The different use of an urban and rural habitat by wintering and resident song sparrows (Melospiza melodia) : a case study from western North Carolina

Differences in environments have the potential to affect the behaviors of animals within these areas. In comparison to rural environments, urban environments provide a warmer microhabitat, different predation risk levels, more anthropogenic food opportunities, and artificial light sources. Non-migratory song birds within urban environments have been shown to have a higher local survival rate, earlier gonad development, and better mating success. For this research, weekly point count surveys were conducted at an urban and a rural site in western North Carolina from October 2009 to April 2010 to count and identify banded and non-banded individuals in order to determine if a difference existed between the proportions of migrating individuals. Each site contained a partial migratory population of song sparrows (Melospiza melodia), that have already been shown to differ in their average levels of aggression and boldness. Results showed that significantly more males remained as yearlong residents in the urban population than in the rural population (p = 0.024), while all females from each population migrated over the winter. Nearly ten times as many migrating song sparrows on average were observed on the rural site than on the urban site during the survey months of November 2009 to January 2010 than within the urban site (p < 0.001). These results, in conjunction with the higher abundance of summer territories in the urban site, may mean that song sparrows have different criteria for evaluating what is considered a good summer territory versus a good wintering area. The higher number of yearlong resident males at the urban site may be due to these individuals occupying their summer territory areas so that these prime sites are not taken by other males during the course of the migration period