Abiotic conditions mediate intraguild interactions between mammalian carnivores

Area of Science:

• Ecology
• Wildlife Biology
• Conservation Science

Background:

• Intraguild interactions, including intraguild predation (IGP) and interspecific killing (IK), are common among mammalian carnivores.
• These interactions are often asymmetrical, with larger, dominant species (IG predators) killing smaller ones (IG prey).
• Ecological theory suggests coexistence depends on consumptive benefits, exploitative competition, and ecosystem productivity.

Purpose of the Study:

• To investigate the drivers of distribution for American martens (IG prey) and fishers (IG predator) in sympatric and allopatric areas.
• To explore the role of apex predators (coyotes) in mediating intraguild interactions.
• To test ecological theory regarding factors influencing the coexistence of competing mesopredators.

Main Methods:

• Utilized resource selection models incorporating spatially explicit age and harvest data for martens and fishers.
• Analyzed landscape variables including late winter abiotic conditions, forest composition, and coyote abundance.
• Assessed marten age structure to infer survival rates in areas with varying predator densities.

Main Results:

• Fisher distribution was strongly influenced by warmer late winter temperatures, deeper snowpack, and higher productivity.
• American martens were restricted to areas with lower fisher and coyote abundance and lower productivity, selecting habitats maximizing prey availability.
• Marten age data indicated reduced survival in high-density fisher and coyote areas, suggesting competitive exclusion.

Conclusions:

• Consistent with theory, dominant predators (fishers, coyotes) competitively excluded martens from more productive, milder habitats.
• Intraguild predator and prey species coexisted in low-productivity environments where martens were superior exploitative competitors.
• Abiotic and biotic factors critically shape intraguild dynamics and spatial distribution of competing carnivores.