EXPERIMENTAL ANALYSIS OF NOVELTY RESPONSES IN A BIRD ASSEMBLAGE INHABITING A SUBURBAN MARSH

ECHEVERRÍA, A. I., VASSALLO A. I. E ISACCH J. P.

CANADIAN JOURNAL OF ZOOLOGY

NRC Canada

Año: 2006 vol. 84 p. 974 - 980

0008-4301

Suburban areas at Pampas region are inhabited by several bird species which sharply differ in their ability to exploit man-modified, urban areas. This assemblage includes species restricted to natural grasslands (e.g. Great Pampa Finch, Embernagra platensis J. F. Gmelin, 1789) and generalist, highly cosmopolitan species such as House Sparrow,  Passer domesticus Linnaeus, 1758). We explored the role of certain aversive responses to novelty in shaping the marked differences in ecological plasticity displayed by the species. In field experiments, we tested for differences in neophobia to feeding in the presence of artificial objects near feeders regularly replenished with seeds. In spite of their granivorous diet, some non-urbanized species did not use the feeders, possibly because an extreme degree of aversion in front of novel situations. The group of birds that visited the feeders included both urbanized (N = 8) as well as non urbanized (N = 2) species. We found that the presence of novel objects discouraged visitation to an otherwise attractive food source, although we observed a weak neophobia reaction for most species. However, we found unexpected levels of neophobia in highly generalist, urbanized species such as House Sparrow and Shiny Cowbird Molotrhus bonariensis J. F. Gmelin, 1789. This response is discussed regarding the influence of post-fledging development in a relatively simple and predictable ecosystem, as compared to urban areas.