Abundance and impacts of fallow deer leks at Point Reyes National Seashore

Fallow deer, Dama dama, were released at Point Reyes National Seashore in the 1940s. A population of about 860 of these non-native deer are now well-established within the park. Fallow deer have an unusual mating system. During the fall, males establish areas known as leks where they display to potential mates. A fallow deerlek is typically an area of 100-150 m2 and usually includes 2-5 males. Using their hooves and antlers, each male clears away most or all of the vegetation and digs a rutting pit that he defends throughout the breeding season. A total of 159 fallow deer leks was located within the 298.8 ha of our study areas. In the Olema Valley, where fallow deer densities are high, there were 116 leks, compared with 43 in the similar sized Estero trailhead study area, where deer density was moderate. A total of 705 rutting pits was found in the two study areas, with a mean of 5.1 pits per lek in the Olema Valley and 2.5 for Estero trailhead. The leks and associated pits have resulted in damage to both the ground and the associated vegetation, especially in riparian areas.