• Duncan, D.A. Effects of urbanization on wildlife in a large subdivision in the blue oak type in Madera County (new project).
• Scott, T.A. The effects of urbanization on wildlife (new project).
  

CDF-Funded Wildlife Research:
Defining the elements within oak woodlands that create value to wildlife has been the focus of CDF-funded research. A previous study indicated that particular habitat elements, such as large blue or valley oak individuals, as well as the pattern of vegetation (e.g. the juxtaposition of dense riparian and open woodland areas) were particularly important to birds that breed in oak woodlands (Noon, B.R. et al. 1988. Silvicultural options in managed oak woodlands to benefit breeding birds). A major IHRMP study examined the composition of avian, mammalian, reptilian and amphibian communities across a number of sites within the oak woodland. The avian data indicate considerable variation across time and space in how individual species and guilds react to specific habitat elements, a result which should direct the further development of habitat relationship models (Block, W. 1989. Spatial and temporal patterns of resource use by birds in California oak woodlands). Species do not appear to react in a simple manner to very particular vegetation variables, but rather appear able to make tradeoffs between habitat elements and therefore exist over a wide range of varying habitats. This suggests that current habitat relationship models can only be legitimately based on rather coarse habitat definitions. Also, habitat diversity may contribute to intra-species diversity and should therefore be a management goal above and beyond any particular “optimal” habitat configuration.

While these studies examined the response of species to naturally-occurring variation in oak woodland vegetation, new research focuses on species response to vegetation change, specifically grazing use, within hardwood riparian habitat. As data from these studies continue to be analyzed, habitat relationship models and guidelines for management of both upland and riparian hardwood habitats can be further refined.


Education and Applied Research Results on Wildlife Habitat

This year California Department of Fish and Game (CDFG) funded a study to analyze acorn production data by oak species, location, and year collected by UC and CDFG personnel since 1977 to recommend future acorn monitoring procedures. An evaluation of blue oak acorn production in Tehama County shows that most of the blue oaks have been poor acorn producers; only about 3% have had good crops of acorns every year. In general, most trees produced few or no acorns consistently year after year. However, in 1990 acorn production was exceptional.

Oak woodland habitat supports a diverse assemblage of wildlife species, many dependent on oaks for food, nesting sites, foraging areas, escape cover, or thermoregulatory cover. Since oaks are being cleared for production of firewood, range forage, and agricultural and residential development, there is a need to manage wildlife within the confines of this loss. A project was initiated in 1989 to look at the utility of using nest boxes to provide nesting sites for specific cavity-nesting species affected by oak clearing, especially western bluebirds. In 1990, 150 nestboxes were placed on cleared rangelands at the UC Hopland and Sierra Foothill Range Field Stations in Mendocino and Yuba Counties, respectively. Preliminary results demonstrated a very high utilization pattern. Future work will involve analysis of habitat variables which characterize locations of utilized nest boxes, and monitoring survival of birds produced in nest boxes.

Much habitat degradation has occurred in cottonwood and sycamore-dominated riparian habitat at two regional parks in San Diego County due to the quarrying of sand and gravel from the river bottom along with the elimination of natural flooding due to flood control structures. Exotic plants and animals have invaded the riparian habitat. San Diego County received state Environmental License Plate Fund monies and contracted with two UC researchers to restore the habitat to its native state and to evaluate wildlife vertebrate species’ abundance and diversify before and after habitat restoration. The three-year restoration/evaluation project consists of three phases. First, a pre-restoration biological survey of all terrestrial vertebrates (amphibians, reptiles, birds, and mammals) is underway. Based on survey results, habitat restoration recommendations will be made. Using the recommendations, San Diego County will conduct the restoration. Finally, during the third year of the project, the faunal survey will be repeated to assess early response to the restoration.

Brushpiles, formed after hardwood rangelands are cleared of firewood, are often burned as waste. UC researchers and a CDFG biologist are evaluating the economics of leaving versus burning brushpiles, and the impact of brushpiles on bird behavior and habitat utilization. In addition, the natural patterns and rates of oak brushpile decomposition is being studied.

A study on California’s central coast has examined the degree and variability of mast production of blue, valley, and coast live oaks. In 1988, county Farm Advisors in San Luis Obispo, Santa Barbara, and San Benito counties identified study sites on ranches within their respective counties. At each site, they established one to several tenth-acre plots. Each fall they have evaluated all oak trees on the plots over four inches DBH for acorn production. Results so far indicate that mast production has been low on the central coast. The majority of trees examined in all counties had no acorns at all, suggesting that low acorn production may be quite widespread.

An apparent decline in the legal harvest of Columbian black-tailed deer in Lake County since 1960 has caused concern among hunters and resource management professionals. A California Department of Fish and Game (CDFG)-funded study was initiated in 1989 by two UC researchers to evaluate various mechanisms which may be impacting the black-tailed deer population in Lake County. CDFG biologists are cooperators in the study. The study focuses on vegetation and land-use changes during the past 30 years, in addition to an analysis of deer harvest trends.

A project was initiated to assist the general public in identifying acorn woodpeckers and the granary trees used by these woodpeckers for the storage of acorns. The presence of granary trees filled with acorns helps to ensure woodpecker reproductive success by providing extra food for the adult birds during the nesting season. This project is focusing on methods for prolonging the life of granary trees, especially large valley oaks.

The Wildlife Habitat Relationship System (WHR) is a collection of computer databases and written educational materials designed for wildlife managers to assess the likely occurrence of various wildlife species on different habitats. In 1989, a shortcourse on the use of WHR by professional biologists was held. A draft of a case study book on practical applications of WHR has been developed, which includes a significant section on evaluating wildlife habitats on hardwood rangelands.

Increasing numbers of people are planting acorns. For those who fail to utilize the proper acorn protection procedures, oftentimes the only material remaining during the next visit is acorn remnants. Acorn fragments from known mortality sources are being collected and evaluated. This collection, and resulting field identification keys, should prove useful in assisting tree planters in determining exactly which species is involved in eating the acorn, and thus which techniques to economically and effectively use to eliminate these mortality sources.

In the north coast area, predation by coyotes and domestic dogs on sheep is significant and, according to the ranching community, a major factor in causing the abandonment of many traditional sheep operations and the subsequent residential development of the former ranches. University of California researchers at the Hopland Field Station are attempting to devise better predation management systems that help sheep producers stay in business, preserving the existing wildlife habitat. To date the work has focused on livestock-guarding dogs and visual-auditory repellents. Future work will also include fencing evaluations.

In March 1990, a two day symposium entitled "Predation management in north coastal California" was attended by over 170 ranchers, resource management professionals, and environmentalists. Participants were exposed to lectures and field demonstrations of current technology used to manage predation on livestock. A post-workshop evaluation indicated that it was very well received. A "Proceedings" was produced and distributed to all UC Cooperative Extension offices in the state, in addition to being made available to interested parties unable to attend the symposium.

Because both hunting and livestock production operations, two major uses of hardwood rangelands, are perceived to be threatened by the publications and actions of animal rights and animal welfare groups, materials have been developed on how wildlife-oriented and livestock production interests can best address these issues. The mountain lion hunting ban, county leghold trap bans, a judicial order to halt the archery bear season, and pending legislation relating to veal production demonstrate the importance of these issues These materials have reached livestock groups such as the California Woolgrowers Association and various professional wildlife management organizations.


Future Needs and Directions
More kinds of wildlife live in California’s oak woodlands habitat than in any other major habitat type in the state. An IHRMP publication titled “Wildlife Among the Oaks” is being developed this year which will make information available in lay terms on the value oaks play in providing food and cover for wildlife and how these values can be maintained and enhanced through proper management of the resource. A draft of the publication is currently near completion, with publication scheduled for early 1991.

Results from a three-year intensive study of vertebrates (amphibians, reptiles, birds, and mammals) are being used to evaluate the Wildlife Habitat Relationships (WHR) System. This IHRMP-funded field study was conducted at three sites (Tejon Ranch, Kern County; San Joaquin Experimental Range, Madera County; and the Sierra Foothill Range Field Station, Yuba County) during 1986 to 1988 in oak or oak-pine woodlands that are representative of much of the oak woodland habitat type. The research will compare field data values with WHR System predictions. Changes will be proposed for errors of omission (i.e., wildlife species that were observed but were not predicted) and errors of commission (i.e., wildlife species that were predicted but were not observed). Currently, the WHR System analysis and writing of results is near completion.

A two-day workshop on the biology and management of Columbian black-tailed deer is planned for April 13-14,1991, in Lake and Mendocino Counties. This workshop will provide the most up-to-date information on deer management in coastal California. The hands-on portion of the workshop will focus on deer habitat evaluation and integrating deer management with livestock production.

331 Vertebrate wildlife species breed in California’s hardwood rangelands.