Territorial Behavior of the Tree Sparrow

Weeden, J

Spatial relations in territorial behavior were intensively studied for 30 pairs of Tree Sparrows (Spizella arborea) in central Alaska. The two chief aspects of spatial relations studied for each pair were total activity spaces throughout the season (combining all observation points) and daily activity spaces (locations visited by the pair in a four-hour observation period on a single day). Total activity spaces for males ranged from 1.5 to 9.3 acres. The mean size of the total activity space differed in each of the three years of the study and reflected differences in population density. For 1960, 1961, and 1962 mean total activity spaces were 4.6, 6.0, and 3.4 acres, respectively, for population densities of 28, 21, and 35 pairs per 100 acres, respectively. Total activity spaces generally had a central core of more concentrated use and an outer cortex where visits were less frequent. This pattern was more pronounced for larger activity spaces than for smaller ones. Some overlapping of total activity spaces occurred in the cortex portion. Some of this overlap was due to shifting of activity spaces throughout the season while some of it was due to simultaneous use of an area. The amount of overlapping in any one year bore no relation to population density. Size of total activity space of males was not influenced by age of individuals. Total activity spaces of females were not related to population density. Their total activity spaces were smaller (range 0.6-4.4 acres, mean for the three years 2.2, 2.6, and 2.1 acres, respectively) than for males and were situated entirely within the total activity spaces of the males. Territorial behavior differed in kind and intensity throughout the day. The diurnal cycle began by reaffirmation of the core through advertisement (song) followed later in the day by more lengthy trips into the cortex. In general, daily activity space was maximum during courting and decreased gradually throughout the season. There was so

Territorial Behavior of the Tree Sparrow

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