Allonursing, the nursing of nonfilial offspring, has been reported in a number of mammalian species; however, very few studies have investigated more than three hypotheses. The aim of our study was to investigate seven hypotheses explaining allonursing in captive giraffes. During 2007-2011, we observed 24 females and 37 calves in four zoological gardens in the Czech Republic, recording 2514 suckling events. We found that 83% of the females allonursed a nonfilial calf and 86.5% of calves allosuckled from a nonmaternal