How does behavior drive population and community dynamics of rodents?

UNCG Author/Contributor (non-UNCG co-authors, if there are any, appear on document)
Angela Lynn Larsen (Creator)
The University of North Carolina at Greensboro (UNCG )
Web Site:
Matina Kalcounis-Rüppell

Abstract: Understanding how population and community dynamics emerge from individual traits is essential to predict responses of animal populations and communities to habitat alterations. Individuals make decisions and are the basic unit of response to changes in the environment. Changes at the individual level can translate to population and community dynamics. Anthropogenic changes to environmental conditions occur frequently and rapidly. One anthropogenic change, biofuel feedstock production, is increasing to reduce dependency on fossil fuels. Switchgrass (Panicum virgatum) is a biofuel feedstock being planted between rows of loblolly pine (Pinus taeda). I hypothesized that changes in understory vegetation from intercropping switchgrass in pine plantations would alter intraspecific interactions, influencing individual behavioral decisions, which would then drive changes in population and community dynamics. My research aims were to assess effects of three treatments (switchgrass monocrop, switchgrass intercropped in loblolly pine, and control loblolly pine) on rodent: 1) population dynamics and community structure; 2) spatial and foraging behaviors, and patterns of reproduction; and 3) behaviors as predictors of population dynamics and community structure. My model species was the hispid cotton rat (Sigmodon hispidus), a common grassland specialist and early successional species. The cotton rat was a suitable model species because it has a relatively large geographic distribution, was easily captured at our site, and was expected to respond to change in grassy understory habitat. I studied the rodent community because they are ecosystem engineers, both prey and predators, and indicators of biodiversity. I used vegetation surveys, live-trapping, radio telemetry, giving-up density surveys, and individual-based modeling (IBM). Monocrop plots were ecological sinks with high adult cotton rat abundance but low juvenile recruitment, and control plots were ecological sources with low adult cotton rat abundance but high juvenile recruitment (Chapter II). Intercrop plots were intermediate for adult cotton rat abundance and juvenile recruitment, likely due to the mixture of cover and food (Chapter II). I also found cotton rats foraged more in monocrop than control plots, with intermediate foraging in intercrop plots (Chapter III). Females in control plots tolerated territory overlap with other females in areas with high amounts of grass (Chapter III). Then, based on an IBM, I found cotton rat populations would persist throughout 10-years of the current management in intercrop plots (Chapter IV). However, if management resulted in reduced non-grass cover, cotton rat populations would decline, whereas if management resulted in additional non-grass cover, cotton rat populations would increase in intercrop plots compared to predicted populations under current management (Chapter IV). Understanding behavioral responses as mechanisms underlying population and community level responses, allowed me to develop and use a functional and predictive IBM. My IBM can be used to predict responses of various prey species to management techniques that affect food and cover resources. My research helped to elucidate properties of populations and communities to better inform, and improve top-down predictive models and management decisions.

Additional Information

Language: English
Date: 2017
Biodiversity, Conservation Behavior, Cotton Rat, Forest Management, Intercropping, Switchgrass
Biodiversity conservation $z Mississippi
Forest management $z Mississippi
Intercropping $z Mississippi
Switchgrass $x Ecology $z Mississippi
Loblolly pine $x Ecology $z Mississippi
Hispid cotton rat $x Ecology $z Mississippi

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