Linking behavior and conservation: The population consequences of reproductive conflict in an endangered bird

The importance of understanding population dynamics from an individual and behavior-based perspective is becoming increasingly accepted. Evolutionary theory predicts that reproductive conflicts will decrease population performance, but this principle has not been applied to real-life conservation. Territoriality is a form of conflict that has often been argued to stabilize population dynamics; however competition for breeding sites can interfere with breeding attempts of established territory owners. Here we show that this process has significantly delayed the recovery of a critically endangered species. Seychelles Magpie Robins Copsychus sechellarum live in social groups in which subordinate presence increases aggression and the takeover frequency of established breeders. Takeovers delay offspring production to an extent that delays the recovery of the species by 33% in simulated populations parameterized with field data. Conflict thus can extend the period of high extinction risk, which we show to have population consequences that should be taken into account in management programs. Moreover, when territories differ in food availability, higher competition for the better territories strongly decreases their productivity. In homogeneous habitats, this effect is weaker and the population is more productive. Manipulating conflict, e.g. by reducing variance in habitat quality, could therefore prove an effective conservation measure in species with strong social conflict.