Reproductive non-seasonality in rhinoceroses: A review of the in-situ literature and birth records of ex-situ institutions

Mammals whose breeding activity is triggered by seasonal photoperiodic cues typically maintain seasonal reproduction in zoos, with births accumulating to various degrees in spring. For zoo-kept rhinoceroses, accumulation of births in autumn has been suggested, which would make this group unusual. We compare birthing (and hence conception) patterns of free-ranging rhinoceros populations from the scientific literature with those of the global zoo populations based on birth data available from Species360, to facilitate deductions on the cues that trigger rhinoceros reproduction. The patterns do not indicate a photoperiodic element in rhinoceros reproduction but suggest suppression of conception in free-ranging populations at times of resource scarcity. This is not evident in zoos. However, a slight accumulation of autumn births, due to a slight reduction in births in spring, is visible in the zoo populations. Given rhinoceros gestation periods, this is linked to reduced conceptions in November–December. The most parsimonious interpretation is management-related, as has been suggested (Roth 2006, Int. Zoo Yb. 40(1): 130–143): not all facilities are prepared to allow mating at times when outdoor husbandry is reduced due to weather restrictions. Given the long interbirth intervals of rhinoceroses, missed conception opportunities of 1–2 months are unlikely to affect population demographics. Nevertheless, detailed recording of approaches to facilitate mating during winter months by those zoos that achieve this may increase the general skill of rhinoceros management. DOI: https://doi.org/10.19227/jzar.v10i1. 628 Posted at the Zurich Open Repository and Archive, University of Zurich ZORA URL: https://doi.org/10.5167/uzh-215262 Journal Article Published Version The following work is licensed under a Creative Commons: Attribution 3.0 Unported (CC BY 3.0) License. Originally published at: Radeke-Auer, Katharina; Wittwer, Anita; Aust, Julia; Roller, Marco; Müller, Dennis W H; von Houwald, Friederike; Steck, Beatrice; Biddle, Rebecca; Versteege, Lars; Clauss, Marcus (2022). Reproductive nonseasonality in rhinoceroses: A review of the in-situ literature and birth records of ex-situ institutions. Journal of Zoo and Aquarium Research, 10(1):23-30. DOI: https://doi.org/10.19227/jzar.v10i1. 628 O P E N A C C E S S JZ AR R es ea rc h ar tic le Journal of Zoo and Aquarium Research 10(1) 2022 https://doi.org/10.19227/jzar.v10i1. 628 23 O P E N A C C E S S Research article Reproductive non-seasonality in rhinoceroses: A review of the in-situ literature and birth records of ex-situ institutions Katharina Radeke-Auer1, Anita Wittwer1, Julia Aust1, Marco Roller2, Dennis W.H. Müller3, Friederike von Houwald4,5, Beatrice Steck4, Rebecca Biddle6, Lars Versteege7 and Marcus Clauss1 Clinic for Zoo Animals, Exotic Pets and Wildlife, Vetsuisse Faculty, University of Zurich, Winterthurerstrasse 260, 8057 Zurich, Switzerland 2Zoological Garden of Karlsruhe, Ettlinger Str. 6, 76137 Karlsruhe, Germany 3Zoological Garden of Halle, Fasanenstrasse 5a, 06114 Halle (Saale), Germany 4Zoological Garden of Basel, Binningerstrasse 40, 4054 Basel, Switzerland 5Zoological Garden of Bern, Tierparkweg 1, 3005 Bern, Switzerland 6Twycross Zoo East Midland Zoological Society, Norton Grange, Norton-Juxta-Twycross, Atherstone, Warwickshire, CV9 3PX, United Kingdom 7Safaripark Beekse Bergen, 5081 NJ Hilvarenbeek, The Netherlands Correspondence: Marcus Clauss, email; mclauss@vetclinics.uzh. ch