Behavior

Adolescent Black Rhinos

 In the wild, dispersal of two male calves occurred at three to four years of age. In contrast, females continued to maintain a home range overlapping that of their mother into adulthood, and disassociations were usually temporary following the birth of a new calf (Lent and Fike, 2003). If a cow and calf are separated from other rhinos at zoological institutions, they may be reintroduced following the cow’s first estrus (Fouraker and Wagener, 1996).

Behaviors Specific to Zoo-Managed Rhinos

A common behavioral abnormality observed in zoo-managed rhinos is excessive horn rubbing (Hutchins and Kreger, 2006), which might indicate boredom or distress, e.g., when rhinos are housed indoors without activity or forage (Dieckhoefer et al., 2006). Stereotypical behaviors among female black rhinos were associated with a greater percentage of wall space over which the rhino could not see, whereas males’ stereotypical behavior was positively correlated with chlorine use (Carlstead et al., 1999a), possibly because it masks or removes their own scent marks. Males that scored higher for “fear” were housed at facilities where there was a greater percentage of outdoor enclosure perimeter that allowed zoo visitors to have unobstructed view into the enclosure at a distance of less than 10 m (32.8 ft)(Carlstead et al., 1999a). This finding is not unexpected given the observation that wild black rhinos choose bedding sites enclosed by tall vegetation and dense thickets (Tatman et al., 2000), suggesting this species prefers the security offered by cover. Fighting among zoo-housed black rhinos was associated with variability in glucocorticoid metabolites, which are secreted during the adrenal stress response (Carlstead and Brown, 2005).

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Behavior During Introductions (from Fouraker and Wagener, 1996)

Aggression between newly introduced black rhinos can be severe, especially if a new rhino(s) is being introduced to an established rhino(s) (Hall-Martin and Penzhorn, 1977). Thus, a “howdy” period and plenty of space for escape upon the first physical introduction is highly advisable. Rhinos of both sexes have been the aggressors. Behaviors that have been noted during rhino introductions are listed in Table 3.27. Territorial defense is often limited to ritualized confrontations, in which two rhinos advance toward each other but stop and engage in a horn to-horn stare (Tables 3.25 and 3.27). Also as part of this ritual, the two individuals may touch horns, back apart, and wipe their horns on the ground (Nowak, 1991). More intensive conflicts (Table 3.28) involve charges and inflicting injuries by horning or ramming. It is important to note that what is often perceived as serious or dangerous aggression between rhinos is, in fact, normal behavior requiring no intervention of any kind. Along with increased size and thick skin comes decreased vulnerability compared with many other animals. In some cases, aggression may proceed to a point at which management should intervene to prevent serious injury. Rhino managers should allow some aggression during an introduction but be prepared to intervene in the event that aggression threatens the lives of one or more animals. Protocols for intervening may vary across institutions, but in general, careful consideration should be given to intervening in an introduction before aggression reaches Level 5 (Table 3.28). Stopping an introduction at a level prior to this will not lessen aggression during a subsequent introduction attempt. Animals that are allowed to “settle their differences” will establish some territorial boundaries and usually will not engage in serious aggression again, with the exception of a male attempting to approach an estrous female. In sum, moderate aggression is commonplace in any rhino introduction; sparring and fighting will occur and result in minor injuries (cutaneous wounds). However, in most cases, aggression levels prior to Level 5 may be allowed to continue using the discretion of management. Animal personality and disposition should always be considered in introductions. A subordinate animal should be introduced to a more dominant animal in an enclosure familiar to the subordinate. In the case of multiple-animal introductions, the most subordinate animal should be introduced to the next most subordinate, and so on up the dominance hierarchy. Greater aggression may be noted in some individuals in the presence of an estrous female; therefore, any introduction attempt at this time should be especially well-monitored or possibly avoided if the attempt involves a male. Aggression may be meaningfully reduced by allowing individuals to become familiar with each other through protected contact (e.g., through enclosure bars) or, possibly, by exposing them to one another’s odors for a period prior to introduction.

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