Territoriality
in Zonotrichia albicollis
(White-throated Sparrow):
Spatial Correlates of Reproductive Behavior
Vincent Formica et al.
I am investigating the behavioral ecology of the socially
North American passerine, the white-throated sparrow. White-throated sparrows are fascinating
because they have a stable genetic polymorphism, caused by a chromosomal
inversion. Plumage, morphology, behavior, and life-history characters have a genetic basis and are correlated with the presence or absence of this
chromosomal inversion. Individuals with the inversion have a white
stripe on their heads, and individuals without the inversion have a tan
stripe. White-throated sparrows are
socially monogamous and always mate dissasortatively, which means that white
morph (stripe) birds always pair with tan birds and visa versa. The males of each morph use differing
reproductive strategies. Tan males tend
to be monogamous and mate guard, where the whites males seek extra-pair
copulations with neighboring females.
I am currently focusing on how territoriality affects the
ecology and intensity of selection on the two sparrow morphs. My methods integrate Geographic Information Systems (GIS), molecular ecology, and behavior. My current results reveal that territory size, vegetation type, and light intensity do not
differ between white and tan territories. I found
evidence that territory settlement differs by habitat type and that tan males
are settling in areas lacking white neighbors.
Tan males appear to lower selection intensity by occupying areas of low
density.
Combining GPS (global positioning system) and GIS technology I can map the territories, movements and other spatial features (i.e. nests and song posts) over habitat data, such as continuous vegetation and contour data. I can then compare the spatial patterns of each of the two different morphs.
My future plans for this research include hormone analysis,
song playback experiments and analysis, and radio tracking.