Effect of social system on allosuckling and adoption in zebras

Abstract

Although nursing non‐filial offspring (allonursing) represents costly behaviour to the female, it occurs in a variety of taxa, including ungulates. The only three currently existing species of zebra differ in their ecology and social system. In the wild, mountain zebra Equus zebra and Grevy's zebra Equus grevyi live in arid environments, while plains zebra Equus quagga inhabit savannahs. Mountain and plains zebra mares form long‐term stable herds associated with a social hierarchy, whereas Grevy's zebra mares form loose associations of short duration. In this study, we investigated the occurrence of allosuckling in three zebra species at the Dvůr Králové Zoo, Czech Republic, during 1626 h of observation. We recorded no successful allosuckling bouts and only 1 and 22 attempts to allosuckle by foals of mountain and plains zebra, respectively, whereas we observed 117 attempts and 13 successful allosuckling bouts by Grevy's zebra foals. Moreover, more than half of all observed Grevy's zebra foals succeeded in allosuckling at least once. When rejecting an allosuckling attempt, Grevy's zebra mares were less aggressive than mountain and plains zebra mares. When a Grevy's zebra mare allowed occasional allosuckling by a non‐filial foal, the probability of long‐term allosuckling was smaller than that in mountain and plains zebra. We also present the first evidence of adoption in Grevy's zebra. We suggest that higher tolerance towards non‐filial offspring, including the occurrence of allosuckling in Grevy's zebra, was affected by the different social systems of zebra species.

Seasonal Patterns of Hormones, Macroparasites, and Microparasites in Wild African Ungulates: The Interplay among Stress, Reproduction, and Disease

“…Breeding and immunity are both expensive and somewhat incompatible, as elevations of one often compromise the other [ 82 ]. However, despite the fact that lactation and estrus behaviors are also very energetically costly [ 83 ], both lactation and FPM significantly predicted higher neutrophil counts in zebras; this may reflect an inflammatory response to the potentially injurious activities against mares of suckling young and mating stallions.…”

Camel Calves as Opportunistic Milk Thefts? The First Description of Allosuckling in Domestic Bactrian Camel (Camelus bactrianus)

“…The youngest calves in the herd were never seen allosucking, despite of the fact that they had the possibility to do it just after joining the herd where other nursing female was present. In other ungulates, except in zebra [33], allosuckling was reported from the first day [4] or the first weeks [11], [20] of the calves' lives. Even calves with the large percentage extent of allosuckling (up to 100%, Table 2) allosucked only occasionally, being weaned by their mothers and using the opportunity to get surplus milk.…”

“…As the gap between the start of sucking and milk let-down is not documented in camels, we consider all bouts longer than 5 seconds as successful as in other studied species e.g. [4], [32], [33]. Sucking bout was considered to terminate when it was interrupted for at least 10 seconds.…”

Time spent suckling is affected by different social organization in three zebra species

“…On the other hand, we revealed higher incidence of allonursing in Grévy's zebra than in plains and mountain zebra, where allonursing was associated with adoption (Olléová, Pluháček & King, ). We suggested that higher tolerance towards non‐filial offspring, including the occurrence of allosuckling in Grévy's zebras, could be affected by different social systems of zebra species as reported in several species of ungulates, rodents and primates (McGuire & Novak, ; Maestripieri, 1994 b ; Ekvall, ; Das, Redbo & Wiktorsson, ; Landete‐Castillejos et al ., ; McGuire et al ., ).…”