Cranberry Lake Biological Station

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Mobbing is an anti-predatory combination of various aggressive behaviors employed by birds to protect themselves and kin through expulsion of threats, as often seen by Black-capped Chickadees. We hypothesized mobbing bird species in edge habitats will exhibit more occurrences of aggressive behaviors, including high frequency calls and physical contact, in response to Black-capped Chickadee alarm calls than playbacks of Chickadee song, Blue-Jay (Cyanocitta cristata), and Red-eyed Vireo (Vireo olivaceus) alarm calls. We further hypothesized there would not be significant differences in bird aggression levels, measured by average fly-ins, between selected edge habitats. We used block sampling to construct three transects, containing four circular quadrates with 10-meter diameters, separated by 200-meters. Playback order was randomly selected for each quadrate, with one playback per day, over four days (n=48). We designed an exhaustive ethogram to log behaviors performed over 5-minutes of playback and 2.5-minutes of additional observation. We used a chi-squared test, for homogeneity of proportions to demonstrate differences in behavior from playbacks. It was determined there is a significant difference between playbacks. Furthermore, we performed an ANOVA test for homogeneity between habitats, which determined there was no significant difference between edge habitats. Data suggested Black-capped Chickadee calls elicit more occurrences of aggressive behaviors around Cranberry Lake Biological Station edge habitats.



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