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Oecologia2023; 203(3-4); 435-451; doi: 10.1007/s00442-023-05477-9

Age-specific effects of density and weather on body condition and birth rates in a large herbivore, the Przewalski’s horse.

Abstract: Reproduction in young females can show a particularly sensitive response to environmental challenges, although empirical support from individual-based long-term studies is scarce. Based on a 20-year data set from a free-roaming Przewalski's horse population (Equus ferus przewalskii), we studied effects of large-herbivore density (horses + cattle) and weather conditions experienced during different life stages on females' annual birth rates. Foaling probability was very low in 2-year-olds, reaching maximum values in 5 to 10-year-olds, followed by a decrease in older females indicating reproductive senescence. Mother's previous reproductive investment affected her current reproduction; young and old mothers (as opposed to middle-aged ones), which had nursed a foal for at least 60 days during the previous year, reproduced with a lower probability. Foaling probability and body condition of young females were lower when large-herbivore density was high. Reproduction was also influenced by interactive weather effects during different life stages. Low late-summer precipitation during the females' year of birth was associated with a pronounced decrease in foaling probability in response to harsh late-winter temperatures prior to the mating season. In turn, increased amounts of late-summer rain during this early age together with more late-summer rain during the females' current pregnancy led to an increased reproductive probability in 2-3-year-olds. These results were corroborated by the ameliorating effects of late-summer rain on body condition in such females. In conclusion, our findings highlight the interactive importance of weather conditions experienced during early life, and of density and weather during current pregnancy on foaling probability, particularly in young females.
© 2023. The Author(s).
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Publication Date: 2023-11-16 PubMed ID: 37971561PubMed Central: PMC10684615DOI: 10.1007/s00442-023-05477-9Google 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 paper investigates how the density of large herbivores and weather conditions during various life stages impact the reproduction rates and body conditions of young female Przewalski’s horses. The findings highlight that early life weather conditions, herd population sizes, and weather during pregnancy significantly affect the likelihood of young mares giving birth.

Research Method

  • The study is constructed around 20 years of data on the Przewalski’s horse population, a species of wild horses. This long-term dataset was used to explore the effects of factors like population density and weather conditions on the females’ birth rates.
  • The hint is focused on how these factors, experienced at different life stages, influence the animal’s reproductive probabilities. It particularly examines young two-year-old horses, middle-aged five to ten-year-olds, and older females beyond that age.

Results Findings

  • The research found that foaling probabilities were at their lowest for two-year-olds, peaked in the age bracket of five to ten years, then started to decline in older females – signifying reproductive senescence or decline in fertility with time. Additionally, it was determined that a mother’s previous reproductive investment also influenced her current reproduction success.
  • It was observed both young and old mothers who had nursed a foal for at least 60 days in the previous year reproduced with a lesser probability, when juxtaposed with middle-aged horses. Furthermore, when there was a high density of large herbivores, both the chances of young females giving birth and their general body condition were adversely affected.

Weather Effects

  • The study also produced compelling findings on how variations of weather conditions during multiple life stages influence reproduction. Specifically, a lower amount of late-summer precipitation during the horse’s birth year was linked to a noticeable decrease in foaling probability if there are harsh late-winter temperatures before the mating season.
  • On the contrary, an increase in late summer rain during both the female’s birth year and her current pregnancy was found to heighten the reproductive probability for two to three-year-olds. These observations were substantiated by the way late-summer rain led to better body conditions in these female horses.

Conclusion

  • The research concludes by pointing out the significant effects of early life weather conditions and the interplay of herd densities and weather during a female horse’s current pregnancy on the foaling probability. The implicated sensitivity to environmental changes among Przewalski’s horses underscores the need to consider these factors for their conservation.

Cite This Article

APA
Rödel HG, Ibler B, Ozogány K, Kerekes V. (2023). Age-specific effects of density and weather on body condition and birth rates in a large herbivore, the Przewalski’s horse. Oecologia, 203(3-4), 435-451. https://doi.org/10.1007/s00442-023-05477-9

Publication

Oecologia
ISSN: 1432-1939
NlmUniqueID: 0150372
Country: Germany
Language: English
Volume: 203
Issue: 3-4
Pages: 435-451

Researcher Affiliations

Rödel, Heiko G
  • Laboratoire d'Ethologie Expérimentale et Comparée UR 4443 (LEEC), Université Sorbonne Paris Nord, 93430, Villetaneuse, France. heiko.rodel@univ-paris13.fr.
Ibler, Benjamin
  • Heimat-Tierpark Olderdissen (Bielefeld Zoo), Dornberger Straße 149a, 33619, Bielefeld, Germany.
Ozogány, Katalin
  • HUN-REN-UD Behavioural Ecology Research Group, University of Debrecen, Egyetem tér 1, 4032, Debrecen, Hungary.
  • Department of Evolutionary Zoology and Human Biology, University of Debrecen, Egyetem tér 1, 4032, Debrecen, Hungary.
Kerekes, Viola
  • Department of Evolutionary Zoology and Human Biology, University of Debrecen, Egyetem tér 1, 4032, Debrecen, Hungary. kerekes.violag@gmail.com.
  • Hortobágy National Park Directorate, Sumen utca. 2, 4024, Debrecen, Hungary. kerekes.violag@gmail.com.

MeSH Terms

  • Female
  • Horses
  • Animals
  • Cattle
  • Birth Rate
  • Herbivory
  • Weather
  • Seasons
  • Age Factors

Grant Funding

  • FK123880 / National Research, Development and Innovation Office

Conflict of Interest Statement

The authors declare that they have no conflict of interest.

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Citations

This article has been cited 3 times.
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  2. Bland AL, Plard F, Giura Negru B, Hernández-Pacheco R. Density-dependent feedback across nested levels of organization in a social primate. J Anim Ecol 2025 May;94(5):971-984.
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  3. Chatha MA, Ahmad N, Abbas MA, Saadullah M, Khan JA. Effect of the intrinsic and extrinsic factors on the growth and development of young foals under subtropical conditions of Pakistan. PLoS One 2025;20(1):e0310784.
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