Geology topics
Publications and source records attributed to L.F. Stickel.
Mallard drakes accumulated mercury rapidly from dietary dosage of methylmercury dicyandiamide and eliminated it slowly, retaining approximately one half at the end of 84 days; no measurable loss occurred between the end of the 7th and 56th days, but loss resumed concurrently with new feather growth, and continued through the 112th day, the close of the study.
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.
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Eastern box turtles (Terrapene c. carolina) in a Maryland bottomland forest were studied over a period of years (1944-1981). Home ranges of 51 males averaged 146 + SD 48 m long and 105 + SD 38 m wide; ranges of 52 females averaged 144 + SD 52 m long and 100 + SD 38 m wide. An approximation of average home range size, based on an ellipse, is 1.20 ha for males and 1.13 ha for females. Sizes of home ranges of individuals did not differ significantly between 1945 and the full term of their captures (0 =14 yr) (AOV; P > 0.05). Mean distance between capture sites, which provides an index to range size, was not significantly different among the years of 1945, 1955, 1965, and 1975 (AOV; P > 0.05). Geographic centers of ranges of 77 males in the bottomlands showed no significant (AOV; P > 0.05) change for 46, and change over relatively short distances (0 =57 + SD 23 m) for the others. Among 70 females, there was no significant change for 46 and change over short distances (0=61 + SD 24 m) for the others. Changes in location were more frequent between 1965 and 1975, a period of pronounced population decline, than between previous decades (significant only for females, x2 P < 0.025). Hibernation sites ordinarily (21 of 23 Individuals) were within the normal bottom]and range; hibernation sites of different years were near each other (all of 4 individuals). In contrast, nesting sites were far distant, extending the home range by 400-700 m, but those of different years were near each other (6 individuals). Mating partners occupied broadly overlapping or contiguous ranges (35 records). Interactions between males (18 records) were identical to courtship behavior, and are believed not to represent territorial aggression.
Growth of box turtles in a bottomland forest in Maryland was studied over a period of years (1944-1981). A bivariate analysis of age related growth showed that between 8 and 13 yr, male turtles grew at an average rate of 6.7% per year in carapace length, whereas females grew at 5.3% per year. Both males and females grew considerably more slowly between 14 and 19 years, males at 2.3% per year and females at 3.4% per year. Growth slowed still more in the twenties. Growth in the six other dimensions that were measured provided additional comparisons. Allometric analysis of the different carapace and plastron dimensions showed that among males length increased proportionally more than either width or height and that width increased more than height. Among females, only the greater increase of length than of width was statistically significant. Fully grown males were larger than females in all dimensions except height. Differences from the normal scutal pattern occurred in 16.8% of fully grown males and 18.4% of the females
During my first employment as a junior biologist conducting food habits analyses at the Patuxent Research Refuge (now Patuxent Wildlife Research Center) of the US Fish and Wildlife Service, the first station director, Arnold L. Nelson, gave each staff biologist the opportunity to spend a little time conducting field studies on the 2,600-acre research area. These studies were to help in ecological evaluation of the area, but also, no doubt, functioned as a morale builder for biologists daily engaged in difficult, demanding and confining laboratory work. I undertook to measure the population density of small mammals in different habitats. The state-of-the-art methods recommended to me and prevalent in the literature worried me, especially after preliminary field work. Reading the classic, paper by W.H. Burt [Terrioriality and home range concepts as applied to mammals. J. Mammalogy 24:346-352, 1943] was a turning point for me in seeing that knowledge of home-range size was the key to measuring population density. My first papers employed these concepts in field evaluations. However, they could give-only limited attention to the question of how home ranges could be measured. Furthermore, the importance of knowledge of the home range to habitat evaluation and to understanding animal behavior was becoming increasingly apparent. Advocacy of many different methods of measuring home ranges appeared in the literature. It did not seem possible to evaluate them objectively. It occurred to me that artificial populations could be used to help in understanding the mechanisms of measuring home ranges. The effects of random trap-visiting, bias toward central traps, trap-spacing, range shape, and other factors could be considered. So grids of traps were inked onto oversize graph paper, and simulated ranges were cut from plastic to be tossed as randomly as possible on the trap-grids. It was a slow, laborious job. Analysis showed that random captures in artificial populations produced patterns that were similar in many ways to those observed in field studies; the necessity of appropriate trap-spacing in relation to range size became obvious. Some commonly used methods of expressing range size proved to be clearly superior to others. However, the artificial populations could not fully simulate actual populations, where use patterns changed as conditions changed and the ?boundaries? of ranges tended to shift continuously or with time. Progress was made, but problems remained. I suspect that the reasons the paper has been cited frequently rest on the continuing interest in home-range behavior and the continuing difficulty in field evaluations, despite the many advances in observational methodology. The sophisticated techniques that became possible with the use of computers [R.I. Jennrich and F.B. Turner. Measurement of non-circular home range. J. Theor. Biol 23:227-237, 1969] also presented new possibilities for analysis and understanding of home-range characteristics and created a resurgence of interest in home-range behavior and its biological significance.
Formalin preservation, freezing, spoiling followed by freezing, and phenoxyethanol were compared in terms of concentrations of DDT, DDD, DDE, endrin, and heptachlor epoxide measured in brain, liver and carcass of birds fed dietary dosages of pesticides and in spiked egg homogenate. Phenoxyethanol proved to be an unsatisfactory preservative; the amount of ‘extractable lipid’ was excessive, and measurements of concentrations in replicates were erratic. Concentrations of residues in formalin-preserved and frozen samples did not differ significantly in any tissue. Percentage lipid in brains and eggs, however, were significantly lower in formalin-preserved samples. Samples of muscle and liver that had been spoiled before freezing yielded less DDD, and muscle samples yielded more DDT than formalin-preserved samples. We conclude that formalin preservation is a satisfactory method for preservation of field samples and that the warming and spoiling of samples that may occur unavoidably in the field will not result in misleading analytical results.
Evaluation of the effects of environmental contaminants on wildlife is geared to interpreting events in the field, especially population effects, and both field and laboratory studies are planned for this purpose; procedures are adapted to specific problems and therefore do not include strict protocols or routine testing. Field evaluations include measurements of cholinesterase inhibition in brain or blood, search for dead or disabled animals, study of nesting success of birds, and general ecological observations. Residue analyses are used in evaluating organochlorine chemicals; samples may include whole bodies for determining level of exposure, brains for mortality diagnosis, whole blood for certain special studies, and eggs to help in evaluation of possible reproductive effects. Bird counts, singing-male census counts, small mammal trapping, and cage-in-field tests have proven to be ineffective or misleading and are not considered suitable for field evaluations under most circumstances. Usefulness of simulated field trials is limited to very special situations. Experimental studies that help predict and interpret field effects include determinations of lethal diagnostic levels, comparative lethal dietary toxicity tests, tests of secondary poisoning, measurement of residue loss rates, measurement of blood enzymes, tests of behavioral effects, and studies of reproductive effects.
(1) The relationships between habitat change and house mouse populations were studied by monthly live trapping in a corn-wheat-hay rotation on a small Maryland farm. (2) Population density reached 53.0/ha in a wheat/hay field in October and 25.4/ha in corn in September. Populations increased by immigration as wheat or corn grew and ripened and decreased by emigration as hay became tall and dense. (3) Survival rates were high in winter in the relatively stable habitat of the wheat/hay field; they were low throughout the summer in both fields, and were reduced by corn harvest, less so by wheat harvest. If they were related to population density or increase, or to breeding condition, the relationships were obscured by the overriding influence of habitat change. (4) In the spring, when the population in the hay field `crashed,' essentially the entire population moved from long-established ranges in the hay field to the field of ripening wheat, where new ranges were established. In the new field, fewer than 30% of the old associations between individuals persisted. (5) Individual mice maintained home ranges (88.1 +- 6.1 m in length) in the same general area during their residence in a field. Ranges shifted from month to month, perhaps in response to changes in populations and habitat; exploratory travels and other movements also modified home range behaviour. (6) Minimum life expectancy (residence time) was greater from November (4-5 months) than from June/July (1-2 months). Maximum individual age was 17 months. (7) The demographic pattern fell at the r extreme of the r-K continuum. Mice bred from May to October, matured and produced litters rapidly, produced several litters in a season, and had a high turnover rate. (8) It was concluded that migration was a primary mechanism of population regulation in the cropfield mosaic and that it was driven by habitat change, a system in contrast to those described for house mice in confined conditions.
Studies of a Maryland population of marked box-turtles (Terrapene carolina) in 1945, 1955, 1965 and 1975 showed a pronounced decline in population size during the three decades; the greatest change came between 1965 and 1975, when numbers were reduced by half. Proportions of females and of young also declined. Fifteen % of the males and 11% of the females that were more than 20 years old in 1945 still were present in 1975; some probably were more than 80 years old.
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.
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Residues of organochlorine pesticides, PCB's, heavy metals, and other toxic chemicals are ubiquitous in the biosphere and are commonly found in tissues and eggs of wild birds. This paper reviews research on the effects of these chemicals, with particular reference to waterfowl. Extensive mortality of waterfowl has occurred in the Gulf Coast region as a result of ingestion of aldrin-treated rice seed. Populations of fulvous tree ducks (Dendrocygna bicolor) have declined in recent years in that area. DDE impaired reproduction of both mallards (Anas platyrhynchos) and black ducks (Arias rubripes) in experimental studies, resulting in thin shells, cracked eggs, and poor hatching success. Eggs incubated by the hens broke and cracked more frequently than those in incubators. In the field, residues are higher in ducks that feed on animal material than in vegetarians; differences are pronounced both geographically and among species. Mercury at levels that occur in certain heavily polluted areas in the United States and Canada has, in experimental studies, lowered the reproductive success of mallards and black ducks and reduced the survival of ducklings. Oil spills have killed many waterfowl as a result of oiled feathers and the intake of oil and more indirect physiological effects have been shown experimentally. Pollutants may affect waterfowl indirectly by changing the habitat and directly as a result of intake of toxic substances. They are unlikely to have been directly limiting factors in populations of such species as mallards. Their involvement with problem of other species, including canvasbacks (Aythya valisineria) and mergansers has still to be explored.
Eggs of wild birds collected for the purpose of measuring concentrations of pesticides or other pollutants vary from nearly fresh to nearly dry so that objective comparisons cannot be made on the basis of weight of the contents at the time of collection. Residue concentrations in the nearly dry eggs can be greatly exaggerated by this artifact. Valid interpretation of residue data depends upon compensation for these losses. A method is presented for making adjustments on the basis of volume of the egg, and formulas are derived for estimating the volume of eggs of eagles, ospreys, and pelicans from egg measurements. The possibility of adjustments on the basis of percentage of moisture, solids, or fat in fresh eggs is discussed also.
SUMMARY: Residues of organochlorine pesticides and their breakdown products are present in the tissues of essentially all wild birds throughout the world. These chemicals accumulate in fat from a relatively small environmental exposure. DDE and dieldrin are most prevalent. Others, such as heptachlor epoxide, chlordane, endrin, and benzene hexachloride also occur, the quantities and kinds generally reflecting local or regional use. Accumulation may be sufficient to kill animals following applications for pest control. This has occurred in several large-scale programmes in the United States. Mortality has also resulted from unintentional leakage of chemical from commercial establishments. Residues may persist in the environment for many years, exposing successive generations of animals. In general, birds that eat other birds, or fish, have higher residues than those that eat seeds and vegetation. The kinetic processes of absorption, metabolism, storage, and output differ according to both kind of chemical and species of animal. When exposure is low and continuous, a balance between intake and excretion may be achieved. Residues reach a balance at an approximate animal body equilibrium or plateau; the storage is generally proportional to dose. Experiments with chickens show that dieldrin and heptachlor epoxide have the greatest propensity for storage, endrin next, then DDT, then lindane. The storage of DDT was complicated by its metabolism to DDE and DDD, but other studies show that DDE has a much greater propensity for storage than either DDD or DDT. Methoxychlor has little cumulative capacity in birds. Residues in eggs reflect and parallel those in the parent bird during accumulation, equilibrium, and decline when dosage is discontinued. Residues with the greatest propensity for storage are also lost most slowly. Rate of loss of residues can be modified by dietary components and is speeded by weight loss of the animal. Under sublethal conditions of continuous exposure to an organochlorine pesticide, the concentrations of residues in the different tissues are ordinarily directly correlated with each other. When the dosage is at lethal levels, or when stored residues are mobilised to lethal levels, the balanced relationship is disrupted. The concentrations of residues in the brain provide the most rigorous criteria for diagnosis of death due to these chemicals, and levels are generally similar across a wide range of species of birds and mammals. Residues in liver are closely correlated with recent dose, either from direct intake or from mobilisation from storage, and so reflect hazardous exposure. Residues in the whole carcass show the storage reserve, and so indicate the potential for adverse effects from lethal mobilisation or from the continuous slow mobilisation that occurs during the normal processes of metabolism and excretion. A synchronous, rapid, and widespread decline in weight and thickness of shells of eggs laid by many species of wild birds occurred in the late 1940's and has persisted. Birds of prey were primarily affected; exceptions apparently are the result of lesser exposure because of different food habits. Many species of fish-eating birds are also affected. Others, however, appear to be more resistant and to accumulate much higher residues before shell-thinning occurs. Seed-eating birds do not appear to have been generally affected; their exposure is ordinarily lower, but physiological factors also seem to be involved. A relationship between shell-thinning and population decline has been established for many species. In exceptional cases, such as the herring gull, persistent re-nesting and other population reactions have overcome adverse effects at the population level. The discovery of shell-thinning among natural populations, and the hypothesis that this thinning was related to the occurrence of organochlorine pesticides, stimulated experimental studies to determine wheth
A survey of organochlorine residues in woodcock wings was undertaken to determine whether these wings are suitable for showing regional differences in residues and to obtain a baseline in 1970-71 for later comparisons. Woodcock wings were obtained from the annual hunter's wing survey. Samples came from eight States (Louisiana, Maine, Michigan, New Hampshire, New Jersey, New York, Pennsylvania, and Wisconsin) and one tri-State area (North Carolina, South Carolina, and Georgia). Wings from the tri-State area contained significantly higher (P<0.01) concentrations of DDT (including DDT, DDD, and DDE) than those from other States. Concentrations of polychlorinated biphenyls (PCB's) also were significantly higher (P<0.05) in samples from these three States. Wings from Louisiana and the tri-State area had significantly higher (P<0.01) concentrations of dieldrin than wings from the other States, and those from Louisiana had significantly higher (P < 0.01) concentrations of mirex than those from other States. (Residues are on lipid base) The compounds detected and the ranges of residue means for all sampling areas were as follows: Total DDT (5.89--65.15 ppm); DDT (0.34 m--14.93 ppm); DDE (4.66--47.47 ppm); DDD (0.11--3.44 ppm); mirex (0.76--16.93 ppm); dieldrin (0.09--3.06 ppm); and PCB's (4.27--8.63 ppm). Woodcock wings appear to be suitable for determining regional differences in organochlorine residues in this species.