Temporal variation in translocated Isle Royale wolf diet

Area of Science:

• Ecology
• Wildlife Biology
• Predator-Prey Dynamics

Background:

• Wolves (Canis lupus) are keystone predators influencing ecosystem structure through predation.
• Understanding wolf foraging strategies is crucial for assessing their ecosystem-level impacts.
• Predator foraging decisions are influenced by trade-offs between prey acquisition costs and benefits, which can vary temporally.

Purpose of the Study:

• To describe the wolf diet on Isle Royale National Park by analyzing prey remains in scats.
• To investigate how temporal variations in prey vulnerability and availability affect wolf diet composition.
• To understand the implications of wolf dietary flexibility for ecological community stability.

Main Methods:

• Analysis of 206 wolf scats collected from May-October 2019 and 2020.
• Quantification of diet by frequency of occurrence and percent biomass of prey remains.
• Logistic regression used to model temporal trends in prey consumption.

Main Results:

• Beaver (Castor spp.) constituted 62% of the diet, moose (Alces alces) 26%, and other species 12%.
• Adult moose were more frequent in scats in May; moose calves peaked in June-July.
• Beaver occurrence in wolf scats remained consistent throughout the study period.

Conclusions:

• Wolf diet composition is responsive to seasonal changes in prey availability and vulnerability.
• The consistent consumption of beavers highlights their importance as a low-handling cost prey for wolves.
• Temporal fluctuations in wolf diet can influence their ecological role and impact prey behavior, potentially affecting community stability.