Male incubation feeding in songbirds responds differently to nest predation risk across hemispheres Beata Matysioková a, * , Andrew Cockburn b, 1 , Vladimír Reme  s a a Laboratory of Ornithology, Palacký University b Division of Evolution, Ecology and Genetics, Australian National University article info Article history: Received 10 May 2011 Initial acceptance 1 July 2011 Final acceptance 7 September 2011 Available online 19 October 2011 MS. number: 11-00386 Keywords: comparative analysis incubation feeding life history nest predation parental care songbird Evolution of parental care behaviour has been of considerable interest to behavioural ecologists for a long time. Incubation feeding, where an individual incubating eggs is provisioned by another indi- vidual, is an important component of avian parental care. It may be critical for breeding success by allowing the incubating bird to spend more time on the eggs. However, very little is known about environmental factors shaping incubation feeding, and incubation behaviour in general, of tropical and southern hemisphere birds, and how this differs compared to northern hemisphere species. We collated available data on the rate of incubation feeding in Australian, New Zealand and North American songbirds (78 species from 25 families). There was a strong positive relationship between female incubation attentiveness and incubation feeding by males; however, female attentiveness was higher in North America than in Australia and New Zealand for the same intensity of male incubation feeding. Incubation feeding was not related to species body mass, social organization, geographical latitude or ambient temperature. It differed significantly between families, but overall was not different between regions. Incubation feeding rate was related to nest predation rate, but differently in the two regions. It increased with nest predation rate in Australia and New Zealand, but decreased with nest predation rate in North America. We suggest that this may be caused by different predatoreprey interactions in North America versus Australia and New Zealand, which could have shaped the evolution of incubation feeding differently. Ó 2011 The Association for the Study of Animal Behaviour. Published by Elsevier Ltd. All rights reserved. Understanding why species differ in patterns and intensity of parental care is a major focus of evolutionary behavioural studies (Clutton-Brock 1991). One of the key components of parental care in egg-laying organisms is caring for eggs (Deeming 2002). In birds, incubation of eggs is energetically demanding (Williams 1996; Thomson et al. 1998) and thus it can negatively influence condition and/or survival of the incubating individual (de Heij et al. 2006). In bird species with uniparental incubation, the female is usually responsible for incubating the eggs (Deeming 2002). Hence, she faces a trade-off between time- and energy-consuming incubation behaviour and foraging for self-maintenance (Drent 1975; Mertens 1977). Males may feed the female during incubation (incubation feeding; Cottam 1941; Matysioková 2010), and this behaviour may be critical for maintaining female condition and incubation effort (von Haartman 1958; Røskaft 1983; Lyon & Montgomerie 1985). Incubation feeding is widespread in birds (Kendeigh 1952), but species differ in the intensity of this behaviour (Martin & Ghalambor 1999). This interspecific variability could be related to various environmental selective forces. For example, latitude is a strong predictor of life history characteristics, including clutch size and adult survival (Ghalambor & Martin 2001). Thus, given that life history theory predicts a positive correlation between parental effort and adult mortality (Roff 1992), we might expect higher incubation feeding rates in areas with low adult survival. Species breeding in thermally extreme environments must protect their progeny from the negative effects of extreme temperatures. This effect could be even stronger during incuba- tion, because the developing embryo is sensitive to both very low (below 26  C) and very high (above 40.5  C) temperatures (Webb 1987; Conway & Martin 2000a). Thus, we might expect higher incubation feeding rates in species experiencing extreme ambient temperatures. Species might differ in parental care on the basis of their social organization as well. Males in species with helpers could be able to provide incubating females with more food that those that breed in pairs. Alternatively, male breeders in social * Correspondence: B. Matysioková, Laboratory of Ornithology, Department of Zoology, Palacký University, T r. Svobody 26, 77146 Olomouc, Czech Republic. E-mail address: betynec@centrum.cz (B. Matysioková). 1 A. Cockburn is at the Division of Evolution, Ecology and Genetics, Research School of Biology, Australian National University, Canberra, ACT 0200, Australia. Contents lists available at SciVerse ScienceDirect Animal Behaviour journal homepage: www.elsevier.com/locate/anbehav 0003-3472/$38.00 Ó 2011 The Association for the Study of Animal Behaviour. Published by Elsevier Ltd. All rights reserved. doi:10.1016/j.anbehav.2011.09.018 Animal Behaviour 82 (2011) 1347e1356