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 - 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 - 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.