Association between reproductive behaviour and androgen metabolite excretion in free-ranging male giraffes (Giraffa camelopardalis)
Little is known on the giraffe’s reproductive behaviour, particularly observations of male sexual behaviour are scarce. Most information results from studies on captive animals, and observations of free-ranging giraffes were mainly focused on social structure within herds and only yield limited data on the bulls‘ tendency of roaming between cows’ herds. In addition, no data […]
Relationships between male giraffes’ colour, age and sociability
In species in which males signal competitive ability through secondary sexual traits, males with different levels of trait expression may adopt different reproductive tactics to maximize their reproductive success. In fission-fusion social systems, the most dominant males often roam widely in search of females in oestrus, and thus exhibit different patterns of sociability from subordinate […]
The impact of age-class and social context on fecal glucocorticoid metabolite levels in free-ranging male giraffes
One of the primary sources of perceived stress is the social environment of an animal and the interactions with conspecifics. An essential component of the response to a stressor is the activation of the hypothalamic–pituitary–adrenocortical axis, which results amongst others in a temporal increase in circulating glucocorticoid (GC) levels. Giraffes occur in a highly flexible […]
Reproductive failure in female Thornicroft’s giraffe (Giraffa camelopardalis thornicrofti) in Zambia
Reproductive suppression is common among mammals residing in cooperative social systems and is characterized by the cessation of ovulation in subordinate females until their social environment releases them from a temporary freeze on ovulating (e.g., dwarf mongoose, Helogale parvula (Creel, Creel, Wildt, & Monfort, 1992); African wild dogs, Lycaon pictus (Creel, Creel, Mills, & Monfort, […]
Giraffe Social Behaviour
Many features recommend the giraffe (Giraffa camelopardalis) for behavioural study: it is big, abundant, conspicuous, active by day, reasonably trusting of people, deliberate, and the best self-marked animal in existence. Surprisingly, its social behaviour has been largely neglected. We studied giraffe exclusively for the following periods: February–March, 1975 and January–December, 1977 in the Serengeti National […]
A Tall Order: Hormones and Behavior in Giraffes
Hormones are chemical messengers produced by specific organs in the body that travel in the blood to target tissues and influence behavior and physiology. The major hormone of interest to us is progesterone, a steroid hormone produced by the ovary and placenta in females. The body is constantly churning out new hormones, while destroying the […]
Androgen changes and flexible rutting behaviour in male giraffes
The social organization of giraffes (Giraffa camelopardalis) imposes a high-cost reproductive strategy on bulls, which adopt a ‘roving male’ tactic. Our observations on wild giraffes confirm that bulls indeed have unsynchronized rut-like periods, not unlike another tropical megaherbivore, the elephant, but on a much shorter timescale. We found profound changes in male sexual and social […]