A case of suckling and allosuckling behaviour in captive common hippopotamus

Abstract

Lactation is a form of maternal investment that is far moredemanding than gestation, oestrus behaviour or ovulation (Martin,1984; Oftedal, 1985). However although suckling behaviour hasbeenstudiedinmanyungulatespeciesindetail(CarsonandWood-Gush, 1983; Lavigueur and Barrette, 1992; Sarno and Franklin,1999), there have been few studies on suckling behaviour ofcommon hippopotamus (Hippopotamus amphibius). The sucklingbouts take place both on land (Bartlett, 1872; Sokolowsky, 1915;Verheyen, 1954; Eltringham, 1999) and in the water (Vosseler,1923; Vevers, 1926; Verheyen, 1954) and last around 3–4.5min(Vosseler,1923)withthemotherusuallylyingonherside(Bartlett,1872; Verheyen, 1954; Eltringham, 1999). Suckling was suggestedto occur mostly in the morning (Olivier and Laurie, 1974). No otherdetails including the exact length of suckling bouts, which animalinitiated (foal or mother) or terminated suckling bout, the numberand the length of interruptions were published (for a review see:Estes, 1991; Eltringham, 1999). Thus, the basic biological informa-tion concerning the suckling behaviour of common hippopotamusis still lacking. Since the observation of hippopotami in the wildis difficult, observations carried out in zoos would improve ourknowledge of this behaviour (Verheyen, 1954).Allosucklinghasbeenreportedinmostmammaliantaxa(Packeret al., 1992; Roulin, 2002). In common hippos, the occurrence ofallosuckling was suggested but not proven (Smuts and Whyte,1981). The allosuckling in monotocous species has been mostly