USGS



BIOLOGICAL AND ECOTOXICOLOGICAL CHARACTERISTICS OF TERRESTRIAL VERTEBRATE SPECIES RESIDING IN ESTUARIES

Forster’s Tern

Forster's Tern Photo by Scott Streit
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Biological Characteristics

Species

Sterna forsteri is 33-36 cm in length with mass ranging between 130 and 190 g. Sexes are similar in appearance. Adult breeding plumage is mostly white with black cap covering crown and nape and often extending just below the eye and ear coverts. Breeding adults have an orange bill with a black tip and bright orange legs. Wings and back are light gray. Tail is deeply forked and outermost rectrices are long and extend beyond primaries when perched. Adults in non-breeding plumage have the black cap replaced by a black mask that covers the eye and ear coverts but does not extend to nape or rear crown. Also the bill is all black and legs are dull orange (McNicholl et al., 2001).

Status in Estuaries

Considered a “marsh tern”, breeding habitat consists of fresh, brackish, or saltwater marshes and marshy borders of lakes, streams, and islands. Generally prefers deeper portions of marshes with open water and large areas of vegetation or mats of floating vegetation. Nests in colonies with Black terns but Forster’s terns prefer higher, drier nest locations, such as muskrat houses, floating mats of vegetation, or heaps of washed-up dead vegetation on shore. Nests vary from simple unlined depression to well-built pile of dead vegetation lined with fine grasses. A clutch consists of 2-3 smooth, olive to buff-colored eggs with large end wreathed by brown splotches. Both sexes incubate. Chicks are semi-precocial at hatching (McNicholl et al., 2001; Harrison, 1975). The maximum age of a Forster’s tern in the wild is 15.8 years (Klimkiewicz, 200 2).

Abundance and Range

Breeding locations are scattered throughout North America. In Canada, breeding Forster’s terns occur in southeast Alberta, southern Saskatchewan, and southeast British Columbia. In the Western United States, they occur in portions of Washington, Oregon, California, Nevada, Idaho, and Utah and in the Midwest, occur in portions of North and South Dakota and Minnesota. Breeding populations also occur in the Great Lakes region in eastern Wisconsin, eastern Michigan, and southern Ontario and along the Atlantic and Gulf coasts. Winter range along Atlantic and Gulf coasts includes all of Florida and inland locations west to southern Texas. The Pacific coast winter range includes the southern California coast and Baja peninsula and across southern Mexico. Estimates of breeding populations within specific geographic areas are: Canada, 2133-4216 pairs; Great Lakes region, 3025 pairs; Atlantic coast, 5766 pairs; Gulf Coast, 23,096 pairs; and Pacific coast (including Baja), 8030 pairs (McNicholl et al., 2001).

Site Fidelity

No specific information available. Marsh colonies shift with changes in breeding habitat (McNicholl et al., 2001).

Ease of Census

Simple

Feeding Habits

Diet consists mainly of small fish and occasionally arthropods. Forages throughout breeding habitat. From 6-8 m above the water, Forster’s tern either plunges directly into water or hovers briefly before diving into water to catch prey. Typically only head is submerged. Will also forage from perches (McNicholl et al., 2001).


Forster’s Tern Contaminant Exposure Data

  I.

Organochlorine Contaminants

A.

Concentrations in Adults and Juveniles

1.

Between 1963 and 1965 samples of fish and wildlife were obtained throughout California and analyzed for chlorinated hydrocarbons (Keith and Hunt, 1966). One Forster’s tern was collected, but location was not noted. Whole body concentrations of DDT , DDE , and DDD were 1.00, 24.00, and 1.00 mg/g ww, respectively.

2.

In 1978 one Forster’s tern was collected by shotgun at Llano Grande Lake on the Arroyo Colorado in the Lower Rio Grande Valley, Texas (White et al., 1983). The carcass was homogenized and analyzed for organochlorine residues . All values given are based on wet weight. The sample contained 27 mg/g DDE , 1.7 mg/g toxaphene, and 2.3 mg/g total PCBs. Fish-eating birds in this area contained levels of DDE and toxaphene that are within or above the range known to cause population declines.

B.

Concentrations in Chicks and Nestlings

1.

Chicks collected in 1983 from Green Bay, Lake Michigan were analyzed for 2,3,7,8-TCDD , 2,3,7,8-TCDF , and non ortho chlorine substituted PCB congeners (Smith et al., 1990). The sample contained 8.5 pg/g wet weight 2,3,7,8-TCDD , trace amounts of 2,3,7,8-TCDF , trace amounts of PCB 77 , 0.305 ng/g PCB 126 , and trace amounts of PCB 169 . Total PCBs in the sample was 4.6 mg/g.

2.

In 1988 seven Forster’s tern chicks, ranging in age from 3 to 27 days old, were collected from a Wisconsin colony located on Renard Island near the mouth of the Fox River at the southern end of Green Bay (Ankley et al., 1993). Homogenized samples were analyzed for PCBs , PCDFs , and PCDDs . Total PCB concentrations were 4.15 mg/g in the 3-day old chick, 3.97 mg/g in the 13-day old chick, 3.89 mg/g in the 15-day old chick, 3.77 mg/g in the 17-day old chick, 4.09 mg/g in the 20-day old chick, 3.64 mg/g in the 26-day old chick, and 5.07 mg/g and 4.18 mg/g in the 27-day old chick (a duplicate sample was analyzed to show data quality and reproducibility of chemical analyses). PCB congeners 77, 105, 126, and 169 were detected in all chick samples. Concentrations of PCB 77, PCB 105, PCB 126, and PCB 169 concentrations in the 3-day old chick were 1.59, 179.0, 1.37, and 0.08 ng/g, respectively; in the 13-day old chick, 7.62, 79.6, 1.18, and 0.03 ng/g, respectively; in the 15-day old chick, 7.85, 84.8, 1.12, and 0.025 ng/g, respectively; in the 17-day old chick, 7.85, 64.8, 1.08, and 0.036 ng/g, respectively; in the 20-day old chick, 13.2, 74.5, 1.26, and 0.0345 ng/g, respectively; in the 26-day old chick, 1.64, 107.0, 2.06, and 0.051 ng/g, respectively; in the 27-day old chick, 6.89, 115.0, 1.55, and 0.044 ng/g, respectively; and in the duplicate 27-day old chick, 6.85, 87.1, 1.50, and 0.049 ng/g, respectively. Substituted PCDDs were detected in the majority of samples and PCDFs were detected in only some of the samples. The 3-day old chick contained 3.6 pg/g TCDD, 6.3 pg/g 1,2,3,6,7,8-HxCDD, 4.2 pg/g 1,2,3,4,6,7,8-HpCDD, 16.9 pg/g OCDD, < 0.7 pg/g 1,2,3,6,7,8-HxCDF, and 9.0 pg/g 1,2,3,4,6,7,8-HpCDF. The 13-day old chick contained 3.1 pg/g TCDD, 2.2 pg/g 1,2,3,7,8-PeCDD, 4.8 pg/g 1,2,3,6,7,8-HxCDD, 5.2 pg/g 1,2,3,4,6,7,8-HpCDD, 8.7 pg/g OCDD, < 1.1 pg/g 2,3,7,8-TCDF, < 0.4 pg/g 1,2,3,6,7,8-HxCDF, and 1.6 pg/g 1,2,3,4,6,7,8-HpCDF. The 15-day old chick contained 2.0 pg/g TCDD, 2.4 pg/g 1,2,3,7,8-PeCDD, 5.1 pg/g 1,2,3,6,7,8-HxCDD, 4.9 pg/g 1,2,3,4,6,7,8-HpCDD, 8.4 pg/g OCDD, < 1.0 pg/g 2,3,7,8-TCDF, < 0.3 pg/g 1,2,3,6,7,8-HxCDF, and 1.5 pg/g 1,2,3,4,6,7,8-HpCDF. The 17-day old chick contained 2.4 pg/g TCDD, 2.1 pg/g 1,2,3,7,8-PeCDD, 3.2 pg/g 1,2,3,6,7,8-HxCDD, < 0.7 pg/g 2,3,7,8-TCDF, and < 0.3 pg/g 1,2,3,6,7,8-HxCDF. The 20-day old chick contained 2.3 pg/g TCDD, 3.4 pg/g 1,2,3,7,8-PeCDD, 7.4 pg/g 1,2,3,6,7,8-HxCDD, 10.6 pg/g 1,2,3,4,6,7,8-HpCDD, 26.6 pg/g OCDD, < 1.6 pg/g 2,3,7,8-TCDF, and 9.0 pg/g 1,2,3,4,6,7,8-HpCDF. The 26-day old chick contained 3.6 pg/g TCDD, 1.9 pg/g 1,2,3,7,8-PeCDD, 5.5 pg/g 1,2,3,6,7,8-HxCDD, 5.2 pg/g 1,2,3,4,6,7,8-HpCDD, 9.8 pg/g OCDD, < 0.1 pg/g 2,3,7,8-TCDF, < 0.4 pg/g 1,2,3,6,7,8-HxCDF, and 2.0 pg/g 1,2,3,4,6,7,8-HpCDF. The two 27-day old chick contained 3.0 and 3.0 pg/g TCDD, 3.4 and 3.1 pg/g 1,2,3,7,8-PeCDD, 6.0 and 6.0 pg/g 1,2,3,6,7,8-HxCDD, 4.3 and 4.5 pg/g 1,2,3,4,6,7,8-HpCDD, 6.1 and 6.0 pg/g OCDD, < 0.3 and NQ pg/g 2,3,7,8-TCDF, < 0.4 and < 0.4 pg/g 1,2,3,6,7,8-HxCDF, and 1.3 and 1.3 pg/g 1,2,3,4,6,7,8-HpCDF.

3.

In 1988 seven Forster’s tern chicks were collected from a Wisconsin colony located on Renard Island near the mouth of the Fox River at the southern end of Green Bay and H4IIE bioassay was performed to determine TCDD-EQ concentrations (Jones et al., 1993). Chicks ranged in age from 3 to 27 days old. All chicks had detectable levels of TCDD-EQ . TCDD-EQ concentrations in chicks were as follows: 3-day old, 90 pg/g wet weight; 13-day old, 114 pg/g; 15-day old, 79.3 pg/g; 17-day old, 116 pg/g; 20-day old, 39 pg/g; 26-day old, 147 pg/g; 27-day old, 101 pg/g. Four additional chicks were also analyzed for TCDD-EQ : 5-day old, 38.25 pg/g; 8-day old, 91.9 pg/g; 8-day old, 78.49 pg/g; 19-day old, 132.1 pg/g.

4.

In June and July 1995, 8 Forster’s tern eggs were collected from Lake St. Clair, Michigan and hatched in the laboratory. Chicks were killed within 24 hours of hatching and livers prepared to examine EROD and porphyrin induction responses of primary hepatocytes to HAHs (Sanderson et al., 1998). The mean EC50 concentration of TCDD for Forster’s tern (150 nM) was significantly higher than in other bird species studied (0.72 nM in domestic chicken, 25 nM in herring gull, 13 nM in double-crested cormorant). Relative potency factors (RPF) for TCDD , 1,2,3,7,8-PCDD , 2,3,4,7,8-PCDF , and PCB 126 were calculated as 1, 10-15, 10-18 and 0.3, 0.4 respectively.

C.

Concentrations in Eggs and Embryos

1.

Between 1963 and 1965 samples of fish and wildlife were obtained throughout California and analyzed for chlorinated hydrocarbons (Keith and Hunt, 1966). One Forster’s tern egg was collected but location was not noted. The yolk contained 35 mg/g DDE , 0.07 mg/g dieldrin, and 15.5 mg/g toxaphene.

2.

Forster’s tern eggs were collected from several locations in California between 1965 and 1967 and analyzed for pesticide residues ( Hagen, 1975). Four eggs were collected in 1965 from the Great Basin region. All eggs contained dieldrin (0.10, 0.12, 0.73, and 1.1 mg/g ) and DDE (2.3, 2.7, 3.2, and 4.1 mg/g). Three out of four eggs contained DDT (0.9, 0.8, and 1.0 mg/g) and DDD (1.0, 0.66, and 0.25 mg/g). Two eggs were collected in 1966 from San Francisco Bay. Both eggs contained DDT (1.0 and 0.7 mg/g), DDD (5.7 and 0.4 mg/g), DDE (28.6 and 4.8 mg/g) and dieldrin (2.7 and 0.5 mg/g). One egg was collected in 1967 from San Francisco Bay. It contained DDT (12.3 mg/g), DDD (14.0 mg/g), DDE (41.9 mg/g),and dieldrin (0.40 mg/g).

3.

In 1970 ten Forster’s tern eggs were collected at several locations along the Texas coast and analyzed for insecticide and PCB residues (King et al., 1978). Mean total DDT concentrationwas 1.74 mg/g wet weight, mean dieldrin concentration was 0.47 mg/g, and mean total PCB concentration was 12.5 mg/g. DDT and dieldrin residues were usually higher in eggs from colonies close to agricultural areas. PCB residues were consistently found in eggs from colonies near urban or industrial areas.

4.

Between 1975 and 1980, ten Forster’s tern eggs were collected from several nesting locations in Wisconsin from Green Bay and northwestern Lake Michigan (Heinz et al., 1985). Eggs were analyzed for organochlorine pesticides and PCBs. Eggs contained some or all of the following contaminants: mean DDE, 2.9 mg/g ww; mean DDD, 0.06 mg/g; mean dieldrin, 0.25 mg/g; mean heptachlor epoxide, 0.08 mg/g; mean oxychlordane, 0.08 mg/g; mean cis-chlordane, 0.14 mg/g; mean trans-nonachlor, 0.24 mg/g; mean cis-nonachlor, 0.06 mg/g; mean toxaphene, 0.15 mg/g; mean endrin, 0.03 mg/g; mean mirex, 0.06 mg/g; and mean total PCBS, 18 mg/g. PCB concentrations in eggs of fish-eating birds were high enough to raise concerns about adverse effects.

5.

Ten Forster’s tern eggs were collected from nests on Bair Island in southern San Francisco Bay ( San Mateo County, California) between 11 June and 17 June 1982. Eggs were analyzed for organochlorine concentrations (Ohlendorf et al., 1988). All 10 eggs had detectable concentrations of DDE, trans-nonachlor, and PCB. Mean DDE concentration was 1.92 mg/g wet weight; mean trans-nonachlor concentration was 0.22 mg/g; mean total PCB concentration was 5.65 mg/g. Six eggs had detectable levels of cis-chlordane (mean concentration 0.09 mg/g). Only 1 egg had detectable concentrations of DDD (0.10 mg/g), oxychlordane (0.09 mg/g), and cis-nonachlor (0.13 mg/g).

6.

Forster’s tern eggs collected in 1982 from Green Bay, Lake Michigan were used in the development and application of a method with activated carbon for the determination of 18 AHH-active PCBs (Smith et al., 1990). Total PCBs in each egg was 10.8 and 13.2 mg/g wet weight. The following PCB congeners were determined: PCB 77 (18 and 18 ng/g), PCB 123 (32 and 35 ng/g), PCB 118 (635 and 620 ng/g), PCB 114 (74 and 72 ng/g), PCB 105 (336 and 376 ng/g), PCB 138 (453 and 286 ng/g), PCB 158 (111 and 155 ng/g), PCB 126 (4.1 and 1.3 ng/g), PCB 166 (14 and 16 ng/g), PCB 128 (304 and 211 ng/g), PCB 167 (84 and 75 ng/g), PCB 156 (205 and 130 ng/g), PCB 157 (43 and 34 ng/g), PCB 170 (327 and 245 ng/g), and PCB 189 (17 and 12 ng/g). Only trace amounts of PCB 81 and PCB 169 were detected.

7.

In 1983 six Forster’s tern eggs were collected from southern Green Bay, Lake Michigan and six from Lake Poygan, Wisconsin and analyzed for AHH-active PCB congeners (Kubiak et al., 1989). All eggs from the Green Bay colony had significantly higher mean concentrations of several PCB congeners than eggs from Lake Poygan: PCB 77 , 0.563 ng/g ww vs. below detection limit; PCB 105 , 560 ng/g vs. 90 ng/g; PCB 114 , 69 ng/g vs. 2 ng/g; PCB 118 , 1120 ng/g vs. 230 ng/g; PCB 126 , 3.84 ng/g vs. 0.295 ng/g; PCB 156 , 140 ng/g vs. 50 ng/g; PCB 169 , 1.06 ng/g vs. 0.295 ng/g.

8.

Samples of tern eggs collected from Green Bay and Lake Poygan, Wisconsin in 1983 for PCB analysis (Schwartz and Stalling, 1991). 10 eggs were collected from Green Bay and six were collected from lake Poygan as part of a study by Kubiak et al. (1989). Total PCBs in the Green Bay eggs were 15.3, 25.6, 6.6, 21.7, 24.3, 28.0, 26.8, 25.0, 26.2, and 10.2 mg/g. Total PCBs in the Lake Poygan eggs were 8.03, 4.88, 5.71, 4.56, 2.65, and 2.90 mg/g.

9.

Eggs collected in 1983 from Green Bay, Lake Michigan were analyzed for 2,3,7,8-TCDD , 2,3,7,8-TCDF , and non ortho chlorine substituted PCB congeners (Smith et al., 1990). The eggs contained 47 pg/g wet weight 2,3,7,8-TCDD , trace amounts of 2,3,7,8-TCDF, 0.01 ng/g PCB 77 , 1.82 ng/g PCB 126 , 0.005 ng/g PCB 169 , and 19.2 mg/g total PCBs.

10.

Forster’s tern eggs were collected in 1983 from a contaminated site at Green Bay, Lake Michigan (Oconto Marshes) and a reference site, Lake Poygan, Wisconsin as part of a reproductive success study by Tillitt et al. (1993) and were analyzed for PCDDs , PCDFs , and PCBs (Stalling et al., 1985). Mean total PCDD concentration was 114 pg/g at Green Bay and 21 pg/g at Lake Poygan. Mean total PCDF concentration was 19 pg/g at Green Bay and 9 pg/g at Lake Poygan. Mean total PCB was 39 mg/g at Green Bay and 7 mg/g at Lake Poygan. PCDDs and total PCB concentrations were elevated at the Green bay colony where reproductive problems have been observed.

11.

Forster’s tern eggs were collected in 1983 from a contaminated site at Green Bay, Lake Michigan (Oconto Marshes) and a reference site, Lake Poygan, Wisconsin to evaluate the toxic potency of PHHs in extracts of collected eggs (Tillitt et al., 1993). Nine and eight eggs were collected from Green Bay and Lake Poygan, respectively, and individually analyzed with the H4IIE bioassay to determine TCDD-EQ in the collected eggs. Eggs from the Green Bay colony had significantly greater concentrations of TCDD-EQ than those at the reference colony on Lake Poygan. TCDD-EQ in eggs from Green Bay ranged from 90 to 339 pg/g (mean 214 pg/g) while TCDD-EQ in eggs from Lake Poygan ranged from 14 to 34 pg/g (mean 23 pg/g). The Lake Poygan TCDD-EQ values were significantly lower than any other Great Lakes water bird eggs analyzed by the H4IIE bioassay and may be below the threshold level for effects. When compared to TCDD-EQ values determined in 1988, there was not a substantial decrease from 1983 at the Green Bay colony and results suggest dioxin-like effects of PHHs are responsible for reproductive problems in Forster’s terns at Green Bay.

12.

In April-July 1984, tern nests were monitored throughout the breeding season at a colony in Lavaca Bay, Texas and a reference colony in San Antonio Bay, Texas. Thirty-three and 38 eggs were collected from nests at Lavaca Bay and San Antonio Bay, respectively and analyzed for organochlorines (King et al., 1991). DDE was detected in all eggs and ranged from 0.1 to 9.0 mg/g wet weight. PCBs were detected in 67 of 71 eggs and ranged from 0.8 to 8.7 mg/g. Mean DDE concentration in tern eggs from Lavaca Bay (1.6 mg/g) was significantly higher than that of eggs from San Antonio Bay (0.8 mg/g). Mean PCB concentration in eggs was also significantly higher at Lavaca Bay (2.3 mg/g) than at San Antonio Bay (1.2 mg/g).

13.

One egg from Long Point Provincial Park ( Lake Erie, Ontario, Canada) and one egg from Walpole Island ( Lake St. Clair, Ontario, Canada) were collected in 1986 and analyzed for contaminant concentrations. Values are given on a wet weight basis. Contaminant levels at the 2 sites were similar, but Walpole Island had slightly higher Total PCBs (Bishop et al., 1992). The Long Point egg contained 0.025 mg/g cis-chlordane , 0.038 mg/g oxychlordane, 0.017 mg/g hexachlorobenzene, 0.0005 mg/g DDD, 1.21 mg/g DDE, 0.03 mg/g DDT, 0.127 mg/g dieldrin, 0.039 mg/g heptachlor epoxide, 0.0005 mg/g beta-BHC, 0.025 mg/g mirex, 0.072 mg/g cis-nonachlor, 0.0005 mg/g photomirex, 0.22 mg/g trans-nonachlor, and 11.4 mg/g Total PCBs. The Walpole Island egg contained 0.028 mg/g cis-chlordane , 0.044 mg/g oxychlordane, 0.044 mg/g hexachlorobenzene, 0.008 mg/g DDD, 1.47 mg/g DDE, 0.052 mg/g DDT, 0.133 mg/g dieldrin, 0.044 mg/g heptachlor epoxide, 0.0005 mg/g beta-BHC, 0.037 mg/g mirex, 0.071 mg/g cis-nonachlor, 0.009 mg/g photomirex, 0.243 mg/g trans-nonachlor, and 12.8 mg/g Total PCBs.

14.

In 1987, five Forster’s tern eggs were collected early in incubation and analyzed for organochlorines (Dale and Stromborg, 1993). Eggs were collected from Kidney Island at the southern end of Green Bay, Lake Michigan, Wisconsin. Mean concentrations of the following organochlorines were observed: oxychlordane , 0.032 mg/g wet weight; trans-nonachlor, 0.13 mg/g; cis-nonachlor, 0.062 mg/g; heptachlor epoxide, 0.046 mg/g; total PCBs, 6.8 mg/g; DDE, 1.2 mg/g; DDD, 0.024 mg/g; and dieldrin, 0.09 mg/g. The mean PCB value in the 1987 eggs was similar to that found by Harris et al. (1993) in 1988 (7.3 mg/g) but lower than PCB values found in 1983 (19.2 mg/g, Kubiak et al., 1989) along Green Bay’s western shore and 1978 (18.0 mg/g, Heinz et al., 1985) at Long-tail Point. Mean1987 DDE and dieldrin concentrationsdecreased from 1978 levels (2.9 and 0.25 mg/g, respectively).

15.

In 1988 five Forster’s tern eggs were collected from a Wisconsin colony located on Renard Island near the mouth of the Fox River at the southern end of Green Bay (Ankley et al., 1993). Homogenized samples were analyzed for PCBs , PCDFs , and PCDDs . Total PCB concentrations in the eggs were 7.38, 6.40, 5.40, 7.97, and 9.52 mg/g. PCB congeners 77, 105, 126, and 169 were detected in all egg samples. PCB 77 concentrations in the eggs were 7.32, 5.07, 5.61, 3.76, and 5.08 ng/g. PCB 105 concentrations in the eggs were 237.0, 225.0, 275.0, 414.0, and 340.0 ng/g. PCB 126 concentrations in the eggs were 2.76, 1.69, 2.0, 2.67, and 3.33 ng/g. PCB 169 concentrations in the eggs were 0.16, 0.62, 0.09, 0.167, and 0.154 ng/g. Substituted PCDDs were detected in the majority of egg samples and PCDFs were detected in only some of the egg samples. TCDD concentrations were 10.6, 4.6, 6.1, 20.4, and 10.7 pg/g. 1,2,3,7,8-PeCDD concentrations were 8.6, 4.1, 4.9, 5.0, and 8.5 pg/g. 1,2,3,6,7,8-HxCDD concentrations were 8.8, 7.7, 6.3, 6.3, and 7.8 pg/g. 1,2,3,4,6,7,8-HpCDD concentrations were 8.8, 7.7, 6.3, 6.3, and 7.8 pg/g. OCDD concentrations were 133.0, 135.0, 82.4, 114.0, and163.0 pg/g. 2,3,7,8-TCDF concentrations in 2 eggs were < 0.8 and < 0.7.pg/g. 2,3,7,8-TCDF concentrations in the other 3 eggs were non-quantifiable. 1,2,3,6,7,8-HxCDF concentrations in 4 eggs were < 0.9, < 0.6, < 0.8, and < 1.4 pg/g. The remaining egg had non-quantifiable concentrations of 1,2,3,6,7,8-HxCDF. 1,2,3,4,6,7,8,-HpCDF concentrations in 4 eggs were 1.5, 2.7, 2.7, and 3.4 pg/g. The remaining egg had non-quantifiable concentrations of 1,2,3,4,6,7,8,-HpCDF.

16.

In 1988 five Forster’s tern eggs were collected from a Wisconsin colony located on Renard Island near the mouth of the Fox River at the southern end of Green Bay and H4IIE bioassay was performed to determine TCDD-EQ concentrations in eggs (Jones et al., 1993). All samples had detectable levels of TCDD-EQ . In the eggs TCDD-EQ concentrations ranged from 185 to 996 pg/g, wet weight. A sixth egg, analyzed separately, had TCDD-EQ concentration of 127.6 pg/g.

17.

Polychorinated biphenyl residues of Forster’s tern eggs from Green Bay was measured in 1988 and compared with data collected in 1983 (Harris et al., 1993). Eggs were analyzed for PCBs . Total PCB concentrations in eggs were 7.38, 6.40, 5.40, 7.97, and 9.52 mg/g wet weight. Total PCB residue was 67% lower in 1988 from 1983. Concentrations of PCB 77 in eggs were7.32, 5.07, 5.61, 3.76, and 5.08 ng/g. Concentrations of PCB 105 in eggs were 237, 225, 275, 414, and 340 ng/g. Concentrations of PCB 126 in eggs were 2.76, 1.69, 2.0, 2.67, and 0.33 ng/g. Concentrations of PCB 169 in eggs were 0.16, 0.062, 0.09, 0.167, and 0.154 ng/g. PCB 105, 126, and 169 all had decreased levels in 1988 from 1983. PCB 77 levels could not be compared between years due to an analytical anomaly. 1988 concentrations of 2,3,7,8-TCDD in eggs were 17, 8, 10, 24, and 17 pg/g, wet weight. Values decreased 54% between 1983 and 1988. TCDD-EQ were also calculated for the 1988 samples. Values ranged from 456 to 751 pg/g wet weight and showed a 42% decrease from 1983.

18.

In 1991, 5 eggs were collected from Crescent Island, near Wallula Washington and 1 egg was collected from a small sand island in Potholes Reservoir near Moses Lake, Washington (Blus et al., 1998). These eggs were analyzed for organochlorine pesticides and total PCBs . The Potholes Reservoir egg contained 1.5 pg/g ww 2,3,7,8-TCDD , 0.02 mg/g HCB, 0.01 mg/g oxychlordane, 0.02 mg/g heptachlor epoxide, 0.04 mg/g trans-nonachlor, 0.89 mg/g total PCBs , 1.2 mg/g DDE, 0.02 mg/g DDD, and 0.03 mg/g DDT . All of the Crescent Island eggs contained 2,3,7,8-TCDD (1.3-3.1 pg/g), HCB (0.01-0.02 mg/g), trans-nonachlor (0.02-0.03 mg/g), DDE (0.72-1.2 mg/g), DDD (0.01-0.03 mg/g), DDT (0.02-0.03 mg/g), and PCBs (0.58-0.94 mg/g). One Crescent island egg contained 0.57 pg/g 2,3,7,8-TCDF. Two eggs contained beta-HCH (ND-0.01 mg/g) and 4 eggs contained oxychlordane (ND-0.01) and heptachlor epoxide (ND-0.01). Hepatic cytochrome P450 enzyme activity in pipped embryos from the 2 colonies seemed unaffected by contaminants.

19.

Forster’s tern eggs were collected in 1991 and 1994 from San Diego Bay, California (Roberts, 1997). In 1991, four eggs were collected and analyzed individually for organochlorines . One of the four eggs contained 0.01 mg/g ww heptachlor epoxide and 0.01 mg/g oxychlordane. Three of the four eggs contained concentrations of trans-chlordane 0.02-0.04 mg/g. All 4 eggs had detectable concentrations of p,p’DDE (0.47-1.5 mg/g) and PCBs (0.32-1.3 mg/g). In 1994, 4 eggs were collected but the samples that were analyzed were composites of 2 eggs each. Heptachlor epoxide concentrations in the composites were 0.044 and 0.017 mg/g. One composite sample contained 0.017 mg/g oxychlordane. Both composite samples contained p,p’DDE (0.36-1.6 mg/g)and PCBs (0.53-1.9 mg/g). Forster’s terns in both years of this study had lower egg concentrations of PCBs than those found by Ohlendorf et al. (1988) in San Francisco Bay.

20.

One egg from Walpole Island ( Lake St. Clair, Ontario, Canada) was collected in 1992 and analyzed for contaminant concentrations. Values are given on a wet weight basis. The egg contained 0.0102 mg/g cis-chlordane , 0.0285 mg/g oxychlordane, 0.0206 mg/g hexachlorobenzene, 0.0044 mg/g DDD, 1.0672 mg/g DDE, 0.0639 mg/g dieldrin, 0.0198 mg/g heptachlor epoxide, 0.0225 mg/g mirex, 0.0071 mg/g photomirex, 0.0504 mg/g cis-nonachlor, 0.1094 mg/g trans-nonachlor, 0.0457 mg/g octachlorostyrene, and 4.53 mg/g Total PCBs. For the period 1989-1992 the levels of chlorinated hydrocarbons in colonial waterbird eggs has remained relatively stable within colonies across the Great Lakes (Pettit et al., 1994).

21.

One egg each was collected from Lake Simcoe and Walpole Island on Lake St. Clair, Canada in 1999 (Jermyn et al., 2002). All values are based on wet weight. The Lake Simcoe egg contained 0.002 mg/g cis-chlordane; 0.006 mg/g oxychlordane; trace amounts of 1,2,4,5-chlorobenzene; 0.004 mg/g hexachlorobenzene; 0.005 mg/g DDD; 0.818 mg/g DDE; trace amounts of DDT; 0.011 mg/g dieldrin; 0.004 mg/g heptachlor epoxide; 0.002 mg/g tris(4-chlorophenyl) methanol; 0.006 mg/g mirex; 0.002 mg/g photomirex; 0.01 mg/g cis-nonachlor; 0.022 mg/g trans-nonachlor; trace amounts of octachlorostyrene; 2.407 mg/g total PCBs; 0.00378 ng/g PCB 37; 0.22132 ng/g PCB 77; 0.04285 ng/g PCB 81; 0.34098 ng/g PCB 126; 0.342 ng/g PCB 169; 0.02615 ng/g PCB 189; 1.91 pg/g 2,3,7,8-teachlorodibenzo-p-dioxin; 2.63 pg/g 1,2,3,7,8-pentachlorodibenzo-p-dioxin; 0.39 pg/g 1,2,3,4,7,8-hexachlodibenzo-p-dioxin; 3.73 pg/g 1,2,3,6,7,8-hexachlodibenzo-p-dioxin; 1.34 pg/g 1,2,3,7,8,9-hexachlodibenzo-p-dioxin; 1.19 pg/g 1,2,3,4,6,7,8-heptachlorodibenzo-p-dioxin; 2.22 pg/g octachlordibenzo-p-dioxin; 0.3 pg/g 2,3,7,8-teachlorodibenzo-furan; 0.22 pg/g 2,3,4,7,8-pentachlorodibenzo-furan; 0.06 pg/g 1,2,4,6,8-pentachlorodibenzo-furan; 0.38 pg/g 1,2,4,7,8-pentachlorodibenzo-furan; 0.11 pg/g 2,3,4,6,7-pentachlorodibenzo-furan; 0.16 pg/g 1,2,3,4,7,8-hexachlorodibenzo-furan; 0.17 pg/g 1,2,4,6,8,9- hexachlorodibenzo-furan; 0.07 pg/g 1,2,4,6,7,8- hexachlorodibenzo-furan; 0.38 pg/g 1,2,3,6,7,8- hexachlorodibenzo-furan; 0.07 pg/g 1,2,3,7,8,9- hexachlorodibenzo-furan; 0.16 pg/g 1,2,3,4,6,7,8- hexachlorodibenzo-furan. The Walpole Island egg contained 0.002 mg/g cis-chlordane; 0.009 mg/g oxychlordane; trace amounts of 1,2,4,5-chlorobenzene; trace amounts of pentachlorobenzene; 0.007 mg/g hexachlorobenzene; trace amounts of DDD; 0.621 mg/g DDE; trace amounts of DDT; 0.016 mg/g dieldrin; 0.007 mg/g heptachlor epoxide; 0.005 mg/g tris(4-chlorophenyl) methanol; 0.014 mg/g mirex; 0.003 mg/g photomirex; 0.018 mg/g cis-nonachlor; 0.042 mg/g trans-nonachlor; 0.033 mg/g octachlorostyrene; 4.404 mg/g total PCBs; 0.0022 ng/g PCB 37; 0.25719 ng/g PCB 77; 0.09881 ng/g PCB 81; 0.56136 ng/g PCB 126; 0.04474 ng/g PCB 169; 0.04406 ng/g PCB 189; 3.47 pg/g 2,3,7,8-teachlorodibenzo-p-dioxin; 3.67 pg/g 1,2,3,7,8-pentachlorodibenzo-p-dioxin; 5.58 pg/g 1,2,3,6,7,8-hexachlodibenzo-p-dioxin; 2.0 pg/g 1,2,3,7,8,9-hexachlodibenzo-p-dioxin; 1.78 pg/g 1,2,3,4,6,7,8-heptachlorodibenzo-p-dioxin; 3.07 pg/g octachlordibenzo-p-dioxin; 0.15 pg/g 2,3,7,8-teachlorodibenzo-furan; 0.2 pg/g 2,3,4,7,8-pentachlorodibenzo-furan; 0.06 pg/g 1,2,4,6,8-pentachlorodibenzo-furan; 0.42 pg/g 1,2,4,7,8-pentachlorodibenzo-furan; 0.03 pg/g 1,2,3,7,8-pentachlorodibenzo-furan; 0.16 pg/g 1,2,3,4,7,8-hexachlorodibenzo-furan; 0.11 pg/g 1,2,4,6,8,9- hexachlorodibenzo-furan; 0.07 pg/g 1,2,4,6,7,8- hexachlorodibenzo-furan; 0.31 pg/g 1,2,3,6,7,8- hexachlorodibenzo-furan; 0.16 pg/g 1,2,3,4,6,7,8- hexachlorodibenzo-furan. Over 50 PCB congeners were detected in each egg as well.

II.

Cholinesterase-Inhibiting Pesticides

 

No direct exposure data available

III.

Trace Elements, Metals, and Metalloids

1.

Between 1975 and 1980, ten Forster’s tern eggs were collected from several nesting locations in Wisconsin from Green Bay and northwestern Lake Michigan (Heinz et al., 1985). Eggs were analyzed for Hg. All 10 eggs contained Hg with mean concentration of 0.66 mg/g ww. The range of Hg concentration was 0.58-0.83 mg/g. A study by Heinz (1979) found mallards had reduced reproductive success when Hg in eggs averaged 0.80 mg/g. Mercury concentrations were within that range in tern eggs.

2.

Ten Forster’s tern eggs were collected from nests on Bair Island in southern San Francisco Bay ( San Mateo County, California) between 11 June and 17 June 1982. Eggs were analyzed for Hg concentrations (Ohlendorf et al., 1988). Mercury was detected in all 10 eggs with m ean concentration 0.90 + 0.07 mg/g wet weight.

3.

In April-July 1984, tern nests were monitored throughout the breeding season at a colony in Lavaca Bay, Texas and a reference colony in San Antonio Bay, Texas. Thirty-six and 44 eggs were collected from nests at Lavaca Bay and San Antonio Bay, respectively and analyzed for Hg and Se (King et al., 1991). Mercury was detected in all eggs from Lavaca Bay and all but one egg from San Antonio Bay. All Hg concentrations were < 1.0 mg/g wet weight . Mean Hg concentration in Lavaca bay eggs (0.40 mg/g) was significantly higher than San Antonio Bay eggs (0.22 mg/g). Mean Se concentration in Lavaca Bay eggs and San Antonio Bay eggs were different (0.71 and 0.68 mg/g, respectively).

4.

In 1987, five Forster’s tern eggs were collected early in incubation and analyzed for metals (Dale and Stromborg, 1993). Concentrations of the following metals were found: Al , 5.2 mg/g dry weight; As, 0.08 mg/g; Cr, 0.70 mg/g; Cu, 3.6 mg/g; Fe, 124 mg/g; Pb, 0.53 mg/g; Mg, 1.8 mg/g; Hg, 2.5 mg/g; Ni, 0.42 mg/g; Zn, 55.7 mg/g. Mean Hg levels in 1987 were higher than 1977-78 Hg levels (0.37 mg/g) in lower Green Bay observed by Heinz (1985).

5.

Eggs and feathers were collected from a Forster’s tern colony at Middle Sedge, New Jersey and analyzed for Pb and Cd (Burger and Gochfeld, 1993). Eight eggs were collected. Mean concentrations of Pb and Cd in the eggs were 0.174 and 0.003 mg/g dry weight, respectively. Feather samples (17) were collected from the breast of 18-25 day old chicks. Mean concentrations of Pb and Cd in the feathers was 1.527 mg/g and 0.116 mg/g respectively.

6.

Forster’s tern eggs were collected from a colony at East Story, NJ and analyzed for Hg (Burger and Gochfeld, 1997). The mean concentration of Hg in eggs was 2.1 mg/g dry weight which was the highest out of all bird eggs analyzed. Forster’s terns in this colony feed relatively far from industrialization, urbanization and agriculture. The levels of Hg in their eggs may be due to exposure prior to arriving on the breeding grounds or the redistribution of Hg throughout the estuary.

7.

One egg each was collected from Lake Simcoe and Walpole Island on Lake St. Clair, Canada in 1999 (Jermyn et al., 2002). The Lake Simcoe egg contained 2.21 mg/g Hg . The Walpole Island egg contained 2.57 mg/g Hg.

8.

Fifteen Forster’s tern eggs were collected from Barnegat Bay, New Jersey in 2000 and analyzed for heavy metal content (Burger, 2002). The eggs contained mean concentrations of the following heavy metals : As , 0.19 mg/g dry weight; Cd , 0.002 mg/g ; Cr , 0.028 mg/g ; Pb , 0.056 mg/g; Mg, 1.702 mg/g; Hg, 1.939 mg/g; Se, 1.688 mg/g. Mean Hg levels exceeded the level known to adversely affect development in tern eggs.

IV.

Petroleum

 

No residue data available


Forster’s Tern Contaminant Response Data

I.

Organochlorine Contaminants

A.

Eggshell Thinning and Reproduction

1.

The thickness of museum specimen Forster’s tern eggs collected prior to widespread use of DDT was compared to the shell thickness of eggs collected in 1970 (King et al., 1978). Both pre-1943 eggs and 1970 eggs were collected along the Texas coast. There was no difference in mean shell thickness between the two groups of eggs.

2.

In 1982, a significant positive correlation was found between DDE and eggshell thickness and DDE and thickness index of tern eggs collected from Bair Island in San Francisco Bay (Ohlendorf et al., 1988).

3.

In 1983 Forster’s tern colonies were monitored during the breeding season. Two colonies were located in northeastern Wisconsin on the shore of Green Bay (South Oconto Marsh and Longview Point) and one colony was located inland at Lake Poygan (Kubiak et al., 1989). Green Bay is known to be contaminated by organochlorines while

Lake Poygan is relatively uncontaminated. Twelve eggs were collected for chemical analyses, 40 eggs were collected for artificial incubation, and 26 eggs were collected for disease screening. In addition, 12 nests at each colony were used in an egg exchange experiment. Eggs from the Oconto colony were placed in Lake Poygan nests and vice versa. In the egg exchange experiment, there was not a significant difference in the ratio of Lake Poygan eggs (clean) hatched and Green Bay eggs (dirty) hatched when incubated by Lake Poygan (clean) adults. More dirty eggs hatched when incubated by clean adults rather than those incubated by dirty adults. The dirty eggs also required on average 8.25 days longer for incubation in the field and 4.57 days longer in an incubator than clean eggs. This suggests that aberrant parental behavior may contribute to the low reproductive success of Green Bay terns. In addition only 21% of the Green Bay eggs reached fledging compared to 45% of the Lake Poygan eggs. This study strongly suggests that organochlorine contaminants were a causal factor for reproductive impairment at the Green bay colony.

4.

On June 1, 1983 20 eggs were collected from Oconto Marsh at Green Bay, Wisconsin and 20 eggs were collected from Lake Poygan, Wisconsin. The Green Bay colony is known to have reproductive problems due to organochlorines and the Lake Poygan colony has normal reproduction and is uncontaminated (Hoffman et al., 1987). Under artificial incubation, hatchability of eggs from Green Bay (39%) was above half that of Lake Poygan eggs (75%). Of the chicks that hatched, Lake Poygan chicks weighed more on average (13.78 g) than Green Bay chicks (11.48 g). This study suggests that part of the reproductive failure experienced by terns at Green Bay may be related to intrinsic embryotoxic factors such as PCBs and PCDDs .

5.

In April-July 1984, to assess reproductive success, 47 tern nests at Lavaca Bay, Texas and 80 nests at a reference colony in San Antonio Bay, Texas were monitored every 2-5 days until eggs hatched and nestlings fledged (King et al., 1991). Lavaca Bay eggs contained higher concentrations of DDE and PCB than San Antonio Bay eggs but hatching success and nest success was similar between the two study areas. DDE concentrations were not significantly different among hatching success groups: no eggs hatched, 0.9 mg/g wet weight; some eggs hatched, 1.1 mg/g; all eggs hatched, 1.4 mg/g. PCB concentrations were not significantly different among hatching success groups: no eggs hatched, 1.5 mg/g wet weight; some eggs hatched, 1.9 mg/g; all eggs hatched, 1.9 mg/g. Eggshell thickness was also measured and compared to eggshells collected in 1970 and museum eggshells collected in Texas before widespread use of DDT . Mean shell thickness of tern eggs from Lavaca Bay was similar to the mean of San Antonio Bay eggs. However, shells were 7% thinner in 1984 than in 1970 and 1943. Eggshell thinning was not correlated with DDE and was probably not biologically significant.

6.

Reproductive success of Forster’s tern from Green Bay was measured in 1988 and compared with data collected in 1983 (Harris et al., 1993). Hatching success, number of young fledged, and length of incubation all improved from 1983. Also from 1983 to 1988 there was a reduction of total PCB residue in eggs and a reduction in 3 of 4 congeners measured.

 

Twelve Forster’s tern eggs collected in 1991 had a mean shell thickness of 0.201 mm (range 0.188-0.216 mm) and 2 eggs collected in 1994 had a mean shell thickness of 0.208 mm (range (0.201-0.216mm). No specific conclusions are drawn regarding these measurements (Roberts, 1997).

B.

Biochemical and Morphological Responses

1.

On June 1, 1983 20 eggs were collected from Oconto Marsh at Green Bay, Wisconsin and 20 eggs were collected from Lake Poygan, Wisconsin. The Green Bay colony is known to have reproductive problems due to organochlorines and the Lake Poygan colony has normal reproduction and is uncontaminated (Hoffman et al., 1987). All eggs were artificially incubated and sacrificed at 1-day old. The Green Bay chicks had a higher liver weight to body weight ratio than the Lake Poygan chicks (0.034 vs. 0.027) and liver microsomal AHH activity was elevated 3x that of the Lake Poygan hatchlings. Femur length of Green Bay chicks was 9% shorter than Lake Poygan chicks (11.6 mm vs. 12.8 mm). The percentage of Green Bay embryos and hatchlings with defects was 16.7%. One embryo that failed to hatch had a crossed beak and the other had a poorly ossified foot and shorter lower beak. One hatchling from Green Bay had abnormal ossification of the ilium. Lake Poygan embryos and hatchlings had no defects. This study suggests that part of the reproductive failure experienced by terns at Green Bay may be related to intrinsic embryotoxic factors such as PCBs and PCDDs .

2.

During field studies in April-July 1984 in Lavaca Bay and San Antonio Bay, Texas, 35 tern chicks found dead or dying were collected. Eggs from the study areas contained DDE and PCB . The brains were removed and bisected with one half examined for lesions or other anomalies and the other half saved for chemical analyses. Ten normal appearing chicks were sacrificed as controls. Only one tern nestling brain contained a minimal perivascular lymphoid cell infiltrate. Brains from the remaining birds showed no abnormal histological development (King et al., 1991).

3.

Pipped eggs of Forster’s terns were collected from Crescent Island (10) and Potholes Reservoir (9), Washington in 1991 and examined for developmental abnormalities (Blus et al., 1998). Crescent Island embryos had significantly shorter tibiotarsal length than Potholes embryos (16.2 mm vs. 17.7 mm). One embryo from Crescent Island was missing its upper mandible and another had a malformed pelvic girdle. No embryos from the Potholes Reservoir had developmental abnormalities. The 20% deformity rate at Crescent Island is similar to the rate of 18% at Green Bay, Wisconsin which is heavily contaminated with PCBs (Hoffmann et al., 1987), but minimal dioxin and PCB residues at Crescent Island suggest other contaminants may be responsible for the deformities.

II.

Cholinesterase-Inhibiting Pesticides

 

No response data available

III.

Trace Elements, Metals, and Metalloids

A.

Eggshell Thinning and Reproduction

1.

In April-July 1984, tern nests were monitored throughout the breeding season at a colony in Lavaca Bay, Texas and a reference colony in San Antonio Bay, Texas. Thirty-six and 44 eggs were collected from nests at Lavaca Bay and San Antonio Bay, respectively and analyzed for Hg and Se (King et al, 1991). Although Lavaca Bay had higher mean Hg concentration in eggs than San Antonio Bay, there was not a significant difference in Hg concentrations among hatching success groups: no eggs hatched, 0.44 mg/g; some eggs hatched, 0.37 mg/g; and all eggs hatched, 0.40 mg/g . At Lavaca Bay, nests where no eggs hatched had higher Se concentrations (1.00 mg/g wet weight) than nests where only some eggs (0.72 mg/g) or all eggs (0.71 mg/g) hatched. At San Antonio Bay, Se concentrations were not significantly different among hatching success groups: no eggs hatched, 0.72 mg/g; some eggs hatched, 0.70 mg/g; and all eggs hatched, 0.61 mg/g.

B.

Biochemical and Morphological Responses

1.

During field studies in April-July 1984 in Lavaca Bay and San Antonio Bay, Texas, 35 tern chicks found dead or dying were collected. Eggs from the study areas contained Hg and Se . The brains were removed and bisected with one half examined for lesions or other anomalies and the other half saved for Hg analyses. Because only one nestling brain contained an anomaly (minimal perivascular lymphoid cell infiltrate) brain tissues were not submitted for Hg residue analyses (King et al., 1991).

IV.

Petroleum

 

No response data available

References for Forster’s Tern

Ankley, G. T., G. J. Niemi, K. B. Lodge, H. J. Harris, D. L. Beaver, D. E. Tillitt, T. R. Schwartz, J. P. Giesy, P. D. Jones, and C. Hagley. 1993. Uptake of planar polychlorinated biphenyls and 2,3,7,8-substituted polychlorinated dibenzofurans and dibenzo-p-dioxins by birds nesting in the Lower Fox River and Green Bay, Wisconsin, USA. Archives of Environmental Contamination and Toxicology 24:332-344.

Bishop, C. A., D. V. Weseloh, N. M. Burgess, J. Struger, R. J. Norstrom, R. Turle, and K. A. Logan. 1992. An atlas of contaminants in eggs of fish-eating colonial birds of the Great Lakes (1970-1988) Vol. 1. Technical Report Series No. 152, Canadian Wildlife Service, Ontario Region.

Blus, L. J., M. J. Melancon, D. J. Hoffman, and C. J. Henny. 1998. Contaminants in eggs of colonial waterbirds and hepatic cytochrome P450 enzyme levels in pipped tern embryos, Washington State. Archives of Environmental Contamination and Toxicology 35:492-497.

Burger, J. 2002. Food chain differences affect heavy metals in bird eggs in Barnegat Bay, New Jersey. Environmental Research Section A 90:33-39.

Burger, J. and M. Gochfeld. 1993. Lead and cadmium accumulation in eggs and fledgling seabirds in the New York Bight. Environmental Toxicology and Chemistry 12:261-267.

Burger, J. and M. Gochfeld. 1997. Risk, mercury levels, and birds: relating adverse laboratory effects to field biomonitoring. Environmental Research 75:160-172.

Dale, T. B. and K. L. Stromborg. 1993. Reconnaissance surveys of contaminants potentially affecting Green Bay and Gravel Island National Wildlife Refuges. Green Bay Ecological Services Field Office, U.S. Fish and Wildlife Service. 35 pp.

Hagen , H. 1975. Chlorinated hydrocarbon pesticide residues in eggs of California birds. Administrative Report No. 75-4. Wildlife Management Branch, California Department of Fish and Game.

Harris, H. J., T. C. Erdman, G. T. Ankley, and K. B. Lodge. 1993. Measures of reproductive success and polychlorinated biphenyl residues in eggs and chicks of Forster’s terns on Green Bay, Lake Michigan, Wisconsin—1988. Archives of Environmental Contamination and Toxicology 25:304-314.

Harrison, H.H. 1975. A Field Guide to the Birds’ Nests, United States east of the Mississippi River. Houghton Mifflin, Boston, Massachusetts. 257 pp.

Heinz, G. H. 1979. Methylmercury: reproductive and behavioral effects on three generations of mallard ducks. Journal of Wildlife Management 43:394-401.

Heinz, G. H., T. C. Erdman, S. D. Haseltine, and C. Stafford. 1985. Contaminant levels in colonial waterbirds from Green Bay and Lake Michigan, 1975-1980. Environmental Monitoring and Assessment 5:223-236.

Hoffman, D. J., B. A. Rattner, L. Sileo, D. Docherty, and T. J. Kubiak. 1987. Embryotoxicity, teratogenicity, and aryl hydrocarbon hydroxylase activity in Forster’s terns on Green Bay, Lake Michigan. Environmental Research 42:176-184.

Jermyn, K., C. Pekarik, T. Havelka, G. Barrett, and D. V. Weseloh. 2002. An atlas of contaminants in eggs of colonial fish-eating birds of the Great Lakes (1998-2001). Vol. 1. Accounts by location. Technical Report Series No. ???. Canadian Wildlife Service, Ontario Region.

Jones, P. D., J. P. Giesy, J. L. Newsted, D. A. Verbrugge, D. L. Beaver, G. T. Ankley, D. E. Tillitt, K. B. Lodge, and G. J. Niemi. 1993. 2,3,7,8-tetrachlorodibenzo-p-dioxin equivalents in tissues of birds at Green Bay, Wisconsin, USA. Archives of Environmental Contamination and Toxicology 24:345-354.

Keith, J. O. and E. G. Hunt. 1966. Levels of insecticide residues in fish and wildlife in California. Thirty-first North American Wildlife Conference 150-177.

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

King, K. A., T. W. Custer, and J. S. Quinn. 1991. Effects of mercury, selenium, and organochlorine contaminants on reproduction of Forster’s terns and black skimmers nesting in a contaminated Texas Bay. Archives of Environmental Contamination and Toxicology 20:32-40.

Klimkiewicz, M. K. 2002. Longevity Records of North American Birds. Version 2002.1. Patuxent Wildlife Research Center. Bird Banding Laboratory. Laurel, MD.

Kubiak, T. J., H. J. Harris, L. M. Smith, T. R. Schwartz, D. L. Stalling, J. A. Trick, L. Sileo, D. E. Docherty, and T. C. Erdman. 1989. Microcontaminants and reproductive impairment of the Forster’s tern on Green bay, Lake Michigan—1983. Archives of Environmental Contamination and Toxicology 18:706-727.

McNicholl, M. K., P. E. Lowther, and J. A. Hall. 2001. Forster’s Tern (Sterna forsteri). In: The Birds of North America, No. 595 (A. Poole and F. Gill, eds.). The Birds of North America, Inc. Philadelphia, Pennsylvania.

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. Colonial Waterbirds 11:85-94.

Pettit, K. E., C. A. Bishop, D.V. Weseloh, and R. J. Norstrom. 1994. An atlas of contaminants in eggs of fish-eating colonial birds of the Great Lakes (1989-1992) Vol. 1. Technical Report Series No. 193, Canadian Wildlife Service, Ecosystems Health Branch, Ontario Region.

Roberts, C. A. 1997. Organochlorine contaminants in eggs of tern species and the western snowy plover nesting in San Diego Bay. Carlsbad Field Office, Division of Environmental Contaminants, U.S. Fish and Wildlife Service.

Sanderson, J. T., S. W. Kennedy, and J. P. Giesy. 1998. In vitro induction of ethoxyresofurin-o-deethylase and porphyrins by halogenated aromatic hydrocarbons in avian primary hepatocytes. Environmental Toxicology and Chemistry 17:2006-2018.

Schwartz, T. R. and D. L. Stalling. 1991. Chemometric comparison of polychlorinated biphenyl residues and toxicologically active polychlorinated biphenyl congeners in the eggs of Forster’s terns (Sterna forsteri). Archives of Environmental Contamination and Toxicology 20:183-199.

Smith, L. M., T. R. Schwartz, K. Feltz, and T. J. Kubiak. 1990. Determination and occurrence of AHH-active polychlorinated biphenyls, 2,3,7,8-tetrachloro-p-dioxin and 2,3,7,8-tetrachlorodibenzofuran in Lake Michigan sediment and biota. The question of their relative toxicological significance. Chemosphere 21:1063-1085.

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 14:627-643.

Tillitt, D. E., T. J. Kubiak, G. T. Ankley, and J. P. Giesy. 1993. Dioxin-like toxic potency in Forster’s tern eggs from Green Bay, Lake Michigan, North America. Chemosphere 26:2079-2084.

White, D. H., C. A. Mitchell, H. D. Kennedy, A. J. Krynitsky, and M. A. Ribick. 1983. Elevated DDE and toxaphene residues in fishes and birds reflect local contamination in the lower Rio Grande Valley, Texas. The Southwestern Naturalist 28:325-333.

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