Communal Nesting of Southern Flying Squirrels in Florida

Use of nest boxes by southern flying squirrels (Glaucomys volans), with emphasis on communal nesting, was studied for 5 years in southcentral Florida. Of 841 occupied boxes, 11% contained litters, 81% contained aggregations of 2–25 individuals, and 9% contained solitary individuals. Of 676 aggregations, 79% contained only adults, and 21% were comprised of adults and subadults and, rarely, nestlings. At least 16% of the aggregations contained related individuals. Aggregations of adults were significantly smaller (X̄ = 7.2) than those of mixed-age groups (X̄ = 9.0). Most aggregations contained both sexes. Sex ratios of original captures of both adults and subadults in communal groups were significantly biased toward males. Communal nesting peaked in January, persisted into spring, and was lowest in September. The proportion of males in aggregations of adults significantly decreased over winter. The population in Florida had a more prolonged period of communal nesting and larger mean size of both cold- and warm-weather aggregations than reported for more northerly populations. The high level of communal nesting in the southern part of the range suggests that, besides a thermoregulatory function, aggregative behavior also may play a significant role in the social organization of populations of flying squirrels.