Data from: Song recognition and heterospecific associations between two fairy-wren species (Maluridae)

Although heterospecific associations beneficial to one or both species
involved (e.g. commensalisms or mutualisms) are common, it is generally
assumed that interactions between species are transient and not particular
to individuals. However, long-term interactions between individuals of
different species do occur. In such heterospecific social groups,
discrimination between heterospecific individuals may be beneficial,
allowing individuals to direct beneficial or aggressive behaviors towards
appropriate targets. Here we describe heterospecific groups composed of
splendid and variegated fairy-wrens (Malurus splendens and M. lamberti)
and provide the first experimental evidence that recognition of
heterospecific group members occurs across species. In these species,
family groups live on overlapping territories and co-defend shared
territories against both heterospecific and conspecific intruders.
Individuals on shared territories were frequently observed traveling and
foraging together. Socially dominant males of both species responded more
aggressively to songs of neighboring and foreign heterospecific
fairy-wrens than they did to those of their co-resident heterospecifics.
Although splendid fairy-wrens did not change their behavior when
associating with heterospecifics, variegated fairy-wrens spent more time
foraging, were less vigilant, had greater first-nest fledging success, and
fewer extra-group young. These findings suggest heterospecific
associations between these two species benefit the variegated fairy-wren.
Our findings are novel and show that recognition and discrimination among
individuals, often considered a prerequisite for conspecific cooperation,
can occur across species.