Variable Breeding Strategies in a Fluctuating Environment: A Feeding Experiment in Eastern Chipmunks

Area of Science:

• Ecology
• Animal Behavior
• Reproductive Biology

Background:

• Small mammals in pulsed-resource environments adjust reproduction based on food availability.
• Eastern chipmunks (Tamias striatus) rely on beech tree (Fagus grandifolia) masting for resources.

Purpose of the Study:

• Investigate how eastern chipmunks anticipate and respond to food pulses for reproduction.
• Determine if food supplementation influences chipmunk reproductive strategies during mast and non-mast years.

Main Methods:

• Supplemented a study site with sunflower seeds for two years (one non-mast, one mast year).
• Monitored chipmunk feeder exploitation, body mass, and reproductive activity.
• Compared supplemented data with control sites and 10 years of historical chipmunk reproduction data.

Main Results:

• Increased feeder exploitation significantly raised the probability of summer estrus compared to controls.
• Feeder exploitation had a greater impact on estrus probability than body mass.
• Beech masting exerted a broader influence on estrus probability across all sites than feeder exploitation.

Conclusions:

• Food supplementation can enhance reproductive readiness in chipmunks, but doesn't guarantee full reproduction.
• Summer reproduction in chipmunks is influenced by current food availability but also by other factors beyond immediate resources.
• Plastic resource allocation in fluctuating environments is complex for small mammals.