Aggressive behaviour and nestsite defence during

Authors: José Carrillo Enrique GonzálezDávila

Publish Date: 2013/03/19

Volume: 31, Issue: 2, Pages: 211-218

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Abstract

We examined the changes in the intensity of intraspecific aggression ISA in a kestrel Falco tinnunculus canariensis population throughout the breeding season in order to evaluate the main hypotheses regarding ISA defence of parentage food nestsite and offspring Each pair was presented with a live caged adult male or female as a conspecific intruder The intensity of ISA did not vary significantly during the breeding season and nor did it correlate with offspring value or food availability Our islanddwelling kestrel population showed low fluctuation in ISA during the breeding season and similar levels of aggression in both members of the pair towards male or female intruders These findings support the nestsite defence hypothesis Pairs with more exposed nestsites showed increased ISA unexplained by offspring value We suggest that this behaviour is related with nestsite conspicuousness and vulnerability The pairs displaying greater ISA also showed greater aggression towards humans the main local predator This may indicate that defensive behaviour evolved in the past when it was advantageous against predators and became a trait Compared with the nonisland reference population we only found differences in ISA during the prelaying phase lower intensity of aggressive behaviour between males and higher between femalesWe are indebted to José Miguel Aparicio for encouragement throughout the project We thank Fini Jorge and Cristina—the family of one of us JC—Nicolás Trujillo José Pedro Martín and Carlos Izquierdo for their help in the field The people of the area let us have access to their lands Plácido Marrero showed us the location of some nestsites The Canary Government gave us permission to study and ring a protected species and lent us two permanently disabled kestrels male and female from the Fauna Rehabilitation Centre in Tenerife Michael Lee McLean helped with the English version of the manuscript José Miguel Aparicio Juan Antonio Fargallo Michael Lee McLean and Pablo Vergara offered valuable comments on an earlier version of the manuscript The fieldwork was performed during JC’s affiliation with the Department of Animal Biology Zoology of La Laguna University EGD’s research was partially supported by a Spanish Ministry of Science Project MTM 201016828 The suggestions from the editor and two anonymous reviewers improved the manuscript

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