Contrasting Alternative Hypotheses to Explain Rut-Induced Hypophagia in Territorial Male Chamois Luca Corlatti*† & Bruno Bassano‡ * Research Unit of Behavioural Ecology, Ethology and Wildlife Management, Department of Life Sciences, University of Siena, Siena, Italy † Institute of Wildlife Biology and Game Management, University of Natural Resources and Life Sciences Vienna, Vienna, Austria ‡ Alpine Wildlife Research Centre, Gran Paradiso National Park, Turin, Italy Correspondence Luca Corlatti, Institute of Wildlife Biology and Game Management, Department of Integrative Biology and Biodiversity Research, University of Natural Resources and Life Sciences Vienna, Gregor-Mendel Strasse 33, A-1180 Vienna, Austria. E-mail: luca.corlatti@boku.ac.at Received: August 5, 2013 Initial acceptance: September 16, 2013 Final acceptance: September 21, 2013 (J. Wright) doi: 10.1111/eth.12177 Abstract Male ungulates in temperate environments often show a severe reduction in time spent foraging during the mating season. Several hypotheses have been put forward to explain this phenomenon but, so far, no study inves- tigated the proximate mechanisms underlying rut-induced hypophagia in ungulates using alternative mating tactics (AMTs). Between the pre-rut and post-rut of 2011 and 2012, we collected data on activity budgets, par- asite burden and androgen levels of territorial and non-territorial male Alpine chamois Rupicapra r. rupicapra in the Gran Paradiso National Park (Italy). We aimed to investigate whether AMTs showed similar reduction in time spent foraging during the mating period and to test the predictions underlying alternative hypotheses that may explain rut-induced hypo- phagia. Only territorial males showed a significant reduction in time spent foraging during the rut; the lack of correlation between proportion of time spent foraging and androgen metabolites or parasite burden did not fully support the physiological and the parasite hypotheses, while the foraging constraint, the energy-saving and the physical rest hypotheses could not be discounted. Territorial males decreased the time spent lying down from the pre-rut to the rut, but not their foraging-to-lying-down ratio. During the mating period, we found negative correlations between time spent foraging or lying down and time spent rutting. Our data suggest that terri- torial males’ behaviour is more consistent with the foraging constraint hypothesis than with the energy-saving hypothesis previously suggested. Yet, during the rut territorial males did not maximise their foraging time, and the optimisation of their energy balance could rather depend upon feeding on relatively high-quality plants. This suggestion – possibly named ‘forage quality hypothesis’ – now requires further investigations. This work showed that alternative mating behaviours may underlie different patterns of foraging strategies: we suggest that tests of alternative hypoth- eses to explain rut-induced hypophagia within ungulate populations should not ignore the occurrence of AMTs. Introduction Rut-induced hypophagia, the reduction in time spent foraging during the mating season, is commonly observed in male ungulates in temperate environ- ments (e.g. American bison Bison bison, Bergman et al. 2001; fallow deer Dama dama, Apollonio & Di Vittorio 2004; bighorn sheep Ovis canadensis, Pelletier 2005; Alpine chamois Rupicapra rupicapra, Willisch & Ingold 2007; Alpine ibex Capra ibex, Brivio et al. 2010). Pelletier et al. (2009), however, pointed out the ‘somewhat paradoxical’ nature of this behaviour, as it may potentially affect the overwinter survival for males that already sustain great energy expenditures. To explain why so many ungulate species do employ such a strategy, different authors tested or Ethology 120 (2014) 32–41 © 2013 Blackwell Verlag GmbH 32 Ethology