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The role of males in the dynamics of ungulate populations

  1. Atle Mysterud1,
  2. Tim Coulson2,
  3. Nils Chr. Stenseth1,*

Article first published online: 1 NOV 2002

DOI: 10.1046/j.1365-2656.2002.00655.x

Issue

Journal of Animal Ecology

Journal of Animal Ecology

Volume 71, Issue 6, pages 907–915, November 2002

Additional Information

How to Cite

Mysterud, A., Coulson, T. and Stenseth, N. Chr. (2002), The role of males in the dynamics of ungulate populations. Journal of Animal Ecology, 71: 907–915. doi: 10.1046/j.1365-2656.2002.00655.x

Author Information

  1. 1

    Department of Biology, Division of Zoology, University of Oslo, PO Box 1050 Blindern, N-0316 Oslo, Norway, and

  2. 2

    Large Animal Research Group, Department of Zoology, University of Cambridge, Cambridge CB2 3EG, UK

* Nils Chr. Stenseth, Department of Biology, Division of Zoology, University of Oslo, PO Box 1050 Blindern, N-0316 Oslo, Norway. Tel: +47 22 85 45 61; Fax: +47 22 85 46 05; E-mail: n.c.stenseth@bio.uio.no

Publication History

  1. Issue published online: 1 NOV 2002
  2. Article first published online: 1 NOV 2002
  3. Received 10 December 2001; revision received 14 May 2002

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Keywords:

  • calving dates;
  • calving synchrony;
  • demography;
  • log-linear models;
  • second-order processes;
  • sexual body-size dimorphism

Summary

  • 1
    In this review, we focus on how males can affect the population dynamics of ungulates (i) by being a component of population density (and thereby affecting interpretation of log-linear models), and (ii) by considering the mechanisms by which males can actively affect the demographic rates of females.
  • 2
    We argue that the choice of measure of density is important, and that the inclusion or exclusion of males into models can influence results. For example, we demonstrate that if the dynamics of a population can be described with a first-order auto-regressive process in a log-linear framework, the asymmetry between the effects of females on the male dynamics and vice versa can introduce a second order process, much in the same way that the interaction between disease and host or predator and prey can. It would be useful for researchers with sufficient data to explore the affects of using different density measures.
  • 3
    In general, even in harvested populations with highly skewed sex ratios, males are usually able to fertilize all females, though detailed studies document a lower proportion of younger females breeding when sex ratios are heavily female biased. It is well documented that the presence of males can induce oestrus in females, and that male age may also be a factor. In populations with both a skewed sex ratio and a young male age structure, calving is delayed and less synchronous. We identify several mechanisms that may be responsible for this.
  • 4
    Delayed calving may lower summer survival and autumn masses, which may lead to higher winter mortality. If females are born light, they may require another year of growth before they start reproducing. Delayed calving can reduce future fertility of the mother. As the proportion of calves predated during the first few weeks of life is often very high, calving synchrony may also be an important strategy to lower predation rates.
  • 5
    We argue that the effects of males on population dynamics of ungulates are likely to be non-trivial, and that their potential effects should not be ignored. The mechanisms we discuss may be important – though much more research is required before we can demonstrate they are.
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