RESUMEN
The effects of urbanization on avian cognition remain poorly understood. Risk-taking behaviors like boldness, neophobia and flight distance are thought to affect opportunism and innovativeness, and should also vary with urbanization. Here, we investigate variation in risk-taking behaviors in the field in an avian assemblage of nine species that forage together in Barbados and for which innovation rate is known from previous work. We predicted that birds from highly urbanized areas would show more risk-taking behavior than conspecifics from less urbanized parts of the island and that the differences would be strongest in the most innovative of the species. Overall, we found that urban birds are bolder, less neophobic and have shorter flight distances than their less urbanized conspecifics. Additionally, we detected between-species differences in the effect of urbanization on flight distance, more innovative species showing smaller differences in flight distance between areas. Our results suggest that, within successful urban colonizers, species differences in innovativeness may affect the way species change their risk-taking behaviors in response to the urban environment.
Asunto(s)
Aves , Vuelo Animal , Asunción de Riesgos , Urbanización , Animales , Barbados , EcosistemaRESUMEN
String-pulling is one of the most popular tests in animal cognition because of its apparent complexity, and of its potential to be applied to very different taxa. In birds, the basic procedure involves a food reward, suspended from a perch by a string, which can be reached by a series of coordinated pulling actions with the beak and holding actions of the pulled lengths of string with the foot. The taxonomic distribution of species that pass the test includes several corvids, parrots and parids, but in other families, data are much spottier and the number of individuals per species that succeed is often low. To date, the association between string-pulling ability and other cognitive traits was never tested. It is generally assumed that string-pulling is a complex form of problem-solving, suggesting that performance on string-pulling and other problem-solving tasks should be correlated. Here, we show that individuals of two innovative species from Barbados, the bullfinch Loxigilla barbadensis and the Carib grackle Quiscalus lugubris fortirostris, pass the string-pulling test. Eighteen of the 42 bullfinches tested succeeded, allowing us to correlate performance on this test to that on several other behavioral measurements. Surprisingly, string-pulling in bullfinches was unrelated to shyness, neophobia, problem-solving, discrimination and reversal learning performance. Only two of 31 grackles tested succeeded, precluding correlational analyses with other measures but still, the two successful birds largely differed in their other behavioral traits.
Asunto(s)
Conducta Animal/fisiología , Cognición , Passeriformes/fisiología , Solución de Problemas , Animales , Barbados , RecompensaRESUMEN
The bullfinch Loxigilla barbadensis is an endemic passerine on the Caribbean island of Barbados that has only recently been taxonomically split from the Lesser Antillean bullfinch L. noctis. The trait that most clearly distinguishes L. barbadensis from L. noctis is the absence in the male of sexually dimorphic coloration of the body and throat feathers, with L. barbadensis males and females sharing the same dull brown plumage. Here we report, in 64 individuals netted throughout the island, the results of a discriminant analysis on two (wing length and tail length) to four morphological traits showing very high (97%) concordance with sexing via PCR using blood samples. Females also show a paler lower mandible, a trait that yields an 80% concordance with PCR sexing. We found one L. barbadensis male that had a noctis-like reddish throat patch, supporting the idea that sexual dichromatism is the ancestral condition and that male Barbados bullfinches have evolved cryptic coloration that now makes the species monochromatic.