Landscape Genetics of Raccoons (Procyon lotor) Associated with Ridges and Valleys of Pennsylvania: Implications for Oral Rabies Vaccination Programs

Raccoons are the reservoir for the raccoon rabies virus variant in the United States. To combat this threat, oral rabies vaccination (ORV) programs are conducted in many eastern states. To aid in these efforts, the genetic structure of raccoons (Procyon lotor) was assessed in southwestern Pennsylvania to determine if select geographic features (i.e., ridges and valleys) serve as corridors or hindrances to raccoon gene flow (e.g., movement) and, therefore, rabies virus trafficking in this physiographic region. Raccoon DNA samples (n = 185) were collected from one ridge site and two adjacent valleys in southwestern Pennsylvania (Westmoreland, Cambria, Fayette, and Somerset counties). Raccoon genetic structure within and among these study sites was characterized at nine microsatellite loci. Results indicated that there was little population subdivision among any sites sampled. Furthermore, analyses using a model-based clustering approach indicated one essentially panmictic population was present among all the raccoons sampled over a reasonably broad geographic area (e.g., sites up to 36 km apart). However, a signature of isolation by distance was detected, suggesting that widths of ORV zones are critical for success. Combined, these data indicate that geographic features within this landscape influence raccoon gene flow only to a limited extent, suggesting that ridges of this physiographic system will not provide substantial long-term natural barriers to rabies virus trafficking. These results may be of value for future ORV efforts in Pennsylvania and other eastern states with similar landscapes.

SETTING UP AN EFFECTIVE URBAN BLACKBIRD ROOST CONTROL PROGRAM

The City of Denton is situated 35 miles north of north-central Texas. This area is within one of the major N-S corridors for migratory birds. It is also far enough south so that winters are generally mild and open. The average rainfall of 30 inches sustains good stands of pecan and several species of oak, which serve as excellent roost sites for blackbirds. For the past several years, summering flocks of blackbirds have chosen Denton as a roosting site. Interviews with oldtimers here indicate that flocks of birds have always been around. It is only in recent years that their numbers seem much greater and the resulting mess deeper. They also say that "in the old days" if flocks appeared and started creating a problem, they were simply shot with little fuss resulting. This method is not generally acceptable today.