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At least 883 records · Page 49Linked to original sources
USGS1977

The decline of brown pelicans on the Louisiana and Texas Gulf Coast

Before 1920, native populations of brown pelicans (Pelecanus occidentalis carolinensis) were estimated at 50,000 to 85,000 birds in Louisiana and 5,000 in Texas. By 1958, brown pelicans had vanished from two wintering areas in each state, and wintering and breeding birds disappeared from additional areas between 1959 and 1961. By 1963, the disappearance of the brown pelican from Louisiana was complete, and in Texas only about 100 birds were observed annually. Mortality before 1939, particularly in Texas, was attributed mostly to hunters and fishermen. Losses in both states were attributed to hurricanes, disease, and extended periods of freezing weather. Pesticides may also have contributed significantly. Widespread endrin-caused fish mortality was documented between 1958 and 1964 in Louisiana. Pelicans undoubtedly were exposed to endrine through eating the fish. Significant levels of DDE were found in Texas fishes in the late 1960's. DDE residues in pelican eggs were high enough to be responsible for nesting failure. Shell thinning averaged 10% in Texas pelican eggs collected in 1970, 1972, and 1974, but in earlier years greater thinning was associated with the collapse and loss of eggs. Poor reproductive success during recent years was believed due to (1) failure of many adult pelicans to nest and (2) a high rate of nestling mortality in the few pairs that did nest and hatch young. The remnant population of brown pelicans on the Texas Coast will disappear unless reproductive success improves, because recruitment is presently insufficient to offset mortality.

Louisiana, Texas↗
USGS1987

Number of oil-killed birds and fate of bird carcasses at crude oil pits in Texas

A survey was taken of bird losses in crude oil pits near the central Texas Gulf Coast and in northwestern Texas. At one pit near the Texas Coast, 297 bird carcasses (largely ducks) were counted. Duck losses from oil pollution in northwestern Texas occurred largely in playa basins of the Permian Basin south of the Panhandle. To determine the fate of birds that die in oil pits, 40 carcasses of nine bird species were placed in two crude oil pits near the central Texas Coast in October (19) 1981 and December (15) 1981 and April (6) 1982 and studied for 5 months. Rate of sinking and disappearance of carcasses were positively related to carcass size. In a comparison of three seasons, the time required for a carcass to disappear was longer in winter when oil temperatures were lowest and shorter in spring and fall when oil temperatures were highest.

Southwestern Naturalist↗
USGS1981

Eustrongylides and pesticide levels in a great blue heron shot in Wisconsin

The parasitic roundworm, Eustrongylides ignotus Jagersk, has been known to cause mortality and morbidity in members of the heron family in the eastern states of North America. To date no previous records exist for this nematode in Wisconsin. Even though eustrongylidiosis was first detected in the District of Columbia in 1926 by Chapin (1926), it was not until 1976 that this parasite was found in the midwest, in central Indiana (Winterfield and Kazacos 1977). The purpose of this report is to document the occurrence of this nematode even further westward in Wisconsin, and to show the debilitating effect it can have on herons.

Wisconsin↗
USGS1982

Migratory peregrine falcons, Falco peregrinus, accumulate pesticides in Latin America during winter

Blood samples from 433 Peregrine Falcons (Falco peregrinus) during fall and spring migrations, 1976-80, indicated that most of their pesticide burden, primarily DDE, was accumulated on wintering grounds in Latin America. DDE in spring migrants returning from Latin America for the first time declined significantly from 1979 to 1980. Only about 10% of breeding-age females contained organochlorine residues likely to adversely affect reproduction. The organochlorine pesticide threat in Latin America may be diminishing.

Canadian Field-Naturalist↗
USGS1982

Fall and winter homesite use by wolves in northeastern Minnesota

Post-abandonment homesite use by wolves (Canis lupus) was studied by radio-tracking and simulated howling in two packs in Superior National Forest, Minnesota. Pups, yearlings, and adults returned intermittently to former homesites up to four months after abandonment, usually after prolonged separation from the pack in early fall. Returns sometimes exceeded one week. Preferred summer homesites were revisited most frequently. Visits declined as the season progressed either because attempts to relocate the pack were not facilitated, or simply because separations became rare. While temporarily at homesites, single wolves replied significantly more to simulated howling than when anywhere else, suggesting that homesites may provide reassurance for separated wolves.

Canadian Field-Naturalist↗
USGS1983

Survival of female black ducks, Anas rubripes, during the breeding season

The Mayfield method was used to estimate the survival rate of 19 radio-marked, female Black Ducks (Anas rubripes) in southcentral Maine during 1977-80. An overall survival rate of 0.74 was estimated for the 121-day monitoring period that included the pre-laying and laying, incubation, brood rearing, and post-rearing stages. No differences in survival rates were detected among these stages. Two instrumented hens were killed by Red-shouldered Hawks (Buteo lineatus) and a third was killed by an unknown predator. We found no evidence that the attachment of radio transmitters affected hen survival.

Canadian Field-Naturalist↗
USGS1985

Areas of localized organochlorine contamination in Arizona and New Mexico

Wings from mallard ducks harvested in 1980 in Arizona, Arkansas, Louisiana, and New Mexico were pooled into county aggregates and analyzed for organochlorine pesticides and PCB's. Organochlorine concentrations in duck wings were compared among counties comprising major river drainages within each state. DDE concentrations in the wings of mallards collected from the Verde River and the lower portion of the Gila River drainages in Arizona ranged up to 6 ppm (wet weight basis), which was 17 times higher than the 1979 Pacific Flyway average. DDE at these high levels may be hazardous to wildlife. In combination with other published data, our findings indicate a serious DDT problem in portions of the Verde River and Gila River drainages. High levels of heptachlor (up to 1.7 ppm) and PCB's (3.7 ppm, 61 times the 1979 Central Flyway average) were found in mallard wings from the upper Rio Grande and Pecos River drainages, respectively. We did not detect areas of heavy local organochlorine pesticide or PCB contamination in Arkansas and Louisiana.

Southwestern Naturalist↗
USGS1980

White-faced ibis populations and pollutants in Texas, 1969-1976

Eggshell thickness, levels of pollutant residues, and population status of the white-faced ibis (Plegadis chihi) were monitored in Texas from 1969 through 1976. Texas ibis nesting populations declined by 42%. Reproductive success apparently was limited by DDE-induced shell thinning and by dieldrin-caused mortality. Eggshells averaged 4% to 10% thinner than the pre-1943 mean thickness. Shells of numerous crushed eggs exceeded 20% thinning. Mean DDE residues in randomly collected eggs decreased from 0.94 ppm in 1970 to 0.25 ppm in 1976. DDE was higher, averaging 2.5 ppm, in thin-shelled eggs. DDE was negatively correlated with shell thickness. Dieldrin and PCB residues increased slightly from 1970 to 1976, but neither was correlated significantly with shell thickness. Residues in brains of many dead and dying ibises collected during years of extreme reproductive failure, 1970 and 1973, contained between 5 and 25 ppm dieldrin. Ibises were exposed to aldrin and dieldrin by feeding in rice fields where aldrin-treated rice seed was planted. Improved nesting success in 1976 may have been related to declining residues of DDE and to the discontinued use of aldrin in rice fields.

Southwestern Naturalist↗
USGS1983

Elevated DDE and toxaphene residues in fishes and birds reflect local contamination in the lower Rio Grande Valley, Texas

A potential organochlorine pesticide problem was identified near Mission, Texas, by the National Pesticide Monitoring Program. Fish samples from this site have consistently contained elevated levels of DDE since 1968. Surveys were made in 1976, 1978, and 1979 to determine the extent of organochlorine pesticide contamination in fishes and birds of the area. Freshwater fishes of the Arroyo Colorado, a major waterway traversing the lower Rio Grande Valley, were highly contaminated with DDE and toxaphene residues compared to samples from other areas in the Valley; both DDE and toxaphene ranged up to 31.5 ppm wet weight in whole-fish composite samples. In addition, median DDE residues in fish-eating bird carcasses from this area ranged up to 34 ppm wet weight, and 81 ppm in individual specimens. The levels of contaminants detected in fishes and birds were within, or above, the range producing adverse effects in certain species. The major sources of contamination to the Arroyo Colorado system likely stem from past and present use of persistent pesticides on surrounding croplands, and possibly from an abandoned pesticide plant at Mission, Texas.

Southwestern Naturalist↗