Maternal behaviour in Giraffes (Giraffidae)

Allomaternal care is one of the most interesting types of cooperation among females. Its most extreme form is allonursing, nursing of a non-filial young, which is still not completely understood, even though many hypotheses have been postulated. This type of cooperation among giraffes had not been expected for long time. This was based on the initial opinion that giraffes do not have social system and form only weak social bonds. However, my bachelor and master theses showed high occurrence of allonursing in captive giraffes. The first aim (1) of this thesis was to test all possible hypotheses explaining allonursing in captive giraffes. However, a lot of the information needed to test them were missing, which resulted in the formulation of further aims. The second aim (2) was to test the hierarchy in captive giraffes. The third aim (3) was to describe the growth and weight of captive giraffes. The fourth aim (4) was to compare nursing patterns in the zoo and in the nature reserve Bandia, Senegal and the last aim (5) was to test the social bonds among giraffes in the nature reserve Bandia, Senegal. (1) From 2007 to 2011, the nursing behaviour of 24 females and 37 calves was observed. Eighty-three percent of the females allonursed a nonfilial calf and 86.5% of calves allosuckled from a nonmaternal female. Allonursing in giraffes was explained by milk-theft from the point of view of the calves and possible reciprocity among females. (2) The agonistic interactions of 31 giraffes were recorded in four herds. A linear hierarchy was been found among giraffes and rank was significantly affected by age and time spent in the herd. (3) The weight data from 43 giraffes in Prague zoo were collected from 2009 to 2013 and provided the basic information about giraffe growth and weight. (4) I also observed the nursing behaviour of seven and four female-calf pairs in the fenced Bandia reserve, Senegal, and in Prague zoo, respectively, both for 22 days. The differences in nursing patterns were likely to reflect anti-predator behaviour, the population density of animals and the distribution of food resources. (5) Finally, I investigated the social preferences of 28 introduced giraffes in semi-captivity in the nature reserve Bandia, Senegal and provided the results supporting the existence of a fission fusion social system among giraffes with social preferences among adult females. The overall results provide unique findings on allonursing in general as well as changing our perspective on giraffe social behaviour

The First Description of Dominance Hierarchy in Captive Giraffe: Not Loose and Egalitarian, but Clear and Linear

<div><p>Wild giraffes live in extensive groups in the fission fusion system, maintaining long social distances and loose social bonds. Within these groups, resources are widely distributed, agonistic encounters are scarce and the dominance hierarchy was reported in males only, while never deeply analysed. In captivity, the possibility to maintain inter-individual distances is limited and part of the resources is not evenly distributed. Consequently, we suggest that agonistic encounters should be more frequent, leading to the establishment of the dominance hierarchy. Based on the differences in resource-holding potential, we suggested that the rank of an individual would be affected by age and sex. Based on hypotheses of prior ownership, we tested whether rank was positively affected by the time spent in a herd and whether it was stable in adult females, which were present long-term in the same herd. We originally monitored four herds of Rothschild giraffes (<i>Giraffa camelopardalis rothschildii</i>) in Dvůr Králové zoo (n = 8), Liberec zoo (n = 6), and two herds in Prague zoo: Prague 1 (n = 8) and Prague 2 (n = 9). The Prague 1 and Prague 2 herds were then combined and the resulting fifth herd was observed over three consecutive years (2009, 2010, and 2011) (n = 14, 13, and 14, respectively). We revealed a significantly linear hierarchy in Dvůr Králové, Prague 2 and in the combined herd in Prague. Rank was significantly affected by age in all herds; older individuals dominated the younger ones. In females, rank was positively affected by the time spent in the herd and adult females in Prague maintained their rank during three consecutive years. This study represents the first analysis of the dominance hierarchy in the captive giraffe, and discusses the behavioural flexibility of the social structure in response to monopolisable resources in a captive environment.</p></div

Rank stability.

<p>Changes in the CBI rank of five adult females during three consecutive years in the combined herd in Prague.</p

Results of linearity in all studied herds.

<p>Results of linearity in all studied herds.</p

Rank vs. time in a herd.

<p>The CBI rank was influenced by time spent in the herd in females only (r² = 0.25, p = 0.017), not in males (r² = 0.35, p = 0.09). Note that the highest rank level is 1 (the first position in a hierarchy).</p

Rank vs. age.

<p>The CBI rank was significantly (F_{(1, 5.168)} = 13.16, <i>P</i> < 0.001) affected by age. Note that the highest rank level is 1 (the first position in a hierarchy).</p