Prey size mediates interference competition and predation dynamics in a large carnivore community

Area of Science:

• Ecology
• Behavioral Ecology
• Community Ecology

Background:

• Direct competition for resources is intense among predators, especially in complex guilds with dominance hierarchies.
• While the costs of losing competition are known, the drivers and indirect effects on prey remain unclear.

Purpose of the Study:

• To evaluate the drivers of interference competition in cougars (Puma concolor).
• To understand how cougar interference competition affects cougar-prey dynamics.

Main Methods:

• Utilized 23 years of cougar predation data from Yellowstone National Park, USA.
• Analyzed cougar kill data in relation to prey size, prey density, and competitor presence (wolves/bears).

Main Results:

• Prey size has a context-dependent effect: smaller prey are killed less often but are more susceptible to kleptoparasitism (scavenging) by other predators.
• Cougars shift to smaller prey when primary prey density decreases, reducing handling time and kleptoparasitism risk.
• Interference competition does not necessarily increase with declining prey density or increasing competitor density, contrary to existing theory.

Conclusions:

• Predator, competitor, and prey traits significantly influence the strength of interference competition.
• These traits can dampen interference competition, potentially promoting coexistence in complex predator communities.