Decline of the Red-Cockaded Woodpecker (Picoides borealis) in Southeastern Oklahoma

Abstract

-A search of 4600 ha of the McCurtain County Wilderness Area (MCWA), Oklahoma, in 1989-1990 yielded 15 groups of red-cockaded woodpeckers (Picoides borealis). The number of groups and number of individuals in a 3795-ha area that was surveyed in 1977 and 1989-1990 declined by 62% and 75%, respectively. The productivity of the population was low during 1989-1990; 0.69 young were fledged per nesting attempt. To assess the adequacy of foraging habitat, forest structure was measured in an area with a high density of groups (1.95/km2) in 1990 and in an area where the group density had declined from 2.92 groups/km2 in 1977 to 0.74 groups/km2 in 1990. Forest structure in both areas was adequate but approached the limits recommended in the Red-cockaded Woodpecker Recovery Plan. To determine if isolation of groups was related to population decline, we estimated nearest neighbor distances from cluster locations (a cluster is the cavity trees used by a group of woodpeckers) in 1977 and 1990. Cluster sites had longer nearest neighbor distances in 1977 than in 1990, which may indicate that isolation by distance reduces the influx of dispersing breeders from elsewhere in the population. Periodic fires occur naturally in the MCWA but have been suppressed since 1926. Re-establishment of a fire regime is important in maintaining the integrity of the MCWA and may be beneficial to its red-cockaded woodpecker population.