USGS



BIOLOGICAL AND ECOTOXICOLOGICAL CHARACTERISTICS OF TERRESTRIAL VERTEBRATE SPECIES RESIDING IN ESTUARIES

Great Blue Heron Great Blue Heron; Photo Courtesy of Francine K. Rattner
Photo Courtesy of Francine K. Rattner
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Biological Characteristics

Species

Ardea herodias (GBH) is 97-137 cm in length, with a mean wingspan of 179 cm. Males tend to have a greater average mass (2.6 kg) than females (2.2 kg) (Dunning, 1993). Both sexes have a blue-gray back, blackish sides and a gray and white striped belly. The crown, cheeks, and throat are white, and a black stripe on the side of its crown merges into a long occipital crest. The bill is yellow and the legs greenish-brown. In breeding condition, grey plumes cover the back and lower neck. An all-white form ("great white heron") occurs in Florida (Hancock and Kushlan, 1984; McVey et al., 1993).

Status in Estuaries

This species can be found along inland freshwater lakes and rivers, brackish marshes, lagoons, mangrove areas, and coastal wetlands. Nesting occurs either in single-species or mixed colonies (Spendelow and Patton, 1988). Nests are usually formed in trees, but ground, rock, cliff edges, reeds or rushes may also be used. Typical clutch size is 3-7 eggs (Hancock and Elliott, 1978). Young are altricial (Ehrlich et al., 1988). The maximum age of a GBH recorded in nature 20 years (Bayer, 1981).

Abundance and Range

The GBH breeds throughout the U.S. and winters as far north as New England and southern Alaska. (Bull and Farrand, 1977). The nationwide population is estimated at 83,000 individuals (NACWCP, 2001).

Site Fidelity

Great blue herons are inclined to renest in the same area year after year. Old nests may be enlarged and reused (Eckert, 1981).

Ease of Census

Simple

Feeding Habits

Generalist. The GBH forages by walking slowly or standing motionless in water and striking at prey. This species rarely forages more than 15 to 20 km from its nesting grounds. Fishing requires shallow waters (up to 0.5 m) with a firm substrate. Main prey items are fish and amphibians, but the GBH will also take small mammals, reptiles, crustaceans, insects, and birds (McVey et al., 1993).

Great Blue Heron Contaminant Exposure Data

I.

Organochlorine Contaminants

A.

Concentrations in Adults

1.

From 1966-78, adult GBHs were collected from Maryland, Virginia, Florida, North Carolina, Illinois, Michigan, Minnesota, and Wisconsin (Ohlendorf et al., 1981). The following ranges of contaminant concentrations were determined (g/g wet weight): DDE: 0.63-130.0 in carcass (excludes head, skin, feet, wing tips, liver, kidneys and gastrointestinal tract) and 0.15-82.0 in brain, TDE: ND-78.0 in carcass and ND-22.0 in brain, dieldrin: ND-7.9 in carcass and ND-14.0 in brain, heptachlor epoxide: <1.0 in carcass and ND-1.9 in brain, cis-chlordane: ND-1.8 in carcass and ND-2.5 in brain, trans-nonachlor: ND-2.5 in carcass and ND-2.7 in brain, and mirex: ND-4.5 in carcass and ND-2.9 in brain. DDT, oxychlordane, cis-nonachlor, endrin, toxaphene, and HCB were detected at concentrations 1.0 g/g. PCB concentrations ranged from ND-130 g/g in carcass and ND-220 g/g in brain.

2.

A GBH found dead in Sacramento County in 1968 contained 4.0 g/g PCBs in brain tissue (Bischoff et al., 1970).

3.

Two GBHs, one dead and one alive and tremoring, were collected from Marshall and Day Counties of northeastern South Dakota in the spring of 1975 (Call et al., 1976, Call et al., 1977). Residues detected from the bird brought in alive were 246.33 g/g wet weight brain and 569.74 g/g liver DDE, 0.98 g/g brain and 1.63 g/g liver DDD, 0.60 g/g brain and 0.64 g/g liver DDT, 0.47 g/g brain and 1.06 g/g liver dieldrin, less than 0.05 g/g brain and liver lindane, 0.35 g/g brain and 0.51 g/g liver heptachlor epoxide, and 1.00 g/g brain and 2.50 g/g liver PCBs. For the bird found dead, only liver concentrations were measured, at 1.21 g/g DDE, 0.98 g/g 0.37 DDD, 0.26 g/g DDT, 0.20 g/g dieldrin, less than 0.05 g/g heptachlor epoxide, and 0.42 g/g PCBs.

4.

Organochlorine residues were measured from the brains of GBHs from Maine, Maryland, Virginia, Florida, North Carolina, Illinois, Minnesota, and Wisconsin (Ohlendorf et al., 1979a). Dieldrin was thought to be the cause of death of most of the herons, with levels ranging from 5.1 g/g wet weight to 14.0 g/g. The highest levels were found in Minnesota birds. Endrin was detected at concentrations of 0.86 g/g and 0.60 g/g from Minnesota and Wisconsin birds, respectively. A North Carolina bird showed high levels of DDE (62 g/g), DDD (21 g/g), and DDT (20 g/g) and a Wisconsin heron had PCBs at 220 g/g.

5.

Three GBHs collected from the Sheboygan River area of Wisconsin between 1976 and 1980 were analyzed for organochlorines and PCBs (Heinz et al., 1984). PCB concentrations were highest in the brain, reaching levels of 220 g/g wet weight and 50 g/g. DDE was reached a high of 16 g/g in the brain and 7.8 g/g in the carcass. Dieldrin was detected in two of the birds, reaching levels of 2.8 g/g in the brain and 0.92 g/g in the carcass.

6.

Adult GBHs found dead in Umatilla, Oregon, and Wenatchee, Washington, from 1977 to 1981 were analyzed for organochlorine brain residues (Fitzner et al., 1988). DDE concentrations for the two birds found in Washington were 25.0 and 0.10 g/g wet weight. The two birds recovered in Oregon contained levels of 14.0 and 15.0 g/g. PCBs were measured at 2.50 and 0.10 g/g in Washington and 7.40 and 12.0 g/g in Oregon. Dieldrin and oxychlordane were found in one Oregon heron at levels of 0.31 g/g and 0.23 g/g, respectively. HCB was detected in both Oregon birds at levels of 0.23 and 0.87 g/g.

7.

A GBH sickened from the parasitic roundworm, Eustrongylides ignotus, shot in Oneida County, Wisconsin, was analyzed for organochlorine residues in the brain (Windingstad and Swineford, 1981). The following organochlorines were detected: DDE (86.00 g/g wet weight), DDD (3.10 g/g), DDT (0.71 g/g), dieldrin (0.82 g/g), heptachlor epoxide (0.23 g/g), cis-chlordane (1.30 g/g), cis-nonachlor (0.16 g/g), toxaphene (0.99 g/g) and PCB (4.60 g/g).

B.

Concentrations in Nestlings

1.

From 1966-78, chicks and fledglings were collected from Maryland, Virginia, Florida, North Carolina, Illinois, Michigan, Minnesota, and Wisconsin (Ohlendorf et al., 1981). DDE residues ranged from ND-20.0 g/g wet weight in the carcass (excludes head, skin, feet, wing tips, liver, kidneys and gastrointestinal tract) and ND-9.7 g/g in the brain. TDE ranged from ND-5.5 g/g in the carcass and ND-2.0 in the brain. Dieldrin ranged from ND-6.5 g/g in the carcass and from ND-3.9 g/g in the brain. Cis-chlordane ranged from ND-1.7 g/g in the carcass and ND-0.75 g/g in the brain. Trans-nonachlor concentrations ranged from ND-3.0 g/g in the carcass and ND-1.0 g/g in the brain. Heptachlor epoxide, oxychlordane, cis-nonachlor, endrin, toxaphene, HCB, and mirex were detected at concentration <1.0 g/g. PCB concentrations ranged from ND-6.4 g/g in the carcass and ND-36 g/g in the brain.

2.

Three GBH nestlings collected in 1969 and 1970 from Bolinas Lagoon, near San Francisco, were analyzed for organochlorine residues (Faber et al., 1972).  Individual contaminant concentrations in the nestlings were 0.49, 1.18, and 0.16 g/g wet weight DDE, 0.56, 1.33, and 0.18 g/g total DDT, and 1.35, 1.82, and 0.49 g/g PCB.

3.

GBH chicks were collected in 1976 from four sites along the Upper Mississippi River in Minnesota (Royalton, South St. Paul, and Wabasha) and Wisconsin (La Crosse) (Ohlendorf et al., 1979). DDE, total DDT, and PCBs were detected in all chicks and mean concentrations were significantly greater in South St. Paul when compared to all other colonies. Means at each locality ranged from 0.37-1.31 DDE, 0.38-1.90 total DDT, and 0.22-6.43 PCB g/g wet weight. Concentrations of DDT, detected in all chicks from La Crosse and South St. Paul, 1 of 10 chicks from Royalton, and 5 of 12 chicks from Wabasha, were 0.1 g/g. Concentrations of TDE, detected in all chicks from South St. Paul and La Crosse, 8 of 12 from Wabasha, and 1 of 10 from Royalton, were 0.72 g/g. In general, residue concentrations tended to decrease as birds increased in weight.

4.

Livers collected from GBH nestlings found dead at Lake Okeechobee, Florida, and great white heron nestlings found dead in Florida Bay, between 1987-1991, were pooled for pesticides analysis (Spalding et al., 1997).  In GBH, mean concentrations of HCB, oxychlordane, heptachlor epoxide, trans-nonachlor, and  DDE were 0.01, 0.03, 0.03, 0.05, and 0.38 g/g wet weight, respectively.  Only DDE was detected in great white herons, at a mean concentration of 0.02 g/g.

5.

Between 1991 and 1994, nestlings were collected from 4 sites in Tennessee: 2 colonies on Oak Ridge Reservation (n=38), K25 and Melton Hill, and 2 reference colonies (n=35), Long Island and Looney Island (Halbrook et al.  1999).   Mean (range) concentrations of Arochlor 1260 for the 4 sites, respectively, were 0.77 (0.10-3.90), 0.25 (0.05-0.15), 0.23 (0.09-0.53), and 0.20 (0.08-0.46) g/g wet weight in liver, 1.05 (0.13-4.00), 0.16 (0.07-0.30), 0.41 (0.04-1.60), and 0.23 (0.09-0.71) g/g in muscle, and 48.63 (5.70-180.00), 10.78 (2.50-28.00), 14.49 (3.90-74.00), and 19.04 (4.00-48.00) g/g  in fat.

6.

In 1993, at Clear Lake, California, one GBH nestling was found to have 2.54 mg/g wet weight DDE in liver (Wolfe and Norman, 1998). Six young GBH were found to have TDE residues >0.3 mg/g. Mean (standard deviation) organochlorine residues found in liver (N=19) were 0.079 (0.116) mg/g.

C.

Concentrations in Eggs, Embryos, and Eggshells

1.

GBH eggs collected in various locations in Alberta, Saskatchewan, and Manitoba in 1968 to 1969 contained mean levels of DDE ranging from 5.71 to 37.01 g/g wet weight (Vermeer and Reynolds, 1970). Mean dieldrin levels ranged from 0.056 to 0.344 g/g. Mean heptachlor epoxide and -BHC levels were less than 0.071 and 0.082 g/g, respectively.

2.

GBH eggs and an embryo collected in 1969 and 1970 from Bolinas Lagoon, near San Francisco, were analyzed for organochlorine residues (Faber et al., 1972). The two eggs contained 108 and 287 g/g lipid weight DDE in the egg yolk. Total DDT levels in the egg yolk lipid were 122 and 320 g/g, respectively. PCB was detected at a concentration of 50.6 in the first egg and not detected in the second egg. The embryo, which was probably a heron, contained 1.2 g/g wet weight DDE, 1.4 g/g total DDT, and 1.2 g/g PCB.

3.

Forty GBH eggs collected from 1969 to 1972 from Alberta contained a geometric mean concentration of 33.9 g/g dry weight DDE and 1.48 g/g PCBs (Gilbertson and Reynolds, 1974).

4.

In 1970, two GBH eggs from Western Oregon contained DDE residues of 3.3 and 4.5 g/g wet weight (Henny and Bethers, 1971). A dead chick from the same colony had a whole body DDE concentration of 10.1 g/g.

5.

Twenty GBH eggs collected in 1970 from sites along the Texas coast were analyzed for organochlorine residues (King et al., 1971). DDE and PCBs were found in all samples at similar mean levels: 5.55 and 5.54 g/g wet weight. Dieldrin was detected in three eggs at a mean concentration of 0.14 g/g

6.

A total of five GBH eggs were collected from the Great Lakes area in Wisconsin in 1970 to determine contaminant concentrations (Faber and Hickey, 1973). Mean values of organochlorines were as follows: 472.1 g/g lipid weight DDE, 175.3 g/g PCBs, 10.10 g/g dieldrin, 44.27 g/g DDT + TDE, and 0.79 g/g BHC.

7.

A GBH egg collected in 1972 along the west coast of Florida contained concentrations of 20.0 g/g dry weight DDE, 29.1 g/g PCB, and 2.18 g/g dieldrin (Lincer and Salkind, 1973).

8.

In 1972 and 1973, a total of 58 GBH eggs were collected from various sites in the eastern United States (Ohlendorf et al., 1979b). Mean DDE concentrations were 6.76 g/g wet weight in the Great Lakes region, 3.90 g/g inland, 2.13 g/g in the Southern Atlantic, and 1.39 g/g in the Gulf Coast. PCBs were also greatest in the Great Lakes at 13.65 g/g, followed by the inland region at 2.95 g/g, the Southern Atlantic at 2.42 g/g, and the Gulf Coast at 0.07 g/g.

9.

Between 1975 and 1978, fifteen GBH eggs were collected from a colony near Fountain City Bay, Wisconsin in the Upper Mississippi River for organochlorine analysis (Nosek and Faber, 1984). PCB levels ranged from 0.44-37.2 g/g wet weight, with a mean of 14.1 g/g. DDT was detected at a mean of 0.094 g/g, with all values <0.74 g/g. Mean DDD levels were 0.12 g/g, with all levels <0.51 g/g. DDE concentrations were at a mean of 1.41 g/g, with all levels <5.72 g/g. HCB ranged from 0.0008 to 0.074 g/g, with a mean of 0.011 g/g. Mirex residues, detected in ten of the eggs were less than 0.34 g/g, with a mean of 0.058 g/g. Heptachlor epoxide values ranged from 0.031-0.339 g/g, with a mean of 0.028 g/g. Dieldrin levels ranged from 0.125-1.43 g/g, with a mean of 0.400 g/g. Endrin was detected in six eggs at levels <0.068 g/g and a mean of 0.019 g/g. trans-Nonachlor, detected in thirteen eggs, was at levels <0.221 g/g and a mean of 0.101 g/g.

10.

From 1977 to 1982, GBH eggs were collected from colonies in Washington, Oregon, and Nevada (Fitzner et al., 1988). DDE means for each colony ranged from 0.44 g/g wet weight in Stillwater National Wildlife Refuge in Nevada, to 4.7 g/g on Foundation Island in the Columbia River. Stillwater also contained the lowest mean concentration of PCBs at 0.36 g/g, and the Fort Lewis colony in the Puget Sound contained the highest at 3.35 g/g. Other organochlorines detected sporadically in the eggs, (excluding those at the Fort Lewis colony), were generally at <1 g/g and included DDD, dieldrin, heptachlor epoxide, oxychlordane, and cis-nonachlor. cis-Chlordane was detected in its highest concentrations of up to 1.36 g/g in the Umatilla National Wildlife Refuge in the Columbia River System.  trans-Nonachlor also reached its peak at Umatilla at 2.25 g/g. Maximum pre-fledgling liver residues of DDE and PCBs were 0.45 and 1.20 g/g, respectively. Hatchlings found dead and collected from the Lake Chatcolet colony in Idaho had maximum residue levels of 21 g/g DDE and 11 g/g PCBs.

11.

In the Columbia River Basin of Washington and Oregon in 1978, organochlorine residues from the eggs of 21 nesting GBHs from the Umatilla National Wildlife Refuge and the McNary Recreation Area were analyzed (Blus et al., 1980). DDE residues were detected in all eggs and had the highest concentrations with a geometric mean of 3.30 g/g wet weight in Umatilla and 4.71 g/g in McNary. PCBs were next with 1.93 and 2.24 g/g, respectively, followed by trans-nonachlor with 0.44 and 0.30 g/g. Other organochlorines detected in various numbers of the eggs tested were DDD (less than 0.49 and 1.00 g/g for the two sites, respectively), dieldrin (less than 0.29 and 1.16 g/g), heptachlor epoxide (less than 0.40 and 0.25 g/g), oxychlordane (less than 0.44 and 0.19 g/g), cis-nonachlor (less than 0.69 and 0.20 g/g), and cis-chlordane (less than 1.36 and 0.63 g/g).

12.

Eggs of GBHs nesting at Nueces Bay, Corpus Christi, Texas in 1978 and 1979 contained DDE levels up to 49.00 g/g wet weight, with median levels of 3.67 g/g and 3.00 g/g for the two years, respectively (Mitchell et al., 1981). PCBs reached 41.00 g/g, with medians of 7.80 g/g and 6.15 g/g. Other compounds detected included dieldrin at <1.80 g/g, and chlordane at <2.38 g/g. HCB was detected in 1978 alone with a median concentration of 0.15 g/g.

13.

GBH eggs collected from five heronries along the St. Lawrence River in Quebec in 1979 all contained organochlorine residues (Laporte, 1982). PCBs concentrations were highest at a mean of 7.78 g/g wet weight, followed by DDE (2.42 g/g), DDD (0.15 g/g), and dieldrin (0.14 g/g). Concentrations of DDT, heptachlor epoxide, and oxychlordane ranged from 0.01 to 1.26 g/g. HCB was detected at a range of 7 to 1093 ng/g, and pentachlorobenzene levels were <33 ng/g. -BHC and tri- and tetrachlorobenzene were generally at or below detection level

14.

In 1980, a total of 40 GBH eggs were collected from four rookeries in the Tennessee Valley: Armstrong Bend, Bellefonte, Duck River, and Sinking Pond (Fleming et al., 1984). Throughout the colonies, DDE, dieldrin, cis-chlordane, trans-nonachlor, and PCBs were all found in at least 70% of the eggs and concentrations did not differ significantly between colonies. The greatest mean levels of the four colonies of each compound were 5.2 g/g wet weight, 0.22 g/g, 0.20 g/g, 0.54 g/g, and 9.2 g/g, respectively. Cis-nonachlor occurred in 50 to 80% of eggs with a high mean of 0.13 g/g. Heptachlor epoxide and oxychlordane had means of 0.14 g/g and 0.11 g/g, respectively, at Sinking Pond, and <0.1 g/g at all other sites. Mean toxaphene levels were 0.14 at Duck River, and <0.1 g/g at all other sites. DDD levels were significantly higher in Duck River (0.53 g/g) and Sinking Pond (0.20 g/g) eggs than other sites (<0.1 g/g). Other organochlorines detected were DDT, endrin, HCB, and mirex, all at levels <0.1 g/g for all colonies.

15.

From 1983 to 1987, GBH eggs collected from five sites along the Strait of Georgia in Vancouver were tested for organochlorine residues (Elliott et al., 1988). 123678-HxCDD was found in the greatest concentrations in all colonies, ranging from 6-1052 ng/kg wet weight. 12378-PnCDD levels were second greatest with a range of 9-1018 ng/kg. 2378-TCDD ranged from 3-444 ng/kg. Other organochlorines detected, at concentrations <104 ng/kg were 123789-HxCDD, 1234678-HpCDD, OCDD, 2378-TCDF, and 23478-PnCDF. Eggs collected at Crofton and University of British Columbia contained significantly higher concentrations of TCDD than eggs collected from Sidney Island and Nicomekl. From 1983 to 1987, TCDD values increased in all colonies that were sampled in multiple years.

16.

GBH eggs collected from the Puget Sound, Washington area in 1984 were tested for PCB and DDT residues (Speich et al., 1992). Concentrations ranged from 1.39 to 15.58 g/g wet weight PCB and 0.35 to 2.22 g/g DDT. The Seattle area eggs contained the highest amounts of both compounds.

17.

GBH eggs were collected from 1986-1987 from four colonies in the Strait of Georgia, British Columbia: Crofton (pulp and paper mill), Vancouver (industrial), Nicomekl (agricultural), and Sidney Island (control) (Elliott et al., 1989). Crofton, in 1987, contained the greatest mean concentrations for all years and all colonies of 2378-TCDD (210 pg/g (ppt) wet weight), 12378-PnCDD (257 pg/g), 123678-HxCDD (402 pg/g), 123789-HpCDD (27 pg/g), 23478-PnCDF (37 pg/g), and total TCDD equivalents (230 pg/g). Vancouver contained the greatest mean of 2378-TCDF at 17 pg/g. Means of 1234678-HpCDD and OCDD were less than 7 pg/g for all colonies. Nicomekl contained the highest mean DDE level at 0.549 g/g. Oxychlordane, trans-nonachlor, heptachlor epoxide, dieldrin, and HCB were detected at low mean levels in all eggs (<0.062 g/g) and DDT, mirex, and -HCH in most eggs (<0.021 g/g). Total mean PCB concentrations, detectable in all eggs, ranged from 0.418 g/g in Sidney to 1.22 g/g at Vancouver, 1987. Only trace levels of PCDD residues were found in nestling regurgitations.

18.

In 1988, GBH eggs were collected and hatched from three sites of increasing contamination levels in British Columbia: Nicomekl (control), Vancouver, and Crofton (Bellward et al., 1990). TCDD levels detected in Vancouver and Crofton eggs were significantly greater than controls with means of 135 pg/g wet weight and 211 pg/g, respectively. 1,2,3,7,8-PnCDD and 1,2,3,6,7,8- and 1,2,3,7,8,9-HxCDD levels showed a significant increase in Crofton eggs at 263, 430, and 48 pg/g, respectively. Also detected were 2,3,7,8-TCDF and 2,3,4,7,8-PnCDF at levels of 11 and 33 pg/g for Vancouver, and 8 and 33 pg/g for Crofton. Means of PCBs detected were 0.636, 1.650, and 0.808 g/g, respectively. Dieldrin and DDE were highest at Nicomekl with levels of 0.0417 and 0.712 g/g, respectively. trans-Nonachlor levels were highest at Vancouver, at 0.0392 g/g. HCB, DDT, oxychlordane, and heptachlor epoxide each had concentrations of <0.0244 g/g for all sites.

19.

In 1988, 1990, 1991, and 1992, GBH heron eggs were collected and hatched from two contaminated sites (University of British Columbia Endowment Lands and Crofton) and three reference sites (Nicomekl, Chilliwack, and Tillicum) in British Columbia (Henshel et al., 1995). Mean concentrations of TCDD ranged from 0.00-0.46 pg/g at reference sites and 0.46-8.81 at contaminated sites. Means of TCDD-TEQs ranged from 0.00-0.77 at reference sites and 0.99-14.63 at contaminated sites.

20.

GBH eggs collected from two sites on the west coast of Canada were analyzed for organochlorine residues (Kennedy et al., 1992). Concentrations of PCB 77, 126, and 169 were <0.18 ng/g for all eggs. PCB 105 was detected at concentrations of 31 and 17 ng/g and PCB 118 at 116 and 63 ng/g. TCDD was detected at 319 ng/g at the Crofton, British Columbia site.

21.

In 1988, GBH eggs were collected with salvaged eggshells from the colony floor for organochlorine analysis from three sites in the Puget Sound area: Dumas Bay, Samish Island, and Nisqually (Cobb et al., 1994). Mean organochlorine concentrations in heron tissue and eggs from Samish Island were 1.15 ng/g pentachlorobenzene, 18 ng/g HCB, and 380 ng/g DDE. The greatest mean PCB levels detected in tissue and eggs from the same location were Arochlor 1254 (2470 ng/g), 1260 (656 ng/g), and 1242 (458 ng/g). Chlorio-allantoic membrane analysis revealed mean organochlorine concentrations of 1.44 ng/g pentachlorobenzene, 7.98 ng/g HCB, and 336 ng/g DDE, and mean Arochlor levels of 1530 ng/g (1254), 496 ng/g (1260), and 56 ng/g (1242). Dumas Bay had higher mean tissue and egg concentrations with 4.37 ng/g pentachlorobenzene, 110 ng/g HCB, and 1670 ng/g DDE; mean arochlor concentration was 16,600 ng/g (1254), 3428 ng/g (1260), and 2140 ng/g (1242).

22.

Organochlorine levels of GBHs nesting on Whidbey Island, WA in 1989 were determined by chorio-allantoic membrane analysis (Cobb et al., 1995). Mean combined DDT, DDE, and DDD concentrations were 0.171 g/g dry weight and mean PCB concentrations were 0.247 g/g. Low correlations among DDT and its metabolites in CAMs suggested inconsistent exposure to these compounds.

23.

In 1991 in Crofton and 1990 and 1992 in Vancouver, GBH eggs were collected from colonies in the Strait of Georgia, British Columbia and determined to have lower concentrations of contaminants than those found in 1988 (Sanderson et al., 1994). TCDD was detected at mean levels of 16, 42, and 10 pg/g wet weight, respectively. Mean 1,2,3,7,8-PnCDD levels were 37, 45, and 10 pg/g, respectively, and those of 1,2,3,6,7,8-HxCDD measured 46, 57, and 11 pg/g, respectively. Other mean PCDD concentrations were <5 pg/g. PCDFs in greatest abundance were 2,3,7,8-TCDF and 2,3,4,7,8-PnCDF with means of 15 and 16 pg/g, respectively, in Vancouver, 1990. Mean PCB residues detected were 101, 293, and 327 pg/g (PCB-126); 20, 43, and 47 pg/g (PCB-169); 5, 22, and 30 ng/g (PCB-105); and 40, 144, and 170 ng/g (PCB-118). Mean TEQ levels were greatest at Vancouver, 1990 (278 pg/g), followed by Vancouver, 1992 (253 pg/g), and Crofton (100 pg/g).

24.

In 1991, 65 GBH eggs were collected from nine heronries (seven along the St. Lawrence River and two reference sites) (Boily et al., 1994). Freshwater and estuarine eggs contained similar concentrations of mirex and photomirex, reaching values of 0.145 and 0.038 g/g, respectively. For other organochlorines tested, estuarine sites consistently had higher concentrations than freshwater sites, with means reaching 0.0089 g/g OCS, 7.818 g/g total PCBs, 175 ng/g PCB 105, 917 ng/g PCB 188, and 63.9 pg/g TCDD-EQs.

25.

Between 1991 and 1994, eggs were collected from 4 sites in Tennessee; 2 colonies on Oak Ridge Reservation (n=33), K25 and Melton Hill, and 2 reference colonies (n=34), Long Island and Looney Island (Halbrook et al., 1999).  Mean (range) concentrations of Arochlor 1260 in the eggs were 2.01 (0.10-8.80), 0.86 (0.07-2.40), 0.53 (0.07-2.20), and 0.34 (0.09-1.10) g/g wet weight for the 4 colonies, respectively. 

26.

In 1993, GBH eggs were collected from 10 colonies on the Upper Mississippi River and incubated until pipping (Custer et al., 1997). Dieldrin, heptachlor epoxide, and HCB had overall mean embryo liver concentrations of 0.10, 0.05 and 0.003 g/g wet weight, respectively. Means for these compounds for the southernmost colonies were significantly higher than those of colonies furthest north. Mean levels of other organochlorines did not differ between colonies: 1.31 g/g DDE, 3.04 g/g PCBs, 0.0031 g/g BHC, 0.0304 g/g oxychlordane, 0.0321 g/g cis-nonachlor, 0.0829 g/g trans-nonachlor, 0.0046 g/g mirex, 0.0149 g/g DDD, and 0.0066 g/g DDT. Endrin and alpha-s.gif (59 bytes)-chlordane were detected in <50% of eggs sampled, at concentrations <0.010 and 0.087 g/g, respectively. Concentrations of the 15 Ah-active congeners represented 13% of the total PCBs. PCBs 118, 105, 126, and 156 accounted for 87% of the total TEQs. TCDD and OCDD were the only PCDDs or PCDFs to be found in at least 50% of eggs sampled and averaged 11.5 and 112.0 pg/g, respectively.

27.

Organochlorine contaminants were measured in 10 GBH eggs collected from the Indiana Dunes National Lakeshore in 1993 (Custer et al., 1998).  Mean concentrations were 0.19 g/g wet weight trans-nonachlor, 0.26 g/g dieldrin, 0.3 g/g toxaphene, 1.58 g/g DDE, 4.9 g/g total PCBs, 0.0871 g/g PCB 105, 0.0057 g/g PCB 114, 0.2647 g/g PCB 118/106, and 0.0005 g/g PCB 156.  One egg had elevated concentrations of DDE (13.0 g/g) and PCBs (56 g/g).  Concentrations of BHC, cis-chlordane, oxychlordane, cis-nonachlor, endrin, HCB, heptachlor epoxide, mirex, DDD, and DDT were <0.08 g/g.  TEQs were 465 pg/g, as calculated by Safe (1990), and 929 pg/g, as calculated by Kennedy (1996). 

28.

In 1993, GBH eggs were collected from the National Audubon Sanctuary Islands of the Lower Laguna Madre, Texas (Mora, 1996a). Total PCB concentrations averaged 0.246 g/g wet weight. PCB congeners detected at the highest concentration were 138, 153, 180, and 110.

29.

In 1993-94, ten GBH eggs were collected from the National Audubon Sanctuary Islands of the Lower Laguna Madre, Texas (Mora, 1996b). Median (range) contaminant concentrations were 0.735 (0.092-2.59) g/g wet weight DDE and 0.396 (0.058-0.199) g/g PCBs.

30.

Eggs were collected from sites near paper or pulp mills and a reference site in the Columbia and Willamette Rivers and Puget Sound in Washington and Oregon in 1994-1995 (Thomas and Anthony 1999). In 1994 and 1995, respectively, mean DDE ranged from 263-1,616 and 183-1,489 ng/g wet weight at study sites and was 101 and 150 ng/g at the reference site.  Mean DDT ranged from 26-34 and 4.5-22 ng/g at study sites and was <16 and 5.0 ng/g at the reference site.  Mean trans-nonachlor ranged from 18-199 and 8.4-88 ng/g at study sites, and was 14 ng/g at the reference site in 1995. Mean total PCBs ranged from 382-3,454 and 423-2,426 ng/g at study sites and was 223 and 369 ng/g at the reference site.  PCB congeners were below detection limits in 1994.  A different lab was used in 1995.  Mean PCB 77 ranged from 0.03-0.23 pg/g at study sites and was 0.05 pg/g at the reference site in 1995.  Mean PCB 126 ranged from 0.12-0.65 pg/g at study sites and was 0.21 pg/g at the reference site in 1995.  Mean PCB 169 ranged from 0.02-0.06 pg/g at study sites and was 0.03 pg/g at the reference site in 1995.  In 1994 and 1995, respectively, mean TCDD ranged from 1.7-8.3 and 2.5-6.4 pg/g at study sites and was 3.7 pg/g at the reference site in 1995.  In 1994 and 1995, respectively, mean OCDD ranged from ND-33 and 10-40 pg/g at study sites and was 34 pg/g at the reference site in 1995.  Levels of 2,3,7,8-TCDF were below detection limits in 1994.  In 1995, mean 2,3,7,8-TCDF ranged from 0.5-1.3 pg/g at study sites and was 1.3 pg/g at the reference site.  In 1994 and 1995, respectively, calculated total TEQs based on Safe ranged from 27-206 and 21-97 pg/g at study sites and was 26 and 33 pg/g at the reference site.  In 1994 and 1995, TEQs measured by H4IIE bioassay ranged from 1.5-30 and <0.6-<1.7 pg/g at study sites and was 1.5 and 2.5 pg/g at the reference site. 

31.

Over the period of 1977-2000, great blue heron eggs were collected from 23 colonies along the Strait of Georgia, British Columbia, Canada (Harris et al., 2003). The sites were divided into three categories; urban, pulp and paper mill, and rural reference. Concentrations of organochlorine pesticides and PCBs (g/g wet weight) in eggs from reference colonies around the Strait of Georgia from 1978-200 were all <0.11 for trans-Nonachlor, cis-Nonachlor, oxy-Chlordane, cis-Chlordane, heptachlor epoxide, dieldrin, DDD, mirex, HCB and HCH. DDE levels were <0.995 and sum PCBs <5.41. Concentrations from contaminated sites near the Fraser River delta between 1977-2000 were <0.154 for trans-Nonachlor, cis-Nonachlor, oxy-Chlordane, cis-Chlordane, heptachlor epoxide, dieldrin, DDD, mirex, HCB and HCH. DDE levels were <2.97 and sum PCBs <9.57.

The most common pesticides detected in eggs, regardless of amount detected, were DDE (100% of samples), HCB (100%),  trans-Nonachlor and cis-Nonachlor (>99%), dieldrin (99%), heptachlor epoxide (95%), DDT (93%), cis-chlordane (92%), HCH (85%), DDD (82%) and mirex (66%).

II.

Cholinesterase-Inhibiting Pesticides

1.

In 1993 and 1994, GBH nestlings were collected from Clear Lake, California, near the Sulphur Bank Mercury Mine (Wolfe and Norman, 1998). Brain ChE activities at Quercus Point and Slater Island were, respectively, 12.9 and 11.4 mmoles acetylthiocholine hydrolyzed/g brain weight. Plasma ChE activities at Quercus Point and Slater Island, were, respectively, 0.25 and 0.27 mmoles acetylthiocholine hydrolyzed/ml plasma. Brain and plasma ChE activity measurements were not depressed for either site.

III.

Trace Elements, Metals, and Metalloids

A.

Concentrations in Adults

1.

The concentration of Pb in the liver of an east coast GBH either captured or shot was 0.7 g/g wet weight (Bagley and Locke, 1967).

2.

In 1978, excrement cast from GBHs was collected from cheesecloth strips placed on the ground beneath nests in four colonies in Washington and Idaho (Fitzner et al., 1982). Cheesecloth strips placed under nearby trees without nests served as controls. Significant differences in mean metal concentrations between treatments and controls were found in only one site, Lake Chatcolet, Idaho, where values in excrement were 46 (5.7 control) g/g Pb, 1.8 (0.22) g/g Cd, and 0.28 (0.085) g/g Hg. Concentrations at other nesting sites (Tacoma, Richland, and Potholes Resevoir, Washington) were similar to control values and are presumed to be associated with airborne deposition and foliage drip.

3.

Heavy metal concentrations residing in fecal matter were assessed from GBHs nesting in various locations in eastern and western Washington in 1982 and 1983 (Fitzner et al, 1995). Lead, Cd, Cr, and Co were detected in all samples from eastern Washington. Cadmium was found in the greatest concentration in Hanford (0.53 g/g). Highest Pb values were found at Hanford (6.01 g/g wet weight) and Foundation Island (5.28 g/g). Foundation Island also contained the highest concentrations of Cr (3.34 g/g) and Co (1.67 g/g), each at values more than twice that of any other area. In western Washington, metal concentrations were similar or higher than eastern levels. Cadmium was found at similar concentrations, reaching a maximum of 0.57 g/g in Samish Island. Concentrations of Pb were highest in Auburn (10.45 g/g) and Dumas Bay (8.53 g/g). Dumas Bay (4.25 g/g) and Deception Pass (4.21 g/g) had the highest levels of Cr, and Oyster Bay contained the greatest level of Co (1.87 g/g). Metal concentrations detected tended to increase with increased proximity to industrial and developed areas, indicating fecal matter concentrations as a potentially reliable biomarker of heavy metal exposure.

4.

Between 1987 and 1989, 64 nestling and 23 adult great white herons (A. herodias occidentalis) in Florida were radio-tagged, monitored and collected upon death to test for Hg concentrations in the liver, which ranged from 0.6 to 59.4 g/g wet weight (Spalding et al., 1994).

5.

Concentration of Hg was determined in herons found dead in southern Florida between 1987 and 1990 (Beyer et al., 1997). One adult GBH contained 4.5 g/g wet weight in the liver and 6.9 g/g dry weight in feathers. Adult great white herons were found to have a mean concentration of 8.2 (4.1-14) g/g dry weight in feathers. One great white heron contained 2.9 g/g wet weight in liver and 6.2 g/g dry weight in feathers.

6.

Adult GBH found dead were collected from four areas in south Florida between 1987-1991 and analyzed for hepatic Hg (Sundlof et al., 1994). Mean Hg concentrations were 0.60, 0.80, 4.25, and 7.62 g/g wet weight at Lake Okeechobee, the Everglades, eastern Florida Bay, and Big Cypress National Preserve, respectively. 

7.

A great blue heron collected in 1989 from Old Woman Creek Estuary, Ohio, had a concentration of 1.62 g/g wet weight Hg in muscle (Francis et al., 1998).

8.

Elemental profiles were determined in flight feathers collected from 19 adult great blue herons at a mercury contaminated site, Clear Lake, California (Cahill et al., 1998).  Mean concentrations were 32,772 g/g S, 3283 g/g Ca, 10.9 g/g Ti, 252 ug.g Fe, 281 g/g Zn, 2.51 g/g Se, 10.3 g/g Br, 19.3 g/g Sr, 6.11 g/g Hg, and 1.07 g/g Pb.  Concentrations of Cr were not detectable, and V, Ni, As, and Rb in trace amounts only.

B.

Concentrations in Nestlings

1.

Nestling GBHs found dead in southern Florida between 1987 and 1990 contained a mean (range) Hg concentration of 3.5 (1.8-7.7) g/g dry weight in feather (Beyer et al., 1997). A comparison to liver concentrations was performed in one nestling, which contained 0.21 g/g wet weight in the liver and 2.7 g/g dry weight in feathers, and one juvenile which contained 75 g/g wet weight in liver and 27 g/g dry weight in feathers. Great white herons were found to have a mean concentration of 6.7 (2.7-15) g/g dry weight in feathers of juveniles and 4.7 (1.0-9.1) g/g dry weight in feathers of nestlings. Four juveniles were found to have concentrations of 0.87-8.3 g/g wet weight in liver and 6.2-8.1 g/g in feathers. Two nestlings were found to contain 7.3 and 1.9 g/g wet weight in liver and 9.1 and 3.9 g/g dry weight in feathers.

2.

Livers were collected between 1987-1991 from GBH nestlings found dead at Lake Okeechobee, Florida and great white heron nestlings found dead in Florida Bay (Spalding et al., 1997).  Mean concentrations of Pb, Cu, and Cd were 0.28, 5.5, and 0.05 g/g wet weight, respectively at Lake Okeechobee and 0.32, 20, and 0.10 g/g ww at Florida Bay.

3.

Nestling and fledgling GBHs found dead were collected from four areas in south Florida (Lake Okeechobee, the Everglades, eastern Florida Bay, and Big Cypress National Preserve) between 1987-1991 and analyzed for hepatic Hg (Sundlof et al., 1994).  Mean Hg concentrations ranged from 0.31-1.53 g/g in nestlings and were 6.65 g/g in fledglings.

4.

Between 1991 and 1994, nestlings were collected from 4 sites in Tennessee:  2 colonies on Oak Ridge Reservation (n=38), K25 and Melton Hill, and 2 reference colonies (n=35), Long Island and Looney Island (Halbrook et al. 1999).  Hg concentrations in the feathers were 2.02 0.28, 1.02 0.13, 0.87 0.08, and 1.02 0.16  g/g dry weight, for the 4 colonies.  Hg concentrations in the liver were 0.29 0.04, 0.15 0.02, 0.12 0.01, and 0.26 0.04 g/g.  Hg concentrations in muscle were 0.09 0.01, 0.05 0.01, 0.07 0.01, and 0.08 0.01  g/g.  Cr concentrations in the feathers were 1.00 0.17, 0.87 0.43, 1.29 0.26, and 0.93 0.18 g/g.  Cr concentrations in the liver were 1.54 0.65, 1.39 0.62, 1.82 0.71, and 0.15 0.02 g/g.  Cr concentrations in the muscle were 1.40 0.63, 3.01 1.18, 3.14 1.14, and 2.26 0.97 g/g.  As concentrations in the liver were 0.65, 0.55, 0.49, and ND.  As concentrations in the muscle were 1.16, 0.41, 0.05and 0.64, and 0.42  g/g. 

5.

From 1993 to 1994, GBH nestlings were collected at Clear Lake, California, near the Sulphur Bank Mercury Mine (Wolfe and Norman, 1998).  Mean (range) Hg concentrations in tissues were 0.35 (0.3-0.4) mg/g wet weight in brain and 1.46 (1.32-1.71) mg/g in liver.

In 1993, at Slater Island, mean (standard deviation) Hg concentrations in tissues of young GBHs (in mg/g wet weight) were as follows: 0.36 (0.15) in brain (N=8), 1.42 (0.67) in liver (N=8), 2.23 (0.77) in feathers (N=7), 1.3 (0.23) in blood (N=4), and 1.15 (0.10) in kidney (N=5). 

In 1994, at Slater Island, mean (standard deviation) Hg concentrations in tissues of young GBHs (in mg/g) were as follows: 0.30 (0.14) in brain (N=6), 1.39 (0.58) in liver (N=11), and 1.97 (1.18) in feathers (N=11). 

In 1993, at Quercus Point, mean (standard deviation) Hg concentrations in tissues of young GBHs (in mg/g) were as follows: 0.35 (0.11) in brain (N=7), 1.71 (0.63) in liver (N=7), 2.43 (0.99) in feathers (N=6), 1.08 (0.32) in blood (N=4), and 1.00 (0.33) in kidney (N=3).

In 1994, at Quercus Point, mean (standard deviation) Hg concentrations in tissues of young GBHs (in mg/g) were as follows: 0.36 (0.15) in brain (N=6), 1.46 (0.57) in liver, and 2.01 (1.18) in feathers (N=11).

In 1993, at Rodman Slough, mean (standard deviation) Hg concentrations in tissues of young GBHs (in mg/g) were as follows: 0.4 (0.09) in brain (N=10), 1.32 (0.59) in liver (N=10), 3.16 (0.82) in feathers (N=10), 1.16 (0.33) in blood (N=5), and 1.12 (0.26) in kidney (N=7).

Mercury concentrations in GBH nestlings were not correlated to distance from the Hg mine.

C.

Concentrations in Eggs and Embryos

1.

A total of five great blue heron eggs collected from the Great Lakes area in Wisconsin in 1970 contained a mean concentration of 0.29 g/g wet weight Hg (Faber and Hickey, 1973).

2.

In 1980, a total of 40 GBH eggs were collected from four rookeries in the Tennessee Valley: Armstrong Bend, Bellefonte, Duck River, and Sinking Pond (Fleming et al., 1984). Mercury was detected in all the eggs with mean levels for the colonies at 0.34 g/g wet weight, 0.29 g/g, 0.49 g/g, and 0.50 g/g, respectively. Chromium was detected in all but one egg with means of 0.23 g/g, 0.18 g/g, 0.16 g/g, and 0.18 g/g, respectively.

3.

GBH eggs and hatchlings from colonies located near sources of heavy metal pollution by Puget Sound, Washington and Lake Chatcolet, Idaho were collected in 1981 and 1982 and tested for residues in tissues and eggs (Blus et al., 1985). Eggs contained levels of Cu up to 2.71 g/g wet weight, Zn up to 6.37 g/g, and Hg up to 0.37 g/g. Arsenic was not detected. Whole body analysis of hatchlings and advanced embryos revealed concentrations not exceeding those of the eggs, except for Zn which reached 11.0 g/g. Lead and Cd were detected in a portion of the samples at levels up to 0.44 and 0.22 g/g, respectively. Young herons from Fort Lewis, Washington contained the highest liver concentrations of Cu, Zn, and Hg, with levels reaching 90, 83, and 1.5 g/g respectively. Lead was detected irregularly among the young birds and Cd was not detected. Other elements detected in a single young heron found dead were Cr, Al, Mg, and Mn.

4.

GBH eggs were collected from 1986-1987 from four colonies in the Strait of Georgia, British Columbia: Crofton (pulp and paper mill), Vancouver (industrial), Nicomekl (agricultural), and Sidney Island (control) (Elliott et al., 1989). Total Hg concentrations were 0.042, 0.094, 0.098, and 0.059 g/g wet weight, respectively. Nestling regurgitation contained concentrations of <0.05 g/g Hg and <0.1 g/g Cd. Total Pb levels reached 1.8 g/g in Vancouver regurgitation samples.

5.

Between 1991 and 1994, eggs were collected from 2 colonies on Oak Ridge Reservation (n=33), K25 and Melton Hill, and 2 reference colonies (n=34), Long Island and Looney Island, all sites were in Tennessee (Halbrook et al 1999).  Hg concentrations in the eggs were 0.17 0.02, 0.13 0.06, 0.14 0.02, and 0.12 0.02.  Hg concentrations were significantly higher in K25 feathers than in feathers from other sites.  Hg concentrations in liver from K25 and Looney Island were significantly higher than the other 2 sites. Cr concentrations in the eggs were 0.15 0.02, 0.22 0.08, 0.11 0.01, and 0.11 0.01g/g  As was below the detection limit (0.4 ppm dry weight) in all eggs. 

6.

In 1993, GBH eggs were collected from 10 colonies on the Upper Mississippi River and incubated until pipping (Custer et al., 1997). Concentrations of Hg from embryo livers ranged from 0.24 to 2.82 g/g dry weight, with a geometric mean of 0.82 g/g. Mean Hg levels did not differ between colonies. Values of Se ranged from 1.76 to 4.17 g/g, with a mean in Vogt Lake, Wisconsin (3.56 g/g) that was significantly higher than Mertes Slough, Wisconsin (2.48 g/g).

7.

Concentrations of Hg and Se were detected in all 10 GBH eggs collected from the Indiana Dunes National Lakeshore in 1993 (Custer et al., 1998).  Mean concentrations were 0.908 g/g dry weight Hg and 3.976 g/g Se.

8.

In 1993-94, ten GBH eggs were collected from the National Audubon Sanctuary Islands of the Lower Laguna Madre, Texas (Mora, 1996b). Median (range) metal concentrations were as follows (g/g wet weight): 0.09 (0.02-0.15) Hg, 0.32 (0.17-0.44) Se, 0.63 (0.53-2.10) B, 0.29 (0.09-11) Cr, 1.70 (0.75-36) Cu, 22.0 (15-53) Fe, 110 (76-170) Mg, 0.48 (0.17-1.1) Mn, 1.90 (1.3-2.9) Sr, and 11.5 (7.2-21) Zn.

9.

Eggs were collected from sites near paper or pulp mills and a reference site in the Columbia and Willamette Rivers and Puget Sound in Washington and Oregon in 1994 (Thomas and Anthony 1999).  Mean Hg concentrations ranged from 0.35-0.66 g/g dry weight at study sites and was 0.53 g/g at the reference site.

IV.

Petroleum

 

No residue data available

V.

Other Contaminants

1.

Rejecta cast from GBH nests of birds feeding in the Columbia River contained higher levels of the biologically active Cs-137, K-40, Zn-65, and Co-60 radionuclides than controls (Rickard et al., 1978). Controls had higher concentrations of Ce-144, Ru-164, Zr-95, and Mn-54 radionuclides. One heron found dead contained detectable amounts of Zr-95, and Mn-54 in the liver.

2.

GBH livers collected from St. Martinville, Louisiana, had the following concentrations (in ng/g) of perfluorooctane sulfonate: 59, 173, 188, 261, and 1061 (Minnesota Mining and Manufacturing Company, 2000).

Great Blue Heron Contaminant Response Data

I.

Organochlorine Contaminants

A.

Eggshell Thinning and Reproduction

1.

GBH eggs were collected from various locations in Alberta from 1968 to 1969 (Vermeer and Reynolds, 1970). Eggshell thickness was inversely related to DDE concentration (wet weight basis).

2.

Expanding on data from Vermeer and Reynolds (1970), DDE residues were shown to be correlated with decreased eggshell thickness in 40 GBHs from Alberta (Vermeer and Risebrough, 1972). This relationship had a greater degree of significance if residue concentrations were expressed on a lipid weight basis rather than on a wet weight basis. Dieldrin concentration was also correlated with eggshell thinning, though the relationship was less significant.

3.

Eggshells collected in 1969 and 1970 from a GBH colony in Bolinas Lagoon near San Francisco showed signs of thinning (Faber et al., 1972). "Hatched" (N=42) and broken (N=17) eggs had a mean thickness of 0.355 mm, representing a 10.4% decrease from pre-1947 specimens. The shells of eggs that "hatched" had a mean thickness of 0.365 mm, a 7.8% thinning, and the broken shells had the lowest mean thickness at 0.328 mm, a 17.2% thinning. The small number of eggs analyzed for organochlorines prohibited correlation analysis with thickness values. Reproductive success varied between 1967 and 1970, with successful nesting attempts ranging from 56 to 87%, and the number of young fledged from 1.5 to 2.0 per breeding pair.

4.

In 1970, two GBH eggs collected from Western Oregon had a mean thickness index of 1.98, which was not significantly different than pre-1947 values (Henny and Bethers, 1971). The colony had 78% successful nests, with 2.04 young fledged per nesting pair.

5.

A total of five GBH eggs collected from the Great Lakes area in Wisconsin in 1970 exhibited a mean decrease in eggshell thickness of 16.0% when compared to pre-1947 values (Faber and Hickey, 1973). The shell thickness index was reduced by 24.9%. These data were combined with that of other herons studied and found to be significantly correlated with DDE.

6.

A total of 74 GBH eggs collected in 1970 from thirty sites on the Texas coast showed a mean eggshell thickness of 0.359 mm, representing a 13% decrease from pre-1943 values (King et al., 1978). DDE concentration was negatively correlated with eggshell thickness.

7.

In 1972 and 1973, GBH eggs were collected from various locations in the eastern United States (Ohlendorf et al., 1979b). Florida eggs showed a 5.2% decrease in thickness compared to pre-1947 values. Eggs from Minnesota, Michigan, and Ohio and showed a 7.9% thinning as compared to pre-1947 values from eggs in the same region.

8.

Between 1975 and 1978, a GBH colony near Fountain City Bay, Wisconsin in the Upper Mississippi River was examined for reproductive success (Nosek and Faber, 1984). Contaminants found in the greatest concentrations in this colony were PCBs and DDE. The total number of nests declined from 586 in 1975 to 463 in 1978, though it is unclear as to the cause of the decline. In 1978, both hatchling success (2.95 per nest) and fledgling success (2.18 per nest) were within normal reproductive bounds reported by other studies. The mean eggshell thickness index was 1.95 in 1978.

9.

GBH eggs collected from 1977 to 1982 in Washington, Oregon, and Nevada showed mean thinning values per colony ranging from 4 to 13% (Fitzner et al., 1988). Foundation Island in the Columbia River showed the greatest thinning at 0.338 mm, compared to the pre-1947 Pacific Northwest value of 0.389 mm. DDE and PCBs accounted for 26 and 3%, respectively, of the variability in eggshell thickness.

10.

In 1978, DDE and PCB residues were correlated with GBH eggshell thinning of 11.8 and 13.1% at the Umatilla National Wildlife Refuge (Washington and Oregon) and McNary Recreation Area (Washington) (Blus et al., 1980). Mean eggshell thickness was 0.343 and 0.338 mm for the two sites, as compared to the historical values of 0.389 mm in the pacific Northwest. Reproductive success was considered normal with 1.84 to 2.12 young fledged per active nest.

11.

GBHs nesting at Nueces Bay, Corpus Christi, Texas in 1978 to 1979, containing DDE levels up to 49 g/g wet weight, were studied for reproductive effects (Mitchell et al., 1981). The colony was considered stable with an average clutch size of 3.58, a hatching rate of 2.45 and fledging rate of 1.61. Eggshell thickness averaged 0.37 mm in 1978, representing 5% thinning, and 0.40 mm in 1979, showing no thinning.

12.

In 1979, GBH eggs containing a mean concentration of 2.42 g/g wet weight DDE exhibited a mean eggshell thickness ranging from 0.294 to 0.425 mm, indicating a 5.3% reduction from pre-1947 material (Laporte, 1982). Measurements of the calcareous portion ranged from 0.258 to 0.378 mm. The thickness index varied from 1.65 to 2.27. DDE residues were significantly correlated to shell thickness indices and shell thickness without inner shell membranes.

13.

In 1980, a total of 40 GBH eggs were collected from four rookeries in the Tennessee Valley: (Fleming et al., 1984). Shell thickness, which was significantly correlated with the log DDE concentration, did not differ among the four colonies and was about 7.5% less than pre-1947 values. Mean values ranged from 0.363 to 0.378 mm. All colonies were showing an increase in number of active nests at the time of the report

14.

GBH eggs collected from the Puget Sound region in Washington in 1984 showed signs of eggshell thinning that correlated with DDT concentrations (Speich et al., 1992). Whole eggs measured 0.360 mm in thickness, an average of 7% thinning compared to historical values. The greatest thinning (12-13%) occurred in the agricultural areas of Samish Island and Marsh Point, north of Seattle. Eggshell fragments averaged at 0.379 mm for a 2% reduction in thickness.

15.

Four GBH colonies in the Strait of Georgia, British Columbia [Crofton (pulp and paper mill), Vancouver (industrial), Nicomekl (agricultural), and Sidney Island ("reference")] were studied for the effects of contaminants on reproductive success (Elliott et al., 1988; 1989). In 1986 all four sites produced a comparable percentage of successful nests, but in 1987, the Crofton colony failed to produce any successful nests. Though 57 active nests in Crofton produced a normal complement of eggs, many eggs were broken and destroyed during incubation and found on the ground below. TCDD levels in eggs collected in 1987 were about three times higher than 1986 concentrations. Eggshells from Vancouver, Crofton, and Nicomekl were significantly thinner (up to 8.6%) than pre-1947 values.

16.

Two GBH colonies, Pea Patch Island and Cumples Woods, Delaware were monitored for reproductive success in 1993 (Parsons and McColpin, 1995). Most heron pairs on both sites were successful in raising at least one young to 20 days post-hatch. Eggshell thickness ranged 0.320-0.404 mm at Pea Patch and 0.277-0.428 mm at Cumples, averaging 7% and 13.5% thinning compared to pre-1947 values.

17.

In 1993, GBH eggs were collected from 10 colonies on the Upper Mississippi River and incubated until pipping (Custer et al., 1997). Eggshell thickness averaged 0.384 mm, a 2.3% thinning over Canadian pre-1947 values. Shell thickness was negatively correlated with DDE concentration.

18.

In 1993, eggshell thickness was 0.380 mm in 10 GBH eggs collected from the Indiana Dunes National Lakeshore, a decrease of 3.4% compared to pre-1947 values (Custer et al., 1998).  

19.

In 1993, GBH eggshell measurements from Clear Lake, California, near a Hg mine, and heronries uncontaminated by Hg were at pre-DDT/DDD levels (Wolfe and Norman, 1998).

20.

Eggs were collected and colonies were observed from sites near paper or pulp mills and a reference site in the Columbia and Willamette Rivers and Puget Sound in Washington and Oregon between 1994-1995 (Thomas and Anthony 1999).  Mean shell thickness ranged from 0.333-0.370 mm at study sites and was 0.352 mm at the reference site, compared to 0.389 mm in pre-1947 museum specimens.  Mean eggshell thinning ranged from 4.9-14.4% at the study sites and was 9.5% at the reference site.  In 1994 and 1995, respectively, number of failed nests ranged from 1-13 and 2-11 at study sites and was 6 and 5 at the reference site.  Mean clutch size ranged from 3.1-4.2 and 3.2-3.7 at study sites and was 3.6 and 3.5 at the reference site.  Hatch rate (# chicks/successful nest) ranged from 2.5-3.2 and 1.8-2.2 at study sites and was 2.4 and 2.1 at the reference site.  Fledge rate (# fledglings/successful nest) ranged from 2.0-3.0 and 2.2-2.6 at study sites and was 1.9 and 2.4 at the reference site.  Reproductive rate (# fledglings / all nests) ranged from 1.8-2.4 and 2.1-2.4 at study sites and was 1.7 and 2.4 at the reference site.  Mean nest failure was positively correlated with mean TCDD concentration in a sample egg, and individual fledge success was negatively correlated with TCDD concentration in a sample egg. 

21.

Over the period of 1977-2000, great blue heron eggs were collected from 23 colonies along the Strait of Georgia, British Columbia, Canada (Harris et al., 2003).

Eggshell thickness varied considerably from 290 m  (Fraser River delta 1977) to 502 m (Vancouver Island 1994). Statistical analysis did indicate a trend of increasing eggshell thickness over time, with a reduction between 1986-1990. Colony location was not a factor. There was a significant linear negative relationship between shell thickness and DDE concentration.

There were no linear relationships between reproductive stress (nest success or productivity) and quantified PCBs, organochlorine pesticides, PCDDs and PCDFs. Causes of poor reproductive success were more likely human disturbance, predation events, and loss and degradation of nesting habitat, not sublethal toxicity.

B.

Biochemical and Morphological Responses

1.

Growth and development were examined in GBH chicks exposed to PCDDs and PCDFs from a nearby pulp mill in 1987 (Hart et al., 1991) The following parameters were found to be related to TCDD exposure (mean concentrations were 135 pg/g wet weight for the Vancouver colony and 211 pg/g for the Crofton colony): plasma calcium concentration, yolk-free body weight, tibia length, wet, dry, and ash weights, beak length, kidney weight, and stomach weight. Fewer down follicles were also observed on the heads of these chicks. Gross abnormalities observed in the chicks included subcutaneous edema of the neck, legs, and abdomen, and one case of a crossed bill.

2.

In 1988, GBH eggs were collected and hatched from three sites of increasing contamination in British Columbia: Nicomekl (reference), Vancouver, and Crofton (Bellward et al., 1990). EROD activity was highly correlated with TCDD concentration. Levels of activity in Crofton chicks were 2.6 times greater than values in Nicomekl chicks, and intermediate in Vancouver chicks.

3.

In 1988, 1990, 1991, and 1992, GBH eggs were collected and hatched from two contaminated sites (University of British Columbia Endowment Lands (UBC) and Crofton), and three reference sites (Nicomekl, Chilliwack, and Tillicum), in British Columbia (Henshel et al., 1995). Asymmetry of brains was significantly greater at UBC and Crofton than at other colonies. The frequency of this abnormality was directly related to TCDD and TCDD-TEQ concentrations in eggs. Body weight and yolk-free body weight decreased with increasing TCDD concentration.

4.

GBH eggs were collected from two sites on the west coast of Canada and found to contain residues of TCDD and PCBs 77, 126, 169, 105, and 118 (Kennedy et al., 1992). Extracts from the eggs caused the induction of EROD activity and an increase in porphyrin concentration in primary cultures of chicken embryo hepatocytes. PCBs 77, 126, 169, 105, and 118 were determined to be the major EROD inducing agents.

5.

GBH eggs from Crofton in 1991, and Vancouver in 1990 and 1992, were collected from the Straight of Georgia in British Columbia, and hatched (Sanderson et al., 1994). Gross abnormalities in hatchlings included subcutaneous edema, fluid in the brain cavity, a blocked cloaca causing intestinal uric acid accumulation, and an unresorbed yolk sac. Contaminant exposure data previously collected from these same colonies in 1988 revealed an overall decrease in concentrations of PCDDs and PCDFs, and a decrease in EROD activity and incidence of chick edema, an increase in body weight, and an overall improvement of reproductive success in Crofton. TCDD concentration was found to be inversely related to body, yolk-free body, stomach, and intestine weight, tibia wet, dry, and ash weight, and tibia length. Hepatic EROD activity directly related to TCDD concentration.

6.

In 1991, 65 GBH eggs were collected from nine heronries, seven along the St. Lawrence River and two reference sites (Boily et al., 1994). Retinyl palmitate levels and ratio of retinol to retinyl palmitate were found to differ significantly between sites, although -carotene and retinol levels did not differ among sites. Retinyl palmitate concentration was deemed the better biomarker because, unlike the retinol:retinyl palmitate ratio, it did not differ significantly with stage of embryonic development. Retinyl palmitate concentrations in freshwater colonies were found to be negatively correlated with PCBs congeners 105 and 118, and TCDD-EQs. Concentrations of mirex, photomirex, and OCS were also inversely related to retinyl palmitate levels.

7.

Between 1991 and 1994, nestlings were collected from 2 colonies on Oak Ridge Reservation (n=38), K25 and Melton Hill, and 2 reference colonies (n=35), Long Island and Looney Island, all sites were in Tennessee (Halbrook et al. 1999).  Chicks were healthy when captured.  Colonies from ORR had significantly more eggs per nest compared to reference colonies, although number of chicks fledged per nest did not differ.  The fraction of double stranded DNA was significantly greater (p=0.031) in chicks from reference sites than in chicks from ORR.   Liver EROD activity did not differ between colonies.

8.

In 1993, GBH eggs were collected from 10 colonies on the Upper Mississippi River and incubated until pipping (Custer et al., 1997). Hepatic microsomal EROD activity was not correlated with total PCBs, TCDD, or TEQs, but was significantly higher in embryos with asymmetrical brains. Thiobarbituric acid reactive substances were negatively correlated with dieldrin concentrations.

9.

In 1993, 20 GBH eggs were collected from the Indiana Dunes National Lakeshore and incubated until hatching (Custer et al., 1998).  Hepatic EROD activity (16.6 pmol/min/mg protein, N=16) was not significantly different from that found at a reference colony at McDougall, Minnesota (12.9 pmol/min/mg protein, N=11).  One of nine (11%) embryo brains examined exhibited asymmetrical width, angle, and depth.  None of the brains were asymmetrical for height.

10.

Embryo deformities were observed at colonies near paper or pulp mills in the Columbia and Willamette Rivers and Puget Sound in Washington and Oregon between 1994-1995 (Thomas and Anthony 1999).  The percent of deformed embryos ranged from 0-40 and 0-20 at study sites. No deformed embryos were observed at the reference site.

II.

Cholinesterase-Inhibiting Pesticides

1.

In 1979, a GBH was found convulsing and dyspneic near a field where fenthion was applied within its recommended limits near Vallejo, California (Zinkl et al., 1981). Brain cholinesterase activity in this individual was 3.0 mU/mg protein in brain, representing approximately 95% depression of activity.

2.

At least one GBH was found dead after the application of the organophosphorus insecticide diazinon to a pond in Maryland (Stone and Gradoni, 1985).

3.

Using ChE reactivation techniques, GBH carcasses collected from San Joaquin County, California were diagnosed as being exposed to carbofuran (Hunt et al., 1995). ChE reactivation levels rose up to 136% over absolute ChE values after 48 hours. Crayfish in the crops contained carbofuran residues of up to 0.6 g/g wet weight.

III.

Trace Elements, Metals, and Metalloids

1.

Between 1987 and 1989, 64 nestling and 23 adult great white herons (A. herodias occidentalis) in Florida were radio-tagged, monitored and collected upon death to test for Hg concentrations in the liver (Spalding et al., 1994). Herons were divided into to two groups according to cause of death. Those in which chronic disease was a factor had higher mean liver Hg concentrations (9.76 g/g wet weight) than those that died of acute causes (1.77 g/g). Kidney disease and gout were present in birds with >25 g/g liver Hg.

2.

In 1993, GBH eggs were collected from 10 colonies on the Upper Mississippi River and incubated until pipping (Custer et al., 1997). Levels of reduced glutathione, total thiol, and protein-bound thiol were all negatively correlated with Hg concentrations.

IV.

Petroleum

 

No response data available

V.

Other Contaminants

1.

Sodium toxicity was suspected in the deaths of hand-reared chicks fed herring frozen in brine (Bennett et al., 1992). Chicks fed herring, or herring mixed with salmonids experienced 88% mortality, compared with no mortality for those fed solely salmonids. Chicks fed only herring, which experienced complete mortality in an average of 3.4 days, ingested a mean of 0.028 g Na/day and ingested less water during the first three days after hatching. Kidneys were enlarged, pale, and firm. Renal lesions ranged from mild to marked generalized nephrosis, which was characterized by degeneration and necrosis of the proximal convoluted tubular epithelium and dilation of the distal convoluted tubules and collecting ducts.

2.

The effect of a methyl-anthranilate bird-repellent (ReJe X-iT TP-40) on feeding behavior and predation was assessed in great blue herons (Dorr et al., 1998).  In laboratory trials, handling time of catfish by herons increased at application rates of 19.6 kg/ha or greater (recommended application rate=22 kg/ha), but decreased as a function of the number of catfish captured.  Behavioral observations suggested that herons became habituated to the repellent after repeated exposures.  In field trials, under simulated aquaculture conditions, TP-40 applied at rates from 0-220 kg/ha did not significantly affect handling time or predation success of herons. 

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