Differences in Neophobia between Naive Song and Swamp Sparrows

Authors

  • Russell Greenberg

    Corresponding author
    1. Smithsonian Migratory Bird Center, National Zoological Park, Washington, D.C.
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      Greenberg, R. 1992: Differences in neophobia between naive song and swamp sparrows. Ethology 91, 17–24.


Smithsonian Migratory Bird Center, National Zoological Park, Washington, D.C. 20008, USA.

Abstract

I measured feeding neophobia in song (Melospiza melodia) and swamp (M. georgiana) sparrows. The experiment had a counter-balanced design with each species divided into two rearing groups and each exposed to a different set of six objects. I tested sparrows at two months of age by measuring their latency to feed at cups placed at familiar and novel objects. These tests were repeated at six months using an additional four novel objects. In comparison with song sparrows, juvenile swamp sparrows had a significantly and consistently lower latency to feed at novel objects. I found this difference in older birds as well. Feeding latencies at familiar objects were statistically indistinguishable between species. These results suggest that song sparrows are more neophobic than swamp sparrows. I obtained opposite results from similar experiments conducted in the field and using wild-caught birds in captivity. Greater neophobia in wild swamp sparrows may be a consequence of differential experience between the two species in nature. Differences found between hand-raised song and swamp sparrows is one of the first demonstrations of interspecific differences in neophobia under similar and controlled rearing conditions. A possible adaptive explanation is that, typically, juvenile swamp sparrows are reared in a simpler, more predictable and hence safer environment and may not require the protection of an aversion to novelty.

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