USGS



BIOLOGICAL AND ECOTOXICOLOGICAL CHARACTERISTICS OF TERRESTRIAL VERTEBRATE SPECIES RESIDING IN ESTUARIES

Black-Crowned Night-Heron Black-Crowned Night-Heron photo, Photo Courtesy of Francine  K. Rattner
Photo Courtesy of Francine K. Rattner
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Biological Characteristics

Species

Nycticorax nycticorax (BCNH) is 58-65 cm in length, with an average mass of 883 grams (Dunning, 1993). Its crown, back, and bill are black, legs are yellowish, ventral surface is white, and wings are grey. In breeding condition, two or more long white plumes extend from the top of the head and legs are pinkish (Bull and Farrand, 1977; Robbins et al., 1983). Females are smaller than males, but similar in appearance (Hancock and Kushlan, 1984). Juveniles are brown with buff spots, and have grey and brown streaking on the ventral surface (Hancock and Kushlan, 1984).

Status in Estuaries

This species is found breeding in freshwater, brackish, and saltwater areas. Within these locations BCNHs nest in colonies, some of which consist of several species of herons and egrets. The nests of BCNHs are found directly on the ground or in shrubs or trees. Typically clutch size is 3-6 eggs (Bull and Farrand, 1977). Young are altricial (Ehrlich et al., 1988). The maximum age of a BCNH recorded in nature is 21 years (Hoffman, 1976).

Abundance and Range

BCNH breed throughout most of the U.S, and can be found wintering in the southern U.S. (Custer et al., 1977; Bull and Farrand, 1977). More than 50,000 individuals are estimated nationwide (NACWCP, 2001).

Site Fidelity

Males often use nests from previous years when attempting to attract females (Hancock and Kushlan, 1984). A study of distribution and species abundance found that more than 90% of heron colonies in 1975 were again occupied in 1976 (Custer et al., 1980).

Ease of Census

Moderate. Problems estimating numbers of BCNHs have occurred when the colony is large or when attempting to census from the air or boat (Hancock and Kushlan, 1984; Spendelow and Patton, 1988).

Feeding Habits

Generalists. The BCNH forages in shallow water, mudflats, and upland habitats by walking slowly, locating prey by sight, and striking (Hoopes et al., 1994). BCNHs are crepuscular feeders. Main prey items include fish, amphibians, crustaceans, insects, chicks of other birds, and small mammals.

Black-Crowned Night-Heron Contaminant Exposure Data

I.

Organochlorine Contaminants

A.

Concentrations in Adults

1.

In the 1970's, herons found dead or moribund were collected and analyzed for organochlorine contaminants (Ohlendorf et al., 1979a). Upon detection of substantial residues in carcass, brain was subsequently analyzed (N=49 herons, including 5 BCNHs). Fifteen of these brain samples, including one BCNH, were considered to contain hazardous or even lethal concentrations of pesticides. The single BCNH brain sample was obtained in 1975 from Ruby Lake, Nevada, and contained DDE and DDT concentrations at 230 and 1.1 g/g wet weight, respectively.

2.

From 1970-78, adult BCNHs were collected from Massachusetts, Alabama, Maryland, Michigan, Wisconsin, and Nevada (Ohlendorf et al., 1981). DDE residues ranged from 6.8-170.0 g/g wet weight in the carcass (excludes head, skin, feet, wing tips, liver, kidneys and gastrointestinal tract) and 1.6-230.0 g/g in the brain. TDE ranged from not detectable to 6.4 g/g in the carcass and was not detectable in the brain. Concentrations of DDT, dieldrin, heptachlor epoxide, oxychlordane, cis-chlordane, trans-nonachlor, cis-nonachlor, endrin, toxaphene, HCB and mirex were < 1.0 g/g. PCB concentrations ranged from <0.50 to 110 g/g in the carcass and 0.96 to 30 g/g in the brain.

3.

Carcass and brain concentrations of organochlorine contaminants were determined in 5 birds from Green Bay, Wisconsin that died from unknown causes in 1978 (Heinz et al., 1985). Residue levels in carcass ranged from 4.3-37.0 g/g wet weight for DDE, 0.12-4.0 g/g for DDD, and ND-5.3 g/g for DDT. Dieldrin concentrations ranged from 0.43-10.0 g/g. Heptachlor epoxide, oxychlordane, cis-chlordane, trans-nonachlor, cis-nonachlor and toxaphene levels were <1 g/g in both carcass and brain. Residues in brain ranged from 0.38-22 g/g for DDE, and ND-2.9 g/g dieldrin. DDT residues in brain tissue were found in only 2 of 5 birds and then <1 g/g. Endrin, HCB and mirex were not found in any of the tissues analyzed. PCBs were found in all tissues ranging from 23.0-108 g/g in carcasses and 6.3-160 g/g in brain.

4.

Residues of organochlorine chemicals were determined in tissues collected from 3 BCNHs from Green Bay and Lake Michigan, Wisconsin areas between 1978 and 1982 (Stalling et al., 1985). Total PCDD concentration ranged from 88-214 pg/g (assumed wet weight), TCDD ranged from 4-59 pg/g with the highest level in the 1982 sample. 2,3,7,8-TCDF residues were detected in 2 birds at 8 and 53 pg/g. PCB levels were quantified in the 2 BCNHs collected in 1978, and were 19 and 115 g/g.

5.

Residues of DDE and PCBs were determined in brain tissue of 14 birds found at the Gallager Fish Hatchery, Nevada in 1980-81 (Henny et al., 1984). DDE residues ranged from ND-11 g/g wet weight in all but one individual that had 65 g/g. PCB residues ranged from ND-36 g/g; the 3 highest concentrations were 10, 15, and 36 g/kg, but most values were <5.5 g/g. Other organochlorine compounds (heptachlor epoxide, cis-chlordane, oxychlordane, trans-nonachlor, dieldrin and toxaphene) were detected at low levels (<0.47 g/g).

6.

The intestinal absorption of PCB and dieldrin in BCNHs was measured in vivo by an in situ luminal perfusion technique (Serafin, 1984). The absorption rates for PCB and dieldrin were 0.006 and 0.031 moles per 20 min per g dry weight intestinal segment.

B.

Concentrations in Nestlings

1.

In 1970 and 1977, BCNH chicks and fledglings were collected from Vermont, Alabama, and New Mexico (Ohlendorf et al., 1981). DDE ranged from 0.60 to 3.8 g/g wet weight in the carcass (excludes head, skin, feet, wing tips, liver, kidneys and gastrointestinal tract) and was 0.32 in the brain of one specimen. Concentrations of TDE and DDT were <1.0 g/g in the carcass and not detected in the brain. Dieldrin, heptachlor epoxide, oxychlordane, cis-chlordane, trans-nonachlor, cis-nonachlor, endrin toxaphene, HCB, and mirex were not detected. PCB ranged from <0.50 to 6.5 g/g in the carcass and was detected at 2.0 in the brain.

2.

Liver and carcass residues of chlorinated hydrocarbons were determined in a 15-day old chick (Rice and Custer, 1991). Octachlorostyrene and heptachlorostyrene were 0.14 and 0.09g/g wet weight in the carcass and 0.05 and 0.02 g/g in the liver.

3.

In 1989, 10-day-old nestlings were collected from Chincoteague National Wildlife Refuge in Virginia, Cat Island in Green Bay, Wisconsin, and Bair and West Marin Islands in San Francisco Bay, California (Rattner et al., 1996). Carcass DDE concentrations were generally <1 g/g wet weight and other organochlorine pesticides were generally <0.1 g/g at the four sites. PCB values in nestlings ranged up to 7.1 g/g. Concentrations of pesticides and PCBs in nestlings were considerably lower that levels concurrently found in eggs and embryos from the same study sites.

4.

In 1991, BCNH offspring were collected from two sites in the Chesapeake Bay watershed (Baltimore Harbor, Maryland and Rock Creek Park, Washington, D.C.) and at a relatively uncontaminated reference site (next to Chincoteague National Wildlife Refuge, Virginia) (Rattner et al., 1997). Concentrations of organochlorine pesticides and metabolites in 10-day-old nestling were low,  <0.2 g/g wet weight, although total PCBs in Baltimore Harbor nestlings were 1.29 g/g compared to only 0.15 g/g at the reference site. Concentrations in 10-day old nestlings were generally lower than those in pipping embryos collected from these sites. 

5.

In 1992 and 1993, freshly dead BCNH nestlings were collected in Thermaikos Gulf, Greece (Albanis et al., 1996). The following mean SD (range) concentrations of organochlorines, in mg/kg dry weight, were found: 9.724.34 (ND-4.24) α-BHC, 12.245.84 (ND-21.1) β-BHC, 20.211.17 (ND-31.4) lindane, 0.670.32 (ND-2.00) DDD, and 1.460.46 (ND-6.51) DDE. Organochlorines o,p-DDD, o,p-DDE, o,p-DDT, heptachlor, heptachlor epoxide, aldrin, dieldrin, and endrin were not detected in the nestlings.

C.

Concentrations in Eggs and Embryos

1.

Composite samples of 10 BCNH eggs collected from two colonies in Alberta and Saskatchewan were analyzed for organochlorine residues (Vermeer and Reynolds, 1970). Mean residues from the two colonies were 0.90 and 2.93 g/g wet weight DDE and 0.026 and 0.139 g/g dieldrin, respectively.

2.

In 1969, eggs were collected from 14 BCNH nests in California (Bischoff et al., 1970). PCBs in the composite samples ranged from 2.6-248 g/g (assumed wet weight), and were present at 459 g/g in a composite of two addled eggs.

3.

BCNH eggs collected from various locations in Canada were analyzed for DDE and PCBs (Gilbertson and Reynolds, 1974). The following geometric means were determined for DDE and PCB respectively for each region: Lake Erie (N=5), 26.2 and 147; and Lake Ontario (N=4), 89.4 and 333 g/g dry weight.

4.

Total DDT concentrations (primarily DDE) in 10 BCNH eggs collected along the Texas Gulf Coast in 1970 averaged 1.76 g/g wet weight (King et al., 1978). Only trace amounts of dieldrin were found, and PCBs were not detected.

5.

BCNH eggs were collected from 22 colonies from Florida to Massachusetts from 1972 to 1973 (Ohlendorf et al., 1978a). Colony geometric means for DDE ranged from 0.30-7.0 g/g wet weight, and colony geometric means for PCBs ranged from 0.14-21.0 g/g.

6.

In 1972 and 1973, eggs from 62 clutches of BCNHs (4 colonies from Rhode Island and Massachusetts, and from 1 colony in Michigan) were analyzed for DDE and PCBs (Custer et al., 1990). Mean (and range) DDE levels at the 5 sites were 3.60 (0.58-25), 2.54 (0.45-14), 4.12 (1.7-8.1), 4.09 (2.0-15), and 3.05 (1.5-6.1) g/g wet weight. PCB levels were 8.95 (1.1-100), 5.43 (1.2-21), 6.93 (0.87-18), 10.62 (3.5-30), and 8.79 (2.3-30) g/g.

7.

From 1972 to 1973, eggs were collected from Lake Erie and Lake Ontario (Gilbertson et al., 1976). PCB residues in eggs were 304 g/g wet weight from Lake Ontario and 144 g/g from Lake Erie.

8.

From 1972 to 1973, eggs were collected from 50 locations along the eastern half of the United States (Ohlendorf et al., 1978b; 1979b). The mean DDE concentration in eggs was higher in BCNH from the northern Atlantic region (4.75 g/g wet weight) followed by the Great Lakes region 2.96 g/g. PCBs were highest also in the northern Atlantic region at 8.73 g/g wet weight followed by the Great Lakes at 7.10 g/g wet weight. Specifically, DDE was highest at 7.0 g/g in samples collected from Long Island, New York and highest in PCBs, 22.0 g/g wet weight in samples collected from Middle Brewster Island, Massachusetts.

9.

PCB levels in 22 BCNH eggs collected from Green Bay, WI and Lake Michigan between 1977-1980 ranged from 0.82-92.0 g/g wet weight (Heinz et al., 1985). Concentrations of DDE and dieldrin ranged from 0.37-17 g/g and ND-0.73 g/g, respectively. Other organochlorine pesticides were found only at low levels.

10.

A total of 220 eggs from 8 nesting sites were collected in 1978-1980 (Henny et al., 1984). DDE was found in all eggs with mean levels ranging from 2.17-8.21 g/g wet weight. Southern colonies generally had the highest levels of residues of DDE, which was associated with reduced productivity in one colony (Ruby Lake in Nevada). PCBs were detected in less than 50% of the eggs sampled, and values were low (<2 g/g). Other organochlorine contaminants were infrequently detected.

11.

BCNH eggs were collected in 1979 from 2 colonies in North Carolina, 2 in Rhode Island and 1 in Massachusetts and analyzed for organochlorine contaminants (Custer et al., 1983a). Means and ranges of DDE were 2.12 (0.59-11.0) g/g wet weight in samples from Clarks Island, MA; 2.60 (0.92-9.3) from Hope Island, RI; 1.31 (0.41-4.1) from Gould Island, RI; 0.66 (0.1-2.8) from Annex subcolony of Newport River, NC; and 1.06 (0.42-11.0) from Marsh Island, NC. Mean PCB residues and ranges were 6.16 (2.2-49) g/g at Clarks Island, 9.99 (4.1-32) at Hope Island, 6.12 (1.5-19) at Gould Island, 0.83 (ND-4.9) at Annex, NC, and 2.42 (0.64-5.6) at Marsh Island. The highest level of DDT was 0.57 g/g in eggs from Marsh Island and the highest residue of DDD was 1.1 g/g from Hope Island. Highest residues of dieldrin were 6.0, 1.3, 0.12, 0.53 and 0.73 g/g in samples from Clarks Island, Hope Island, Gould Island, Annex and Marsh Island, respectively. Concentrations of other organochlorine chemicals including heptachlor epoxide, mirex, oxychlordane, cis-chlordane, cis-nonachlor and trans-nonachlor were <1 g/g. Mean concentrations in addled eggs from New England sites were similar to levels in the randomly selected eggs. DDE levels were lower in the samples from New England in 1979 than in eggs collected in 1973 in a related study (Ohlendorf et al., 1978a).

12.

In 1979, one egg per nest was collected for analysis for DDE and PCB residues coincident with the study of reproductive success in 3 BCNH colonies in New England and in 2 colonies in North Carolina (Custer et al., 1983b). Mean DDE levels in eggs from nests in New England with 100% hatch or <100% were 1.78 g/g wet weight and 2.29 g/g, respectively; in the North Carolina colonies, mean levels of DDE were 0.78 and 0.75 g/g, respectively. Mean PCB levels in the New England colonies were 7.58 g/g in eggs from nests with 100% hatchability and 7.20 g/g in eggs with <100% hatchability; in the North Carolina colonies, mean PCB levels were 1.16 and 1.12 g/g, respectively. Concentrations of DDE or PCB did not differ with clutch size, but PCB levels were lower in eggs laid late in the season.

13.

In 1979, eggs were collected from 7 nesting sites in Colorado and Wyoming (McEwen et al., 1984). DDE was detected in all eggs collected (N=147) at a mean concentration of 3.1 g/g wet weight; mean values at the 7 sites ranged from 1.8 to 7.6 g/g. PCBs were detected in 81 eggs, (mean 1.0 g/g); the highest mean concentration at any of the collection sites was 2.2 g/g. A total of 12 other organochlorine chemicals were detected in 1 to 30 eggs at the various sites, usually at <1.0 g/g.

14.

In 1979, eggs were collected from Minidoka National Wildlife Refuge, Mud Lake Wildlife Management Area, and Blackfoot Reservoir in southeast Idaho (Findholt and Trost, 1985). DDE was detected in all eggs; mean residues and ranges from each site were 3.5 (0.92-24), 2.4 (0.37-10) and 2.2 (0.27-20) g/g wet weight. DDD was found in 8 eggs (21%) and maximum values at each of the sites were 0.36, 0.10 and 0.63 g/g. Parent DDT was detected in 37% of the eggs; the greatest value at each site was 0.41, 1.1 and 1.7 g/g. PCBs were detected in 7 eggs (18%) at only 2 of the 3 sites; mean levels were 0.41 and 0.31 g/g with maximum values of 1.4 and 1.6 g/g. Other pesticides detected included dieldrin (5 of 38 eggs) at 3 sites, heptachlor epoxide, (7 of 38 eggs) at 2 sites, oxychlordane (9 of 38 eggs) at 2 sites, and HCB (1 egg at 1 site); mean concentrations of these contaminants were <0.1 g/g.

15.

During a 5 year study, one egg was collected from each of 250 BCNH nests in Oregon and Nevada (Henny et al., 1985). Mean DDE residues for eggs collected from the Ruby Lake in years 1979, 1980, 1982 and 1983 were 8.21, 4.13, 3.43, and 2.79 g/g wet weight, respectively; maximum concentrations for each year were 130, 21, 16, and 12 g/g, respectively. Similar results were obtained at the other sites. At Malheur Lake, mean (and maximum) residues for 1979, 1980, 1982 and 1983 were 4.70 (22), 2.73 (14), 1.23 (8), and 1.06 (12) g/g, respectively. At Stillwater, mean (maximum) residues for years 1980-1983) were 5.08 (26), 2.50 (14), 3.06 (12), and 2.03 (13) g/g, respectively. At Halleck, mean (maximum) DDE concentrations for years 1981, 1982, and 1983 were 4.63 (56), 2.21 (11) and 2.65 (28) g/g, respectively. PCB levels were reported quantitatively only from Ruby Lake samples for the years of 1979, 1980, 1982, and 1983 (1.70, 1.45, 1.25, and 0.82 g/g, respectively) and for the 1981 eggs collected at Halleck (1.37 g/g). Other pesticides detected, but reported only as incidence (% eggs with residues), included DDT, DDD, dieldrin, BHC, HCB, endrin, toxaphene, and chlordanes (heptachlor epoxide, oxychlordane, trans-nonachlor, and cis-chlordane).

16.

Residues of DDE and PCBs were detected in all BCNH eggs (N=31) collected from 3 sites in the Tennessee Valley in 1980 (Fleming et al., 1984). Mean values of DDE from the 3 colonies were 2.8, 0.82 and 1.3 g/g wet weight; the highest DDE concentrations, 13 and 17 g/g, in 2 of the eggs exceeded levels usually associated with reproductive impairment. Mean PCB levels ranged from 5.6 to 19 g/g with individual values ranging from 1.5 to 100 g/g. Prevalence of other compounds, including DDD, DDT, dieldrin, heptachlor epoxide, oxychlordane, cis-chlordane, trans-nonachlor, cis-nonachlor, HCB, and mirex varied with colony location, and concentrations were generally low.

17.

Eggs collected in 1982 from the Bair Island colony in San Francisco Bay, California included 12 each from the early and late incubation period, 11 which failed to hatch and 12 that were dumped or abandoned outside the nest (Ohlendorf et al., 1988). Mean (range) residues of DDE were 2.92 (0.88-15), 2.77 (0.59-15), 2.48 (0.71-26), and 1.27 (0.58-65) g/g wet weight, respectively. PCB concentrations were 1.85 (0.48-8.0), 4.84 (1.4-18), 3.77 (1.0-31), and 2.66 (0.80-7.9) g/g, respectively. Other residues detected in some but not all egg samples included DDD (5 eggs), parent DDT (6 eggs), dieldrin (14 eggs-1.3 g/g maximum), heptachlor epoxide (3 eggs), oxychlordane (26 eggs-0.92 g/g maximum), cis-chlordane (34 eggs-2.0 g/g maximum), trans-chlordane (34 eggs-1.9 g/g maximum), trans-nonachlor (20 eggs-1.9 g/g maximum), cis-nonachlor (20 eggs-1.2 g/g maximum), and toxaphene (3 eggs).

18.

Eggs were collected from Bair Island (1982 and 1983) and Mallard Slough (1983) in the San Francisco Bay area, 3 sites in the San Joaquin Valley (1984), and 1 site from the Salton Sea area (1985) (Ohlendorf and Marois, 1990). DDE was detected in all samples with mean (range) values of 8.62 (2.5-20) g/g wet weight in the 1985 Salton Sea eggs; 2.85, 1.73, and 3.14 (0.57 to 16) g/g in the 3 San Francisco Bay area sites; and 1.64, 2.27, and 3.97 (0.77 to 12) g/g in the 3 San Joaquin Valley sites. DDE concentrations in 14 of the 87 (16%) of the eggs were higher than those associated with reduced reproductive success in the BCNH (8 g/g). Other organochlorine chemicals including PCBs were only occasionally detected in eggs from the sites in the San Joaquin Valley and Salton Sea.

19.

Eggs were collected in Italy in 1982-83 and in 1993-94, and analyzed for organochlorine pesticides and PCBs (Fasola et al., 1998).  In 1982-83, mean pesticide concentrations (g/g wet weight) were 0.09 aldrin, 0.02 dieldrin, 0.11 endrin, 0.82 p,p-DDE, 0.07 o,p-DDD, and  0.09 p,p-DDD.  Lindane and heptachlor were not detected.  In 1993-94, mean concentrations were 0.026  -HCH, 0.006  -HCH, 0.003 lindane, 0.007 heptachlor, 0.008 heptachlor epoxide, 0.018 aldrin, 0.008 dieldrin, 0.010 endrin, 0.025 o,p-DDT, 0.023 p,p-DDT, 0.014 p,p-DDE, 0.011 o,p-DDD, and  0.041 p,p-DDD.  In 1993-94, mean PCBs were 0.04 g/g total PCBs and 0.775, 0.013, 0.011, 0.029, and 0.005 g/g mono-, di-, tri-, tetra-, and pentachlorobiphenyl congeners, respectively.  Hexa- and heptachlorobiphenyl congeners were detected.

20.

In 1983, eggs were collected from Bair Island for quantification of organochlorine contaminants (Hoffman et al., 1986). DDE concentrations ranged from 0.57 to 5.6 g/g wet weight and PCB values ranged from 0.75 to 52 g/g.

21.

In 1983, BCNH eggs were collected from Corpus Christi, Texas, Loving, New Mexico, and Artesia, New Mexico (White and Krynitsky, 1986). DDE was detected at geometric mean concentrations 6.0 g/g wet weight at Artesia, 1.4 g/g at Loving, and 1.4 g/g at Corpus Christi. PCBs and chlordane isomers occurred at mean concentrations of <1 g/g at all three sites.

22.

The potency of PCB-containing extracts from BCNH eggs collected from Great Lakes colonies in 1986-87 were bioassayed by their ability to induce cytochrome P-450IA1-associated EROD activity in H4IIE rat hepatoma cells using TCDD as a standard (Tillitt et al, 1991). TCDD-EQs for BCNH egg extract from Saginaw Bay, Lake Huron were 221.7 pg/g. Even though the biological significance of these values have not been established and may not be predictive of toxicological effects, when extracts from several species were considered together, the greatest values were found in areas with the most severely affected reproduction effects.

23.

Octachlorostyrene and heptachlorostyrene were 1.6 and 0.06 g/g wet weight, respectively, in a BCNH egg (Rice and Custer, 1991).

24.

In 1989, pipped BCNH eggs (N=61) were collected from 4 sites, including a colony next to the Chincoteague National Wildlife Refuge (CNWR) in Virginia, Cat Island in Green Bay, Wisconsin, and Bair and West Marin Islands in San Francisco Bay, California (Rattner et al., 1993). Mean levels and ranges (embryo carcass minus liver) for DDE were 0.52 (0.06-5.2), 1.44 (0.33-3.8), 1.24 (0.24-5.2) and 1.02 (0.02-6.9) g/g wet weight in carcass samples from CNWR, Cat Island, Bair Island and West Marin Island, respectively. Total PCB concentrations were 1.13 (0.24-4.0), 9.32 (2.40-53), 2.56 (0.57-12), and 0.86 (ND-5.2), respectively, at the CNWR, Cat Island, Bair Island and West Marin Island sites. Concentrations of 11 other pesticides or their metabolites were low (<0.01 g/g).

25.

Contaminant analyses of pipping embryos collected in 1989 (Rattner et al., 1993) were expanded to quantify specific arylhydrocarbon-receptor active PCB congeners 77, 126, 169, 105, 118, 128, 138, 156, 158, 167, 170 and 189 (Rattner et al., 1994), TEQs (mathematically predicted) and dioxin equivalents (derived by bioassay). Concentrations of several PCB congeners, TEQs, and dioxin equivalents were greatest in samples from Cat Island, Green Bay, Wisconsin compared to Chincoteague National Wildlife Refuge, Virginia. At Cat Island, average concentrations of toxic PCB congeners 126 and 105 were 1,134 pg/g wet weight and 638 ng/g, with TEQs and dioxin equivalents at least fivefold greater than the CNWR site.

26.

In 1991, pipping embryos collected from Cat Island, Wisconsin contained 2.2 g/g wet weight DDE and 11.0 g/g PCBs (Custer and Custer, 1995). Other chemicals including cis-nonachlor, oxychlordane, trans-nonachlor, heptachlor epoxide, dieldrin, DDD, and DDT were present at concentrations of <0.1 g/g. Mean concentrations of DDE and PCB decreased with age, reaching levels of 0.70 and 4.3 g/g, respectively, in 5-day old chicks. Concentrations of 7 of the other organochlorine contaminants decreased with time or remained unchanged. However, total mass (g/individual) of these chemicals either increased with time or remained the same.

27.

Between 1989 and 1991, BCNH eggs were collected from 5 major nesting sites (>50 nests/site) in the San Francisco Bay area (Hothem et al., 1995). DDE was detected in all eggs; mean yearly residue concentrations ranged from 0.466 (0.16-0.91) g/g wet weight from Brooks Island in 1991 to 1.78 (0.67-8.9) g/g from Bair Island in 1990. At the site in the San Joaquin Valley, mean (range) DDE concentrations were 5.97 (4.3-9.4) g/g in 1991. PCBs were detected in 99% of the egg samples; means (ranges) of yearly concentrations varied from 0.603 (ND-5.1) g/g in eggs from West Marin Island in 1989 to 6.08 (1.6-46) g/g in eggs from Alcatraz Island in 1991. Contaminants detected at low levels (<1 g/g) or only infrequently included heptachlor epoxide, trans-nonachlor, cis-nonachlor, chlordanes, oxychlordane, DDD, DDT, BHC, dieldrin, toxaphene, endrin, and mirex. There were no statistically significant inter-year differences for mean concentrations of PCBs or DDE.

28.

In 1991, a total of 14 eggs were collected from 4 colonies of BCNHs on the Columbia River, and from 1 near a reservoir in Washington state (Blus et al., 1997). The geometric mean (range) of residues for TCDD, DDE, and total PCBs were 3.98 (1.3-31) pg/g wet weight, 2.01 (0.4-4.6) g/g, and 0.29 (ND-0.61) g/g, respectively. Concentrations of PCBs, heptachlor epoxide, HCB, oxychlordane, DDT, BHC, trans-nonachlor, DDD and dieldrin were low, averaging <0.1 g/g.

29.

In 1991, BCNH offspring were collected from two sites in the Chesapeake Bay watershed (Baltimore Harbor, Maryland and Rock Creek Park, Washington, D.C.) and at a relatively uncontaminated reference site (next to Chincoteague National Wildlife Refuge, Virginia) (Rattner et al., 1997). Mean concentrations of DDE in pipping embryos were 1.59 and 1.39 g/g wet weight at Baltimore Harbor and Rock Creek Park, respectively, and were greater than embryos at the reference site (0.23 g/g). Values of other pesticides (heptachlor epoxide, trans-nonachlor, cis-nonachlor, chlordanes, oxychlordane, DDD, DDT, BHC, dieldrin, toxaphene, endrin, and mirex) in embryos were low, averaging <0.3 g/g. Total PCBs means of Chesapeake region embryos were nearly one order of magnitude greater compared to the reference site (3.40 and 2.64 g/g compared to 0.29 g/g at Chincoteague). Concentrations of 10 arylhydrocarbon receptor-active PCB congeners and estimated TEQs were up to 37-fold greater in embryos collected from these two sites in the Chesapeake Bay region, with values for toxic PCB congeners 77 and 126 exceeding those observed in heron embryos from the Great Lakes. Concentrations in embryos were generally greater than those in 10-day old nestlings collected from these sites. 

30.

In April May 1996, BCNH eggs (N=9) were collected from Alexander Island, in Galveston Bay, TX, USA (Frank et al.,  2001).  Hexachlorocyclohexane isomers (α, β, γ, and δ) were detected generally at concentrations <100 ng/g wet weight in eggs, specific values were not reported.  Geometric mean and ranges (ng/g) for hexachlorobenzene and DDE concentrations respectively, were: 59 (2-975) and 401 (35-12,900).  Geometric means of PCB congeners (ng/g)  ranged from 17 for PCB28, to 250 for PCB138.  Congeners 28, 74, 66, 99, 128, 146, 153, 105, 138, 158, 187, 183, 128, 156/171, 180, 194, and 209 were detected.  The geometric mean and range of total PCBs was 2,100 (242 5,576).  Non-ortho and mono-ortho congeners detected (in 3 eggs) and their arithmetic means (pg/g, in parentheses) were: PCB77 (453), PCB126 (1,204), PCB169 (130), PCB105 (59,162), PCB118 (314,348), PCB156 (52,611), PCB167 (25,447), and PCB189 (5,085).  Mean TCDD was 163 pg/g; PeCDD was detected in one egg at 25 pg/g; HxCDD was detected in one egg at 26 pg/g; mean TCDF was 9 pg/g, mean instrumental TEQ was 337, mean bioassay TCDD-EQ was 231. 

31.

In 1997, pipping BCNH eggs were collected from Pea Patch Island in Delaware Bay (N=15), and a reference site, Middle Island in Rehoboth Bay, Delaware (N=9) (Rattner et al. 2000).  Mean concentrations of p,p-DDE did not differ between Middle Island (0.38 g/g wet weight) and Pea Patch Island (0.54 g/g), and concentrations of p,p-DDD, p,p-DDT, dieldrin, heptachlor epoxide, cis-nonachlor, trans-nonachlor, HCB , and oxychlordane were #0.23 g/g for all samples analyzed. Concentrations of α-BHC, β-BHC, Δ-BHC, γ-BHC, o,p-DDD, o,p-DDE, o,p-DDT, α-chlordane, γ-chlordane, endrin, mirex, and toxaphene were not detected in any eggs.  Mean (range) concentrations of total PCBs were significantly greater at Pea Patch Island, 1.22 (0.28-6.10) g/g, then Middle Island, 0.42 (0.10-0.94).  Congeners 77, 169, and 166 (Middle Island only), were detected in less than half of the samples from each site.  Other congeners (geometric means in parentheses) detected at Middle Island and Pea Patch Island were, respectively: 126 (264, 317 pg/g), 81 (0.19, 0.24 ng/g), 105 (15.75, 22.51 ng/g), 114 (0.94, 1.60 ng/g), 118 (63.82, 81.45, ng/g), 128 (7.32, 13.45 ng/g), 138 (63.77, 133.54 ng/g), 156 (6.21, 14.34 ng/g), 157 (1.89, 3.24 ng/g), 158 (2.76, 9.79 ng/g), 166 (0.41 ng/g Pea Patch Island only), 167 (4.95, 8.98 ng/g), 170 (12.69, 35.28 ng/g), 189 (0.63, 1.73 ng/g), 2,3,7,8-TetraCDD (3.15, 2.65 pg/g).  Congeners 156 and 158 were significantly different between sites (p < 0.05), concentrations of other orgnochlorines did not differ significantly between sites.  Frequency of detection and level of detection was higher for Pea Patch Island samples. 

32.

One egg and two embryos from BCNH nests were collected in 1997 from the Danube Delta, Romania (Aurigi et al., 2000).  Mean concentrations (ng/g dry weight) in egg yolk and embryo, respectively, were 2430.21 and 4315.30 DDT (p,p-DDT + p,p-DDE), 5.01 and 3.62 HCB, and 265.86 and 241.54 PCB.  Mean concentrations (pg/g) of PCB-77, -126, and 169 were ND, 2.47, and ND in yolk and ND, 4.88, and 8.06 in embryo.  TEQs (pg/g) of PCB, non-ortho, mono-ortho-substituted, and total were 0.24, 0.19, and 0.43 in yolk, and 0.51, 0.14, and 0.65 in embryo.  Levels of contaminants in eggs collected in 1997 were lower than levels from eggs collected in 1982 in the same area. 

33.

Eggs were collected from 9 BCNH nests at Falcon Reservoir, Texas, in 1997 (Wainwright et al., 2001). Geometric mean (range) concentrations of trans-nonachlor, dieldrin, DDD, DDE, DDT, and total PCBs were, respectively: 7 (3-29), 4 (1-13), 7 (1-16), 1480 (562-4876), 4 (1-48), and 264 (92-659) ng/g wet weight. Toxaphene was not detected.

34.

In 1998, 65 BCNH eggs were collected from Fort Carroll, Baltimore Harbor and 12 eggs from Holland Island, Maryland (Rattner et al., 2001). In addition, 6 fertile eggs that failed to hatch (including 1 cracked egg) were collected from Fort Carroll, Baltimore Harbor. 

Geometric means (ranges) of organochlorine contaminant concentrations found in the Fort Carroll, Baltimore Harbor eggs were: 0.199 (0.023-1.292) DDE, 0.026 (ND-0.262) dieldrin, 0.001 (ND-0.014) heptachlor, 0.026 (ND-0.288) heptachlor epoxide, 0.093 (0.005-1.022) α-chlordane, 0.066 (0.005-0.530) trans-nonachlor, 0.076 (0.002-5.497) oxychlordane, 0.006 (ND-0.056) mirex, and 3.830 (0.542-16.51) total PCBs mg/g wet weight. Congeners (geometric means, and ranges, in parentheses) detected were: 77 (138, ND-2,167 pg/g), 81 (80, ND-840 pg/g), 126 (433, 27-4,870 pg/g), 169 (54, ND-424 pg/g), 105 (53.15, 5.19-753 ng/g), 114 (3.46, ND-70.5 ng/g), 118 (132.17, 19.6-1,602 ng/g), 123 (8.25, 1.05-79.5 ng/g), 156 (33.0, 2.38-532 ng/g), 157 (5.97, 0.60-172 ng/g), 167 (16.88, 1.79-135 ng/g) , and 189 (4.60, ND-55.0 ng/g).  Geometric mean (range) for DDE and total PCBs of the eggs that failed to hatch were 0.218 (0.092-0.919) mg/g and 3.75 (1.445-9.17) mg/g, respectively. 

Geometric means (ranges), in mg/g wet weight, of organochlorine contaminant concentrations found in Holland Island eggs were: 0.059 (0.018-0.953) DDE, 0.005 (ND-0.033) dieldrin, 0.002 (ND-0.025) heptachlor, 0.007 (0.001-0.032) heptachlor epoxide, 0.009 (0.004-0.022) α-chlordane, 0.007 (ND-0.022) trans-nonachlor, 0.011 (0.004-0.062) oxychlordane, 0.006 (0.001-0.049) mirex, and 0.648 (0.220-2.328) total PCBs. Congeners (geometric means, and ranges, in parentheses) detected were: 105 (5.68, 2.64-11.5 ng/g), 118 (17.41, 8.35-36.0 ng/g), 123 (0.92, ND-1.74 ng/g), 156 (2.52, 1.11-5.47 ng/g), 157 (0.61, ND-1.64 ng/g), and 167 (2.27, 0.87-9.13 ng/g).  Congeners 126, 114, and 189 were detected in less than half of the eggs and had ranges of ND-87, ND-0.68, and ND-0.67, respectively.  Congeners 77, 81, and 169 were not detected in any of the eggs. 

Predicted TEQs based upon mammalian TEFs were 312 (38-3837) pg/g for Fort Carroll, Baltimore Harbor and 30 (13-60) pg/g for Holland Island.  Predicted TEQs using WHO TEFs for wildlife were 71 (3-851) pg/g for Fort Carroll Baltimore Harbor eggs, 2 (0.5-10) pg/g for Holland Island eggs, and 41 (9-228) pg/g for the Fort Carroll Baltimore Harbor eggs that failed to hatch. 

35.

Egg content concentrations of organochlorine contaminants were determined in 3-5 eggs from Edwards Air Force Base in 1996 and 1999 (Hothem et al., 2006).  Residue levels in eggs range from 1.74, nd, and 0.019 µg/g fw for DDE, DDD, and DDT, respectively.  Dieldrin and oxychlordane concentrations ranged from nd-0.09 µg/g fw.  Total PCBs were detected in all tissues and ranged from 0.20-0.99 µg/g fw.

II.

Cholinesterase-Inhibiting Pesticides

1.

Plasma (serum) samples were collected from nestling BCNHs (8-31 days old) between 1991 and 1996 from Boston Harbor, MA (Sarah Island, Gallops Island, and Middle Brewster Island); New York Harbor, NY (Pralls Island, and Isle of Meadows); Nantucket Sound, MA (Sampsons Island, Monomoy Island, and Coatue Island); Delaware Bay, DE (Pea Patch Island); and Rehoboth Bay, DE (Middle Island) (Parsons et al., 2000).  Immune status (total white-blood-cell counts), nutritional status (size: mass ratio), and exposure to anti-ChE compounds (ChE reactivation assay and land use pattern around the estuary) were measured.  For all sites combined, mean total ChE activity was 1.344 U/ml (n=235), mean AChE activity was 0.265 U/ml (n=127), and mean BChE was 0.336 U/ml (n=127).  Nestlings in Delaware Bay and New York Harbor had a higher number of carbamate reactivations that nestlings in other colonies, and AChE activity was found to vary by estuary.

III.

Trace Elements, Metals, and Metalloids

A.

Concentrations in Adults

1.

Mercury concentrations were determined in breast muscle, liver, brain and wing feathers samples collected in 1972 and 1973 from 2 heronries and 3 diked marshes located in the southwestern Lake Erie region (Hoffman and Curnow, 1979). In adults, median Hg concentrations in brain and breast muscle were <1 g/g wet weight. Median Hg levels were 6.88 g/g in wing feathers and 2.89 g/g in liver.

2.

Tissues samples were collected in 1973 from a 21-year-old BCNH on West Sister Island, Ohio (Hoffman, 1976). In this single bird, Hg concentrations were 0.9 g/g wet weight in muscle, 3.1 g/g in liver, 0.5 g/g in brain, and 17.9 g/g in primary wing feathers.

3.

Mercury concentration was determined in liver and breast muscle from 3 BCNHs collected in 1977-1978 from the Brunswick estuary in Georgia (Odom, 1978; 1981). Values ranged from 1.33-1.86 g/g wet weight in muscle and 2.36-4.67 g/g in liver.

4.

In 1982, BCNHs (N=2) collected in Texas were one of five non-probing bird species (fish, insect, and plant eaters) that did not have ingested Pb shot (Hall and Fisher, 1985).

5.

The intestinal absorption of Hg in BCNHs was measured in vivo by an in situ luminal perfusion technique (Serafin, 1984). The absorption rate was determined as 0.40 moles per 20 min per g dry weight intestinal segment.

6.

In 1994, adult BCNH feathers were collected at Agassiz NWR in Minnesota (Burger and Gochfeld, 1996). The mean concentrations in adult feathers were (in ng/g dry weight): 671105 Pb, 12929 Cd, 5331666 Hg, 497126 Se, 1045248 Cr, and 12,5022630 Mn.

7.

During April and May 2000, molted feathers and primary feathers from carcasses were collected from egretries at A Chau (AC) and Mai Po Village (MPV), China (Connell et al., 2002). Concentration means and ranges in g/g dry weight.

AC: Zn 118.9 (109.5-146.7), Fe 75.5 (23.3-320.1), Mn 4.0 (0.9-14.6), Cu 6.0 (3.0-9.0), Hg 1.7 (0.2-3.8), Cd 0.04 (0.00-0.17), Cr 0.9 (0.50-1.46), Pb 0.7 (0.9-2.71).

MPV: Zn 122.3 (110.4-134.2), Fe 160.4 (50.1-270.6), Mn 13.9 (3.4-24.3), Cu 6.9 (5.0-8.8), Hg 0.3 (0.2-0.4), Cd 0.06 (0.03-0.09), Cr 1.1 (1.02-1.14), Pb 2.6 (1.3-4.0).

B.

Concentrations in Nestlings and Juveniles

1.

Mercury concentrations were determined in breast muscle, liver, brain and wing feathers of nestling and juvenile BCNHs collected in 1972 and 1973 from 2 heronries and 3 diked marshes located in the southwestern Lake Erie region (Hoffman and Curnow, 1979). Median Hg concentrations in brain and breast muscle were <1 g/g wet weight. In wing feathers, median Hg concentration in wing feathers was 2.74 g/g for nestlings and 4.03 g/g for juveniles, whereas median concentrations in liver of nestlings and juveniles were 0.53 and 4.03 g/g, respectively.

2.

In 1975, BCNH young were collected from Rush Lake in Winnebago County, Wisconsin (Sigurslid, 1984). Mean (range) Pb concentration in combined bone, liver and feathers was 18.35 (0.3-123.1) g/g wet weight.

3.

Pre-fledgling BCNHs (1-4 weeks of age) found dead (N=22) were collected from 3 Atlantic Coast colonies (Clarks Island, Massachusetts; Hope Island, Rhode Island; Annex subcolony of Newport River, North Carolina) in 1979 (Custer and Mulhern, 1983). Copper, Zn, and Co were found in all liver samples, Pb in more than 75% of the samples, and Cr, Ni, and Cd in less than 50% of the samples. Mean concentrations of Pb were generally similar in the 3 colonies (1.07, 0.83, and 1.24, ranging from ND-5.26 g/g dry weight). Mean Cu levels were 86.1, 257.26, and 119.99 g/g in the 3 colonies, respectively, with values ranging from 23.6-381 g/g. Mean Zn levels were similar in the three colonies, 648.83, 602.11, and 503.02 g/g, with values ranging from 246-885 g/g. Cobalt concentration was low, with means of 0.96, 0.65, and 0.71 g/g, and individual values ranging from 0.3-1.32 g/g. Mean concentrations of Cr in samples from Hope Island were 0.20 g/g, but was rarely detected at other sites. Mean Ni and Cd were not calculated in these liver samples.

4.

Feathers collected from chicks in Italy in 1994 were analyzed for heavy metal contamination (Fasola et al., 1998).  Mean concentrations in feathers were 1.98 g/g dry weight Hg, 0.55 g/g Cd, and 3.36 g/g Pb.

5.

Mean Hg concentration was approximately 2.5 g/g dry weight in breast feathers of BCNH nestlings from Lavellette, New Jersey in the New York Bight in 1995 (Burger and Gochfeld, 1997).

6.

In 1993 and 1994, feathers were collected from between the shoulder blades of BCNH chicks estimated to be 15-30 days old in the Axios Delta, Greece (Goutner and Furness, 1997).  In 1993 the median and range Hg concentrations in feathers were 2.11 ug/g dry weight and 0.53-9.54 ug/g (n=33); and in 1994 they were 3.32 and 1.40-9.11 ug/g (n=20).  In 1993, there was a significant negative correlation between chick age and Hg content of feathers.

7.

In 1994, fledgling BCNH feathers were collected at Agassiz NWR in Minnesota (Burger and Gochfeld, 1996). The mean concentrations in fledgling feathers were (in ng/g dry weight): 400110 Pb, 1300206 Cd, 3630244 Hg, 1070166 Se, 540142 Cr, and 3590578 Mn.

8.

In May and June of 1998, blood, feathers and regurgitated food boluses were collected from nestlings in three heronries in Delaware and Chesapeake Bays (Golden et al., 2003). 

Feathers: (mean concentrations in μg/g dry weight) Pea Patch Island (n=12), Al 78.85, As 0.19, B 0.71, Ba 1.51, Cr 2.49, Cu 6.63, Fe 154.3, Hg 1.25, Mg 359.0, Mn 7.59, Ni 0.26, Pb 0.41, Se 2.16, Sr 7.67, Zn 168.8. Baltimore Harbor (n=12), Al 9.18, As 0.25, B 0.41, Ba 0.52, Cd 0.016, Cr 3.28, Cu 6.05, Fe 36.4, Hg 0.805, Mg 218.9, Mn 2.28, Ni 0.27, Pb 0.32, Se 2.18, Sr 4.56, Zn 127.4.  Holland Island (n=9), Al 42.3, As 0.41, B 0.19, Ba 0.60, Cr 3.17, Cu 7.90, Fe 63.29, Hg 0.81, Mg 331.9, Mn 3.11, Ni 0.20, Pb 0.11, Se 2.11, Sr 5.11, Zn 155.1. 

Blood: (mean concentrations in μg/g wet weight) Pea Patch Island (n=12), As 0.111, Cd 0.102, Cu 0.425, Fe 352.4, Hg 0.138, Mg 94.48, Mn 0.0306, Se 0.347, Zn 4.32. Baltimore Harbor (n=12), As 0.072, Cu 0.408, Fe 349.6, Hg 0.080, Mg 94.6, Mn 0.023, Se 0.539, Zn 4.37. Holland Island (n=9) As 0.128, Cd 0.011, Cu 0.379, Fe 412.5, Hg 0.0759, Mg 99.39, Mn 0.0220, Se 0.499, Zn 4.36. 

Food boluses: concentrations were elevated at Pea Patch Island and Baltimore Harbor for Al (442 and 714 μg/g dry weight), Mn (152 and 98.5 μg/g), Pb (1.54 and 7.82 μg/g), Sr (534 and 382 μg/g) and Zn (181 and 213 μg/g).

C.

Concentrations in Eggs, Embryos, and Eggshells

1.

In 1972-73, eggs were collected from BCNH nests along the coast from Florida to Massachusetts (Ohlendorf et al., 1978a). Arsenic concentrations were highest in samples from South Carolina at 0.032 g/g wet weight. Cadmium was highest in Louisiana, Florida, South Carolina, and Maryland-Virginia at 0.013 g/g. Chromium, at 0.179 g/g, was highest in Florida and Cu, at 1027 g/g, was highest in South Carolina. Lead was highest in samples from Chincoteague Bay in Maryland-Virginia at 0.27 g/g. Mercury was highest in Massachusetts at 0.254 g/g and Zn was highest in Florida at 13.40 g/g.

2.

Mercury concentration was determined in complete clutches from 6 BCNH nests collected in 1973-74 from West Sister Island heronry in the southwestern region of Lake Erie (Hoffman, 1980). Mean values ranged from 0.09 to 0.37 g/g and the overall mean was 0.19 g/g.

3.

In 1975, BCNH eggs, embryos, and young were collected from Rush Lake in Winnebago County, Wisconsin (Sigurslid, 1984). Mean (range) Pb concentration was 4.78 (0-40.1) g/g wet weight in eggshells, 3.6 (0.2-14.9) g/g in egg contents, and 0.35 (0.01- 0.7) g/g in embryos.

4.

In 1980, an egg from each of 21 nests in 3 BCNH rookeries was collected and analyzed for Hg (Fleming et al., 1984). Mercury was present in eggs from each of the 3 sites (Fort Loudoun, German Creek, and Sevierville); mean levels were 0.16, 0.38, and 0.27 g/g wet weight from the 3 sites, respectively, and values ranged from 0.08 to 0.88 g/g. Chromium was found in all eggs from the Fort Loudoun site, in 70% of eggs from German Creek, and in 90% of the eggs from Sevierville; mean concentration (ranges) in samples from each site were 0.31 (0.09-0.90); <0.1 (<0.1-0.22), and <0.1 (<0.1-0.62) g/g, respectively.

5.

Twenty-two BCNH eggs were collected from 1977 to 1980 from two sites around Green Bay (Oconto Marsh and Willow Island), Wisconsin, and one site in Lake Michigan (Spider Island) (Heinz et al., 1985). Mercury levels in eggs collected in 1977 and 1978 from Oconto Marsh and Spider Island were 0.53 g/g wet weight and 0.06 g/g, respectively. Mean Hg concentrations (range) at Willow Island (N=10 eggs each in 1978 and 1980) were 0.05 (0.005-0.41) and 0.17 (0.08-0.50) g/g, respectively. Multiple eggs from the same clutches in 1977 and 1978 were collected and analyzed to determine if results from a single egg will be representative of the entire clutch. Individual values ranged from 0.53-0.76 g/g in eggs from Oconto Marsh in 1977, 0.10-0.12 g/g in samples from Willow Island in 1978, and 0.06-0.13 in samples from Spider Island in 1978. These results suggested that a single egg reflects concentrations in the entire clutch.

6.

A total of 42 BCNH eggs were collected in 1982 from Bair Island in San Francisco Bay and characterized as random early, random late, hatch failure or "dumped" (Ohlendorf et al. 1988). The overall mean Hg concentration was 0.41 g/g wet weight wet; means in the 4 categories ranged from 0.28-0.45 g/g.

7.

Eggs were collected in 1983 from 2 sites in San Francisco Bay (Bair Island and Mallard Slough) and in 1984 from 3 sites in the San Joaquin Valley (Kesterson National Wildlife Refuge, Volta Wildlife Area, and Menodota Wildlife Area) (Ohlendorf and Marois, 1990). Selenium was found in all but 1 of the 46 eggs from the 5 sites. Geometric mean values were 0.432, 0.483, 0.313, 0.282, and 0.440 g/g wet weight, respectively; individual values in the 45 eggs collectively from the 5 sites ranged from 0.054-0.96 g/g.

8.

From 1989-91, eggs were collected from San Francisco Bay and analyzed for Hg and Se (Hothem et al., 1995). The geometric mean concentration for Hg ranged from 0.502 g/g dry weight at Bair Island in 1990 to 1.41 g/g at Brooks Island in 1991. Selenium ranged from 3.06 g/g at West Marin Island in 1990 to 5.68 g/g from Alcatraz Island in 1990.

9.

In 1994, BCNH eggs were collected at Agassiz NWR in Minnesota (Burger and Gochfeld, 1996). The mean heavy metal concentrations in the eggs were: 3911 ng/g dry weight Pb, 529195 ng/g Cd, 986201 ng/g Hg, 3072190 ng/g Se, 48766 ng/g Cr, and 3419283 ng/g Mn.

10.

Mean Hg concentration was approximately 0.35 g/g in eggs of BCNH nestlings from Lavellette, New Jersey in the New York Bight in 1995 (Burger and Gochfeld, 1997).

11.

In 1997, pipping BCNH eggs were collected from Pea Patch Island in Delaware Bay (N=15), and a reference site, Middle Island in Rehoboth Bay, Delaware (N=9) (Rattner et al. 2000).  Mean element concentrations (g/g dry weight) for Middle Island and Pea Patch Island, respectively, were Al (14.72, 19.15), Ba (0.170, 0.223), Cd (0.0576, 0.236), Cr (4.64, 4.12), Cu (3.57, 3.63), Fe (104.0, 97.44), Hg (0.454, 0.596), Mg (553.06, 580.85), Mn (2.79. 3.83), Mo (0.846, 0.886), Se (4.00, 4.23), Sr (11.33, 6.18), V (0.639, 0.745), and Zn (62.49, 64.22).  Cd, Mn, and Sr were significantly different (p < 0.05) between sites.  Concentrations of other metals did not differ between sites.  Be, Ni, and Pb were detected in less than half of the samples from both sites.

IV.

Petroleum

 

No residue data available

Black-Crowned Night-Heron Contaminant Response Data

I.

Organochlorine Contaminants

A.

Eggshell Thinning and Reproduction

1.

Eggs collected in 1970 along the Texas coast were significantly thinner (0.266 mm) than pre-1943 eggs (0.278 mm) (King et al., 1978).

2.

From 1972-73, eggs were collected at sites from Florida to Massachusetts (Ohlendorf et al., 1978a). Eggs from New Jersey, Massachusetts, New York, Rhode Island, Connecticut, Ohio, Michigan, Florida, Georgia, and South Carolina were significantly thinner when compared to pre-1947 eggs.

3.

Eggshell thickness decreased between 1.8% (Minnesota) to 12.3% (New Jersey) in samples collected in 1973 compared to pre-1947 reference samples (Ohlendorf et al., 1978b; 1979b).

4.

A negative correlation between thickness of eggshells and DDE concentrations was reported for samples collected from Washington and Oregon in 1978 and 1979 (Henny et al., 1984). In addition, as the DDE concentration in eggs increased, the number of young successfully fledged decreased. For example, when DDE concentration was <1 g/g wet weight, the mean young fledged was 2.53 per nest, but when the mean concentration of DDE was between 8.01-12.0, the number of young successfully raised per nest dropped to 1.90.

5.

In 1979, eggs were collected from Massachusetts, Rhode Island, and North Carolina (Custer et al., 1983a). A similar collection of BCNH eggs occurred in 1973. In Massachusetts, DDE concentrations decreased significantly between 1973 and 1979, and eggshells were found to be slightly thicker at the Gould Island, Massachusetts location in 1979 compared to 1973. A significant correlation was found shell thickness and DDE concentrations at all sites examined.

6.

Shell thickness of eggs from Idaho in 1979 decreased by about 8% when compared to archival material (Findholt et al., 1985). Over 20% of the eggs laid either disappeared, were dented, or were broken. The disappearance and breakage of eggs was correlated with DDE concentration.

7.

A 1979 collection of BCNH eggs from Colorado and Wyoming revealed an 8.8% decrease in shell thickness compared to values in eggs collected from 1896 to 1914 (McEwan et al., 1984). In addition, more young were found around nests with lower DDE concentrations than at nests with higher DDE concentrations

8.

In 1979, the existence of a relationship between organochlorine contamination and various breeding parameters was studied (Custer et al., 1983b). No correlation between PCBs, DDE and clutch size were noted. In addition, there was also no correlation between DDE and the date of laying. PCB concentrations were higher in eggs laid earlier in the breeding season than those laid later in the breeding season.

9.

In 1980, eggs were collected from the Tennessee Valley, and only a 3% decrease in shell thickness was noted compared to 1947 egg samples collected from the same area (Fleming et al., 1984). A correlation was found between shell thickness and log transformed DDE concentration .

10.

A negative correlation was found between eggshell thickness and DDE concentration in a 1982 collection at Bair Island in San Francisco Bay, California (Ohlendorf et al., 1988).

11.

Eggshell thickness was measured in the samples collected from California between 1982-1984 (Ohlendorf and Marois, 1990). A significant decrease in eggshell thickness was seen for San Joaquin and San Francisco Bay. As no pre-1945 values for Salton Sea were available, no comparison for this location could be made.

12.

In Loving, New Mexico, eggshells collected in 1983 were significantly thinner than they were prior to the use of DDT (White and Krynitsky, 1986). However, eggshell thickness in samples from Corpus Christi, Texas was no thinner than prior to the use of DDT.

13.

Nest and fledgling success was monitored in BCNH nests in San Francisco Bay from 1989 to 1991 (Hothem et al., 1995). There was some evidence of impaired reproduction (21 eggs were found cracked or dented), athough contaminant concentrations were generally below known effect thresholds.

14.

In 1997, BCNH nesting success at Falcon Reservoir, Texas, was low compared to other recorded sites (Wainwright et al., 2001). This lowered reproduction was attributed to nest destruction from flooding rather than the below-threshold concentrations of organochlorine contaminants found in 9 BCNH eggs.

15.

In 1998, 65 BCNH eggs were collected from Fort Carroll, Baltimore Harbor and 12 eggs from Holland Island, Maryland (Rattner et al., 2001). In addition, 6 fertile eggs that failed to hatch (including 1 cracked egg) were collected from Fort Carroll, Baltimore Harbor.

Mean eggshell thickness was marginally less in the Fort Carroll, Baltimore Harbor eggs (0.300 0.027 mm) than in the Holland Island eggs (0.317 0.029 mm). Eggshell thickness was not inversely correlated with DDE concentration. The cracked eggshell had a thickness of 0.290 mm and the five that failed to hatch ranged from 0.305 to 0.348 mm. Hatching success, fledging success, and overall reproductive success were not significantly correlated to contaminant or TEQ concentrations.

B.

Biochemical and Morphological Responses

1.

A 1972 and 1973 study at Lake Ontario and Lake Erie examined BCNH embryos for physical abnormalities (Gilbertson et al., 1976). In 1972, 33 chicks were examined from Pigeon Island (Lake Ontario) and no abnormalities were detected. In two colonies located on Lake Erie, 154 chicks were examined and no abnormalities were detected. In 1973, 1 of 39 chicks examined had a cross-bill.

2.

In 1983 samples collected from Bair Island, no obvious anomalies or any type of skeletal defects were detected (Hoffman et al., 1986). Embryo weight minus the yolk sac was significantly less at Bair Island when compared to Patuxent Wildlife Research Center controls. As the PCB residue concentration increased, embryonic weight (minus the yolk sac) decreased. In addition, crown-rump length was significantly lower in Bair Island embryos when compared to controls.

3.

Embryos were collected from Saginaw Bay, Green Bay, and Patuxent Wildlife Research Center (reference site) in June, 1984 (Hoffman et al., 1993). Liver weight was significantly greater in Green Bay samples compared to the reference site. Femur length was significantly decreased in Saginaw Bay embryos. No abnormal embryos were found from the reference site, however 60% of those from Green Bay, and 40% of those from Saginaw Bay, were abnormal. The main anomaly detected was edema in the neck and throat region. In addition, one embryo from Saginaw Bay had a shortened lower mandible. Microsomal AHH activity concentrations were significantly elevated at Saginaw Bay and Green Bay compared to controls.

4.

Pipping embryos and 10 day-old nestlings were collected from Chincoteague National Wildlife Refuge, Virginia, Cat Island in Green Bay, Wisconsin, and Bair and West Marin Islands in San Francisco Bay, California (Rattner et al., 1993). In pipping BCNHs, there was a significant correlation between total PCB concentration and cytochrome P450-associated monoxygenase activity and cytochrome P450 proteins. In 11-day-old nestlings, there was no significant relationship between organochlorine contaminants and most cytochrome P450-associated monooxygenase activities. However, there was an inverse relationship between DDE, total PCBs and log-transformed ECOD activity.

5.

Teratogenesis was monitored in BCNH nests in San Francisco Bay from 1989 to 1991 (Hothem et al., 1995). Developmental anomalies were observed in 2 of 18 embryos that failed to hatch at Alcatraz Island; one deformed chicks was also found at this site.

6.

In 1991, pipping and 10-day old nestlings were collected from two sites in the Chesapeake Bay and next to the Chincoteague National Wildlife Center in Virginia (Rattner et al., 1997). Hepatic microsomal cytochrome P450 was significantly elevated in pipping embryos from the Baltimore Harbor colony compared to the reference site, whereas values in embryos from the Rock Creek Park colony were intermediate. Cytochrome P450 in pipping embryos was associated with concentrations of several organochlorine pesticides, total PCBs, arylhydrocarbon receptor-active PCB congeners and toxic equivalents, providing further evidence of the value of cytochrome P450 as a biomarker of organic contaminant exposure. Body and liver weight, and cytocrome P450 were unaffected in nestlings.

7.

In 1997, pipping BCNH eggs were collected from Pea Patch Island in Delaware Bay (N=15), and a reference site, Middle Island in Rehoboth Bay, Delaware (N=9) (Rattner et al. 2000).   There was no evidence of malformation or hepatic histopathological lesions in any of the pipping embryos.  There was no significant difference between sites in embryo weight, liver weight, liver: body weight ratio, or EROD or BROD activities.  Three embryos from Pea Patch Island showed EROD activity that was up to 8.5 fold greater than the mean activity from the reference site, and 3 embryos showed BROD activity up to 3.5 fold greater. 

II.

Cholinesterase-Inhibiting Pesticides

1.

Adult BCNHs were exposed to fenthion by standing in a water filled chamber that had been sprayed with this organophosphorus insecticide at 1 or 10 times the standard application rate (1.12 kg/ha) (Smith et al., 1986). No mortality was observed in the BCNH exposed to fenthion, through the dermal route or through the dermal and oral route. In addition there was no sign of decrease cholinesterase activity between the controls and the treatments for either sex. There was significant inhibition of plasma butyrylcholinesterase activity at the high exposure, but brain acetylcholinesterase activity was not affected at either level of exposure.

2.

Suspect exposure to the carbamate insecticide carbofuran, through either dermal routes or consumption of contaminated prey, was studied in juvenile and adult BCNH carcasses using a brain ChE reactivation assay (Hunt et al., 1995). Prior to initiation of the reactivation assay, the absolute activity varied from 16.5 to 0.891 moles acetylthiocholine iodide hydrolyzed/min/g wet weight. In this assay system, reactivation of brain ChE occurred in 5 of 6 brain samples from dead herons, averaging 700% of initial values after a 96 hour incubation period.

III.

Trace Elements, Metals, and Metalloids

1.

When 10 g/g of Se (as selenomethionine) was added to the diet of BCNHs there were no significant difference in the number of fertile eggs or in the hatching success compared to controls (Smith et al., 1988). No difference in the weight of the spleen, heart, and liver weight were noted. The only morphological difference noted was shorter femurs and radius-ulna in hatchlings of parents fed Se. Liver malondialdehyde was significantly higher in hatchlings, and is suggestive of oxidative damage.

IV.

Petroleum

1.

In 1991, pipping embryos and chicks were collected from five BCNH colonies: Chincoteague Bay Virginia (reference site), Baltimore Harbor, Maryland, Rabbit Island, Louisiana, Alexander Island, Texas, and Lonetree Island, Wisconsin (Custer et al., 1994). The mean coefficient of variation in DNA from embryo blood was significantly higher in samples at the suspected petroleum contaminated Rabbit Island, Louisiana site compared to the reference site. In addition, blood from the chicks collected from the Texas site (suspect petroleum contamination) also had a higher coefficient of variation in DNA than the reference site.

2.

Reproductive success of BCNHs in New York Harbor was apparently unaffected following an oil spill, in contrast to other wading bird species (Parsons, 1996). This was attributed to the generalistic feeding habits of BCNHs compared to other tidal-foraging wading bird species whose prey-base was adversely affected by the spill.

V.

Other Contaminants

1.

Fluoride exposure did not significantly affect breaking strength of tibiae from juvenile and adult BCNHs (Henny and Burke, 1990).

 References for Black-Crowned Night-Heron

Albanis, T.A., D. Hela, G. Papakostas, V. Goutner. 1996. Concentration and bioaccumulation of organochlorine pesticide residues in herons and their prey in wetlands of Thermaikos Gulf, Macedonia, Greece. Science of the Total Environ. 182: 11-19.

Aurigi, S., S. Focardi, D.Hulea, and A. Renzoni.  2000.  Organochlorine contamination in birds eggs from the Danube Delta.  Environ. Pollut. 109:61-67. 

Bischoff, A.I., Azevedo, J.A. and L.A. Woods. 1970. Pesticides investigations: Current fish and wildlife problems. California Department of Fish and Game. 3 pp.

Blus, L.J., B.A. Rattner, M.J. Melancon and C.J. Henny. 1997. Reproduction of black-crowned night-herons related to predation and contaminants in Oregon and Washington, USA. Colon. Waterbirds 20:185-197.

Bull, J. and J. Farrand, Jr. 1977. The Audubon Society Field Guide to North American Birds. Alfred A. Knopf, New York. 784 pp.

Burger, J. and M. Gochfeld. 1996. Heavy metal and selenium levels in birds at Agassiz National Wildlife Refuge, Minnesota: food chain differences. Environ. Monitoring and Assessment 43: 267-282.

Burger, J., and M. Gochfeld. 1997. Risk, mercury levels, and birds: Relating adverse laboratory effects to field biomonitoring. Environ. Res. 75:160-172.

Connell, D.W., B.S.F. Wong, P.K.S. Lam, K.F. Poon, M.H.W. Lam, R.S.S. Wu, B.J. Richardson and Y.F. Yen. 2002. Risk to breeding success of ardeids by contaminants in Hong Kong: evidence from trace metals in feathers. Ecotoxicology. 11:49-59.

Custer, T.W., and C.M. Custer. 1995. Transfer and accumulation of organochlorines from black-crowned night-heron eggs to chicks. Environ. Toxicol. Chem. 14:533-536.

Custer, T.W., and B.L. Mulhern. 1983. Heavy metal residues in prefledgling black-crowned night-herons from three Atlantic coast colonies. Bull. Environ. Contam. Toxicol. 30:178-185.

Custer, T.W., and R.G. Osborn. 1977. Wading birds as biological indicators: 1975 colony survey. Special Scientific Report--Wildlife No. 206. U. S. Department of the Interior, Fish and Wildlife Service, Washington, D.C.

Custer, T.W., R.G. Osborn, and W.F. Stout. 1980. Distribution, species abundance, and nesting-site use of Atlantic Coast colonies of herons and their allies. Auk 97:591-600.

Custer, T.W., C.M. Bunck and T.E. Kaiser. 1983a. Organochlorine residues in Atlantic coast black-crowned night-heron eggs, 1979. Colon. Waterbirds 6:160-167.

Custer, T.W., G.L. Hensler and T.E. Kaiser. 1983b. Clutch size, reproductive success, and organochlorine contaminants in Atlantic coast black-crowned night-herons. Auk 100:699-701.

Custer, T.W., G. Pendleton and H.M. Ohlendorf. 1990. Within- and among-clutch variation of organochlorine residues in eggs of black-crowned night-herons. Environ. Monit. Assess. 15:83-89.

Custer, T.W., J.W. Bickham, T.B. Lyne, T. Lewis, L.A. Ruedas, C.M. Custer and M.J. Melancon. 1994. Flow cytometry for monitoring contaminant exposure in black-crowned night-herons. Arch. Environ. Contam. Toxicol. 27:176-179.

Dunning, Jr., J.B., ed. 1993. CRC Handbook of Avian Body Masses. CRC Press, Ann Arbor. 371 pp.

Ehrlich, P.R., D.S. Dobkin, and D. Wheye. 1988. The Birders Handbook. Simon & Schuster, New York. 785 pp.

Fasola, M., P.A. Movalli, and C. Gandini. 1998. Heavy metal, organochlorine pesticide, and PCB residues in eggs and feathers of herons breeding in northern Italy. Arch. Environ. Contam. Toxicol. 34:87-93.

Findholt, S.L., and C.H. Trost. 1985. Organochlorine pollutants, eggshell thickness, and reproductive success of black-crowned night-herons in Idaho, 1979. Colon. Waterbirds 8:32-41.

Fleming, W.J., B.P. Pullin and D.M. Swineford. 1984. Population trends and environmental contaminants in herons in the Tennessee Valley, 1980-81. Colon. Waterbirds 7:63-73.

Frank, D.S., M.A. Mora, J.L. Sericano, A.L. Blankenship, K. Kannan, and J.P. Giesy.  2001.  Persistent organochlorine pollutants in eggs of colonial waterbirds from Galveston Bay and East Texas, USA.  Environ. Toxicol. Chem. 20:608-617. 

Gilbertson, M. and L. Reynolds. 1974. A summary of DDE and PCB determinations in Canadian birds, 1969 to 1972. Can. Wildl. Serv. Occas. Pap.; no. 19. 18 pp.

Gilbertson, M., R.D. Morris, and R.A. Hunter. 1976. Abnormal chicks and PCB residue levels in eggs of colonial birds on the lower Great Lakes (1971-73). Auk 93:434-442.

Golden, N.H., B.A. Rattner, P.C. McGowan, K.C. Parsons and M.A. Ottinger. 2003. Concentrations of metals in feathers and blood of nestling black-crowned-night-herons (Nycticorax nycticorax) in Chesapeake and Delaware Bays. Bull. Environ. Toxicol. Chem. 70: in press.

Goutner, V., and R.W. Furness.  1997.  Mercury in feathers of Little Egret Egretta garzetta and Night Heron Nycticorax nycticorax chicks and their prey in the Axios Delta, Greece.  Arch. Environ. Contam. Toxicol. 32:211-216. 

Hall, S.L. and F.M. Fisher Jr. 1985. Lead concentrations in tissues of marsh birds: relationship of feeding habits and grit preferences to spent shot ingestion. Bull. Environ. Contam. Toxicol. 35:1-8.

Hancock, J. and J. Kushlan. 1984. The Herons Handbook. Harper and Row Publishers, New York. 288 pp.

Heinz, G.H., T.C. Erdman, S.D. Haseltine, and C. Stafford. 1985 . Contaminant levels in colonial waterbirds from Green Bay and Lake Michigan, 1975-80. Environ. Monit. Assess. 5:223-236.

Henny, C.J., and P.M. Burke. 1990. Fluoride accumulation and bone strength in wild black-crowned night-herons. Arch. Environ. Contam. Toxicol. 19:132-137.

Henny, C.J., L.J. Blus, A.J. Krynitsky, and C.M. Bunck. 1984. Current impact of DDE on black-crowned night-herons in the intermountain west. J. Wildl. Manage. 48:1-13.

Henny, C.J., L.J. Blus, and C.S. Hulse. 1985. Trends and effects of organochlorine residues on Oregon and Nevada wading birds, 1979-83. Colon. Waterbirds 8:117-128.

Hoffman, D.J., B.A. Rattner, C.M. Bunck, A. Krynitsky, H.M. Ohlendorf and R.W. Lowe. 1986. Association between PCBs and lower embryonic weight in black-crowned night herons in San Francisco Bay. J. Toxicol. Environ. Health 19:383-392.

Hoffman, D.J., G.J. Smith and B.A. Rattner. 1993. Biomarkers of contaminant exposure in common terns and black-crowned night herons in the Great Lakes. Environ. Toxicol. Chem. 12:1095-1103.

Hoffman, R.D. 1976. Mercury levels in a 21-year-old black-crowned night heron (Nycticorax nycticorax). Ohio J. Sci. 76:18.

Hoffman, R.D. 1980. Total mercury in heron and egret eggs and excreta. Ohio J. Sci. 80:43-45.

Hoffman, R.D., and R.D. Curnow. 1979. Mercury in herons, egrets, and their foods. J. Wildl. Manage. 43:85-93.

Hoopes, E.M., P.M. Cavanagh, C.R. Griffin, and J.T. Finn. 1994. Synthesis of information on marine and coastal birds of the Atlantic Coast: Abundance, distribution, and potential risks from oil and gas activities. Volume II: Species accounts, abundance, distribution, and status. Massachusetts Cooperative Fish and Wildlife Research Unit, Amherst, Massachusetts. 178 pp.

Hothem, R.L., D.L. Roster, K.A. King, T. J. Keldsen, K.C. Marios, and S.E. Wainwright. 1995. Spatial and temporal trends of contaminants in eggs of wading birds from San Francisco Bay, California. Environ. Toxicol. Chem. 14:1319-1331.

Hothem, R.L., J.J. Crayon, and M.A. Law.  2006.  Effects of contaminants on reproductive success of aquatic birds nesting at Edwards Air Force Base, California.  Arch. Environ. Contam. Toxicol. 51:711-719.

Hunt, K.A., M.J. Hooper, and E.E. Littrell. 1995. Carbofuran poisoning in herons: diagnosis using cholinesterase reactivation techniques. J. Wildl. Dis. 31:186-192.

King, K.A., E.L. Flickinger, and H.H. Hildebrand. 1978. Shell thinning and pesticide residues in Texas aquatic bird eggs, 1970. Pestic. Monit. J. 12:16-21.

McEwen, L.C., C.J. Stafford, and G.L. Hensler. 1984. Organochlorine residues in eggs of black-crowned night-herons from Colorado and Wyoming. Environ. Toxicol. Chem. 3:367-376.

NACWCP.  2001.  Review Draft IINorth American Waterbird Conservation Plan. Volume One: Seabirds and Colonial Waterbirds, 23 October 2001, Waterbird Conservation Steering Committee, Washington DC (www.nacwcp.org/).

Odom, R.R. 1978. Statewide wildlife investigations.: Mercury contamination studies. Georgia Game and Fish Div. 17pp.

Odom, R. R. 1981. Statewide wildlife investigations.: Mercury contamination studies. Georgia Game and Fish Div. 15 pp

Ohlendorf, H.M., and K.C. Marois. 1990. Organochlorines and selenium in California night-heron and egret eggs. Environ. Monit. Assess. 15:91-104.

Ohlendorf, H.M., E.E. Klans, and T.E. Kaiser. 1978a. Environmental pollutants and eggshell thinning in the black-crowned night heron. In A. Sprint IV, J.C.D. Ogden and S. Winkler, eds., Wading Birds, Research Report 7, National Audubon Society, New York, NY, pp. 63-82.

Ohlendorf, H.M., E.E. Klaas, and T.E. Kaiser. 1978b. Organochlorine residues and eggshell thinning in anhingas and waders. Proc. Conf. Colon. Waterbird Group 3:185-195.

Ohlendorf, H.M., D.M. Swineford, and L.N. Locke. 1979a. Organochlorine poisoning of herons. Proc. Conf. Colon. Waterbird Group 3:176-185.

Ohlendorf, H.M., E.E. Klaas, and T.E. Kaiser. 1979b. Environmental pollutants and eggshell thickness: Anhingas and wading birds in the eastern United States. Special Scientific Report--Wildlife No. 216. U.S. Department of the Interior, Fish and Wildlife Service, Washington, D.C.

Ohlendorf, H.M., D.M. Swineford, and L.N. Locke. 1981. Organochlorine residues and mortality of herons. Pestic. Monit. J. 14:125-135.

Ohlendorf, H.M., T.W. Custer, R.W. Lowe, M. Rigney, and E. Cromartie. 1988. Organochlorines and mercury in eggs of coastal terns and herons in California, USA. Colon. Waterbirds 11:85-94.

Parsons, K.C. 1996. Recovering from oil spills: the role of proactive science in mitigating adverse effects. Colon. Waterbirds 19:149-153.

Parsons, K.C., A.C. Matz, M.J. Hooper, and M.A. Pokras.  2000.  Monitoring wading bird exposure to agricultural chemicals using serum cholinesterase activity.  Environ. Toxicol. Chem.  19:1317-1323.

Rattner, B.A., M.J. Melancon, T.W. Custer, R.L. Hothem, K.A. King, L.J. LeCaptain, J.W. Spann, B.R. Woodin, and J.J. Stegeman. 1993. Biomonitoring environmental contamination with pipping black-crowned night heron embryos: induction of cytochrome P450. Environ. Toxicol. Chem. 12:1719-1732.

Rattner, B.A., J.S. Hatfield, M.J. Melancon, T.W. Custer, and D.E. Tillitt. 1994. Relation among cytochrome P450, Ah-active PCB congeners and dioxin equivalents in pipping black-crowned night-heron embryos. Environ. Toxicol. Chem. 13:1805-1812.

Rattner, B.A., M.J. Melancon, T.W. Custer, and R.L. Hothem. 1996. Cytochrome P450 and contaminant concentrations in nestling black-crowned night-herons and their interrelation with sibling embryos. Environ. Toxicol. Chem. 15:715-721.

Rattner, B.A., M.J. Melancon, C.P. Rice, W. Riley Jr., J. Eisemann, and R.K. Hines. 1997. Cytochrome P450 and organochlorine contaminants in black-crowned night-herons from the Chesapeake Region. Environ. Toxicol. Chem. 16:2315-2322.

Rattner, B.A., D.J. Hoffman, M.J. Melancon, G.H. Olsen, S.R. Schmidt, K.C. Parsons.  2000.  Organochlorine and metal contaminant exposure and effects in hatching black-crowned night herons (Nyticorax nycticorax) in Delaware Bay.  Arch. Environ. Contam. Toxicol. 39:38-45. 

Rattner, B.A., P.C. McGowan, J.S. Hatfield, C.-S. Hong, and S.G. Chu. 2001. Organochlorine contaminant exposure and reproductive success of black-crowned night-herons (Nycticorax nycticorax) nesting in Baltimore Harbor, Maryland. Arch. Environ. Contam. Toxicol. 41:73-82.

Rice, C.P., and T.W. Custer. 1991. The occurrence of chlorostyrenes in egrets and herons collected in Galveston Bay. Proceedings: Galveston Bay Characterization Workshop, February 21-23, 1991. Galveston Bay Natl. Estuary Program Publ. GBNEP-6. p. 80-82.

Robbins, C.S., B. Brunn, and H.S. Zim. 1983. A Guide to Field Identification Birds of North America. Golden Press, New York. 360 pp.

Serafin, J.A. 1984. Avian species differences in the intestinal absorption of xenobiotics (PCB, dieldrin, Hg2+). Comp. Biochem. Physiol. 78C:491-496.

Sigurslid, D. 1984. Environmental uptake of lead in black-crowned night herons. In: T. N. Veziroglu, ed., The Biosphere: Problems and Solutions. pp. 629-637.

Smith, G.J., J.W. Spann, and E.F. Hill. 1986. Cholinesterase activity in black-crowned night-herons exposed to fenthion-treated water. Arch. Environ. Contam. Toxicol. 15:83-86.

Smith, G.J., G.H. Heinz, D.J. Hoffman, J.W. Spann, and A.J. Krynitsky. 1988. Reproduction in black-crowned night-herons fed selenium. Lake Reservoir Manage. 4:175-180.

Stalling, D.L., R.J. Norstrom, L.M. Smith, and M. Simon. 1985. Patterns of PCDD, PCDF, and PCB contamination in Great Lakes fish and birds and their characterization by principal components analysis. Chemosphere 14:624-643.

Tillitt, D.E., G.T. Ankley, D.A. Verbrugge, J.P. Giesy, J.P. Ludwig, and T.J. Kubiak. 1991. H4IIE rat hepatoma cell bioassay-derived 2,3,7,8-tetrachlorodibenzo-p-dioxin equivalents in colonial fish-eating waterbirds from the Great Lakes. Arch. Environ. Contam. Toxicol. 21:91-101.

Vermeer, K. and L.M. Reynolds. 1970. Organochlorine residues in aquatic birds in the Canadian prairie provinces. Can. Field-Nat. 84:117-130.

Wainwright, S.E., M.A. Mora, J.L. Sericano, P. Thomas. 2001. Chlorinated hydrocarbons and biomarkers of exposure in wading birds and fish of the lower Rio Grande Valley, Texas. Arch. Environ. Contam. Toxicol. 40:101-111.

White, D.H. and A.J. Krynitsky. 1986. Wildlife in some areas of New Mexico and Texas accumulate elevated DDE residues, 1983. Arch. Environ. Contam. Toxicol. 15:149-157.

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