Feeding Behavior and Chick-a-dee Calls in the Presence of Predator Models: A Field Study of Carolina Chickadees (Peocile carolinensis)

This study describes feeding and chick-a-dee calling behavior of Carolina chickadees (Poecile carolinensis) in the presence of predator models. Chickadees occur in stable social groups over much of the year, and birds in social groups often indicate the presence of predators through alarm calling and calling related to mobbing behavior. Research with two other chickadee species has found a relationship between predator stimuli and calling behavior, including the note composition of chick-a-dee calls.

Here, I presented Carolina chickadees with avian models, and a “no model” control. The species represented by the avian models were the Cooper’s hawk (Accipiter cooperii), a natural predator of chickadees; the great horned owl (Bubo virginianus), a bird of prey but not a predator of chickadees; and the American crow (Corvus brachyrhynchos), a non-bird of prey. Stimuli were initially covered with a cloth and then exposed during the experimental procedure. Audio recordings of flocks were obtained at 16 field sites in eastern Tennessee from October 2004 to March 2005.

Chickadees took significantly fewer seeds and produced more chick-a-dee calls during the post-exposure period than during pre-exposure for both the hawk and owl stimuli, but not for the crow and no model stimuli. I detected no effect of stimulus type on note composition of chick-a-dee calls, but note composition was affected by the proximity of the signaler to the seed stand for all four note types measured in this study.

Note composition in chick-a-dee calls in Carolina chickadees may not be strongly influenced by external referents like predator type. Instead, note composition may be influenced by the state of arousal of the signaler or its behavioral tendencies. An increase in calling rate in Carolina chickadees may serve a general recruitment function, though playback studies are needed to test these ideas.