Evidence of Red-cockaded Woodpecker nestling displacement by southern flying squirrels
Red-cockaded Woodpeckers (Picoides borealis) are unique among woodpeckers in that they excavate their roost and nest cavities entirely within living pines (Ligon 1970). A number of secondary cavity nesters and other vertebrates are dependent on Red-cockaded Woodpeckers for the cavities they create (Rudolph et al. 1990, Loeb 1993, LaBranche and Walters 1994, Conner et al. 1997). Harlow and Lennartz (1983), Rudolph eta!. (1990), Loeb (1993), and Conner eta!. 1996, 1997) showed that southern flying squirrels (Glaucomys volans) in Texas and South Carolina were the most common occupants observed in the cavities other than Red-cockaded Woodpeckers and that these cavities were selected primarily on the basis of entrance size. While these studies showed that there is a propensity for squirrels to use unenlarged cavities, none have shown evidence of Red-cockaded Woodpeckers being killed by southern flying squirrels. Stabb eta!. (1989) proposed that smaller birds may suffer mortality or disturbance from flying squirrels usurping the occupied cavities. Jackson (1978a), along with Hooper and Lennartz (1983), noted that southern flying squirrels have usurped Red-cockaded Woodpecker cavities without killing the birds. We report an instance of two 12- to 15-day-old nestlings found dead at the base of the nest tree and 3 flying squirrels inside the nest cavity.