding patterns within a community.
Main Methods:
- Examined temporal changes in plasma stable isotope signatures (δ(15)N and δ(13)C) of Lincoln's sparrows (Melospiza lincolnii) and white-crowned sparrows (Zonotrichia leucophrys).
- Correlated isotopic data with seasonal changes in habitat maturity and food availability from spring to early summer.
- Analyzed shifts in diet composition based on isotopic markers.
Main Results:
- No significant trophic segregation was observed between the two sparrow species when food resources were scarce in spring.
- As resource availability and competitor density increased, Lincoln's sparrows exhibited lower δ(15)N values, indicating consumption of lower trophic level prey.
- White-crowned sparrows maintained higher δ(15)N values, suggesting a preference for higher trophic level prey, leading to dietary divergence.
Conclusions:
- Trophic segregation between Lincoln's and white-crowned sparrows is dynamic and directly influenced by resource availability and interspecific competition.
- Changes in foraging opportunities and increased competition likely drive the observed feeding divergence.
- Environmental variability is a fundamental factor shaping resource partitioning and coexistence in animal communities.
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