by Gretchen Kell
A first-of-its kind study of urban deer in California is underway by researchers here, prompted by the rising number of black-tailed deer and the potential for serious problems between deer and humans in metropolitan coastal communities.
Recently, surveys were mailed to sections of El Cerrito and Kensington in Contra Costa County, asking residents for information including the number of deer seen within two blocks of their homes, the level of deer feeding on their vegetation and whether they are annoyed, indifferent or pleased to see the animals on their property.
The mail surveys are the first step in what will be an in-depth look at the invasion of deer into urban areas, their ecology, their effect on human habitat, and how homeowners, agencies and biologists should respond.
"While deer in the urban setting are not yet a serious problem, all indications are that deer populations in the urban environment are continuing to increase and are spreading into previously deer-free neighborhoods," said Dale McCullough, professor of wildlife biology and management at Berkeley's College of Natural Resources. He and his graduate students are conducting the study.
While earlier in the century deer avoided humans, today they literally are living in residential yards, he said. The plants they eat, the places they find shelter and the types of predators and hazards they face indicate that their lives are much different than those of deer living in wild lands.
"It is of particular interest," said McCullough, "that it is our own human habitat that has been invaded." Beyond the nuisance problems of deer feeding on gardens and ornamental plants, deer also can collide with cars and present other risks.
"These risks and hazards are small, but nonetheless real and are likely to increase in the future if the deer continue to increase," said McCullough. "The adjustment of deer to people and the urban environment, and vice versa, is not complete. An aware public is important to reduce the extent to which the behavior of people contributes to these problems."
"Hopefully, deer numbers will stabilize before the deer become a serious problem," he added.
But since high populations of deer usually lead to calls for their control or removal--a costly and sometimes controversial situation, "it is preferable that research be done now," said McCullough.
The surveys were sent this summer to a sample area that stretches from the BART line on the west to the neighborhoods adjacent to Wildcat Canyon Regional Park. The study may extend to surrounding Bay Area communities in the future.
The objective is to produce maps of the current distribution and abundance of deer in the area, to obtain some sense of human attitudes towards deer in the urban environment and to identify residents willing to keep data logs on deer in their yards and to allow study activities on their properties.
"Because we do not have biological data for comparable wild lands," he said, "we need these data for valid comparisons."
McCullough said trapping will be conducted through early winter. Only fully adult animals will be fitted with permanent collars, designed with a three-year battery life. Any fawns trapped will be fitted with either drop-away collars or ear-tag transmitters. Newborn fawns captured by hand will be given ear-tag transmitters.
By following deer captured in both the urban and wild land sites, researchers hope to obtain the degree of movement of deer between the two areas. Also, a cooperating network of residents will be organized and given training to keep reliable records on deer observations.
McCullough said currently there is little known in the urban environment about the size and character of the deer or their movement patterns. "From observations of homeowners, it seems likely that some deer reside in urban areas year-round," he said. "But do others move back and forth across the urban-wild land interface? Do deer occupying wild lands most of the time move into urban areas to feed on green vegetation when the natural vegetation dries up in summer?"
He said his research also will address whether the population is continuing to grow, what the birth and death rates are and the causes of mortality, and what the survival rates are for fawns.