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International audience; Public information (PI), which is the information that can be derived from the behavior and performance of conspecifics, has been demonstrated to be used in many fitnessenhancing decisions. In the context of breeding habitat choice, PI use has been called ''habitat copying.'' We experimentally tested the existence of habitat copying in the Blue Tit (Cyanistes caeruleus), a nonmigratory, short-lived hole-nesting bird. We manipulated the mean number of fledglings raised locally (quantity) and their condition (quality) as components of PI by transferring nestlings from Decreased (D) patches to Increased (I) patches. Our manipulations caused a negative relationship between fledgling quantity and quality that does not exist naturally: I patches had a higher number of fledglings that were in poorer condition, whereas D patches had a lower number in better condition. Control (C) patches, whether manipulated or not, had intermediate levels in terms of fledgling quantity and quality. Adult emigration the following year was higher from D than from C or I patches. Similarly, adult dispersal distance decreased for individuals coming from D to C to I patches. This suggests that resident breeders rely mainly on fledgling quantity to make emigration decisions. Emigration patterns of juveniles did not vary in relation to our patch manipulation. Immigration rates were higher and similar in I and D patches than in C patches. Hence, immigrant Blue Tits seem to rely on one of the manipulated components of PI and are insensitive to the discrepancy between fledgling quantity and quality. This shows that even nonmigratory species, such as Blue Tits, may use PI in their dispersal decisions but weigh its components differently for emigration and immigration. Differences among species in the importance of PI in breeding habitat choices may be explained by differences in life histories.

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.