Michael Osbourn | Geology Reports

USGS2009

Fire effects on the Point Reyes Mountain Beaver ( Aplodontia rufa phaea ) at Point Reyes National Seashore, 10 years after the Vision Fire

The 1995 Vision Fire burned 5000 ha and destroyed 40% of the habitat of the Point Reyes Mountain Beaver ( Aplodontia rufa phaea ). Surveys immediately post-fire and in 2000 showed that only 0.4 to 1.7% of Mountain Beavers within the burn area survived. In 2000, dense, ground-hugging Blue-blossom Ceanothus ( Ceanothus thrysiflorus ) appeared to make coastal scrub thickets much less suitable for Mountain Beavers even though the number of burrows at our 11 study sites had returned to 88% of pre-fire numbers. In 2005 (10 y post-fire), the habitat appeared to be better for Mountain Beavers; Blue-blossom Ceanothus had diminished and vegetation more typical of northern coastal scrub, such as Coyote Brush ( Baccharis pilularis ) overstory with a lower layer of herbaceous vegetation, had greatly increased; but the number of Mountain Beaver burrows had declined to 52% of pre-fire numbers and there was little change in the number of sites occupied between our 2000 and 2005 surveys. With the expected successional changes in thicket structure, Mountain Beaver populations are likely to recover further, but there will probably be considerable variation in how each population stabilizes.

Northwestern Naturalist↗

USGS2006

Distribution and abundance of fallow deer leks at Point Reyes National Seashore, California

Only two species of ungulates (hoofed mammals) are native to Marin County, tule elk (Cervis elaphus nannodes) and Columbian black-tailed deer (Odocoileus hemionus columbianus). In the 1940s, European fallow deer (Dama dama) obtained from the San Francisco Zoo were released at Point Reyes. When Point Reyes National Seashore was established in 1962, fallow deer were well established within the boundaries of the National Seashore. The fallow deer population was estimated to be 500 in 1973 (Wehausen, 1973) and that number increased to 860 by 2005 (National Park Service, unpubl. data). Fallow deer have an unusual mating system. During the fall mating season (or rut), male fallow deer establish areas known as leks where they display to potential mates (Hirth, 1997). This behavior is unique among deer and elk, but it is similar to breeding systems used by grouse and a few other birds and mammals. Formation of leks in ungulates decreases the number of aggressive encounters in which dominant males are involved when the local male density becomes too high, because the spatial stability of territories in leks reduces the number of aggressive encounters between males (Hovi et al., 1996; Pelabon et al., 1999). A fallow deer lek is typically an area of about 100-150 m2 and typically includes two to five 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.

Scientific Investigations Report↗