PERSPECTIVES ON RED SQUIRREL (TAMIASCIURUS HUDSONICUS) AND EASTERN CHIPMUNK (TAMIAS STRIATUS) DISTRIBUTION AND DETECTABILITY IN NEWFOUNDLAND FROM CITIZEN SCIENCE AND OCCUPANCY MODELING

Spicer, Heather E. (2017) PERSPECTIVES ON RED SQUIRREL (TAMIASCIURUS HUDSONICUS) AND EASTERN CHIPMUNK (TAMIAS STRIATUS) DISTRIBUTION AND DETECTABILITY IN NEWFOUNDLAND FROM CITIZEN SCIENCE AND OCCUPANCY MODELING. Memorial University of Newfoundland. (Unpublished)

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Abstract

Red squirrels (Tamiasciurus hudsonicus) and eastern chipmunks (Tamias striatus) are both introduced species on the island of Newfoundland. There is evidence that T. hudsonicus have contributed to significant changes in the ecology of several native animal and plant species. Little is known about the ecological implications of the introduction of T. striatus. The full extent of both the T. hudsonicus and T. striatus ranges across insular Newfoundland and the nearshore islands have not been described. Tamiasciurus hudsonicus reliably respond to broadcasts of recorded conspecific territorial vocalizations, both through calling back and approaching the speaker. However, variation in the responsiveness of T. hudsonicus to call broadcasts (detectability) over time is not well understood. I investigated T. hudsonicus and T. striatus distribution across Newfoundland ecoregions and T. hudsonicus detectability in Newfoundland through a two-part study. First, I recruited elementary school students to participate in a citizen science investigation. Participants submitted data about T. hudsonicus and T. striatus presence at locations across Newfoundland, including the results of surveys using call broadcasts, observations made while walking in the woods, and qualitative data from student interviews with family/friends. I received data from 50 teachers and 899 elementary school students affiliated with 29 schools around the island of Newfoundland. This included 43 class point count/call broadcast surveys (including a total of 85 point counts), as well as 159 individual walks in the woods, and 142 interviews with family and friends. The proportion of sites with T. hudsonicus present did not vary significantly among ecoregions (χ2= 0.725, df=5, p>0.05), however, the proportion of sites with T. striatus did (χ2=12.61, df=5, p<0.05), suggesting that T. striatus are more restricted in their range than T. hudsonicus. Second, I investigated how T. hudsonicus detection probability varied over time and during silent and playback treatments by conducting monthly point count/call broadcasts along standardized survey routes at two locations on the west coast of Newfoundland. Probability of detection estimates steadily declined from autumn to winter and detection probability was always higher during playback treatments than during silent treatments. This demonstrates the efficacy of using call broadcasts during point count surveys for T. hudsonicus, and suggests that call broadcasts are most effectively used for this purpose in the summer and early fall.

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