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These concerns over human disturbance of nesting hawks are based on statements by Estep, 1989, and the DFG Management Guidelines for this species. It is also noted that local intolerance of human presence may be contrary to the behavior of this raptor in the eastern portion of the United States. One other practice associated with golf course management which may also impact the Swainson's hawk and all other avian and mammalian carnivores is that of using rodenticides to periodically reduce small rodent numbers in the fairway and green areas. Not only does such a control program reduce the supply of prey adjacent to nesting sites, but it also creates a situation in which hawks may occasionally die as a result of catching and eating dying, poisoned rodents. Presently, the most popular rodenticide for ground squirrels and gophers is oats laced with zinc phosphide. This chemical reacts when wetted by saliva to produce a phosphide-type gas in the mouth and throat. This gas then enters the respiratory system during subsequent inhalations and eventually blocks neural conduction throughout the body, causing death. Although many squirrels retreat into their burrows when first confronted with the effects of the gas, some become disoriented and move away from burrow areas in an uncoordinated fashion. It is such individuals which hawks and other predators are most likely to catch, and if some dried poison grain had been stored in the squirrel's cheek pouches prior to consumption, this material would then become volatile in a raptor's crop or stomach. An additional consideration is the potential loss of foraging habitat for the Swainson's hawk as a result of the proposed project. Direct loss would occur through the conversion of approximately 49 acres for lots bordering the two lakes as depicted on the applicant's site plan. Because rodent production was observed to be optimal in the lightly grazed areas near the lakeshores, hawk foraging habitat would be eliminated. The additional loss of grassland through the construction of recreational facilities, such as the proposed 18-hole golf course, tennis courts, and horse stables and paddocks,would eliminate about 75 additional acres of foraging area. The annual creation of a rodent habitat in the shallow bay areas of North Tracy Lake and the western portion of South Tracy Lake would be eliminated with the proposed deepening. Although the applicant is proposing to retain seasonal wetlands through the use of weirs on the eastern half of South Tracy Lake, this does not offset the loss of rodent habitat which presently exists around the lakes. A lush new growth of grasses and forbs emerge on these horizontal plots of moist soil during summer and fall after the lakes begin to drain. This inshore drying and sprouting of green forage occurs about the time that the upland pasture areas are drying out. Prolific rodent species such as the California meadow vole need green grass and forbs in order to sustain a high reproductive rate throughout the summer and fall. These newly drained lake shallows are soon colonized by migrant mice from the adjacent uplands, and soon rodent populations higher than those which existed in the spring grasslands are present. All of this occurs just as the local nesting Swainson's hawks are beginning to forage for rodent prey to feed their voracious chicks. In steep-sided lakes, the steep banks dry rapidly as the water recedes, thus preventing the establishment of such pastures. Because this new habitat is forming in the shallow areas of Tracy Lakes during the nesting season for Swainson's hawks on and adjacent to the site, a significant portion of foraging habitat would be eliminated. 24