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Reproductive success of American White Pelicans (Pelecanus erythrorhynchos) was monitored at a nesting colony on Anaho Island, Pyramid Lake, Nevada in 1996 as part of an environmental contaminants study. Reproductive success was normal based on hatching rates of eggs (≥ 75% in undisturbed areas) and survival of nestlings. We entered 2 subcolonies after dark to reduce impacts of our egg collecting activities. Human disturbance from egg collection activities did not result in reduced production at one subcolony, where 80% of eggs in both sampled and unsampled nests resulted in 2-wk-old young. However, in a second subcolony only 60% of eggs in sampled nests and 30% in unsampled nests resulted in 2-wk-old young. Data from this study suggests colony visits for sample collection be done at night rather than the day to preclude gull predation and reduce heat stress on eggs and nestlings.

American White Pelicans (Pelecanus erythrorhynchos) that breed on Anaho Island, Pyramid Lake, Nevada, are potentially exposed to a variety of contaminants. Therefore, the reproductive success of this colony was monitored in 1996 and eggs, blood and feathers from nestlings, livers from adults and nestlings, regurgitated fish from nestlings, and fish from representative feeding areas were collected and analyzed for mercury and selenium to determine exposure to the pelicans and sources of contamination. Additional samples were collected and analyzed in 1988, 1992, and 2004. Reproductive success at the Anaho Island colony was normal in 1996 based on hatching rates of eggs (≥75% in undisturbed areas) and survival of nestlings. Mercury and selenium concentrations in eggs were generally below known effect levels and did not appear to have an adverse impact on hatching success. Mercury and selenium concentrations in fish ranged widely, with mercury of greatest concern. Microscopic lesions characteristic ...

Lead-induced mortality appears to have been a major factor in the decline of the California condor (Gymnogyps californianus). We orally dosed turkey vultures (Cathartes aura) with BB-sized lead shot from January 1988 through July 1988 to determine physiologic response (delta-aminolevulinic acid dehydratase inhibition, erythrocyte protoporphyrin levels, anemia), diagnostic tissue lead concentrations (blood, liver, and kidney), and comparative sensitivity of this species. Two turkey vultures died and two became so intoxicated they were euthanized. Overall, responses of measured parameters were comparable to other species exposed to lead although there was considerable individual variation. Survival time (143-211 days), even with the large numbers of shot and constant redosing, was much longer than reported for other species of birds, suggesting considerable tolerance by turkey vultures to the deleterious effects of lead ingestion. Based on these observations, turkey vultures appear to be poor models for assessing the risk of lead poisoning to California condors or predicting their physiologic response.

American kestrels (Falco sparverius) were fed diets containing 0 (control), 1, 3, 10, and 30 μg/g (wet wt) of Kelthane®. Residues of dicofol and its metabolites were then analyzed in the eggs and carcasses of females. Significant differences occurred among treatments for residues of both p,p′-dicofol and p,p′-dechlorodicofol (DCD) in both eggs and carcasses and for p,p′-dicholorbenzophenone (DCBP) in eggs. Residue concentrations increased with increasing treatment exposure. Residues of p,p′-dicofol, p,p′-DCD, and p,p′-DCBP in eggs were significantly correlated with eggshell quality parameters. Significant correlations also occurred among contaminants in eggs and for individual contaminants between eggs and carcasses. The lowest-observed-dietary-effect concentration for eggshell thinning was 3 μg/g, whereas 1 μg/g may be considered to be near a no-observable-adverse-effect concentration. Concentrations of dicofol in potential prey items and eggs of wild birds generally have been lower than dietary-effect concentrations or concentrations in tissues or eggs associated with eggshell thinning and reduced reproductive success.

Moriarty et al. (1986) used field data to conclude that DDE decreased the size or altered the shape of avian eggs; therefore, they postulated that decreased eggshell thickness was a secondary effect because, as a general rule, thickness and egg size are positively correlated. To further test this relationship, the present authors analyzed data from eggs of captive American kestrels. Falco sparverius given DDT- or DDE-contaminated or clean diets and from wild brown pelicans Pelecanus occidentalis collected both before (pre-1946) and after (post-1945) DDT was introduced into the environment. Pertinent data from other field and laboratory studies were also summarized. DDE was not related to and did not affect size, mass, or shape of eggs of the brown pelican or American kestrel; but the relationship of DDE to eggshell thinning held true. Size and shape of eggs of brown pelicans from the post-1945 era and those of kestrels, on DDT-contaminated diets showed some significant, but inconsistent, changes compared to brown pelican data from the pre-1946 era or kestrels on clean diets. In contrast, nearly all samples of eggs of experimental kestrels given DDT-contaminated diets and those of wild brown pelicans from the post-1945 era exhibited significant eggshell thinning. Pertinent experimental studies with other sensitive avian species indicated no effects of DDE on the size or shape of eggs, even though the high dietary concentrations caused extreme eggshell thinning and mortality of some adult mallards (Anas platyrhynchos) in one study. These findings essentially controvert the argument that decreased eggshell thickness is a secondary effect resulting from the primary effect of DDE-induced changes in the size or shape of eggs.

Bald eagle (Haliaeetus leucocephalus) eggs were collected in 15 States in the United States in 1980–1984 and analyzed for organochlorine pesticides, polychlorinated biphenyls (PCBs), and mercury. Data were compared and combined with data from earlier studies to examine trends and refine relationships of contaminants to shell thickness and young production. Moderate shell thinning occurred in eggs from several States. The frequency of occurrence of detectable residues of several contaminants declined during 1969–84. DDE concentrations declined significantly in Wisconsin, Maine, and the Chesapeake Bay region. Some other contaminant residues declined, but usually not significantly. During 1980–84, DDE, PCB, and mercury concentrations were highest in eggs from Maine, whereas most contaminant concentrations were lowest in eggs from Arizona. DDE was most closely related to shell thickness and young production at sampled breeding areas. Fifteen percent shell thinning was associated with 16 μg/g DDE (wet weight) for eggs collected early in incubation. Young production was normal when eggs at sampled breeding areas contained < 3.6 μg/g DDE (wet weight), was nearly halved between 3.6 to 6.3 μg/g, and halved again when concentrations exceeded 6.3 μg/g. Several other contaminants were also associated with poor reproduction and eggshell thinning; however, their impact appeared to be secondary to that of DDE and was probably related to their high correlation with DDE. Data relating contaminant concentrations to mean 5-year production are applicable only to breeding areas where eggs are collected after failure to hatch, because such breeding areas are not representative of all nesting bald eagles in a given population.

American kestrels (Falco sparverius), eastern screech-owls (Otus asio), and northern bobwhites (Colinus virginianus) were given single acute oral doses of four widely diverse anticholinesterase pesticides: EPN, fenthion, carbofuran, and monocrotophos. LD50s, based on birds that died within 5 d of dosage, were computed for each chemical in each species. Sex differences in the sensitivity of northern bobwhites in reproductive condition were examined. American kestrels were highly sensitive to all chemicals tested (LD50s 0.6–4.0 mg/kg). Eastern screech-owls were highly tolerant to EPN (LD50 274 mg/kg) but sensitive to the remaining chemicals (LD50s 1.5–3.9 mg/kg). Northern bobwhites were highly sensitive to monocrotophos (LD50 0.8 mg/kg) and less sensitive to the remaining chemicals (LD50s 4.6–31 mg/kg). Female bobwhites (LD50 3.1 mg/kg) were more sensitive to fenthion than males (LD50 7.0 mg/kg). Mean percent depression of brain cholinesterase (ChE) of birds that died on the day of dosing exceeded 65% for all chemicals in all species. The response of one species to a given pesticide should not be used to predict the sensitivity of other species to the same pesticide. The need for research on several topics is discussed.

Elevated lead in the tissues of raptors, especially those that scavenge, is a common occurrence, and lead poisoning appears to be a significant problem in the ongoing recovery effort for California condors (Gymnogyps californianus). Elevated blood lead levels have been found in released birds, and a number of birds have died of lead poisoning. In earlier work, we dosed turkey vultures (Cathartes aura) with lead shot but found them to be a poor model for lead poisoning. In this study, we dosed four Andean condors (Vultur gryphus) with lead shot and found them to be quite sensitive, as two of the birds died and the other two exhibit signs of lead poisoning within 50 days. All lead-responsive parameters were affected, and regurgitation of dosed shot occurred only once. The response of the Andean condors appeared to mimic California condors, suggesting that once exposed to lead, the possibility of survival is poor. This is consistent with observations in the wild, where otherwise healthy birds exposed to metallic lead quickly succumb. At the very least, the release program has to maintain constant surveillance and an active lead monitoring program.

Cyanide extraction of gold through milling of high-grade ores and heap leaching of low-grade ores requires cycling of millions of liters of alkaline water containing high concentrations of potentially toxic sodium cyanide (NaCN), free cyanide, and metal-cyanide complexes. Some milling operations result in tailings ponds of 150 ha and larger. Heap leach operations that spray or drip cyanide onto the flattened top of the ore heap require solution processing ponds of about 1 ha in surface area. Puddles of various sizes may occur on the top of heaps, where the highest concentrations of NaCN are found. Solution recovery channels are usually constructed at the base of leach heaps, some of which may be exposed. All these cyanide-containing water bodies are hazardous to wildlife, especially migratory waterfowl and bats, if not properly managed. Accidental spills of cyanide solutions into rivers and streams have produced massive kills of fish and other aquatic biota. Freshwater fish are the most cyanide-sensitive group of aquatic organisms tested, with high mortality documented at free cyanide concentrations20 microg/L and adverse effects on swimming and reproduction at5 microg/L. Exclusion from cyanide solutions or reductions of cyanide concentrations to nontoxic levels are the only certain methods of protecting terrestrial vertebrate wildlife from cyanide poisoning; a variety of exclusion/cyanide reduction techniques are presented and discussed. Additional research is recommended on (1) effects of low-level, long-term, cyanide intoxication in birds and mammals by oral and inhalation routes in the vicinity of high cyanide concentrations; (2) long-term effects of low concentrations of cyanide on aquatic biota; (3) adaptive resistance to cyanide; and (4) usefulness of various biochemical indicators of cyanide poisoning. To prevent flooding in mine open pits, and to enable earth moving on a large scale, it is often necessary to withdraw groundwater and use it for irrigation, discharge it to rapid infiltration basins, or, in some cases, discharge it to surface waters. Surface waters are diverted around surface mining operations. Adverse effects of groundwater drawdown include formation of sinkholes within 5 km of groundwater drawdown; reduced stream flows with reduced quantities of wate available for irrigation, stock watering, and domestic, mining and milling, and municipal uses; reduction or loss of vegetation cover for wildlife, with reduced carrying capacity for terrestrial wildlife; loss of aquatic habitat for native fishes and their prey; and disruption of Native American cultural traditions. Surface discharge of excess mine dewatering water and other waters to main waterways may contain excess quantities of arsenic, total dissolved solids, boron, copper, fluoride, and zinc. When mining operations cease, and the water pumps are dismantled, these large open pits may slowly fill with water, forming lakes. The water quality of pit lakes may present a variety of pressing environmental problems.

Highly toxic sodium cyanide (NaCN) is used by the international mining community to extract gold and other precious metals through milling of high-grade ores and heap leaching of low-grade ores (Korte et al. 2000). The process to concentrate gold using cyanide was developed in Scotland in 1887 and was used almost immediately in the Witwatersrand gold fields of the Republic of South Africa. Heap leaching with cyanide was proposed by the U.S. Bureau of Mines in 1969 as a means of extracting gold from low-grade ores. The gold industry adopted the technique in the 1970s, soon making heap leaching the dominant technology in gold extraction (Da Rosa and Lyon 1997). The heap leach and milling processes, which involve dewatering of gold-bearing ores, spraying of dilute cyanide solutions on extremely large heaps of ores containing low concentrations of gold, or the milling of ores with the use of cyanide and subsequent recovery of the gold-cyanide complex, have created a number of serious environmental problems affecting wildlife and water management. In this account, we review the history of cyanide use in gold mining with emphasis on heap leach gold mining, cyanide hazards to plants and animals, water management issues associated with gold mining, and proposed mitigation and research needs.

Highly toxic sodium cyanide (NaCN) is used increasingly by the international mining community to extract gold and other precious metals through milling of high grade ores and heap leaching of low grade ores. Of the 98 million kg cyanide (CN) consumed in North America in 1989, about 80% was used in gold mining (Knudson 1990). In Canada, more than 90% of the mined gold is extracted from ores with the cyanidation process. This process consists of leaching gold from the ore as a gold-cyanide complex, and gold being recovered by precipitation (Simovic and Snodgrass 1985). Milling and heap leaching require cycling of millions of liters of alkaline water containing high concentrations of potentially toxic NaCN, free cyanide, and metal cyanide complexes that are frequently accessible to wildlife. Some milling operations result in tailings ponds of 150 ha and larger. Heap leach operations that spray or drip cyanide solution onto the flattened top of the ore heap require solution processing ponds of about 1 ha in surface area. Although not intentional or desired, puddles of various sizes may occur on the top of heaps where the highest concentrations of NaCN are found. Exposed solution recovery channels are usually constructed at the base of leach heaps. All of these cyanidecontaining water bodies are hazardous to wildlife if not properly managed (Henny et al. 1994). In this account we emphasize hazards of cyanide from mining operations to fish and wildlife species and proposed mitigation to protect them.

Raptors are occasionally exposed to excessive selenium from contaminated prey, but the effects of this exposure on reproduction are unknown. Therefore, we fed captive eastern screech-owls (Otus asio) diets containing 0, 4.4, or 13.2 ppm (wet wt) added selenium in the form of seleno-DL-methionine. Adult mass at sacrifice and reproductive success of birds receiving 13.2 ppm selenium were depressed (P < 0.05) relative to controls. Parents given 4.4 ppm selenium produced no malformed nestlings, but femur lengths of young were shorter (P = 0.015) than those of controls. Liver biochemistries indicative of oxidative stress were affected (P < 0.05) in 5-day-old nestlings from parents fed 4.4 ppm selenium and included a 19% increase in glutathione peroxidase activity, a 43% increase in the ratio of oxidized glutathione (GSSG) to reduced glutathione (GSH), and a 17% increase in lipid peroxidation. Based on reproductive effects relative to dietary exposure, sensitivity of eastern screech-owls to selenium was similar to that of black-crowned night-herons (Nycticorax nycticorax) but less than that of mallards (Anas platyrhynchos).

California condor (Gymnogyps californianus) foods and feathers, and turkey vultures (Cathartes aura), common ravens (Corvus corax), and their eggs were collected within the condor range to determine exposure of condors to environmental contaminants. Samples were analyzed for organochlorines and trace elements. Food items contained low concentrations of organochlorines and generally low concentrations of lead. DDE was detected in all vulture carcasses and nearly all raven carcasses at generally moderate concentrations. Other organochlorines occurred infrequently in carcasses and generally at low concentrations. Turkey vulture eggshells were 16% thinner than the pre-DDT mean; there was no change in shell thickness of raven eggs. Vulture eggs contained an average of 6.9 ppm DDE and two contained excessive concentrations of endrin. DDE concentrations were low in raven eggs. Residues of As, Cd, Cr, Cu, Fe, Hg, Ni, Se, Tl, and Zn in tissues of vultures and ravens appeared normal when compared with reference values for other species. Lead concentrations in bone of turkey vultures and feathers of condors appeared to be elevated above normal background concentrations in some cases. Current exposure of condors to organochlorines appears low; however, we are concerned about the excessive exposure of turkey vultures to organochlorines, possibly in Central America. Lead exposure to vultures and condors has occurred, but its significance to their populations is unknown.

The effects on reproduction in screech owls (Otus asio) of chronic dietary sodium fluoride administration at 0, 40, and 200 ppm were examined. Fluoride at 40 ppm resulted in a significantly smaller egg volume, while 200 ppm also resulted in lower egg weights and lengths. Day-one hatchlings in the 200 ppm group weighed almost 10% less than controls and had shorter crown-rump lengths. No gross abnormalities were apparent. Skeletal clearing and staining revealed significantly shorter tibiotarsus lengths in the 40 ppm and 200 ppm groups and a shorter radius-ulna length in the 200 ppm group. By 7 days of age, body weights and lengths did not differ from controls, but the tibiotarsus in the 200 ppm group remained shorter. No significant differences were detected in hematocrit, hemoglobin, plasma calcium or alkaline phosphatase. Plasma phosphorus levels were higher in the 40 ppm group than in controls. These results, in combination with the findings of Pattee et al. [25], revealed significant impairment of overall reproduction, suggesting that sodium fluoride could cause slight to moderate reproduction disorders in owls in fluoride-polluted areas.

Dicofol in avian eggs was completely oxidized to dichlorobenzophenone (DCBP) when a hexane Soxhlet extraction procedure was used. This degradation did not occur with other avian tissues (muscle and liver). For this reason, a combined extraction-cleanup column chromatographic procedure, without added heat, was developed for the determination of dicofol in avian eggs. Homogenized subsamples of eggs were mixed with sodium sulfate, and the mixture was added as the top layer on a column prepacked with Florisil. The dicofol and other compounds of interest were then eluted with ethyl etherhexane. The extracts, relatively free from lipids, were quantitated on a gas chromatograph equipped with a 63Ni electron-capture detector and a methyl silicone capillary column. Recoveries from chicken eggs, fortified with dicofol and other DDT-related compounds, averaged 96%. Analysis of eggs of eastern screech-owls, fed a meat diet containing 10 ppm technical Kelthane, showed that both dicofol and DCBP were present. Results were confirmed by gas chromatography/ mass spectrometry. This method is rapid and reliable, involves a minimum of sample handling, and is well suited for high volume determination of dicofol in eggs and other avian tissues

Field investigators often take blood samples from wild birds for residue analysis to determine their exposure to various environmental contaminants, such as metals and organochlorines. Under field conditions immediate freezing of blood samples, one common technique of preservation, is not always possible or practical. Therefore, specific techniques of blood preservation must be tested to determine which method is most suitable when blood is to be analyzed for contaminants. In addition, techniques of homogenization of formalin-preserved blood must be adequate if such samples are to be analyzed for both organochlorines and metals or for metals requiring different analytical techniques. The objectives of our study were to test the adequacy of a homogenization technique for formalin-preserved blood and determine which of two preservation techniques is better when samples are to be analyzed for metals and DDE.

Eastern screech-owls (Otus asio) were fed diets containing 10 ppm Kelthane® with 3.4% DDT-related contaminants (old technical formulation), 10 ppm Kelthane with no detectable DDT contaminants (new technical formulation) or a control diet. Food consumption, adult weight and date of initiation of egg laying were similar for birds in control and dosed treatment groups. Most measures of reproductive success were similar for control and dosed treatment groups. Shell weight and thickness index were significantly lower for both dosed groups than for controls. Shell thickness was significantly lower for the new Kelthane treatment than for controls. Concentrations of p,p'-DDE were significantly higher in eggs laid by pairs receiving old Kelthane than in those of birds receiving new Kelthane or in controls. Concentrations of dichlorobenzophenone, dicofol and dechlorodicofols were significantly higher in carcasses of dosed owls than in controls, whereas concentrations of DDE were significantly higher in carcasses of owls fed old Kelthane than in controls or owls fed new Kelthane.

Sixty-six eastern screech-owls (Otus asio) were paired and randomly assigned to dietary treatment groups of 0, 40, or 200 ppm (mg/kg) fluoride (as sodium fluoride) in November 1981. Hatching success was adversely affected at the 200 ppm (mg/kg) level, suggesting potential detrimental impacts to wild populations exposed to fluoride pollution. Eggshell thickness was unaffected. Although fluoride concentrations were elevated in bone and eggshells, large variations among individuals were observed as well as a trend for eggshell residues to increase with sequence of laying. Females had higher residues of fluoride in bone than males. Although fluoride levels in bone and eggshells are useful indicators of exposure, the variability in residues among individuals makes residue data from field collections of limited usefulness in assessing hazards in wild birds.

1. Activities of creatine phosphokinase, glutamic oxalacetic transaminase, glutamic pyruvic transaminase, lactate dehydrogenase, fructose diphosphate aldolase and cholinesterase were measured in plasma of bald eagles. 2. There were no sex differences in the plasma enzyme activities. 3. An acute dieldrin dosage (10 mg/kg) of a female bald eagle resulted in 400% increases in activities of plasma creatine phosphokinase and glutamic oxalacetic transaminase and 250% increases in activities of lactate dehydrogenase and glutamic pyruvic transaminase. 4. At 11 days post-dosage all but one of the plasma enzyme activities had returned to normal; glutamic oxalacetic transaminase activity remained 100% above pre-dosage values. 5. Plasma enzyme assays constitute a non-destrcutive procedure that can be used in valuable wildlife species to screen for the presence and prevalence of environmental contaminants.

Bald eagle (Haliaeetus leucocephalus) eggs were collected in 14 States in 1969–79 and analyzed for organochlorine pesticides, polychlorobiphenyls, and mercury. Moderate shell thinning occurred in eggs from several areas. Eggs from the Chesapeake Bay area contained the highest residue levels of most organochlorines. DDE was detected in all eggs; other organochlorines were detected less frequently. Mercury levels were highest in eggs from Maine. Eight contaminants were significantly negatively correlated with shell thickness or reproduction at sampled breeding areas; DDE was most closely related to these factors. Production of young was near normal at breeding areas when DDE was ⩽3 ppm (wet weight); reproductive failure approached 100% for those breeding areas where DDE in eggs was >15 ppm. Five ppm DDE was associated with 10% shell thinning. The other contaminants that were associated with these factors were also highly correlated with DDE; their impact appeared minor in relation to those of DDE.

Lead shot ingestion by bald eagles (Haliaeetus leucocephalus) is considered to be widespread and has been implicated in the death of eagles in nature. It was recently demonstrated under experimental conditions that ingestion of as few as 10 lead shot resulted in death within 12 to 20 days. In the present study hematological responses to lead toxicity including red blood cell ALAD activity, hemoglobin concentration and 23 different blood serum chemistries were examined in five captive bald eagles that were unsuitable for rehabilitation and release. Eagles were dosed by force-feeding with 10 lead shot; they were redosed if regurgitation occurred. Red blood cell ALAD activity was inhibited by nearly 80% within 24 hours when mean blood lead concentration had increased to 0.8 parts per million (ppm). By the end of 1 week there was a significant decrease (20-25%) in hematocrit and hemoglobin, and the mean blood lead concentration was over 3 ppm. Within as little as 1-2 weeks after dosing, significant elevations in serum creatinine and serum alanine aminotransferase occurred, as well as a significant decrease in the ratio of serum aspartic aminotransferase to serum alanine aminotransferase. The mean blood lead concentration was over 5 ppm by the end of 2 weeks. These changes in serum chemistry may be indicative of kidney and liver alterations.

Twenty-three ospreys (Pandion haliaetus) found dead or moribund in the eastern United States during 1975-1982 were necropsied and selected tissues were analyzed for organochlorines and metals. Major causes or factors contributing to death were trauma, impact injuries, and emaciation. DDE was detected in 96% of the osprey carcases, DDD in 65%, DDT and heptachlor epoxide in 13%, dieldrin, oxychlordane, and cis-nonachlor in 35%, cis-chlordane in 52%, trans-nonachlor in 45%, and PCB's in 83%. Carcasses of immature ospreys from the Chesapeake Bay had significantly lower concentrations of DDE, DDD + DDT, cis-chlordane, and PCB's than carcasses of adults from the same area. Concentrations of some organochlorines in ospreys from the Chesapeake Bay declined significantly from 1971-1973 to 1975-1982. Significant differences in concentrations of certain metals in the ospreys' livers were noted between time periods, and sex and age groups for birds from the Chesapeake Bay. During 1975-1982, adults had significantly lower concentrations of chromium, copper, and arsenic than immatures and nestlings, and adult males had higher mercury concentrations than adult females. Adult females had lower zinc concentrations in 1975-1982 than in 1971-1973. Immatures and nestlings had higher concentrations of chromium and lead in 1975-1982 than in 1971-1973. A slightly elevated concentration of chromium (1.7 ppm) or arsenic (3.2 ppm) was found in the livers of individual ospreys. Several ospreys had elevated concentrations of mercury in their livers; two ospreys had more than 20 ppm which may have contributed to their deaths.

Sensitivities of six avian species, black vulture (Coragyps atratus), American kestrel (Falco sparverius), Japanese quail (Coturnix japonica), domestic chicken (Gallus domesticus), eastern screech-owl (Otus asio), and European starling (Sturnus vulgaris), to acute poisoning by sodium cyanide (NaCN) were compared by single dose LD50's. Three species, domestic chickens, black vultures, and turkey vultures (Cathartes aura), were dosed with NaCN to determine cyanide residues in those that died and also in survivors, in addition to postmortem fate. Three flesh-eating species (black vulture, American kestrel, and eastern screech-owl; LD50's 4.0-8.6 mg/kg) were more sensitive to NaCN than three species (Japanese quail, domestic chicken, and European starling; LD50's 9.4-21 mg/kg) that fed predominantly on plant material. Elevated concentrations of cyanide were found in the blood of birds that died of cyanide poisoning; however, concentrations in birds that died overlapped those in survivors. Blood was superior to liver as the tissue of choice for detecting cyanide exposure. No gross pathological changes related to dosing were observed at necropsy.

Patterns of reproductive failure in declining populations of several European and North American raptorial species were duplicated experimentally with captive American sparrow hawks Falco sparvcrius that were given a diet containing two commonly used organochlorine insecticides. Major effects on reproduction were increased egg disappearance, increased egg destruction by parent birds, and reduced eggshell thickness.

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.

Two of 14 male American kestrels died after 14 and 16 months on a diet containing 2.8 p.p.m., wet weight, p,p′-DDE. The brains of the two birds contained DDE residues of 213 and 301 p.p.m. compared with 14.9 p.p.m. (range, 4.47–26.6 p.p.m.) (wet weights) for 11 of the adult males which were sacrificed after 12 to 16 months on dosage. Autopsies of the two birds compared with autopsies of the sacrificed birds, revealed other characteristics typical of DDE poisoning. Neither bird, when autopsied, displayed characteristics which would suggest that they died of causes other than DDE poisoning.

EGGSHELL thinning in several species of raptorial and fish-eating birds, whose populations and/or reproductive success have declined dramatically in recent years, has been correlated with residues of DDE [1,1-dichloro-2,2-bis (p-chlorophenyl) ethylene] in their eggs1–3. DDE, a common metabolite of DDT [1,1,1-trichloro-2,2-bis(p-chlorophenyl) ethane] and a nearly universal contaminant in the food of these birds, has been considered to be the major chemical responsible for eggshell thinning.

Thirty-three ospreys (Pandion haliaetus) that were found dead or moribund in the Eastern United States between 1964 and 1973 were necropsied. The brains and carcasses of 26 of these birds were analyzed for organochlorines. The livers of 18 and the kidneys of 7 were analyzed for selected metals. Most adults were recovered in April and May and most immatures were recovered in August through October. The adult sex ratio was highly unbalanced in favor of females. Major causes of mortality were impact injuries, emaciation, shooting, and respiratory infections. Of special interest were two birds with malignant tumors and one with steatitis. Many birds had undergone marked weight losses resulting in mobilization and redistribution of organochlorine residues. Organochlorines were detected in the birds at the following percentages: DDE 100%, PCB 96%, DDD 92%, dieldrin 88%, chlordanes (including nonachlors) 82%, DDT 65%, and heptachlor expoxide 38%. Organochlorine levels tended to be higher in adults than in immatures. One adult from South Carolina had a potentially dangerous level of dieldrin in its brain, which might have contributed to its death. Immature ospreys from Maryland had extremely elevated levels of copper in their livers compared with immatures from other areas and all adults. One immature from Maryland had an elevated level of arsenic in its liver, which might have contributed to its death. One adult from Florida that had died of impact injuries had potentially dangerous levels of mercury in both liver and kidney and slightly elevated levels of cadmium in these tissues. Additional birds appeared to have been exposed to contamination of the environment by arsenic and mercury. The levels of chromium, zinc, and lead in livers appeared normal.

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

Eggs of canvasback ducks (Aythya valisineria) from several major breeding areas were analyzed for organochlorine and mercury residues. Polychlorinated biphenyls (PCBs) were detected in 96 of 97 eggs, in concentrations up to 29 ppM (wet wt.). DDE occurred in 79% of the samples with a maximum residue of 12 ppM (wet wt.). DDT, DDD, dieldrin, hexachlorobenzene, cis-chlordane, heptachlor epoxide, and oxychlordane were detected less frequently. Mercury was detected in only 6 of 34 eggs analyzed. Most of the eggs contained concentrations of organochlorines and mercury below levels known to cause adverse effects on avian survival or reproduction.

Five wild California condors (Gymnogyps californianus) that died in 1980-86 were necropsied and tissues were analyzed for environmental contaminants. Three died of lead (Pb) poisoning, 1 presumably of cyanide (CN) poisoning, and 1 nestling of handling shock. Organochlorine concentrations were low in 4 condors that were analyzed for these contaminants. Blood samples from 14 wild and 14 captive condors were analyzed primarily for Pb. Five of 14 wild condors sampled had elevated (>0.70 ppm) concentrations of Pb in blood whereas Pb concentrations in all captive condors were low. Lead levels in individual birds often fluctuated over time. Lead exposure, especially poisoning, was a major factor affecting the wild California condor population during 1982-86. The probable source of Pb was bullet fragments in carrion on which condors were feeding. J. WILDL. MANAGE. 52(2):238-247 The wild population of California condors has been declining for many years (Koford 1953, Wilbur 1978, Snyder and Johnson 1985). In the winter of 1984-85 it declined from 15 to 9 individuals and 4 of 5 known breeding pairs were lost. Since 1985 1 wild California condor has died and the remaining 8 were placed in captivity to enhance the captive flock. Many causes have contributed to the decline of the condor although most are poorly documented (Wilbur 1978, Ogden 1983, Harlow et al. 1984). Some causes that appear to have contributed to the decline are shooting, loss of habitat, disturbance, inadequate food supply, and environmental contaminants. The role of contaminants in the decline of California condors has only been partially assessed (Kiff et al. 1979, Wiemeyer et al. 1983, 1986b). Contaminants such as 1,1-dichloro-2,2-bis(pchlorophenyl)ethylene (DDE); strychnine; sodium monofluoroacetate (Compound 1080); and Pb have been implicated in the condor decline but little corroborative evidence has been provided. The contaminant levels in potential condor food and in the tissues of turkey vultures (Cathartes aura) and common ravens (Corvus corax) that occur within the condor range were assessed in 1980-81 (Wiemeyer et al. 1986b). Wiemeyer et al. (1986b) determined that, in some cases, Pb concentrations in bones of turkey vultures and feathers of California condors were elevated above normal background levels. Elevated levels of organochlorines were also found in turkey vultures, but not in potential condor food. These findings prompted us to sample tissues and determine causes of mortality of all dead condors, and obtain blood samples from all condors captured for telemetry studies during 198286 or for use in captive flocks. Our objective was to identify contaminants that may have been involved in the decline of the condor population. For field assistance we gratefully acknowledge L. Andaloro, D. B. Barbour, D. A. Clendenen, J. Grantham, J. A. Hamber, S. B. Kimple, D. B. Ledig, V. J. Meretsky, J. C. Ogden, L. A. Riopelle, G. D. Sanders, H. A. Snyder, N. F. R. Snyder, and J. J. Woods of the Condor Research Center and veterinarians B. Gonzales of the Los Angeles Zoo; J. L. Allen, D. L. Janssen, and J. E. Oosterhuis of the San Diego Wild Animal Park; P. K. Ensley of the San Diego Zoo; and P. A. Gullett of the National Wildlife Health Center. N. J. Thomas provided analytical methods used at the National Wildlife Health Center. We thank S. H. Fritts, R. M. Jurek, H. R. Perry, J. E. Semberski, and M. G. Holmes for administrative support. We owe special thanks to the ranchers of Kern County who allowed us to trap California condors on their property. We thank J. Grantham, C. E. Grue, L. F. Kiff, O. H. Pattee, and S. R. Wilbur for reviewing the manuscript. The Idaho Cooperative Fish and Wildlife Research unit is funded and supported by Idaho Department of Fish and Game, University of Idaho, U.S. Fish and Wildlife Service, and the 1 Present address: Idaho Cooperative Fish and Wildlife Research Unit, College of Forestry, University of Idaho, Moscow, ID 83843.

Osprey (Pandion haliaetus) eggs were exchanged between Connecticut and Maryland osprey nests in 1968 and 1969 to test the hypothesis that the decline in reproductive success of Connecticut ospreys was caused by something within the external environment of the eggs. Incubation of 30 Connecticut osprey eggs by Maryland ospreys did not improve the hatching rate. Forty-five Maryland osprey eggs incubated by Connecticut ospreys hatched at their normal rate. The results of the egg exchanges and associated observations indicated that the most probable cause of the poor reproduction of Connecticut ospreys was related to contamination of the birds and their eggs. Residues of DDT and its metabolites, dieldrin, and PCBs were generally higher in fish from Connecticut than from Maryland. During 1968-69, average residues (on a nest basis) in osprey eggs from Maryland were: p,p'-DDE, 2.4 ppm; dieldrin, 0.25 ppm; PCB, 2.6 ppm. Average residues in eggs from Connecticut for the same period were: p,p'DDE, 8.9 ppm; dieldrin, 0.61 ppm; PCB, 15 ppm. There were no major changes in residue content of Connecticut eggs collected in 1964 compared with those collected in 1968-69. One Connecticut osprey had a concentration of dieldrin in its brain which was in the lethal range. The average shell thickness of recently collected osprey eggs from Connecticut had declined 18 percent, and those from Maryland had declined 10 percent from pre-1947 norms. Dieldrin, DDE, and PCB are three environmental pollutants that have most likely been important factors in the greatly reduced reproductive success and rapid population decline of Connecticut ospreys. J. WILDL. MANAGE. 39(1):124-139 Ospreys traditionally nested in large numbers along the coasts of New York and Connecticut around Long Island Sound (Bent 1937) and of Chesapeake Bay (Tyrrell 1936). In the late 1960's the osprey population on Chesapeake Bay appeared to be relatively stable (Stickel et al. 1965, Reese 1970); production of young averaged about one per active nest. In contrast, the population on Long Island Sound, particularly near the mouth of the Connecticut River, had undergone a severe decline in number of breeding pairs during the late 1950's and early 1960's (Ames and Mersereau 1964, Ames 1966). Poor production of young was the primary cause of the population decline (Ames and Mersereau 1964). A high percentage of eggs failed to hatch, some of which disappeared during the incubation period for reasons unknown, and others were incubated far longer than normal. Mammalian predation, a possible cause of egg disappearance, was effectively eliminated at most nests. Human disturbance was thought to have minimal effects on osprey reproduction. Survival of nestlings appeared normal. Production of fledglings for the years 1960-63 averaged only 0.23 per active nest (36 young in 157 nestings) (Ames and Mersereau 1964), which is far below that found by Reese (1970) on Chesapeake Bay, and also well below the rate required to maintain a stable population (Henny and Wight 1969). Others have reported severe declines in osprey populations on areas adjacent to Long Island Sound (Emerson and Davenport 1963, Peterson 1969). As a result of these findings regarding 1 Present address: Section of Ecology and Systematics, Cornell University, Ithaca, New York 14850. 2 Present address: Charles M. Russell National Wildlife Range, Lewiston, Montana 59457. 124 J. Wildl. Manage. 39(1):1975 This content downloaded from 40.77.167.85 on Mon, 11 Jul 2016 05:35:58 UTC All use subject to http://about.jstor.org/terms EFFECTS OF POLLUTANTS ON OSPREYS ? Wiemeyer et al. 125 reproduction of ospreys in the Northeast, we initiated a study involving both Maryland and Connecticut ospreys. By comparing differences in hatching rates of eggs within, and those moved between, the two areas, we hoped to determine whether the recurrent nesting failure of Connecticut ospreys was caused by one or more of the following types of factors: (1) external environmental effects such as human disturbance, predation, and/or an inadequate food supply, (2) abnormal adult behavior, especially during incubation, and (3) adverse effects of environmental pollutants within the birds and/or their eggs. This paper documents the results of the egg exchange and provides additional information relevant to the declines in the population and reproductive success of Connecticut ospreys. We wish to thank B. B. Collette, formerly with the U.S. Bureau of Commercial Fisheries, for identification of the fish samples. L. N. Locke autopsied the birds and provided the data regarding his findings. R. S. Christensen of WARF Institute, Inc., Madison, Wisconsin, kindly provided the method used in the mercury analyses. R. G. Heath provided advice regarding the statistical analyses. The Division of Management and Enforcement of the U.S. Bureau of Sport Fisheries and Wildlife provided a pilot and aircraft used in transferring the eggs in 1969. J. R. Maestrelli assisted with field work on the Maryland study area. T. E. Lovejoy made available to us the adult ospreys and several eggs that he collected in 1967. E. H. Dustman reviewed a draft of the manuscript and provided helpful suggestions. MATERIALS AND METHODS An experiment was initiated in 1968 in which eggs from nests in Connecticut estuarine areas (Fig. 1) were exchanged CONN. N 5

A colony of kestrels (Falco sparverius) was established at the Patuxent Wildlife Research Center in 1964 in connection with work on pesticides. The kestrels were acquired from the wild, both as nestlings and as full-grown birds, and were housed in several rows of outdoor pens. Each 50 X 20 ft pen was covered with wire netting and had its long sides in common with adjacent pens. During the first two reproductive seasons, untreated parent birds (dosed birds are not included in this paper) ate eggs and young. Cannibalism virtually ceased after the diet was changed from ground beef or horsemeat supplemented with liver, vitamins, and minerals to one containing a finely ground mixture of laboratory rodents, chicken heads, skinned chicken necks, and supplements; hatching success thereafter generally equalled that of a wild population. In 1967, 16 pairs of untreated hawks (3-year-old females) laid clutches averaging 4.9 eggs, hatched 88 percent of their eggs, and fledged 88 percent of their young. In 1968, 10 pairs of this group (4-year-old females) laid clutches averaging 4.9 eggs, hatched 51 percent of their eggs, and fledged 85 percent of their young. Nine yearling pairs (hatched in captivity) laid clutches in 1968 averaging 5.1 eggs, hatched 87 percent of their eggs, and fledged all of their young. In 1964 a colony of American kestrels was established at Patuxent Wildlife Research Center to test the effects of organochlorine pesticides on the reproduction of this species. Because pesticides reduced the reproductive success of dosed birds (Porter and Wiemeyer 1969), the present paper includes only data from experimental birds fed untreated food, and data from additional birds not involved in the pesticide experiment. The smaller falcons (Falco spp.) have shown a propensity towards breeding in captivity. Two pairs of American kestrels housed in outdoor pens in Germany from 1961 through 1968 raised 61 young, and two males and four females of the second generation raised six young (Koehler 1968: 28-29). Willoughby and Cade (1964:8990) kept six pairs of kestrels in indoor breeding rooms in 1962; the kestrels fledged two young. Two pairs of captive European kestrels (F. tinnunculus) bred by Koehler (1968:30) in 1967 and 1968, raised 14 young. A number of additional records of kestrels nesting successfully in captivity have been compiled by Koehler (1968). Among the larger falcons, both the pere594 grine (F. peregrinus) (Waller 1968, Peterson 1968) and the prairie falcon (F. mexicanus) (Kendall 1968) have hatched eggs and reared young successfully in captivity. The Patuxent colony was established, and the pens were equipped by W. H. Stickel and F. C. Schmid. Their experience and advice provided us with important background when the kestrel research became our responsibility in February, 1967. L. N. Locke, histopathologist at Patuxent, autopsied a number of the birds. J. A. Newman, Department of Veterinary Science, University of Maryland, conducted bacteriological studies to help determine causes of embry nic mortality. The Forest Glen Annex of the Walter Reed Army Medical Center and the National Institutes of Health provided the rodents used in the kestrel diet. L. C. Goldman, photographer, U. S. Bureau of Sport Fisheries and Wildlife, provided the photograph.

Osprey reproductive success on the Potomac River during 1970 is described. Thirty-five percent of the accessible active nests fledged young and only 0.70 young were fledged per active nest. Egg failure was the major cause of poor success. Reproduction was below that considered normal for a stable population.

A colony of captive American Kestrels (Falco sparverius) was established in outdoor pens at Patuxent Wildlife Research Center, Laurel, Maryland, in 1964 to investigate effects of pesticides on raptor reproduction. We have reported on the breeding success, clutch size, and management of the colony (Porter and Wiemeyer 1970), on effects of DDT and dieldrin on reproduction (Porter and Wiemeyer 1969), and on effects of DDE on eggshells (Wiemeyer and Porter 1970). In this paper we report on the chronology of egg laying, incubation behavior, duration of incubation and nestling periods, and nestling sex ratios of captive kestrels untreated with pesticides. There are relatively few published accounts on the breeding biology of either captive or wild American Kestrels. Basic reproductive behavior of kestrels housed in indoor pens was investigated by Willoughby and Cade (1964). Heintzelman and Nagy (1968) reported on clutch sizes, success of hatch, and nestling sex ratios of wild kestrels nesting in artificial nest boxes in Pennsylvania. Koehler (1968) gave similar data for captive kestrels of two species (F. s. sparverius and F. tinnunculus) in Germany. Sherman (1913) published detailed observations of the nest life of an Iowa pair. Nesting chronology was reported by Enderson (1960) for Illinois, by Craighead and Craighead (1956) for Michigan and Wyoming, by Roest (1957) for the Pacific Northwest, and by Cade (1955) for southern California. Clutch size, success of hatch, and fledging success also were reported in the Michigan-Wyoming study (Craighead and Craighead 1956). More generalized reproductive data have been summarized by Bent (1938) for the species in the United States and Canada.