Male age structure influences females’ mass change during rut in a polygynous ungulate: the reindeer (Rangifer tarandus) |
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Authors: | Ø Holand R B Weladji K H Røed H Gjøstein J Kumpula J-M Gaillard M E Smith M Nieminen |
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Institution: | 1. Department of Animal and Aquacultural Sciences, Norwegian University of Life Sciences, P.O. Box 5003, 1432, ?s, Norway 2. Department of Morphology, Genetics and Aquatic Biology, Norwegian School of Veterinary Medicine, P.O. Box 8146, Dep. 0033, Oslo, Norway 3. Finnish Game and Fisheries Research Institute, Reindeer Research Station, 99910, Kaamanen, Finland 4. Laboratoire de Biométrie et Biologie Evolutive (UMR 5558), CNRS, Université Lyon 1, 43 Bd 11 Novembre, 69622, Villeurbanne, Cedex, France
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Abstract: | The manipulation of the sex ratio and age structure in many managed ungulate populations calls for a better understanding
of their potential consequences on females’ condition and behavior during rut. During 1996–2002, we manipulated the male age
structure and male percentage (nine treatments during 7 years) within an experimental herd of semidomestic reindeer (Rangifer tarandus) and investigated their influence on both the body mass change and the behavior of females during rut. On average, the females
lost body mass (−0.95±SE 0.18 kg) during rut, which we contend to reflect somatic costs. The females’ losses increased as
the percentage of male decreased, but this was certainly ascribed to one treatment with high male percentage (27.7%) as compared
to the others (ranging from 3.9 to 12.2%). Female losses were highest for treatments including both young and adult males
as compared to only adult or only young males, and higher for treatments including only young compared to only adult males.
This is supported by (1) the higher female harassment frequency when females are exposed to only young or a mixture of young
and adult males as compared to only adults, (2) the higher female harassment frequency by young males as compared to adults
in the mixed treatments, and (3) the reduced females’ feeding activity in treatments including both young and adult males.
We conclude that the male age structure during rut will influence the females’ behavior and mass change and may have implications
for females’ life history and for population dynamics. |
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Keywords: | Male age structure Mating tactics Somatic cost Females’ behavior Rangifer tarandus |
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