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Home / Equine Research Bank / Proc Biol Sci / Poor horse traders: large mammals trade survival for reprodu...
Proceedings. Biological sciences2009; 276(1663); 1911-1919; doi: 10.1098/rspb.2008.1828

Poor horse traders: large mammals trade survival for reproduction during the process of feralization.

Abstract: We investigated density dependence on the demographic parameters of a population of Camargue horses (Equus caballus), individually monitored and unmanaged for eight years. We also analysed the contributions of individual demographic parameters to changes in the population growth rates. The decrease in resources caused a loss of body condition. Adult male survival was not affected, but the survival of foals and adult females decreased with increasing density. Prime-aged females maintained high reproductive performance at high density, and their survival decreased. The higher survival of adult males compared with females at high density presumably results from higher investment in reproduction by mares. The high fecundity in prime-aged females, even when at high density, may result from artificial selection for high reproductive performance, which is known to have occurred in all the major domestic ungulates. Other studies suggest that feral ungulates including cattle and sheep, as these horses, respond differently from wild ungulates to increases in density, by trading adult survival for reproduction. As a consequence, populations of feral animals should oscillate more strongly than their wild counterparts, since they should be both more invasive (as they breed faster), and more sensitive to harsh environmental conditions (as the population growth rate of long-lived species is consistently more sensitive to a given proportional change in adult survival than to the same change in any other vital rate). If this principle proves to be general, it has important implications for management of populations of feral ungulates.
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Publication Date: 2009-03-04 PubMed ID: 19324787PubMed Central: PMC2674491DOI: 10.1098/rspb.2008.1828Google Scholar: Lookup
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  • Journal Article

Summary

This research summary has been generated with artificial intelligence and may contain errors and omissions. Refer to the original study to confirm details provided. Submit correction.

The research focuses on how a population of Camargue horses trade survival for reproduction during feralization, where high-density environments and diminished resources impact the survival rates of foals and adult females, while males remain unaffected. This is due to higher investment in reproduction by females.

Investigation Process

  • Researchers monitored a population of Camargue horses over eight years to observe demographic behaviors in unmanaged conditions.
  • Particular focus was given to the impact of environment density, which refers to the quantity of horses in relation to available resources.
  • Over time, recorded data revealed changes in the horses’ body conditions, survival rates and reproductive performance.

Key Findings

  • Increasing density of horses, coupled with a decrease in available resources, led to worsening health or body conditions among the herd.
  • While the survival rate of adult males remained unaffected by density, both foals and adult female survival rates declined as density increased.
  • Despite the decreased survival rates and high-density conditions, reproduction rates among prime-aged females remained high. Researchers attribute this to the evolutionary selection for high fertility, a trait seen in major domestic ungulates.
  • The study proposes that adult male survival rates remained stable as female horses bore most of the reproductive responsibilities, even in resource-depleted environments.

Comparisons and Implications

  • The study compares this behavior with other feral ungulates, such as cows and sheep, suggesting a pattern of trading survival rates for continued high reproduction rates amongst feral populations.
  • The behavior contrasts with wild ungulates which maintain balanced survival and reproduction rates in high-density landscapes.
  • As a result of these trading behaviors, feral animal populations may experience more severe population fluctuations than their wild counterparts, due to rapid breeding rates alongside sensitivity to harsh environments.
  • Understanding these behaviors is critical in managing feral animal populations and creating proper conservation strategies to ensure both survival and reproductive health.

Cite This Article

APA
Grange S, Duncan P, Gaillard JM. (2009). Poor horse traders: large mammals trade survival for reproduction during the process of feralization. Proc Biol Sci, 276(1663), 1911-1919. https://doi.org/10.1098/rspb.2008.1828

Publication

Proceedings. Biological sciences
ISSN: 0962-8452
NlmUniqueID: 101245157
Country: England
Language: English
Volume: 276
Issue: 1663
Pages: 1911-1919

Researcher Affiliations

Grange, Sophie
  • Centre d'Etudes Biologiques de Chizé, CNRS UPR 1934, 79360 Beauvoir-sur-Niort, France. sophie_zebes@yahoo.fr
Duncan, Patrick
    Gaillard, Jean-Michel

      MeSH Terms

      • Age Factors
      • Animals
      • Animals, Wild / anatomy & histology
      • Animals, Wild / physiology
      • Body Constitution
      • Female
      • Fertility
      • Horses / anatomy & histology
      • Horses / physiology
      • Longevity
      • Male
      • Population Density
      • Population Dynamics
      • Reproduction
      • Sexual Behavior, Animal

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      Citations

      This article has been cited 8 times.
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      2. Harvey AM, Ramp D, Mellor DJ. Review of the Foundational Knowledge Required for Assessing Horse Welfare.. Animals (Basel) 2022 Dec 1;12(23).
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      3. Robbins AM, Manguette ML, Breuer T, Groenenberg M, Parnell RJ, Stephan C, Stokes EJ, Robbins MM. Population dynamics of western gorillas at Mbeli Bai.. PLoS One 2022;17(10):e0275635.
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      4. Douhard F, Douhard M, Gilbert H, Monget P, Gaillard JM, Lemaître JF. How much energetic trade-offs limit selection? Insights from livestock and related laboratory model species.. Evol Appl 2021 Dec;14(12):2726-2749.
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      5. Harvey AM, Morton JM, Mellor DJ, Russell V, Chapple RS, Ramp D. Use of Remote Camera Traps to Evaluate Animal-Based Welfare Indicators in Individual Free-Roaming Wild Horses.. Animals (Basel) 2021 Jul 15;11(7).
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      6. Harvey AM, Beausoleil NJ, Ramp D, Mellor DJ. A Ten-Stage Protocol for Assessing the Welfare of Individual Non-Captive Wild Animals: Free-Roaming Horses (Equus Ferus Caballus) as an Example.. Animals (Basel) 2020 Jan 16;10(1).
        doi: 10.3390/ani10010148pubmed: 31963232google scholar: lookup
      7. Debeffe L, Poissant J, McLoughlin PD. Individual quality and age but not environmental or social conditions modulate costs of reproduction in a capital breeder.. Ecol Evol 2017 Aug;7(15):5580-5591.
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      8. Richard E, Simpson SE, Medill SA, McLoughlin PD. Interacting effects of age, density, and weather on survival and current reproduction for a large mammal.. Ecol Evol 2014 Oct;4(19):3851-60.
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