3. Transects for monitoring plant community WATERSHED WILDLIFE Existing Studies: Gustafson (1968a) mentions those species directly dependent on the Lagoon and limits his discussion to the harbor seal, raccoon, the coastal blacktailed deer, mice and the bobcat. Although it is difficult to census wildlife, the most comprehensive assessment of the upland species will be found in the Department of Fish and Game report on the Natural Resources of Bolinas Lagoon, to be issued in Winter, 1970. Two studies specific to the black-tailed deer are Longhurst, Leopold and Dasmann (1952) and Taber and Dasmann (1958). These reports describe management problems of coastal deer herds as they are related to water, forage, and breeding habitats similar to those on the Bolinas Lagoon Watershed and with local data from Fish and Game hunting records they can assist in describing potential changes in this species. The Department of Fish and Game (1970) estimates that deer herds vary from about 30 to 60 animals per square mile but use only about half the watershed, concentrating themselves in the more open plant communities. Of the total herd of between 240-480 animals about 20-25 are removed by hunters each year. Taber and Dasmann (1958, p.56) suggest that a saturation point for deer is reached when there are about 36 breeding does per square mile. A cursory comparison with the Fish and Game estimates suggests that herds on the watershed are in satisfactory numbers. Additional data describing animal weights and reproduction should be analyzed before any firm conclusions are made on the health and trend of populations. Potential Changes in Wildlife: Each species utilizes a variety of environments and plant communities during its diurnal and seasonal cycles and it is spurious to predict qualitative or quantitative changes in wildlife until a better understanding of the populations is reached. It is possible, however, to sketch a general picture of the relationship between vegetation and black-tailed deer herds. Deer populations will increase generally with the increase in grassland, oak-grassland, and most brush communities. They will decrease with the increase in Douglas Fir and Redwood Forests, particularly second-growth stands of between 75-150 years where there is insufficient light on the forest floor for most species of brush and inadequate time for shade-tolerant herbaceous species to establish themselves. Generally, fire, logging, agriculture, and light grazing of cattle are conducive to deer populations while fire protection and vegetation succession are not. In areas where low intensity housing development and roads tend to open up dense forest communities, deer populations will increase with other wildlife species that benefit from residential gardens and garbage (e.g. raccoons). High density subdivisions and heavy traffic work against the abundance and diversity of wildlife, however. 1. Recommendations: Habitat Manipulation: In the absence of more specific data about species populations and their reliance on various micro-environments, it is safe to recommend that a diversity of habitats be conserved in order to enhance the variety and numbers of upland vertebrates. Generally, this means that about two-thirds of the existing grassland could be managed to remain in its present state while roughly a third of the present grassland on the watershed would be allowed to convert to coastal scrub and forest. There should be no attempts to burn existing chaparral communities to enhance deer forage as is done elsewhere. The larger portion of existing forest communities should be preserved as typeenvironments for wildlife relying on these habitats. |