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Reliable Method for Assessing Seed Germination, Dormancy, and Mortality under Field Conditions
Published on: November 6, 2016
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Context-dependent seed dispersal by a scatter-hoarding corvid.
Mario B Pesendorfer1,2, T Scott Sillett2, Scott A Morrison3
1School of Biological Sciences, University of Nebraska-Lincoln, 348 Manter Hall, Lincoln, NE, 68588-0118, USA.
The Journal of Animal Ecology
|February 16, 2016
Summary
Island scrub jays adjust their seed caching behavior based on acorn availability and social interactions. Caching distances increase with larger acorn crops, while rates are influenced by both food abundance and aggression from other jays.
Area of Science:
- Ecology
- Animal Behavior
- Conservation Biology
Background:
- Corvids are crucial dispersers of large-seeded plants, exhibiting flexible scatter-hoarding behavior.
- Seed production in many trees varies annually, potentially impacting corvid foraging strategies.
- Understanding context-dependent caching is vital for plant dispersal dynamics.
Purpose of the Study:
- To investigate how seed availability and social dynamics influence scatter-hoarding in island scrub jays (Aphelocoma insularis).
- To test predictions of the predator dispersal hypothesis regarding caching and seed abundance.
- To determine the impact of conspecific aggression on caching behavior.
Main Methods:
- Quantified scatter-hoarding rates and territorial defense in 26 color-marked island scrub jays over three years.
- Correlated caching parameters with annual oak acorn crop size and rates of territorial aggression.
- Compared foraging and caching rates under varying acorn availability and social contexts.
Main Results:
- Caching distances positively correlated with acorn crop size, increasing up to 40% between years.
- Caching rates declined in low-acorn years but increased in high-acorn years.
- Acorn foraging and caching rates were negatively correlated with territorial aggression, independent of overall foraging time.
Conclusions:
- Island scrub jay scatter-hoarding behavior is context-dependent, influenced by both food availability and social interactions.
- Results support the predator dispersal hypothesis, indicating that caching strategies benefit masting tree species.
- Social dynamics and variable seed crops significantly affect seed dispersal by corvids.
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