Interspecific assistance: fiddler crabs help heterospecific neighbours in territory defence

Abstract

Theory predicts that territory owners will help established neighbours to repel intruders, when doing so is less costly than renegotiating boundaries with successful usurpers of neighbouring territories. Here, we show for the first time, to our knowledge, cooperative territory defence between heterospecific male neighbours in the fiddler crabs Uca elegans and Uca mjoebergi. We show experimentally that resident U. elegans were equally likely to help a smaller U. mjoebergi or U. elegans neighbour during simulated intrusions by intermediate sized U. elegans males (50% of cases for both). Helping was, however, significantly less likely to occur when the intruder was a U. mjoebergi male (only 15% of cases).

Social networking in territorial great tits: slow explorers have the least central social network positions

“…Familiarity between individuals, which exhibit consistent behavioural differences (personality), is predicted to promote social responsiveness, as it makes individuals predictable and so allows individuals to match their behaviour to that of their interaction partner (McNamara, Barta, & Houston, 2004;Wolf, Van Doorn, & Weissing, 2011). This can mediate the use of tit-for-tat strategies (Akçay et al, 2009), reducing unnecessary aggressive interactions and allowing for cooperative alliances (Booksmythe, Jennions, & Backwell, 2010;Elfstr€ om, 1997;Goodwin & Podos, 2014;. For example, neighbouring great tits that shared a territory boundary the previous year were more likely to join each other in nest defence than neighbours that had not shared a boundary .…”

Everybody Needs Good Neighbours: Coalition Formation Influences Floater Fight Choice

“…Such defensive coalitions have now been reported in a bird species (Arthus petrosus, Elfstrom 1997) and three fiddler crabs (Uca mjoebergi, U. annulipes and U. elegans; Backwell & Jennions 2004;Booksmythe et al 2010;Detto et al 2010;Milner et al 2010a). By doing so, a resident removes the cost of having to re-establish territory boundaries with a new male neighbour that is on average likely to be larger and stronger than the former neighbour.…”

Team of rivals: alliance formation in territorial songbirds is predicted by vocal signal structure

“…Prior studies on cues guiding coalition formation have focused on size disparities and their visual assessment. For example, empirical work on fiddler crabs [13,14] reports coalitions forming most often when territorial allies are larger than intruders, and when intruders in turn are larger than residents. This pattern is predicted because allies should expend less energy evicting an intruder than in re-establishing territory boundaries with a new, larger neighbour.…”