Physiological stress in eastern black rhinoceros (Diceros bicornis michaeli) as influenced by their density, climatological variables and sexes

Okita-Ouma, Benson; Gort, Gerrit; Millspaugh, Joshua J.; Prins, Herbert H. T. (2024). Physiological stress in eastern black rhinoceros (Diceros bicornis michaeli) as influenced by their density, climatological variables and sexes. African Journal of Ecology, 62(1) Wiley 10.1111/aje.13239

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It is important to understand the physiological stressors in animals especially for threatened species or intensively managed to improve their conservation and optimise their reproduction. We sought to understand changes in stress hormones (faecal glucocorticoid metabolites) in black rhinoceros (Diceros bicornis michaeli) in relation to population density and sex (intrinsic factors) and plant minerals, rainfall and land surface temperature (extrinsic factors). We used non-invasive faecal sampling techniques on animals of known sex, age and dominance in seven populations of contrasting population densities over 1 year. We measured variability in faecal corticosterone metabolites through radioimmunoassay and related them to population density, sex and faecal calcium, phosphorus, copper, zinc and potassium as characteristic of plant minerals, rainfall and temperature. We used linear mixed models (LMM) to analyse the data. We did not detect a significant relationship between physiological stress parameters and population density. However, we have indications that stress levels increased as rainfall and temperature increased and were correlated negatively and positively with concentration of faecal phosphorus and copper respectively; we found higher stress levels in females than in males. These results suggest that both intrinsic and extrinsic factors explain the variation in physiological stress observed in black rhinoceros.

Item Type:

Journal Article (Original Article)

Division/Institute:

10 Strategic Research Centers > Wyss Academy for Nature

ISSN:

0141-6707

Publisher:

Wiley

Language:

English

Submitter:

Madlaina Michelotti

Date Deposited:

16 Feb 2024 08:46

Last Modified:

16 Feb 2024 08:54

Publisher DOI:

10.1111/aje.13239

BORIS DOI:

10.48350/192957

URI:

https://boris.unibe.ch/id/eprint/192957

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