Melanin-based colour polymorphism signals aggressive personality in nest and territory defence in the tawny owl ( Strix
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ORIGINAL PAPER
Melanin-based colour polymorphism signals aggressive personality in nest and territory defence in the tawny owl (Strix aluco) Arnaud Da Silva & Valentijn van den Brink & Guillaume Emaresi & Ester Luzio & Pierre Bize & Amélie N. Dreiss & Alexandre Roulin
Received: 23 January 2013 / Revised: 15 March 2013 / Accepted: 15 March 2013 / Published online: 5 April 2013 # Springer-Verlag Berlin Heidelberg 2013
Abstract Nest and territory defence are risky and potentially dangerous behaviours. If the resolution of life history trade-offs differs between individuals, the level of defence may also vary among individuals. Because melanin-based colour traits can be associated with life history strategies, differently coloured individuals may display different nest and territory defence strategies. We investigated this issue in the colour polymorphic tawny owl (Strix aluco) for which plumage varies from dark to light reddish melanic. Accordingly, we found that (1) our presence induced a greater response (flying around) from dark-coloured than light-coloured females and (2) dark reddish males suffered lower nest predation rates than light-coloured males. In experimentally enlarged broods, the probability that females reacted after
we played back the hoot calls of a stranger male was higher if these females were lighter reddish; the opposite pattern was found in experimentally reduced broods with dark parents being more reactive than light parents. Finally, darker females alarmed more frequently when paired with a light than with a dark male, suggesting that partners adjust their behaviour to each other. We also tested whether colouration is used as a signal by conspecifics to adjust the level of their defensive behaviour. Accordingly, breeding females responded more vigorously to a dark than a light reddish stuffed tawny owl placed beside their nest. We conclude that melaninbased colouration is a signal of alternative nest and territory defence behaviour that depends on ecological factors.
Communicated by K. McGraw
Keywords Nest defence . Colour polymorphism . Personality . Pheomelanin . Predation
Arnaud Da Silva and Valentijn van den Brink contributed equally to this work. A. Da Silva : V. van den Brink : G. Emaresi : E. Luzio : P. Bize : A. N. Dreiss : A. Roulin (*) Department of Ecology and Evolution, University of Lausanne, Biophore Building, 1015 Lausanne, Switzerland e-mail: [email protected] A. Da Silva Equipe Ecologie Evolutive, UMR CNRS 5561 Biogéosciences, Université de Bourgogne, 6 Boulevard Gabriel, 21000 Dijon, France Present Address: A. Da Silva Behavioural Ecology and Evolutionary Genetics, Eberhard-Gwinner-Straße, 82319 Seewiesen, Germany
Introduction The life history theory proposes that individuals optimally allocate resources among energy-demanding and time-consuming life history traits (Stearns 1992). Some of the best-known life history trade-offs are resource allocation between reproduction and self-maintenance, between offspring number and quality and between current and future rep
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