Integrating behaviour and conseravtion management: insights from studies on Montagu’s Harriers

Resumen del trabajo presentado a la 9th Conference of the European Ornithologists' Union, celebrada en la University of East Anglia (UK) del 27 al 31 de agosto de 2013.The connections between behavioural sciences and conservation have been emphasized in recent years. Various studies have shown that even descriptive behavioural studies can play a part in solving conservation problems, and that ignoring behavioural data may lead to failure of management programs. There is also a growing interest in behavioural responses to anthropogenic disturbance, and these may also include management programs themselves. The Montagu´s harrier (Circus pygargus) is a groundnesting raptor with two striking characteristics: it is very sociable, being a facultative colonial breeder which may nest in loose groups of up to 20-30 pairs; and it nests mainly within crops in western Europe (its original breeding habitat being grasslands and marshlands). Work with this species has thus focused on two distinct areas. On the one hand, conservation efforts to protect nests and nestlings at harvest time have been carried out for decades in different European countries. On the other hand, studies to evaluate causes and consequences of social behaviour in this species have also been numerous. I review both, highlighting how these two aspects are tightly interrelated. Various empirical and experimental studies have assessed the putative causal factors promoting coloniality in this species. Montagu´s harriers use colonies as platforms to advertise individual quality for mate choice, and social behaviour is associated with more efficient defense against predators and higher interspecific competition for food. Advantages and disadvantages of coloniality are not equally shared among different individuals. Conspecific attraction influences spatial distribution, and explains a mismatch between harrier and resource distributions. Additionally, and as other non-territorial species, Montagu´s harriers may forage at great distances from the nests. These characteristics imply that conservation based on reserves or protected areas is mostly inefficient for this species: occupancy of those reserves for breeding is not directly dependent on reserve quality, and these areas would need to be very large to provide for foraging needs. Cost-efficiency of alternative measures (like negotiating with farmers to delay harvest, leaving an unharvested buffer around the nest, or removal-relocation of nestlings at harvest time) varies according to the number of nests within each field and predation risks, and thus with degree of coloniality. Knowledge of factors influencing the degree of coloniality in given areas, and the relationship between individual quality and social behaviour, may thus help with decision-making for management programs. Finally, data from 17 years research in France suggests that repeated exposure of harriers to humans selects for aggressive individuals. Therefore, “invasive” conservation management (visiting nests and manipulating nestlings to protect at harvest time) may in turn affect their social behaviour and spatial patterns. These data highlight the role animal behaviour plays in conservation practice, and I discuss the advantages of integrating data from both disciplines for developing practical and efficient conservation solutions.Peer Reviewe