Attack success in Bonelli’s Eagle Aquila fasciata José Enrique Martínez*, Iñigo Zuberogoitia, Ginés Gómez, José Manuel Escarabajal, Ester Cerezo, María Victoria Jiménez-Franco & José Francisco Calvo J.E. Martínez, Bonelli’s Eagle Study and Conservation Group. Apdo. 4009, E-30080 Murcia, Spain; present address: Departamento de Ecología e Hidrología. Universidad de Murcia. Campus de Espinardo, E-30100 Murcia, Spain. * Corresponding author’s e- mail: ecoljemt@um.es I. Zuberogoitia, Estudios Medioambientales Icarus S.L. Pintor Sorolla 6, 1° C. E-26007 Logroño, Spain G. Gómez, J.M. Escarabajal & E. Cerezo, Bonelli’s Eagle Study and Conservation Group. Apdo. 4009, E-30080 Murcia, Spain M.V. Jiménez-Franco & J.F. Calvo, Departamento de Ecología e Hidrología. Universidad de Murcia. Campus de Espinardo, E-30100 Murcia, Spain Received 11 March 2013, accepted 18 November 2013 This paper presents the first study of foraging behaviour and hunting success in Bonelli’s Eagle. Attack success was modelled as a function of biological and environmental vari- ables using observations made during a long-term monitoring. The overall attack success was 28.2%, based on 110 attack observations recorded between 1985 and 2008 in south- eastern Spain. Group size of prey was the most explicative independent variable, indicat- ing that the probability of attack success declined with increasing prey group size. Sur- prise was the main and most successful attack mode, mainly on preys foraging on the ground. The probability of success in surprise and non-surprise attacks probably declined with prey group size due to the effects of vigilance and confusion, respectively. The best model for attack success also suggested that attacks were more likely to be successful when directed at prey in areas with low bush canopy cover. This finding highlights the im- portance of open habitat types which provide foraging opportunities for the Bonelli’s Eagle. Management measures for increasing open habitats in territories may create a habi- tat structure more favourable for prey detection by Bonelli’s Eagles. 1. Introduction Many prey-related factors may affect hunting suc- cess, such as species, behaviour and vulnerability (Quinn & Cresswell 2004, Cresswell et al. 2010), sex and age (Kenward 2006) and group size (Ken- ward 1978, Lindström 1989, Funston et al. 2001, Roth & Lima 2003, Cresswell & Quinn 2010). Al- ternatively, from the predator point of view, hunt- ing success may be related to the type of predator, sex and age or experience (Desrochers 1992, Rutz et al. 2006, Daunt et al. 2007), but also by the indi- vidual characteristics of the predator (Sand et al. 2006). Finally, environmental factors such as sea- son, habitat type (Redpath et al. 2002, Blumstein et al. 2004, Ebensperger & Hurtado 2005, Katzner Ornis Fennica 91:67–78. 2014