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Cooper, Erika T., Mylinh T. Nguyen, and Sharon E. Wise.


VARIATION IN TERRITORIAL BEHAVIOR OF RED-BACKED SALAMANDERS FROM VIRGINIA AND NEW YORK

Cooper presents at Northeastern Natural History Conference

The terrestrial red-backed salamander, Plethodon cinereus, is territorial in portions of its range, using threat displays and overt aggression for defense. However, the widespread distribution of this species throughout eastern forests of North America and previous studies suggest that salamanders from different populations may vary in territorial behavior. We compared the territorial behavior of salamanders from Giles County, Virginia and Herkimer County, New York. Within each population, the aggressive and exploratory behavior of resident/intruder pairs (matched for size) were observed in staged territorial contests in the laboratory. Because salamanders were significantly larger from the Virginia population than from the New York population and size may influence aggressive behavior, we analyzed our data in two ways: (1) we retained the size disparity between populations, and (2) we removed the largest pairs from the Virginia population, eliminating the size difference between populations. Salamanders from the Virginia population exhibited significantly more aggression and exploratory behavior than salamanders from the New York population, even when the size disparity was removed. We hypothesize that (1) environmental and/or genetic differences in these two populations influenced behavior, resulting in less territorial defense in the salamanders from the New York population, or (2) salamanders
from the New York population were territorial, but used fewer visual displays in territorial defense than salamanders from the Virginia population. We found weak evidence supporting the second hypothesis; only salamanders from the New York population bit opponents, indicating that these salamanders may have been more overtly aggressive in territorial contests.