Ritualized fights among foraging cattle egrets following Père David's deer in Dafeng Nature Reserve

AbstractThe outcome success of animals competing for food resources may be influenced by their differences in resource holding potential and motivation to acquire these resources. This study investigated the naturally occurring aggressive interactions during ritualized fights of the cattle egret (Bubulcus ibis) foraging with Père David's deer (Elaphurus davidianus). The study was conducted in the first core zone of Dafeng Père David's Deer National Nature Reserve, Jiangsu, China during the summers of 2012 and 2013. The foraging and vigilance variables of resident cattle egrets feeding with a deer with and without intrusion were calculated and compared. Cases of ritualized fights between residents and intruders were recorded in naturally occurring aggressive interactions. The prey capture success rate and the total foraging earnings of resident cattle egrets following a deer with intrusion were significantly higher than those of resident foragers without intrusion. The resident status did not affect the outcomes of the ritualized fights of the cattle egrets, although adult residents or intruders had more cases of winning in contesting ownership of the deer. Thus, age is the major resource holding factor in foraging cattle egrets competing for host ownership.