NATIVE POPULATION IS MALADAPTED IN COMPETING WITH INVASIVE SPECIES, BUT INTRASPECIFIC VARIATION SUGGESTS CHANGING BEHAVIOR
Human activities that alter habitats, introduce non-native species, and redistribute species through climate change can all result in novel communities. Changing species compositions may be problematic for native species as new interspecific interactions develop between populations that did not evolve together. In Appalachian Georgia, the relatively recent invasion of house wrens (Troglodytes aedon) is a potential cause of population decline of Carolina chickadees (Poecile carolinensis). We hypothesized that native species behave maladaptively toward a threatening novel species until the population evolves and/or learns adaptive behavior. Based on previous research, we predicted that chickadees would respond more to a threatening house wren model than to a control model, but with half of the population not responding to either model. Adaptive responses included vocalizing and approaching more towards the threatening model. We used taxidermy models and audio playbacks to manipulate the intrusion of a house wren (experimental treatment) and a non-threatening mourning dove (control treatment) near active nests of chickadees. Our within-subject design exposed breeding pairs of chickadees to both treatments, and consisted of 10-minute trials. During these trials, we collected data on chickadee vocalizations, and we estimated the distance between each chickadee and the model in 10-second intervals. Vocalizations towards both models were about the same (P =0.59). More chickadees chose not to approach a model (P <0.0001) but those that did, approached the house wren model more than the mourning dove when analyzing only those that approached within 3 meters of any model (P =0.02). Our hypothesis was partially supported because so few chickadees approached the house wren model. While a few individuals did respond to the house wren model, the population overall did not, suggesting the beginning of a trend within this population of Carolina chickadees.
We thank the various land owners who allowed us to install bird boxes on their properties, including Young Harris College, Brasstown Valley Resort & Spa, Brasstown Valley Golf Course, and many others. We could not have accomplished this without the continued support of the faculty, students and staff at Young Harris College. We are also deeply grateful to the funding recieved from the Young Harris College Undergraduate Research Fund and the Highlands Plateau Audubon Society.
Crowell*, Aubrey P.; McKay, J. Lindley; Eden*, Kaveh; and Milenkaya, Olga
"NATIVE POPULATION IS MALADAPTED IN COMPETING WITH INVASIVE SPECIES, BUT INTRASPECIFIC VARIATION SUGGESTS CHANGING BEHAVIOR,"
Georgia Journal of Science, Vol. 77, No. 1, Article 93.
Available at: https://digitalcommons.gaacademy.org/gjs/vol77/iss1/93