CLAS: Colby Liberal Arts Symposium

Variations in Intra- and Interspecific Response to Mobbing Calls by Black-capped Chickadees (Poecile atricapillus)

Diamond 153

Mobbing calls are produced by a variety of bird species in response to predator sightings. These mobbing calls often function in intraspecific recruitment, but have recently been shown to have an interspecific response component as well. The mobbing calls produced by the black-capped chickadee (Poecile atricapillus) are distinct and encode information about the threat level of the predator. Conservation biologists often use playbacks of chickadee mobbing calls to detect species of birds and numbers of individuals in an area with higher accuracy than counts conducted without the use of playbacks. In this study, the factors that could potentially influence intra- and interspecific response to chickadee mobbing calls were investigated, including: threat level encoded in the mobbing call (low or high), time of day, season, type and amount of tree cover, and weather conditions. The species and number of birds responding to playbacks of mobbing calls were compared to baseline levels of birds in the area, as well as to the response to territorial chickadee songs, an intraspecific signal. Playbacks took place in Perkins Arboretum. More species and a greater number of total birds responded to low dee playbacks in the morning than they did at midday or afternoon. A greater number of total birds responded to low dee calls in conditions without wind when compared to conditions with wind. More species and a greater number of birds responded to low dee calls in the rain when compared to conditions with snow or without precipitation. These results suggest that the most accurate estimate of bird populations in an area can be assessed via low dee playbacks on mornings with no wind. Preliminary results also suggest that heterospecifics may be able to detect predator threat level in chickadee mobbing calls.

https://digitalcommons.colby.edu/clas/2014/program/240