Scale‐dependent foraging tradeoff allows competitive coexistence

Abstract

In spatially heterogeneous environments, coexistence between competing species can be facilitated by spatially mediated tradeoffs. In this paper we develop a mechanistic model to investigate under which circumstances interspecific differences in the tradeoff between foraging efficiency and travel costs can allow two central place foraging species to coexist in spite of considerable overlap in resource use. One species (Flyer) has a high basal metabolic rate, but a low relative cost of travelling such that it can use patches at a greater distance from its central place while the minimum patch quality it can economically use is high. The other species (Forager), by contrast, has a lower basal metabolic rate, but higher relative cost of travelling, and can therefore be a more efficient forager and able to use foraging patches of low quality, as long as they are not too far from the nest. We demonstrate that the coexistence of these two species critically depends on landscape composition and structure, with the Flyer outcompeting the Forager in structurally simple, coarse‐grained, landscapes with abundant high‐quality forage and the Forager outcompeting the Flyer in fine‐grained highly diverse landscapes. Coexistence between the two species is possible when the landscape is structurally and compositionally complex, fine‐grained, and has both high and low quality forage. Our results demonstrate that exploitative competition between two contrasting life histories can produce very different community dynamics depending on landscape composition and structure.