Strength in numbers: males in a carnivore grow bigger when they associate and hunt cooperatively

Abstract

Group-living has been recognized as one of the major transitions in evolution. Male sociality along with solitary females is rare in mammals, but it can provide unique insights into the evolution of sociality and cooperation. Because males compete with each other over females, male cooperation in mammals has been explained by joint defense of females against other males. Here, we demonstrate that the benefits of male cooperative hunting can play a major role in shaping sociality. By quantifying differences in morphology, activity, diet, and mating success, we show that in Madagascar's top predator, the fosa (Cryptoprocta ferox), some males associate to jointly hunt large prey, which allows them to grow bigger than both solitary males and females. These associated males' physical superiority also represents an advantage in contest competition for females, as reflected by higher mating success. Our results demonstrate that enhanced access to food resources by cooperative hunting is a key to physical development and competitiveness in fosas. In contrast to previous findings, we show that male sociality must not be limited to joint defense of territory and females, but that cooperation in food acquisition can favor sociality in sexually dimorphic species.

Social structure in a critically endangered Indo‐Pacific humpback dolphin (Sousa chinensis) population

“…Social behaviours are essentially a collection of strategies that positively influence survivorship and reproductive fitness (Wilson, 1975), which make them integral components of population health in many mammal species. For example, social structure can be the basis for successful foraging (Sargeant et al, 2005;Luehrs et al, 2013), successful parenting (Whitehead, 1996a), defence from predators (da Silva and Terhune, 1988;Tanner and Jackson, 2012), and learning important survival skills (Goodall, 1986;Mann et al, 2012). As such, the relationship between social behaviour and population health can have important conservation implications.…”

Relatedness Does not Affect Competitive Behavior of Rival Males or Offspring Growth in Multiply Sired Litters of Bank Voles (Myodes glareolus)

“…A particular interesting system for studying this question would be the fossa, Cryptoprocta ferox , in which rival males (that are associated in coalitions) can be either highly related or completely unrelated (Lührs et al. ).…”

Warring arthropod societies: Social spider colonies can delay annihilation by predatory ants via reduced apparency and increased group size

“…The evolution of sociality has afforded group-living predators ample benefits, including 43 advantages gleaned by cooperative hunting (e.g., Lührs, Dammhahn, and Kappeler 2012;Boesch 44 1994; Creel and Creel 1995) and anti-predator defenses via increased group vigilance (Roberts 45 1996; e.g., the 'many eyes' effect; Powell 1974). Thus, sociality undoubtedly plays a major role 46 in mediating countless predator-prey interactions in nature.…”