William H. Stickel

DDE in birds: Lethal residues and loss rates

Lethal brain residues of DDE2 were determined experimentally in four species of wild birds given dietary dosage of 1,500 ppm DDE until one-half had died, then sacrificing the survivors, chemically analyzing the tissues, and comparing results in dead birds and survivors. In all species, residues of 300 to 400 ppm of DDE in the brain were considered to show increasing likelihood of death from DDE, confirming results of an earlier study with a single species. Body residues (ppm wet weight) were not diagnostic, overlapping grossly in dead birds and survivors, but averaging higher in survivors. Body residues (ppm lipid base), however, were higher in dead birds and did not overlap those in survivors.Loss rate was followed in grackles fed 1,500 ppm DDE for 7 days, then given untreated feed and sacrificed at intervals of 7, 28, 56, and 112 days. DDE was lost slowly from the bodies, at a rate of 0.30% per day (estimated half-life 229 days). DDE was lost more rapidly from brains, half of the initial concentration being reached in 25 days; concentrations in brains increased thereafter in close correlation with percentage of fat in the body.

Aroclor 1254® residues in birds: Lethal levels and loss rates

Lethal residues of polychlorinated biphenyls (PCBs) were determined experimentally in four species of wild birds given dietary dosage of 1,500 ppm of Aroclor 1254® until one-half had died, sacrificing the survivors, chemically analyzing the tissues, and comparing results in dead birds and survivors. For all species, residues of 310 ppm or higher in the brain showed increasing likelihood of death from PCB poisoning. Residues in dead birds did not differ among species except for starlings (Sturnus vulgaris), which averaged slightly lower than the others. However, the species differed in the length of time to 50% mortality and in the levels of PCBs in brains at sacrifice.Concentrations in bodies and livers were not diagnostic when expressed on a wet weight basis. On a lipid basis, however, concentrations of PCBs in bodies of dead birds were higher than in sacrificed birds, but in both groups residues increased with time, suggesting that overlapping values could be expected.Loss rates were followed in grackles (Quiscalus quiscula) fed 1,500 ppm PCBs for 8 days, then given untreated feed and sacrificed at intervals of 7, 28, 56, 112, and 224 days. PCB residues were lost from bodies at somewhat irregular rates; overall, the rate was estimated at 0.77% per day (half-life 89 days). Residues in brains generally were related to the percentage of body fat, but also showed a somewhat irregular pattern.

CHLORDANE IN BIRDS: A STUDY OF LETHAL RESIDUES AND LOSS RATES

Lethal residues of heptachlor epoxide in brains of birds fed heptachlor ranged from 9 to 27 ppm wet weight; residues of oxychlordane in birds fed oxychlordane ranged from 6 to 16 ppm; both were diagnostically distinct from those in equally exposed survivors. In birds fed chlordane, brains of those that died contained less than 30% of these amounts but also contained trans -nonachlor, compound C, and compound E, suggesting additivity or synergism. In birds fed chlordane followed by untreated feed, oxychlordane was most persistent; trans -nonachlor, heptachlor epoxide, and compounds C and E followed, in that order. Loss rates were best expressed on a wet weight basis because lipid-based rates were distorted by seasonal weight gains.

Ecology of a Maryland population of black rat snakes (Elaphe o. obsoleta)

Behavior, growth and age of black rat snakes under natural conditions were investigated by mark-recapture methods at the Patuxent Wildlife Research Center for 22 years (1942-1963), with limited observations for 13 more years (1964-1976). Over the 35-year period, 330 snakes were recorded a total of 704 times. Individual home ranges remained stable for many years ; male ranges averaged at least 600 m in diam and female ranges at least 500 m, each including a diversity of habitats, evidenced also in records of foods. Population density was low, probably less than 0.5 snake/ha. Peak activity of both sexes was in May and June, with a secondary peak in September. Large trees in the midst of open areas appeared to serve a significant functional role in the behavioral life pattern of the snake population. Male combat was observed three times in the field. Male snakes grew more rapidly than females, attained larger sizes and lived longer. Some individuals of both sexes probably lived 20 years or more. Weight-length relationships changed as the snakes grew and developed heavier bodies in proportion to length. Growth apparently continued throughout life. Some individuals, however, both male and female, stopped growing for periods of 1 or 2 years and then resumed, a condition probably related to poor health, suggested by skin ailments.

Mercury residues in tissues of dead and surviving birds fed methylmercury

SummaryConcentrations of mercury in passerine birds fed diets containing 40 ppm methylmercury were similar in tissues of birds that died from mercury poisoning and in those that were sacrificed after half the group had died. Residues were higher in tissues of birds that died, but the differences were not statistically significant. Residue levels were highest in livers, followed by kidneys and brains. Levels of mercury were similar in breast muscle, carcass, and whole body. Mercury levels were highest in redwinged blackbirds, lowest in grackles, and intermediate in starlings and cowbirds. Mercury concentrations exceeded 20 ppm in all tissues of all species and were similar to levels reported in wild birds known to have died of mercury poisoning.

The home range and wanderings of snakes

NE of the basic instincts of animals is to establish home areas within which the individuals are familiar with their surroundings. As more groups are studied more examples of such relationships appear. Some type of territorial behavior has been found in each major class of vertebrates and in certain invertebrates (Pearse, 1926: 92-93; Heape, 1931: 322-323). The details vary widely with the nature of the animal and its environment, as may be seen from the numerous examples cited by Heape, but the general principle is now so well established that it would be surprising to find unquestionable proof that adult members of any species of terrestrial vertebrate habitually moved about at random. An important distinction is made between the home range and the territory (Burt, 1943). The home range is the area within which the individual ordinarily moves about in the course of its day to day activities. Journeys away from the home range may be made for varying periods of time, or the home range may be shifted, without violation of this concept. The territory is the part of the home range that is defended. It usually includes nesting or food storing sites. The territory is exclusive to an individual or a family of a given species, but much of the home range may be neutral country. Species may have home ranges but no territories. Summaries and references on this subject are given for fishes by Breder (1936), Noble (1938), Noble and Curtis (1939), and Rodeheffer (1941); for birds by Nice (1941), and for mammals by Burt (1943). Frogs and toads of many kinds have resting sites and calling stations to which they habitually return (Noble, 1931: 403-407). Field studies have demonstrated the presence of homing ability in the Salientia, and have shown that while some individuals travel thousands of feet many others remain within a few hundred feet or less of the point of first collection (McAtee, 1921; Breder, Breder and Redmond, 1927; Raney, 1940; Ingram and Raney, 1943). Apparently neither home ranges nor homing have been observed for salamanders, but this may be due to the lack of any satisfactory method of marking these animals for long term studies. Territoriality in lizards is well known (for discussion and references see Evans, 1938; Fitch, 1940; Stebbins, 1944 and 1946; Woodbury and Woodbury, 1945). Various authors have concluded that both aquatic and terrestrial turtles have home ranges to which they will usually attempt to return if displaced. Knowledge of the ranges and travels of turtles has recently been summarized and extended by Cagle (1944). He found no evidence of defensive territorialism. Mcllhenny (1935: 26, 87, 88) states that the alligator usually returns to the same wintering den each year throughout life, and that females frequently use the same nesting site year after year. Territoriality evidently occurs in the alligator, for Mcllhenny remarks that:

Effects of heptachlor-contaminated earthworms on woodcocks

The effects on woodcocks (Philohela minor) of eating heptachlor-contaminated earthworms were studied experimentally in a series of feeding trials in Louisiana in the winter of 1960-61. Six of 12 woodcocks fed worms which had been contaminated at an average of 2.86 ppm of heptachlor epoxide died within 35 days; 4 more had died by the fifty-third day, when the other 2 were killed for analysis. Worms from areas in Louisiana treated with 2 pounds of heptachlor per acre often contain more than 3 ppm of heptachlor epoxide. Eleven of 12 woodcocks fed worms contaminated at an average of 0.65 ppm survived the full 60 days of the experiment; one died on the forty-fifth day, apparently from other causes. All 11 untreated birds survived. Survivors were kept on one-quarter rations of untreated worms for 11 days. Two woodcocks, untreated previously, died during this starvation period. Five previously treated died; two were observed in spasms at death, and these contained 5.9 and 7.2 ppm heptachlor epoxide in their tissues, suggesting that the previous contaminated diet may have influenced mortality, even though the difference between two of nine dying and five of nine dying is not statistically significant. Surviving starved birds given an unrestricted supply of treated or untreated worms for 5 days survived and gained weight. Residues accumulated in their tissues in this time approached levels in birds that died of heptachlor poisoning. Residues in tissues of birds with different histories suggested residue loss at a rate of approximately 2.8 percent per day. Toxicant absorption was estimated to be in the approximate range of 16-20 percent. Residues in birds fed worms containing 0.65 ppm heptachlor epoxide were in the same general magnitude as those in field-caught birds, suggesting a similar average contamination of food supply. Weights and weight changes did not differ significantly between untreated birds and those receiving the lower level of toxicant. Among birds on one-quarter rations, the percentage of weight that could be lost without danger seemed to be near 20 percent. Woodcocks ate 18-208 grams of worms per day (average, 121 grams), representing 11-143 percent (average, 77 percent) of their body weights; birds ate contaminated and uncontaminated food in essentially equivalent amounts. Symptoms of heptachlor poisoning differed considerably between birds. The program initiated in 1958 for control of the imported fire ant (Solernopsis saevissima) created active concern for the woodcock population of North America, for most American woodcocks winter in the Gulf States, where 27 million acres were scheduled for treatment with heptachlor or dieldrin at the dangerous rate of 2 pounds

Oxychlordane, HCS-3260, and nonachlor in birds: Lethal residues and loss rates

Oxychlordane reached lethal levels in birds given dietary dosages of HCS-3260 (70.75% cis-chlordane and 23.51% trans-chlordane) at 6 levels from 50 to 500 ppm. Oxychlordane ranged from 9.4 to 22.1 ppm in brains of cowbirds (Molothrus ater), grackles (Quiscalus quiscula), and red-winged blackbirds (Agelaius phoeniceus) that died on dosage and from 1.3 to 4.8 ppm in sacrificed birds, providing a clear diagnostic separation. Among starlings (Sturnus vulgaris), however, oxychlordane ranged from 5.0 to 19.1 ppm in brains of birds that died, significantly lower than in the other species, and from 1.4 to 10.5 ppm in sacrificed birds, overlapping the levels in those that died. Lethal levels, therefore, begin near 5.0 ppm, as in a previous study in which oxychlordane itself was fed, but the data from starlings emphasizes the need for confirmatory necropsy findings in diagnosis of poisoning. Nonachlor had a very low order of toxicity, killing only 1 of 12 birds dosed at 100 ppm for 35 d; 3 others died and 1 was incapacitated during a short period of food deprivation. Lethal levels of oxychlordane were present in the brains of birds that died. Oxychlordane accumulated in the bodies of birds on dietary dosage of HCS-3260 in proportion to dosage and time, but did not approach equilibrium at the levels (10, 50, and 100 ppm) that were fed. Loss rates of oxychlordane from HCS-3260, oxychlordane, or technical chlordane dosages (the last in a previous study) did not differ significantly from each other; respective half-lives were 57, 63, and 74 d. Residues of cis-chlordane in birds fed HCS-3260 were consistently lower than oxychlordane during the accumulation period and declined abruptly when dosage ceased; individual variation was high.

Body condition and response to pesticides in woodcocks

Response of woodcocks (Philohela minor) to heptachlor dosage was closely related to the physical condition of the birds, as reflected by body weight and by body weight in relation to capture weight: in a series of tests with underweight birds, nearly all woodcocks died at dosage levels well below those at which nearly all the birds in a normal-weight series lived. Heptachlor residues in tissues were determined and their loss with time was estimated. Dieldrin proved more toxic than heptachlor to birds of similar weight. Birds in good weight survived massive doses of DDT; some succumbed to smaller spaced serial doses, but only when these were accompanied by starvation rations. When birds were placed in foil-lined boxes after doses of heptachlor added to butter oil or corn oil, it became evident that they passed quantities of oil in about 3 hours, thus very likely ridding themselves of a large part of the heptachlor dose. It was concluded that other methods than dosage with encapsulated chemicals would be needed for appraisal of field effects of toxicants on woodcocks. Investigations of the effects of heptachlor on woodcocks were begun in 1959 because of the potential hazard of this chemical on the southern wintering grounds, which are within the area treated extensively for control of the imported fire ant (Solenopsis saevissima). As a first step, exploratory tests of acute toxicity of heptachlor were made at the Massachusetts Cooperative Wildlife Research Unit at Amherst. DDT and dieldrin dosages were tried also, because they, too, are chemicals to which woodcocks may be exposed in many areas. Additional tests with heptachlor were made at the Patuxent Wildlife Research Center, Maryland, in 1960. The purposes of this paper are (1) to show the relationship between weight, time in captivity, and effect of toxicant; (2) to demonstrate the resistance of woodcocks to large doses of encapsulated toxicant; (3) to record residue content of dosed birds and to approximate the loss rate of heptachlor residues; and (4) to record mortality data-these are given in some detail, for, although they are not in standard LD50 form, they provide the only available data for a species that offers unusually difficult problems in xperimentation. For the studies of both years, woodcocks were caught in mist nets near Amherst. Housing and care of the birds were as described by Stickel, Sheldon, and Stickel (1965). Assistance was received from several people in various parts of the work. John L. Buckley facilitated and encouraged the tests in 1960 and the analyses that followed; Don W. Hayne helped plan the 1960 tests and provided critical analysis of data from the entire study. Allyn Coombs helped perform the experiments at Amherst in 1959. Residue analyses were made at the Patuxent Wildlife Research Center by Vyto Adomaitis, Calvin Menzie, and William Reichel. EXPERIMENTS WITH HEPTACHLOR Tests in 1959 explored the lethal levels of capsule dosages of heptachlor to captive woodcocks. With this rangefinding as background, tests in 1960 were planned to refine the 1959 determinations, using a stepwise procedure recommended by Hayne for obtaining an LD50 determination with the most economical use of birds. When it was

Endrin in birds: Lethal residues and secondary poisoning

Endrin residues in brains that are diagnostic of death were determined for several species of birds. Residues of 0.8 ppm or more of endrin in brain meant death; 0.6 ppm or less meant survival; between was a zone of overlap. These criteria indicate that some wild birds of the U.S., particularly white pelicans in the Northwest and two bald eagles, have been killed by endrin. Signs of endrin poisoning in experimental birds are described. The important and highly toxic metabolite in rodents, 12-ketoendrin, was sought but not found.