Alternative reproductive tactics: a fixed trait in a large mammal?

Polygamous species vary in alternative reproductive tactics (ARTs) in relation to individual or environ-mental factors. Individuals may adopt fixed ARTs consistently across years, or may show flexible behaviour, changing tactic in different years. Different cost-benefit trade-offs should occur in relation to the adoption of each ART, possibly also influencing spatial behaviour and thus leading to alternative spatial tactics. Fixed ARTs are rare in mammals, whereas environmental variability is expected to favour flexibility in ARTs. We evaluated the potential for fixed versus flexible ARTs, and their correspondence with different spatial tactics, in a polygynous herbivore, the Alpine chamois, Rupicapra rupicapra rupi-capra. We collected data on mating behaviour of 31 individually recognizable adult males during five rutting seasons and on their spatial behaviour throughout the same years. Fifteen males were classified as territorial and 16 as nonterritorial. No individual changed ART during our research. Moreover, we report a previously undocumented occurrence of different patterns of spatial behaviour across territorial males. Half of these individuals had overlapping or continuous winter and summer ranges, whereas the others moved between different areas (in winter, immediately after the rut, or between summer and autumn). No differences between males adopting diverse ARTs were found in age or body mass, or in their respective frequencies of intrasexual aggressive interactions. On the other hand, territorial males, dominant over nonterritorial individuals in aggressive interactions, had more mating opportunities than nonterritorial ones. Further work should test for the consistency of our results across broader spatial and temporal scales, as well as species. Differences in key aspects of behaviour (e.g. space use) and life history (e.g. reproductive success) would help explain ART evolution and coexistence in a population. If ARTs were fixed in male chamois, neither ART should have been selected against long enough to determine its extinction, over evolutionary times.(c) 2022 The Association for the Study of Animal Behaviour. Published by Elsevier Ltd. All rights reserved.