Landscape structure and population density affect intraspecific aggression in beavers.

Area of Science:

• Ecology
• Animal Behavior
• Conservation Biology

Background:

• Intraspecific competition influences territory acquisition, occupancy, and individual fitness.
• Understanding drivers of intraspecific aggression is key to comprehending population dynamics.

Purpose of the Study:

• To investigate intraspecific aggression in Eurasian (Castor fiber) and North American (Castor canadensis) beavers.
• To examine the influence of landscape structure, population density, and other factors on beaver aggression.

Main Methods:

• Analysis of tail scars from over 1,000 beavers across two long-term studies in Norway and the USA.
• Investigated factors including landscape structure, population density, sex, age, social status, and group size.

Main Results:

• Tail scar count, an indicator of aggression, was influenced by population density in well-connected landscapes (lakes, rivers) but not isolated ones (ponds).
• North American beavers showed increased aggression with higher population density in large lakes.
• Eurasian beavers exhibited decreased aggression with population density, potentially due to disperser pressure.

Conclusions:

• Population density's effect on intraspecific aggression is modulated by landscape structure.
• Findings highlight implications for dispersal, mate change, and territory occupancy, influencing population dynamics.