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Tree squirrel habitat selection and predispersal seed predation in a declining subalpine conifer
Shawn T McKinney1, Carl E Fiedler
1College of Forestry and Conservation, University of Montana, Missoula, MT 59812, USA. shawn_mckinney@nps.gov
Oecologia
|November 17, 2009
Summary
Red squirrels do not prefer whitebark pine habitats, leading to increased seed predation when pine populations decline. Managing competing conifers can reduce predation and aid pine regeneration.
Area of Science:
- Forest Ecology
- Plant-Animal Interactions
- Conservation Biology
Background:
- Modern forest ecosystems face perturbations impacting species interactions.
- Declines in plant species, without corresponding declines in seed predators, can worsen plant population issues.
- Whitebark pine (Pinus albicaulis) is a declining subalpine species, with red squirrels (Tamiasciurus hudsonicus) as key seed predators.
Purpose of the Study:
- To investigate the interaction between whitebark pine and red squirrels.
- To determine how forest conditions influence red squirrel habitat use and cone predation.
- To test hypotheses regarding squirrel habitat preferences and their impact on pine seed availability.
Main Methods:
- Habitat selection modeling and variable ranking using Akaike's information criterion.
- Comparison of squirrel habitat use in whitebark pine-dominant versus mixed conifer forests.
- Modeling the relationship between whitebark pine abundance and predispersal cone predation.
Main Results:
- Red squirrels showed no strong preference for whitebark pine habitats.
- Whitebark pine habitat variables were least important for squirrel habitat selection.
- Predispersal cone predation decreased linearly with increasing whitebark pine abundance.
Conclusions:
- Declining whitebark pine populations are not met with proportional declines in red squirrel habitat use, exacerbating pine decline.
- Altered plant-squirrel interactions reduce seed availability for whitebark pine recruitment.
- Managing competing conifers can create suboptimal squirrel habitat, reduce predation, and increase seed availability for dispersal.
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