University of Central Florida Undergraduate Research Journal - Social Behavior in a Herd of Captive Male Giraffes
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Social Behavior in a Herd of Captive Male Giraffes

By: Patrick Ziarnowski and Kaidi Fenrich | Mentor: Frank Logiudice

Results

1.1 Affiliative Gestures

Affiliative gestures in the giraffe are comprised of behaviors including social exams, rubbing, following, cofeeding, and co-browsing (Bashaw, 2004). The giraffes in our study were sometimes observed placing their snouts close to the body of another giraffe, not including the anogenital region, to presumably sniff, a behavior constituting a social exam. Rubbing also sometimes occurred, with one giraffe rubbing his head or neck against the neck or torso of another. For example, Emba, the adult giraffe, sometimes rubbed his head against the body or neck of Rafiki, and Gage typically rubbed against Rafiki before initiating sparring.

All three male giraffes in our study were observed socially examining the others (Table 1). Gage primarily sniffed Rafiki, and Emba also primarily sniffed Rafiki. Rafiki preferentially sniffed Gage. In contrast, not all giraffes socially rubbed against the other giraffes (Table 2): Emba only rubbed against Rafiki, and Gage only rubbed against Rafiki. In five instances, Rafiki rubbed against Gage, but was never observed to rub against Emba. The data suggests that the eldest giraffe possessed social preferences, as his behavior was nonrandomly distributed between the two subadult giraffes. Meanwhile, the observations of social rubbing and social exams by the two subadult giraffes conformed to our expectation that affiliative behavior by subadult giraffes would be more commonly directed to a giraffe equal in dominance ranking.

In ten instances, Rafiki and Gage co-fed, and in fortysix instances, Rafiki and Gage co-browsed. Either Gage or Rafiki would typically walk away after less than one minute, although they had been observed co-browsing for as long as five minutes. These observations confirm our expectation that co-browsing and co-feeding would be limited to giraffes close in the dominance hierarchy.

1.2 Courtship and Mate Guarding

Emba frequently sniffed the anogenital region of Rafiki, after which he would typically stand tall, following Rafiki whenever he walked away. This behavior is consistent with courtship by male giraffes in the wild (Pratt and Anderson, 1985). More recently, the aforementioned behavior has been explained as mate guarding when it accompanies mounting attempts, enabling the male to restrict access to the female at the expense of browsing time (Bercovitch et al., 2006). On all of the days this behavior was observed, Emba investigated Rafiki on multiple occasions. These periods of close following sometimes lasted over 20 minutes, and, frequently, less than 5&38211;10 minutes of browsing separated sessions before Emba resumed investigating Rafiki. Sometimes after being investigated, Rafiki urinated, which Emba typically sampled and then flehmened. Additionally, Emba was sometimes observed with his penis unsheathed as he stood tall behind Rafiki; his erections were only observed during periods of persistent following and during attempts to mount.

In response to Emba standing tall behind him, Rafiki often pointed his snout upwards, consistent with Dagg’s (1976) description of submissive gestures where one giraffe adopts a posture as if to browse with the neck exposed. Pointing the snout up is also a behavior observed in juvenile males and young bulls during sparring. Pratt and Anderson (1985), who found no evidence that it was a threat display or submissive gesture, also observed the snout up behavior in juvenile females when a mature bull passed by them, which they interpreted as a sign of sexual arousal, as it often accompanied urinating. The context in which Rafiki assumed a snout up posture appeared consistent with the behavior being an indication of submission, as suggested by Dagg. However, Rafiki often elevated his snout such that it was nearly touching Emba’s snout, and in multiple instances Rafiki made snout–snout contact with Emba. On more than one occasion, Emba hit Rafiki immediately after Rafiki made contact with his snout.

We recorded over one hundred fifteen instances of flehmen responses (Table 3). Emba, being the oldest and the dominant animal in the herd, was typically the one investigating and flehmening, as expected; however, Rafiki has also demonstrated investigating behavior. There were no instances of Gage conducting the flehmen response, though we observed him conducting anogenital exams.

Gage was rarely investigated by either of the other two, and Emba was never seen following Gage for any significant length of time. When Rafiki investigated Gage, it was occasional and was never followed or preceded by an extended period of following. In eight instances, Rafiki conducted the flehmen response after investigating Gage.

A giraffe husbandry manual published online in 2003 noted similar sociosexual behaviors as above between males, specifically urine testing and mounting, occurring in retired bulls and in bulls that have not yet mated (Jolly, 2003). The literature lacks other examples of such behavior in captivity. Due to the lack of females, and the motivation to perform these sociosexual behaviors, the bull performs these behaviors with other male giraffes. Our study did not expect to find the degree of sociosexual behaviors as was performed by the dominant giraffe. Specifically, while male-male mounting was expected, the courtship-like behaviors, including anogenital exams with extensive following, was not expected.

Surprisingly, Emba demonstrated sociosexual behaviors—specifically anogenital exams and flehmen responses—most often performed by male giraffes towards female giraffes. In addition, he preferentially performed such behavior on one giraffe, as he did with affiliative gestures. As expected, the oldest and most dominant giraffe conducted the majority of flehmen responses, and the youngest, still maturing giraffe performed none.

1.3 Sparring and Hitting

Rafiki and Gage engaged in a total of 24 sparring matches, each generally exchanging an equal number of gentle blows. One giraffe would swing his neck toward the other’s neck or torso, typically twisting his head and landing his ossicones against the torso or neck of the other. They frequently also pressed their bodies sideways into one another at the hindquarters, as well as at the shoulder region. Rafiki and Gage were sometimes observed swinging gently almost simultaneously. More often than not, Gage initiated the sparring and on some days hit Rafiki much more often than conversely. Sparring was noted to occur for as long as twenty minutes in this study, although the majority of matches observed lasted less than ten minutes. Emba sometimes approached Rafiki and Gage while they were sparring, which appeared to have the effect of concluding the match. In one instance, Emba joined a sparring match between Rafiki and Gage by standing next to Rafiki and beginning to swing gently.

On multiple occasions, Emba was seen swinging his neck at Rafiki, typically gently but sometimes hitting with force much greater than that witnessed during Gage and Rafiki’s sparring sessions. In total, Emba hit Rafiki 352 times. No instances of Emba hitting Gage occurred. Rafiki generally did not reciprocate the hits and typically attempted to walk away, although Emba often followed him and sometimes continued to occasionally hit him. On four occasions between May and July, Rafiki reciprocated hits delivered by Emba. In the moments preceding hitting, Emba was typically following Rafiki, investigating frequently and standing tall directly behind. Ostensibly, these are courtship and mate guarding behaviors. Typically, these behaviors were observed to resume immediately after hitting.

There was a single instance of Rafiki pawing in response to Emba hitting him, a response putatively regarded as a displacement activity in anxiety-causing situations (Innis, 1958; Seeber et al., 2012). Seeber, et al. (2012) note that pawing occurs relatively rarely, but Dagg née Innis (1958) stated that she observed pawing frequently in wild giraffes.

Sparring was generally limited to the giraffe equal in dominance ranking, while most of the hitting, an agonistic behavior, was performed by the eldest and most dominant giraffe, with the less dominant giraffes almost never reciprocating, instead walking away. The behavior of the giraffes thus confirmed our expectations.

1.4 Dominance

Emba has clearly displaced Rafiki and Gage on multiple occasions. No evidence of a difference in rank between Rafiki and Gage was observed during the course of this study. In some instances, Emba simply looked at another giraffe with his head held low and approximately parallel to the ground, leading the other individual to walk away or change directions. On one occasion, Gage approached Emba while he was drinking. Emba paused and looked up at him, causing Gage to stop walking. Gage approached again when Emba resumed drinking but promptly walked away when Emba raised his head from the water and held it low a second time. Further examples include Emba chasing off Rafiki or Gage and Emba, walking as if to intercept Rafiki, in response to which Rafiki cantered. In some instances, Emba cantered after Rafiki, causing him to canter, and as both giraffes passed Gage, he also began cantering.

Gage also made active efforts to avoid Emba, the eldest giraffe, when Emba was following Rafiki and passed in close proximity. Gage frequently stood up if laying down when Emba passed in close proximity, or he would otherwise walk away, or sometimes canter, if Rafiki and Emba were both approaching. In these cases, the dominant giraffe, Emba, effectively displaced Gage.

Their dominance and submissive behaviors, specifically displacement and yielding, were as expected, based on size and the large age difference between the eldest and the two subadult giraffes. Although a slight size and age difference exists between the two subadult giraffes, there was no discernible difference in their rank based on dominance behaviors.

1.5 Mounting

All of the giraffes have been observed mounting, as was expected due to the prevalence of male-male mounting in the wild. In total, 78 mountings were witnessed (Table 4). Emba exclusively mounted Rafiki. It was expected that the non-dominant giraffes would not mount the dominant giraffe, but our results did not strictly support this. Gage exclusively mounted Rafiki, as expected given their closeness in age. Rafiki mounted Emba preferentially, which was not expected, although he also mounted Gage. Given Rafiki’s approaching sexual maturity, his mountings of the dominant giraffe may represent a challenge to the dominance hierarchy. Conversely, Gage’s mounting of Rafiki appear more analogous to play (see Discussion). Generally, all giraffes were noted to be erect while mounting; however, it could not be determined in all instances whether the mounted giraffe was erect. Erections were only observed in association with mounting or courtship behavior. In one instance, Emba mounted Rafiki after urine testing and flehmening.

Mounting was another behavior where social preferences were implied by nonrandom actor and recipient distributions unrelated to the dominance hierarchy. Based on the dominance hierarchy, it would be expected that Rafiki would preferentially mount Gage, a giraffe equal in rank, but instead he mounted the most dominant giraffe significantly more often. Interestingly, as seen with affiliative and other sociosexual behaviors, Emba appears to display a preference for Rafiki over Gage. Bashaw (2004) studied affiliative interactions between individual female giraffes that supported the existence of social preferences. Our results suggest that male giraffes can also develop social preferences despite the relatively solitary nature of male giraffes. Rafiki and Emba both arrived at the Central Florida Zoo around the same time, while Gage arrived eight months later, potentially resulting in the pattern of interactions we have observed. Similar long-term associations between male giraffes over a period of months have not observed in the wild. Additionally, the literature lacks examples of apparent social preferences in captive male giraffes.

Discussion >>