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H. M. Ohlendorf

Publications and source records attributed to H. M. Ohlendorf.

45 records · Page 3Linked to original sources
USGS1979

Organochlorine residues in young herons from the upper Mississippi River-1976

Chicks of great blue herons (Ardea herodias) from four heronaries located near South St. Paul, Royalton, and Wabasha, Minnesota, and La Crosse, Wisconsin, were analyzed for organochlorines, Highest mean wet-weight concentrations, 6.43 ppm PCBs. 1.31 ppm DDE, and 1.90 ppm sigma DDT, were found in the South St. Paul chicks. Among chicks from the other three heronries, most levels were similar, but were significantly lower than levels in South St. Paul chicks. Lowest mean organochlorine levels, 0.37 ppm DDE, 0.38 ppm sigma DDT, and 0.22 ppm PCBs, were found in chicks from Royalton. All birds from South St. Paul and La Crosse contained residues of DDT and TDE whereas only one of the 10 birds from Royalton contained DDT and one contained TDE residues. Five of the 12 birds from Wabasha contained DDT; eight contained TDE. Except for PCB residues in La Crosse heron chicks, the rate of organochlorine residue accumulation in the birds was generally less than the rate of dilution caused by growth.

Pesticides Monitoring Journal↗
USGS1978

Organochlorine residues, eggshell thickness, and nest success in barn owls from the Chesapeake Bay

Eggs of barn owls ( Tyto alba ) were collected from 18 nests in offshore duck blinds on the Maryland side of the lower Potomac River estuary in 1972 and 1973 and analyzed for organochlorine residues. DDE was found in 100% of the clutches, PCBs in 89%, and dieldrin in 78%. Eggshell thickness was inversely correlated with concentrations of DDE, DDD, and dieldrin residues. Six of the 18 clutches had mean DDE residues above 5 ppm, and eggshell thickness in these six clutches was significantly less (P<0.001) than in the other 12 clutches. The owls produced 1.7 young per active nest in 1973. This rate is slightly below the reproductive rate needed to maintain a stable population. An estimated 15% of the population carried concentrations of organochlorine residues that may have been detrimental to their reproduction. Passerine birds, taken extensively as food by a small proportion of the population, are believed to have been the source of elevated concentrations of organochlorines in these barn owls.

Maryland, Virginia↗
USGS1978

Organochlorine residues and eggshell thinning in wood storks and anhingas

All 10 Wood Stork eggs collected at Merritt Island National Wildlife Refuge in 1973 contained residues of DDE (geometric mean 4.0 ppm wet weight) and PCBs (1.2 ppm). Nine other organochlorines were found at lower frequencies in the eggs. Eggshells from the recent period were 8.9% thinner (P < 0.001) than pre-1947 samples; decrease in eggshell thickness was more closely correlated with DDE than other organochlorines and correlation of DDE and eggshell thickness approached significance (P = 0.115).....Anhinga eggs were collected at 7 localities; 45 of the 46 eggs analyzed contained DDE residues and 24 contained PCBs. Residues of other organochlorines were found less frequently. Shell thickness of recent eggs from Louisiana and Mississippi was significantly less (-7.5%; P < 0.05) than the mean for pre-1947 eggs, but there was no significant change in shell thickness of eggs from Florida. The change in clutch mean eggshell thickness was significantly negatively correlated (P < 0.05) with the concentration of DDE in the eggs.

The Wilson Bulletin↗
USGS1977

Impact of estuarine pollution on birds

Pollution of estuaries affects bird populations indirectly through changes in habitat and food supply. The multi-factor pollution of Chesapeake Bay has resulted in diminution of submerged aquatic plants and consequent change in food habits of the canvasback duck. Although dredge-spoil operations can improve wildlife habitat, they often result in its demise. Pollution of estuaries also affects birds directly, through chemical toxication, which may result in outright mortality or in reproductive impairment. Lead from industrial sources and roadways enters the estuaries and is accumulated in tissues of birds. Lead pellets deposited in estuaries as a result of hunting are consumed by ducks with sufficient frequency .to result m large annual die-offs from lead poisoning. Fish in certain areas, usually near industrial sources, may contain levels of mercury high enough to be hazardous to birds that consume them. Other heavy metals are present in estuarine birds, but their significance is poorly known. Oil exerts lethal or sublethal effects on birds by oiling their feathers, oiling eggs and young by contaminated parents, and by ingestion of oil-contaminated food. Organochlorine chemicals, of both agricultural and industrial origin, travel through the food chains and reach harmful levels in susceptible species of birds in certain estuarine ecosystems. Both outright mortality and reproductive impairment have occurred.

Book chapter↗
USGS1976

Mercury in eggs of aquatic birds, Lake St. Clair-1973

Eggs from four species of aquatic birds inhabiting waterways of the Lake St. Clair region were collected in 1973 and analyzed for mercury. Species analyzed were mallard ducks (Anas platyrhynchos), common terns (Sterna hirundo), black-crowned night herons (Nycticorax nycticorax), and great egrets (Casmerodius albus). Mallard eggs contained relatively low residue levels, less than 0.05-0.26 ppm, and common tern eggs contained the highest residues, ranging up to 1.31 ppm. Mercury levels in the eggs were appreciably lower than those in the same species in 1970. The declines are attributed to the 1970 restrictions placed on industrial discharges of mercury into the St. Clair and Detroit Rivers.

Pesticides Monitoring Journal↗
USGS1974

Salmonellosis in a captive heron colony

Salmonellosis caused by Salmonella typhimurium was one of several factors responsible for losses among young herons being held at the Patuxent Wildlife Research Center. The infection was demonstrated in five black-crowned night herons ( Nycticorax nycticorax ), three common egrets ( Casmerodius albus ), two little blue herons ( Florida caerulea ), one cattle egret ( Bubulcus ibis ), one snowy egret ( Leucophoyx thula ) and one Louisiana heron ( Hydranassa tricolor ). The disease was characterized by emaciation, focal liver necrosis, and frequently by a caseo-necrotic enteritis.

Maryland↗
USGS1974

Avian eggshell thickness: Variability and sampling

Measurements of shell thickness of the eggs of five species were subjected to nested analyses of variance. The analyses separated variation into two or three levels for which variances and percentages of the total variation were derived. The results show that differences among measurements of the same egg contribute little to the sample variance whereas differences among eggs within clutches contribute nearly as much as differences among clutches. It is more efficient and less costly to collect entire clutches of eggs in most studies of shell thickness. Using entire clutches, sample sizes needed to detect differences of 10 percent in shell thickness (at given significance levels and power) were estimated to be eight to 11 clutches for the species studied. For differences of five percent, 26 to 38 clutches are required. Guidelines are presented which may assist other workers in evaluating the efficiency of their sampling designs, and in estimating sample sizes for detecting differences in eggshell thickness in wild birds.

The Wilson Bulletin↗