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S.R. Wilbur

Publications and source records attributed to S.R. Wilbur.

At least 37 records · Page 2Linked to original sources
USGS1977

Report of the American Ornithologists' Union Committee on Conservation, 1976-77. The recovery team-recovery plan approach to conservation of endangered species; A status summary and appraisal

The U.S. Endangered Species Act of 1973 (P.L. 93-205) identifies the U.S. Fish and Wildlife Service (USFWS), under authority delegated by the Secretary of the Interior, as the lead agency charged with the conservation of most endangered species in the United States. Some marine species are the responsibility of the Secretary of Commerce, and the responsibility for marine turtles is shared. In 1972 the USFWS sent preliminary instructions to certain field researchers to develop a unified coordinated plan for the recovery of the species they were working with. These were the precursors of recovery teams and recovery plans. The plans, and the teams to draft and help implement them, became one significant means of fulfilling the USFWS' obligations under the Endangered Species Act, particularly Sections 6 and 7, which deal with state and interagency cooperation.

The Auk↗
USGS1975

California condor plumage and molt as field study aids

An analysis is made of the reliability of plumage and molt characteristics of the California condor for estimating age and identifying individual birds. Neither character seems sufficiently reliable to use in more than a general way.

California Fish and Game↗
USGS1974

Supplemental feeding program for California condors

A 2-year supplemental feeding program for the endangered California condor ( Gymnogyps californianus ) was of insufficient length to definitely show that a dependable food supply will stimulate additional breeding; however, production did increase during the study, and food supply appears a likely cause. Because no undesirable effects of feeding were noted, and because condor production is now critically low, an expanded supplemental feeding program is recommended.

California↗
USGS1974

The status of the light-footed clapper rail

Only 12 California marsh areas are presently believed to be inhabited by the Light-footed Clapper Rail, and eight of these appear to support only 5-15 birds apiece. Tentative estimates for the other four are: Anaheim Bay 200, Upper Newport 30-35, Los Penasquitos 30, and Tijuana Estuary 150. These estimates, admittedly very rough, indicate a total Light-footed Rail population on only about 500 birds. Recognizing that rails are secretive and hard to inventory, the actual count could be somewhat higher, but I feel it is most unlikely that the number could be more than 750 birds altogether. Reductions in Light-footed Clapper Rail populations can be attributed almost entirely to loss of habitat. An estimated 26,000 acres of saltmarsh once existed between Santa Barbara and the Mexican border. At present there are approximately 8500 acres, much of which has been degraded by pollution, water diversion, and restriction of tidal flow. Of those areas currently occupied by Clapper Rails, few can be considered to have a very secure future. Of the four major areas only Anaheim Bay appears to be relatively safe from future habitat destruction. Tijuana Estuary, Los Penasquitos Lagoon, and Upper Newport Bay are all threatened by commercial developments that could reduce or destroy local rail populations. I have not visited Baja California, but I believe there is still a substantial population of Clapper Rails in the marshes around San Quintin Bay. Taxonomists do not agree on the subspecific identity of these birds, but some feel they are representatives of the Light-footed race. If so, it is fortunate to have a relatively secure (for now) reservoir of these birds, but whether the Light-footed Clapper Rail survives within the United States may well be decided within the next few years.

American Birds↗
USGS1973

The California condor in the Pacific Northwest

The California Condor ( Gymnogyps californianus ), once found along the Pacific Coast from Baja California to British Columbia, had become very rare north of California by 1850. Koford (1953), summarizing information available on the species in the Pacific Northwest, tentatively concluded that birds seen in that area were wanderers from California, perhaps forced north in some years by food shortages. As support for his theory he noted that there were no records of fossil condors in this northern region, known occurrences there were all in winter, and only a few individuals seemed to be present at any one time. Recently information has come to light that suggests the Pacific Northwest condors were permanent residents with a long history there. An Indian midden on the Columbia River near The Dalles, Oregon, has yielded a considerable number of California Condor bones, dating back thousands of years (Miller, 1957). A more recent, but still precaucasian condor bone was found in another midden in southwestern Oregon (Miller, 1942). These finds indicate the condors are not recent invaders from California.

The Auk↗