The heterospecific habitat copying hypothesis: can competitors indicate habitat quality?

According to the "habitat copying" hypothesis, animals use the reproductive performance of conspecifics to assess habitat suitability and choose their future breeding site. This is because conspecifics share ecological needs and thus indicate habitat suitability. Here, we propose the "heterospecific habitat copying" hypothesis, which states that animals should use public information (i.e., information derived from the performance of others) from con- and heterospecifics sharing ecological needs. In a correlational approach we test some assumptions and predictions of this hypothesis with a data set from two sympatric bird populations, rollers (Coracias garrulus) and kestrels (Falco tinnunculus), using the same nest-boxes and exploiting similar food resources. Since kestrels are residents and breed earlier, we assumed that they are dominant over rollers for nest-box acquisition. The environment appears to be patchy for both species and temporally predictable for kestrels only. Two results suggest that the use of heterospecific public information in breeding habitat selection may be at work: (1) an increase in the reoccupancy probability by kestrels of previous roller nests with increasing nest success, and (2) an increase in roller breeding population with increasing local kestrel success. Most of the other observed patterns could be explained by alternative mechanisms such as natal philopatry, breeding fidelity, conspecific attraction, intraspecific habitat copying, and the effect of interspecific competition. Copyright 2005.