When is the bait worth the risk? A mechanistic model of a compensatory ecological trap in seabirds

Abstract

Abstract Ecological traps occur when organisms preferentially select habitats that reduce fitness. In seabird–fishery systems, fishery‐derived trophic subsidies can increase foraging success, reinforce habitat preference and indirectly enhance reproductive output or recruitment, while bycatch simultaneously reduces survival. This subsidy–mortality coupling can generate a compensatory ecological trap when short‐term demographic benefits partly offset survival costs and obscure negative long‐term population consequences. We developed a spatially explicit, individual‐based model to evaluate how compensatory ecological traps emerge from the interplay among trophic subsidies, bycatch mortality and life‐history strategy. The model represented three seabird life‐history strategies—slow, intermediate and fast—and a trade‐off in which trophic subsidies increased energy intake and indirectly enhanced reproductive performance, whereas repeated use of subsidised risky cells increased mortality. Population responses were non‐linear and reflected the joint effects of subsidy level, mortality risk and life history. When mortality risk in subsidised cells was low, trophic subsidies increased population size, particularly in faster life‐history strategies. However, once mortality exceeded life‐history‐specific thresholds, subsidies continued to promote the use of risky areas, increasing exposure to trap mortality and shifting population responses from growth to decline or extinction. Short‐term improvements in reproductive performance sometimes produced transient population growth. Under equivalent behavioural, energetic and subsidy–mortality conditions, slow, albatross‐like life‐history strategies were most vulnerable in terms of long‐term persistence, whereas faster strategies were more resilient and better able to translate additional food intake into positive demographic responses. Trap configuration further modulated these outcomes: negative responses intensified when subsidised risky areas were larger or located in high‐energy habitat. Our results extend ecological‐trap theory by showing how immediate habitat benefits, such as enhanced foraging success, can generate trade‐offs among fitness components and alter trap outcomes across the slow–fast life‐history continuum. They also highlight the need to manage bycatch and trophic subsidies jointly, because their combined effects can reinforce maladaptive habitat selection, increase exposure to mortality and elevate extinction risk. Read the free Plain Language Summary for this article on the Journal blog.