Common Loon Contaminant Exposure Data

  I.

Organochlorine Contaminants

A.

Concentrations in adults, juveniles and nestlings

1.

From 1966 to 1972 the Toxic Chemical section of the Canadian Wildlife Service collected a number of bird and egg samples including common loons (Gilbertson and Reynolds, 1973). Tissues from the common loons were analyzed for DDE and PCB with the following concentrations (mg/g , dry wt.) found: Alberta: Brain (n=14, DDE=1.54, PCB=1.38), Liver (n=14, DDE=2.28,  PCB=2.34), Fat (n=14, DDE=23, PCB=16.8).

2.

During 1967 three common loons were collected from lakes in the Superior National Forest in northern Minnesota (Ream, 1976).  The following concentrations (mg/g , lipid wt.) for the three respective loons were found in the listed tissues: Muscle: DDE (4.13, 3.23,1030.88), DDD (1.01, .88, 797.6), DDT (1.11, .91, 69.49), Dieldrin (<.52, <.59, 18.27).   Liver: DDE (4.71, 2.68, 1214.49), DDD (2.25, <.72, 1023.83), DDT (1.12, <.72, 25.36), Dieldrin (<.72, <.72, 23.83).  Brain:  DDE (1.72, 4.83, 552.2), DDD (<.37, 1.48, 265.56), DDT (.49, 2.76, 530.00), Dieldrin (<.37, <.49,  6.56).  Fat: DDE (4.07, 3.22, 1624.43), DDD (.65, 1.59, 685.52), DDT (1.48, .68, 1469.01), Dieldrin (<.02, <.03, 5.44). 

3.

Between 1968 and 1979, 215 common loon carcasses (185 healthy, 30 sick or emaciated, 207 drowned, 4 shot, 1 strangled, 3 with fish hooks) were collected across Ontario, Canada (Frank et al., 1983).  Individual carcasses were divided into specific tissue samples as follows:

One group of loon carcasses collected from 1971 to 1974 (n = 157) were divided into brain (b), liver (l), pectoral muscle (m), and body fat (f) samples. The mean concentrations (mg/g , wet weight) for 128 healthy birds found were as follows and listed in the order of (b,l,m,f): SDDT: Juvenile n=21 (0.18, 0.27, 0.81, 12.5), Male adult n=49 (0.83, 1.67, 2.32, 58.0), Female adult n=58 (0.79, 2.05, 2.32, 70.6).  Dieldrin: Juvenile (0.01, 0.02, 0.06, 0.83), Male adult (0.04, 0.10, 0.09, 1.92), Female adult (0.06, 0.14, 0.13, 4.02).  PCB:  Juvenile (0.61, 0.75, 1.78, 29.2), Male adult (1.77, 4.20, 4.47, 103), Female adult (1.98, 5.52, 4.39, 126).  The mean concentrations for 29 emaciated birds were as follows: SDDT: Juvenile  n=6 (35.6, 78.1, 12.6, 452), Male adult n=13 (25.2, 35, 16.3, 1008), Female adult n=10 (27.9, 36.3, 11.7, 754).  Dieldrin: Juvenile (1.23, 0.79, 0.13, 11.9), Male adult (0.48, 0.41, 0.16, 8.23), Female adult (0.81, 1.01, 0.24, 10.7).  PCB:  Juvenile (45.5, 68.9, 10.1), Male adult (58.5, 87.1, 23.4, 1224), Female adult (62.9, 81.8, 19.8, 1570).             

A second group of loon carcasses collected from 1971 to 1974 (n = 103) were divided into body fat (f), uropygial gland (ug), uropygial oil (uo), back feather (bk) and belly feather (bl) samples. The mean concentrations (mg/g , wet weight) for 87 healthy birds found were as follows and listed in the order of (f, ug, uo, bk, bl): SDDT: Juvenile n=15 (16.5, 7.53, 7.45, 0.18, 0.14),  Adult n=72 (80.6, 42.7, 34.7, 1.17, 0.32).  Dieldrin: Juvenile (1.09, 0.63, 0.34, trace, 0.01), Adult (3.63, 1.34, 1.06, 0.03, 0.01).  PCB:  Juvenile (39.2, 8.76, 29.9, 0.56, 0.34), Adult (144, 43.3, 104, 3.75, 1.80).  The mean concentrations for 16 emaciated birds were as follows: SDDT: Juvenile, n=3 (541, 70.5, 300, 8.9, 4.08), Adult n=13 (1198, 280, 470, 3.64, 1.62).  Dieldrin: Juvenile (4.85, 1.22, 2.54, 0.38, 0.12), Adult (10.9, 4.42, 5.82, 0.02, 0.01).  PCB:  Juvenile (783, 255, 275, 6.78, 4.33), Adult (1696, 394, 549, 13.4, 4.55).                                                

A third group of loon carcasses collected from 1971 to 1974 (n = 31) were divided into the following internal body organ and tissue components: gizzard (g), intestine (i), blood (b), liver (l), heart (h), lung (lu), brain (br), kidney (k). Mean concentrations (mg/g , wet weight) were found as follows: SDDT: healthy juveniles (n=8) (g=0.38, i=0.78, b=0.03, l=0.11, h=0.54, lu=0.15, br=0.07, k=0.09), healthy adults (n=13) (g=3.33, i=2.92, b=0.11, l=1.25, h=4.34, lu=0.77, br=0.83, k=0.45), emaciated adults (n=10) (g=5.45, i=15.8, b=1.75, l=25.3, h=9.64, lu=4.04, br=20.5, k=20.0).  Dieldrin: healthy juveniles (n=8) (g=0.03, i=0.07, b=ND, l=0.01, h=0.02, lu=trace, br=trace, k=trace), healthy adults (n=13) (g=0.08, i=0.17, b=trace, l=0.02, h=0.05, lu=0.01, br=0.02, k=0.01), emaciated adults (n=10) (g=0.18, i=0.34, b=0.01, l=0.43, h=0.07, lu=0.04, br=0.53, k=0.31). PCB: healthy juveniles (n=8) (g=0.88, i=2.12, b=0.04, l=0.29, h=1.08, lu=0.14, br=0.21, k=0.20), healthy adults (n=13) (g=3.94, i=7.40, b=0.24, l=2.53, h=9.72, lu=2.68, br=1.66, k=1.97), emaciated adults (n=10) (g=10.6, i=35.4, b=2.33, l=101, h=37.3, lu=13.1, br=76.4, k=58.7).  

4.

Liver, brain and fat samples from 14 common loons were collected in Alberta, Canada from 1969 to 1972 (Falandysz and Szefer, 1982). The following mean concentrations (mg/g , wet weight) were found: PCB in liver (2.3), PCB in brain (1.4), PCB in Fat (17), SDDT in liver (2.3), SDDT in brain (1.5), SDDT in fat (23). One individual loon collected in Port Alexander, British Columbia had a fat SDDT concentration of 0.42 mg/g .

5.

From 1971 to 1975 liver and muscle tissue were collected from common loons found dead at various sites (Bourne and Bogan, 1976). The following are the concentrations (mg/g, wet weight) found: North Britain, n = 3, DDE in liver (2.0, 1.8, 0.5), DDE in muscle (1.0, 1.0, 1.0), PCB in liver (2.0, 14.2, 2.8), PCB in muscle (1.0, 6.5, 5.4); Jersey, England, n = 2, DDE in liver (6.1, 14.5), DDE in muscle (1.7, 2.1), PCB in liver (28.1, 25.3), PCB in muscle (6.1, 3.4), Dieldrin in liver (0.5, 0.7), Dieldrin in muscle (1.0, 0.2); Massachusetts, n = 1, DDE in liver (0.1), PCB in liver (0.4). 

6.

Between 1972 and 1999, dead or debilitated common loons (n = 105) were collected in New York (Stone and Okoniewski, 2001).  Of the 105 loons, 39 were chosen for analysis of organochlorines in brain tissue (geometric mean concentration) with the following results: DDE, occurred in 92% of samples, 0.47 mg/g, wet weight; PCB occurred in 92% of samples, (2.02); Dieldrin occurred in 79% of samples, (0.06); Oxychlordane occurred in 64% of samples, (0.02); trans-Nonachlor occurred in 53% of samples, (0.02); Heptachlor epoxide occurred in 51% of samples, (0.01); and Mirex occurred in 49% of the samples, (0.02).  The highest PCB concentration (60) was found in an emaciated adult male loon, while the highest DDE concentrations (11) was found in a thin adult female loon succumbing to fish hook ingestion. 

7.

A moribund common loon (female, subadult weighing 4 lbs.) was found in Madison County, Mississippi in December 1973 (Prouty et al., 1975). After dying, the loon carcass and a separate brain sample were analyzed for organochlorine contaminants (mg/g, wet weight, ND=not detected, NA=not analyzed) with the following results listed as (carcass, brain): p,p’-DDE (680, 130),  p,p’-DDD  (1400, 200),  p,p’-DDT (10, 2.1),  Dieldrin (0.18, ND), p,p'-DDD-olefin (67, NA),  p,p’- Dichlorobenzophenone (DCBP) (5, ND),  p,p’-DDMS (34, NA),  o,p’-DDD (33, NA),  o,p’-DDE (55, NA), Dicofol (26, NA),  PCB (180, 15).

8.

A total of 68 oiled common loons were collected between late January and 23 March 1979 from the coasts of Shetland, UK following the Esso Bernicia oil spill and the carcasses were placed in frozen storage (Heubeck et al., 1993). Later, pectoral muscle and liver tissue from 12 randomly selected loons were analyzed for organochlorine residues and mercury. The following mean concentrations in mg/g, wet weight were found: DDE in muscle (0.84), DDE in liver (1.46), PCB in muscle (1.05), PCB in liver (2.99).

9.

On 4 November 1981, 4 loons were found dead and 2 birds were randomly selected for analytical toxicology (Coppock and Somers, 1990). The body fat was analyzed for organochlorine contamination with the following concentrations found in ug/g: loon A- PCB=93, dieldrin=3.0; loon B- PCB=101, dieldrin=1.4. No other organochlorine compounds were detected.  

10.

Brain tissue samples (n=13) were collected from dead common loons (n=173) during an epizootic along the north Gulf Coast of Florida from January to March 1983 in which more than 13,000 loons were estimated to have died (Forrester et al. 1997). Residues of DDE and PCBs (Aroclor 1260) were found in all brain samples, the mean concentrations (mg/g, wet weight) were: DDE = 7.8, Aroclor 1260 = 23.  Low concentrations (< 1) were found of dieldrin (n=7), heptachlor epoxide (n=6), oxychlordane (n=6), trans-nonachlor (n=6), and cis-chlordane (n=1). Residues of other organochlorine compounds were not detected.

 11.

Muscle and brain tissue samples were collected from common loons found dead in northern Wisconsin from 1984 to 1987 (Belant and Anderson, 1990). The following concentrations in mg/g, wet weight, were found in individual loons and are listed as (muscle/brain):  Bayfield County, Adult 1: PCB (3.3/0.59), dieldrin (0.19/0.03), DDE (0.98/0.16); Adult 2, PCB (3.4/0.49), dieldrin (0.06/<0.02), DDE (0.61/0.07); Adult 3, PCB (3.2/0.3), dieldrin (0.22/0.03), DDE (0.77/0.06).  Portage County, Juvenile: PCB (2.2/0.46), dieldrin (0.07/0.02), DDE (0.43/0.09).  Iron County, Adult: PCB (18.0/29.0), dieldrin (0.88/2.20), DDE (4.7/7.7).  Vilas County, Adult (muscle only): PCB (26.0), dieldrin (2.0), DDE (7.0).

12.

A liver sample from a juvenile common loon weighing 1684 grams and found dead near Cley-next-the-Sea, Norfolk, England on 13 November 1985 was analyzed for organochlorines (Mason and MacDonald, 1988). Concentrations in mg/g were found for the following compounds: PCBs (0.24), dieldrin (5.15), lindane (4.01), DDE (8.99), DDT (1.78).

13.

Livers (n=13) selected from 75 common loons found dead or moribund from 1989 to 1990 at fresh-water lakes throughout New England (Maine n=14, New Hampshire n=31, Vermont n=1), and in coastal shorelines of Maine (n=2) and Massachusetts (n=27), were analyzed for organochlorine contamination (Pokras et al., 1991).  The following mean concentrations (mg/g wet weight) were found (adult n=8, immature n=5): DDE (3.8, 1.9), DDT (0.4, 0.1), PCB 1248 (0.8, 0.8), PCB 1260 (14.7, 8.7).     

14.

Common loons (n=124) found dead or moribund from 1989 to 1992 were collected throughout New England (Pokras et al., 1992). Liver samples from 16 loons (8 adults, 5 juveniles, and 3 chicks) had the following mean concentrations (mg/g, wet weight) and listed in order of (adults, juveniles, chicks): DDE (3.89, 1.94, 1.31); DDT (0.43, 0.14, 0.07); PCB 1248 (15.27, 9.43, 3.45); PCB 1254 (24.45, 40.95, 4.09); PCB 1260 ( 0.29, trace, trace); dieldrin (0.04, 0.12, 0.16); oxychlordane (0.10, 0.05, 0.03); trans-nonachlor (0.16, 0.09, 0.40).

15.

Livers from common loons found dead at wildlife refuges or that had died at rehabilitation centers during 1997 to 1998 were analyzed for perfluorooctane sulfanate (PFOS) (Kannan et al. 2001).  The following mean concentrations (ng/g, wet weight) were found: Carteret County, NC (n =5, 1 adult and 4 juvenile), 280; Monterey Bay, CA (n = 4, 4 adult), 37;  Pompano, FL (n=4, 3 adult, 1 juvenile), 40 ;  Ft Lauderdale, FL (n = 1, subadult), 115 ;  Carlsbad, CA (n = 1),   < 12 ;  San Diego, CA 11/97 (n = 2), 62 ; Coronado, CA (n = 1), 451 ;  San Diego, CA 12/97 (n = 1), 112.

B.

Concentrations in eggs

1.

From 1966 to 1972 the Toxic Chemical section of the Canadian Wildlife Service collected a number of bird and egg samples including common loons (Gilbertson and Reynolds, 1973). Eggs from common loons contained the following mean concentrations (mg/g dry weight): Alberta (n=17, DDE=7.53, PCB=5.43), Saskatchewan (n=5, DDE=54.4, PCB=87.9).

2.

During 1967, 5 common loon eggs were collected from the Superior National Forest in northern Minnesota (Ream, 1976).  The following concentrations (mg/g lipid weight) were found for the five eggs respectively: DDE (176.29, 323.88, 240.51, 223.83, 173.31), DDD (5.96, .64, 16.95, 12.89, 19.23), DDT (16.26, 1.80, 40.89, 32.55, 25.04), dieldrin (4.97, 16.19, 8.26, 4.56, 5.97).  

3.

Between 1968 and 1980, 98 common loon eggs were collected from active nests at locations in Ontario, Canada (Algonquin, Kinoje Lake, Algonquin Parry Sound) (Frank et al., 1983). The following are the years and mean concentrations (mg/g wet weight) found: DDE: 1968, n = 4, (41.4); 1969, n = 14, (8.6); 1970, n = 34, (33.6); 1972, n = 15, (24.8); 1978, n = 12, (6.6); 1980, n =19, (3.98). DDD: 1968 (6.3), 1969 (1.7), 1970 (2.3), 1972 (0.0), 1978 (0.17), 1980 (0.36).  DDT:  1968 (4.7), 1969 (1.7), 1970 (2.3), 1972 (0.1), 1978 (0.0), 1980 (0.0).  Dieldrin:  1968 (0.24), 1969 (0.58), 1970 (1.55), 1972 (0.74), 1978 (0.08), 1980 (0.26).  HE: 1978 (0.05), 1980 (0.07).  Chlordane: 1978 (0.05), 1980 (0.21).  PCB:  1970 (33), 1972 (65), 1978 (10.5), 1980 (6.1).  HCB: 1978 (0.01), 1980 (0.01).  Mirex: 1978 (0.49), 1980 (0.23).

4.

Common loon eggs (n=17) were collected in Alberta, Canada from 1969 to 1972 (Falandysz and Szefer, 1982). The following mean concentrations (mg/g wet weight) were found: PCB (5.4), SDDT (7.5).

5.

A common loon egg was collected from each of 15 clutches in the Lac La Biche- St. Paul region of Alberta, Canada during 1972 (Vermeer, 1973).  Eggshell thickness was also measured to see if a correlation could be found between thickness and contaminant concentrations. The following mean concentrations were found (mg/g wet weight): PCB = 1.2, DDE = 1.7, DDD = trace, DDT = trace, dieldrin = trace, endrin = trace, heptachlor epoxide = trace, benzene hexachloride = trace. The following are the individual egg DDE concentrations for the 15 eggs: (4.82, 1.28, 1.02, 0.84, 1.38, 1.55, 0.89, 2.06, 1.19, 2.31, 1.07, 1.09, 1.16, 3.03, 1.31).  The PCB and organochlorine residues in loon eggs were low compared to those found in 1968 in other fish-eating birds in Alberta.

6.

From 1974 to 1975 common loon eggs (n=31) were collected from Hanson Lake, Saskatchewan (Fox et al., 1980).  The following geometric mean concentrations (mg/g wet weight ) were found: DDE (5.80), DDD (0.10), DDT (0.08), dieldrin (0.43), heptachlor epoxide (0.08), HCB (0.06), PCBs (14.10). The values from this study were compared with other studies, including unpublished data on loon eggs from Ontario, Canada (n=7) as follows: DDE (6.6), dieldrin (0.28),  PCBs (9.5).

7.

Common loon eggs (n=51) from 3 New Hampshire lakes were collected from 1975 to 1976 after they had either been abandoned following disturbance, abandoned after prolonged incubation, or knocked into the water by an incubating adult (Sutcliffe, 1978). Of the 51 eggs collected, 14 eggs were analyzed for organochlorine content with the following geometric means recorded (mg/g wet weight): DDE (5.88), DDT (2.44), dieldrin (0.105), total PCB (24.6), DDD (<0.05), PCB as Arochlor 1254 (n=8, 18.30). A significant correlation was noted between PCB and DDE residues.                                                                                                         The geometric mean concentrations from these 14 New Hampshire eggs were then compared to concentrations found in eggs from other studies. The comparison values are as follows (total PCB was not included): 1975 North Central Minnesota (n = 9): DDE (4.99), DDT (0.51), dieldrin (0.29), DDD (1.28), PCB as Arochlor 1254 (12.7).  1975 New Hampshire study (n = 3): DDE (4.76), DDT (0.17), Dieldrin (0.26), PCB as Arochlor 1254 (20.39).  1975 Saskatchewan (n = 7): DDE (6.28), DDT (0.99), Dieldrin (0.29), PCB as Arochlor 1254 (14.7).  1973 Alberta (n = 15): DDE (1.7), PCB as Arochlor 1254 (1.2).

8.

Non-viable common loon eggs were collected from 15 locations on six New Hampshire lakes and from 28 lakes in the Adirondacks of New York from 1978 to 1986 (McIntyre et al., 1992). The following mean concentrations (mg/g wet weight) were found and are listed in the order of years (1978 n=13, 1979 n=5, 1980 n=8, 1982 n=2, 1984 n=12, 1985 n=14, 1986 n=9): dieldrin (0.22, 0.10, 0.14, 0.15, 0.15, 0.20, 0.05); total chlordane (0.35, 0.23, 0.28, 0.38, 0.34, 0.41, 0.09); total DDT (3.91, 2.42, 2.43, 1.97, 1.94, 2.48, 0.74); total PCB (10.73, 3.83, 4.65, 7.42, 4.96, 5.59, 1.79); mirex (0.07, NA, 0.03, 0.05, NA, 0.07, NA); HCB (ND, ND, ND, ND, 0.009, 0.010, 0.004).  Mean concentrations were also compared by location collected between 1983 and 1985 and listed as (New Hampshire n=15 / New York n=26): dieldrin (0.10 / 0.17); chlordane (0.24 / 0.38); SDDT (1.59 / 2.21); PCBs (3.96 / 5.29); HCB (NA / 0.01) mirex (NA / 0.08).

9.

Non-viable common loon eggs were collected from Stillwater reservoir, New York from 1978 to 1986 (McIntyre et al., 1992).  The following mean concentrations (mg/g wet weight) were found and listed as (1978 n=8 / 1986 n=9): dieldrin (0.189 / 0.059); chlordane (0.336 / 0.101); total DDT (3.375 / 0.846); total PCBs (7.30 / 1.833).  Mean concentrations of DDT for individual eggs was as follows: 1978 (5.55, 5.18, 3.08, 2.36, 2.89, 1.76, 3.14. 3.04); 1980 (1.61, 1.10, 0.63); 1982 (1.59) ; 1984 (2.61, 2.38), 1985 (2.17, 2.65), 1986 (0.75, 0.69, 1.33, 0.56, 1.42, 0.46, 0.47, 0.60, 2.1). Mean concentrations of PCBs for individual eggs were as follows: 1978 (9.2, 8.1, 3.6, 3.7, 12.0, 9.7, 4.9, 7.2) ; 1980 (2.4, 2.6, 4.4) ; 1982 (5.0) ; 1984 (6.1, 6.6) ; 1985 (5.1, 7.2) ; 1986 ( 2.3, 1.9, 2.4, 1.5, 0.66, 1.3, 1.4, 1.6, 2.0).

10.

Failed eggs were collected from New Hampshire common loon nests in 1979 (n=15) and 1981 (n=21) (Haseltine et al., 1983). The following are the geometric mean concentrations (mg/g, wet wt.) found, listed in order of (1979, 1981): DDE (2.9, 1.9), DDD (0.09, 0.08), dieldrin (0.10, 0.09), oxychlordane (0.07, 0.06), cis-chlordane (0.06, 0.07), trans-nonachlor (NA, 0.13), cis-nonachlor (0.05, 0.05), PCB (10, 6.28). The two principal contaminants of loon eggs, DDE and PCBs, decreased significantly between sampling periods.

11.

Common loon eggs (n = 12) were collected at Turtle-Flambeau Flowage in Iron County, Wisconsin from 1986 to 1987 (Belant and Anderson, 1990). The mean concentrations (n=12) were: PCB = 4.04 mg/g wet weight, dieldrin = 0.47 mg/g, DDE = 1.22 mg/g.

II.

Cholinesterase-Inhibiting Pesticides

No direct exposure data available

III.

Trace Elements, Metals, and Metalloids

A.

Concentrations in adults, juveniles and nestlings

1.

Between 1968 and 1979, 215 common loon carcasses (185 healthy, 30 sick or emaciated) were collected across Ontario, Canada (Frank et al. 1983). Individual carcasses were divided into specific tissue samples and analyzed Hg as follows:  One group of loon carcasses collected from 1971 to 1974 (n = 157) were divided into brain (b), liver (l), pectoral muscle (m), and body fat (f) samples. The mean concentrations (mg/g wet weight) for 128 healthy birds found were as follows and listed in the order of (b,l,m,f): Juvenile  (0.44, 1.92, 0.79, 0.15), Male adult (0.57, 6.35, 1.14, 0.22), Female adult (0.51, 5.04, 1.02, 0.22). The mean concentrations for 29 emaciated birds were as follows: Juvenile  (1.82, 26.4, 5.41, 0.21), Male adult (1.04, 16.3, 3.26, 0.47), Female adult (1.03, 19.0, 2.71, 0.65).               

A second group of loon carcasses collected from 1971 to 1974 (n = 103) were divided into body fat (f), uropygial gland (ug), back feather (bk) and belly feather (bl) samples. The mean concentrations (mg/g wet weight) for 87 healthy birds found were as follows and listed in the order of (f, ug,  bk, bl): Juvenile (0.18, 0.30, 5.0, 4.74), Adult (0.24, 0.30, 3.75, 10.7).  The mean concentrations for 16 emaciated birds were as follows: Juvenile (0.22, 1.49, 12.9, 19.4), Adult (0.48, 0.59, 13.4, 14.9).         

A third group of loon carcasses collected from 1971 to 1974 (n = 31) were divided into the following internal body organ and tissue components: gizzard (g), intestine (i), blood (b), liver (l), heart (h), lung (lu), brain (br), kidney (k). Mean concentrations (mg/g wet weight) were as follows: healthy juveniles (n=8) (g=0.87, i=0.73, b=0.93, l=1.73, h=0.62, lu=0.55, br=0.44, k=1.12), healthy adults (n=13) (g=1.00, i=0.77, b=1.74, l=5.32, h=1.10, lu=1.08, br=0.65, k=6.58), emaciated adults (n=10) (g=1.62, i=2.43, b=2.52, l=17.0, h=1.76, lu=1.90, br=0.95, k=22.0). 

2.

Common loons were among 184 specimens that were collected (shot) between 20 July and 05 August 1970 and between 20 June and 28 July 1971 from lakes along the Wabigoon River in Ontario, Canada (Fimreite, 1974). Liver and breast samples were analyzed for Hg: Ball Lake (n=4 adult loons) 51.9 mg/g wet wt. Hg; Sydney Lake (n=3 adult loons) 10.3 Hg. Mean liver and breast concentrations (n=5) for selected loons from northwestern Ontario were liver 43 and breast 14.9. The concentration of Hg in the breast muscle correlated to the concentration of Hg in the liver samples.

3.

From 1970 through 1994, primarily during December to April, common loons found sick or dead on Florida beaches were collected, the carcasses (n=434) were examined for cause of death, and the livers and kidneys of some individuals were analyzed for trace metal contamination (Forrester et al. 1997). Many of the carcasses examined (n=173) were obtained during an epizootic that occurred from January to March 1983 along the north Gulf Coast in which more than 13,000 loons were estimated to have died. The following concentrations were found for the dates and areas indicated, listed as (Hg/Se, number of samples): Atlantic Coast: Emaciated Loons: 1987 (2.3/NA, n=9), 1990-1991 (1.4/NA, n=2), 1993 (4.8/NA, n=2), 1994 (4.3/NA, n=5); Oiled Loons: 1974 (5.2/7.3, n=6).  Gulf Coast: Emaciated Loons: 1973-1974 (17/12, n=5), 1974-1975 (13/6.8, n=6), 1983 (22/10, n=13), 1984 (7.9/8.7, n=1), 1991 (7.7/NA, n=8); Normal Loons: 1984 (4.5/5.8, n=23).   Residues of Hg and Se in livers of male and female loons were not significantly different, however residues of Hg were significantly higher in loons from the Gulf Coast than loons from the Atlantic Coast, (Se was not compared because Atlantic emaciated loons were not tested for Se). Residues of both Hg and Se were higher in emaciated loons than in normal birds and there was a linear correlation between residues of Hg and Se.

4

Between 1972 and 1999, dead or debilitated common loons (n = 105) were collected in New York (Stone and Okoniewski, 2001).  Concentrations of Hg were determined in the livers of 82 loons and ranged from 0.07 mg/g wet weight, in a Pb-poisoned unfledged chick, to 371 mg/g in an adult female with air sacculitis. The geometric mean Hg concentration for all 89 liver samples was 10.3 mg/g. Lead fishing weights were found ingested by 21 loons and Pb in livers of these loons exceeded the 5 to 6 mg/g thresholds for lethal Pb poisoning determined for waterfowl. The mean concentration of Pb in loons not digesting Pb sinkers (n=48) was 0.07, with 21 loons having hepatic Pb concentrations below detection limits. .

5.

In 1976 common loons (38 adults, 11 chicks) were collected (adults shot) from various lakes in northwestern Ontario, Canada (Barr, 1986). The 34 lakes within the Wabigoon-English River watershed were grouped in 4 classes according to proximity to Hg contamination sources. C1 lakes are directly downstream of a Hg contamination source, C2 lakes are not within the flow of contaminated waters but are accessible to contaminated fish, C3 are upstream of the contamination source, and C4 are independent control lakes. The following concentrations (mg/g wet weight) were found in the various tissues listed as (Hg/MeHg): C1 lakes (5 adults, 1 chick): Adult liver (29.73/1.53), Chick liver (1.28/0.97), Adult muscle (4.57/2.32), Chick muscle (0.89, 0.80), Adult brain (1.49/0.76), Chick brain (0.78/0.75).  C2 lakes (4 adults, no chicks): Adult liver (16.65/1.09), Adult muscle (3.41, 1.59), Adult brain (1.15, 0.50).  C3 lakes (12 adults, 6 chicks):  Adult liver (5.10/1.04), Chick liver (0.91/0.84), Adult muscle (1.22/1.04), Chick muscle (0.38/0.33), Adult brain (0.42/0.39), Chick brain (0.30/0.30).  C4 lakes (10 adults, 4 chicks):  Adult liver (8.81/0.20), Chick liver (0.83/0.71), Adult muscle (1.20/0.85), Chick muscle (0.42/0.30), Adult brain (0.43/0.33), Chick brain (0.37/0.37).                                   

For all lake locations combined (37 adult loons, 10 chicks) the Hg/MeHg concentrations were as follows: Adult liver (12.95/11.67), Chick liver (0.91/0.80), Adult muscle (2.33/1.65), Chick muscle (0.44/0.37), Adult brain (0.86/0.65), Chick brain (0.37/0.37).          

Mercury concentrations were significantly higher in brains of nesting loons from C1 lakes 150 to 320 km downstream in the path of waterborne Hg and from C2 lakes, although not significantly different from each other, were significantly higher than in loons from C3 and C4 lakes, which were not significantly different than each other. The concentration of total Hg residue in loon tissues decreased in the sequence liver>muscle>brain but the percentage of MeHg increased from liver<muscle<brain. Adult male loons generally contained higher levels of Hg than did their mates or other females from the same lake class.  

6.

Common loons were collected from 3 locations in New England (Locke et al., 1982).  A loon found dead on September 6, 1976 at Squam Lake, New Hampshire (female, with an ingested Pb fishing sinker) was divided into various samples for Pb analysis as follows (mg/g wet weight): femur (39.22), heart (0.91), blood clot from heart (9.91), lung (2.34), spleen (3.24), cerebrum (1.40), cerebellum (1.02), liver (20.6), kidney (61.4).  Another loon found dead on May 13, 1980 at Little Lake, Wisconsin (male, with an ingested Pb fishing sinker) had the following Pb concentrations: liver (46.1) and kidney (15.7).  A third loon found dead at Indian Lake, Maine on July 16, 1979 (male, no ingested lead found) contained a lead liver concentration of 38.52 mg/g. Lead concentrations in livers of 13 common loons dying from causes other than lead poisoning were all <1 mg/g.

7.

A total of 68 oiled common loons were collected between late January and 23 March 1979 from the coasts of Shetland, UK following the Esso Bernicia oil spill (Heubeck et al., 1993). Twelve randomly selected loons contained 0.61 mg/g wet weight Hg in pectoral muscle and 15.03 mg/g in liver.

8.

On 4 November 1981, 4 loons were found dead and 2 birds were randomly selected for analytical toxicology (Coppock and Somers, 1990). The liver from one loon was contained 0.50 mg/g Pb and 0.25 mg/g Hg.

9.

Livers and breast feather samples from 221 common loons were collected between 1984-90 from 18 counties in the northern and central portions of Minnesota (Ensor et al., 1992). All loons had detectable hepatic Hg, with a range of 0.08 to 83 mg/g wet weight and a geometric mean value of 3.6 mg/g, while feather concentrations ranged from 0.05 to 29 mg/g and a geometric mean of 3.21 mg/g. Three loons had excessively high (>45 mg/) hepatic Hg concentrations. The liver Hg concentrations in 22 % of the loons equaled or exceeded the mean concentration associated with impaired reproduction in Ontario loons (13 mg/g). Lead poisoning was diagnosed as the cause of death for 17% (n=7) of adult loons necropsied.       

Mercury accumulation was not significantly affected by sex. However, adult loons had significantly higher mean total Hg concentrations in both liver and feather than juvenile loons (however, 5 juveniles accumulated mean Hg concentrations in feathers (8.7 mg/g) equivalent to that of adults. Live juveniles from the northeastern part of the state had significantly higher Hg concentrations in feathers than in the northwestern part. Juveniles that died from disease had a significantly higher mean Hg concentration than either juveniles that died from injury or live-caught juveniles. Whether death was from disease or injury, emaciated loons tended to exhibit significantly elevated concentrations of Hg in liver and feathers.  

10.

Breast feathers were collected from common loons captured by night lighting and livers from common loons found dead from 1985 to 1987 in northern Wisconsin (Belant and Anderson, 1990). Adult hepatic Hg concentrations (mg/g wet weight) were as follows: Portage County (9.5), Iron County (33.0) and (90.0), Vilas County (31.0).  Feather Hg concentrations (all from Turtle-Flambeau Flowage, mg/g wet weight) were as follows: Adults: (18.0), (12.0), (18.0), and (11.0).  Juveniles: (5.3), (5.0), (3.7), and (2.0).   

11.

A liver sample from a juvenile common loon weighing 1684 grams and found dead near Cley-next-the-Sea, Norfolk, England on 13 November 1985 contained 9.19 mg/g Hg, 1.13 mg/g Cd, and 2.54 mg/g Pb (Mason and MacDonald, 1988).

12.

Liver tissue was collected from 54 common loons found dead or ill and later dying in Michigan during the period between July 1988 and February 1993 (O’Brien et al., 1995). The following concentrations (mg/g wet weight) were found: Ca=5.12, Cd=2.37, Cu=3.00, Fe=6.89, Hg=3.03, Mg=5.23, Mn=2.61, Mo=2.32, P=7.96, Pb=2.69, Se=2.88, Zn=3.94.

13.

Livers (n=13) were selected from 75 common loons found dead or moribund from 1989 to 1990 at fresh-water lakes throughout New England (Maine n=14, New Hampshire n=31, Vermont n=1) and in coastal shorelines of Maine (n=2) and Massachusetts (n=27) (Pokras et al., 1991).  The following mean concentrations (mg/g wet weight) were found (adult n=8, immature n=5): Pb (5.8, 0.05), Hg (23.6, 8.0), Se (adult n=6: 11.5, immature n=2: 3.6), Cd (2.2, 0.9), Al (4.6, 3.2). Blood serum from selected loons was also analyzed for Pb (n=17, 0.02 mg/g) and Hg (n=5, 0.82 mg/g). One additional loon that ingested a Pb sinker had Pb serum concentrations of 0.89 mg/g.

14.

Common loons (n=124) found dead or moribund from 1989 to 1992 were collected throughout New England (Pokras et al., 1992). Tissues from 38 loons (25 adults: 12 females and 13 males, 8 juveniles, and 5 chicks) were analyzed for metals and trace elements. The following concentrations (mg/g wet weight) were found and are listed in order of (adult, immature, chick): Pb (6.73, trace, 0.67); Hg (Adult female = 17.07, adult male = 39.09, 9.616, 1.199); Cd (1.80, 0.68, trace); Al (2.03, 2.35, 8.05); Se (10.21, 4.36, 0.85).  Liver samples from 25 loons were analyzed for Pb with the following concentrations (mg/g, wet weight) found: Loons without ingested Pb in gizzard (n=13, mean 2.75, range <0.05 – 22.60); Loons with ingested lead in liver (n=12, mean 10.97, range <0.05 – 18.00).  Blood Pb concentrations were determined for 27 loons that were recovered alive. Blood Pb concentrations for adult loons that had not ingested Pb fishing sinkers (n = 26) were: (0.01 for 12 birds, 0.02 for 6 birds, 0.03 for 2 birds, 0.04, 0.05 for 3 birds, 0.07, 0.08). The blood Pb concentration for one loon with an ingested sinker was 0.78.  Blood Hg concentrations for 14 loons recovered alive were:  (1.4, 2.1, 4.1, 5.4, 5.4, 6.0, 6.4, 8.7, 1.14, 1.32, 1.38, 1.56, 2.06, 5.52).                     

Feather samples taken from selected loons (15 adults and 13 juveniles) had the following concentrations (mg/g dry weight) listed in order of (adult, immature): Pb (1.314, 1.116); Cd (0.080 / 0.083); Hg (20.245 / 9.677); Se (1.055 / 1.176); Cr (7.6 / 9.242); Mn (2.758 / 1.913); Cu (35.066 / 34.072). Adults had significantly higher Hg concentrations than juveniles, other metals did not vary significantly from adults to juveniles and there were no sex related differences for adult feather samples.    Mean body weights of loons with renal Pb concentrations above and below the threshold for Pb toxicosis (5 mg/g) were compared as follows: Male loons below threshold n = 4 (4.1 g), Male loons above threshold n = 8 (4.4 g), Female loons below threshold n = 6 (2.5 g), Female loons above threshold n = 4 (4.0 g).          

15.

Livers were collected from common loons (n = 24) found dead or moribund in freshwater lakes and from coastal shorelines in Maine, New Hampshire, Massachusetts, and Rhode Island between 1990 and 1994 (Pokras et al., 1998). Mean concentrations (mg/g wet weight) found were: Entire sample population (n=24) 41.06 Hg / 3.57 MeHg, chicks (n=6) 0.285 Hg / 1.38 MeHg, adult females (n=7) 45.99 Hg / 3.9 MeHg, and adult males (n=14) 56.06 Hg / 4.3 MeHg. 

16.

Blood and feather samples were collected from common loons captured from 20 lakes in northern Wisconsin (Meyer et al., 1995). These samples were then compared by the pH of the lakes from which they came. The following Hg concentrations (mg/g fresh weight) were found: Low pH lakes: adult male feathers (n=5, 15), adult female feathers (n=7, 9), all adult feathers (n=12, 12), adult male blood (n=5, 6), adult female blood (n=7, 4), all adult blood (n=12, 5); Neutral pH lakes: adult male feathers (n=7, 11), adult female feathers (n=4, 7), all adult feathers (n=11, 9), adult male blood (n=7, 2), adult female blood (n=4, 1), all adult blood (n=11, 2). The following Se and Ca are concentrations were found in blood samples: Low pH lakes: adult male Se (n=7, 3), adult female Se (n=6, 4),  all adults Se (n=13, 3), adult male Ca (n=7, 3), adult female Ca (n=6, 4),  all adults Ca (n=13, 3;  Neutral pH lakes: adult male Se (n=7, 23), adult female Se (n=6, 16),  all adults Se (n=13, 20), adult male Ca (n=7, 31), adult female Ca (n=4, 28),  all adults Ca (n=11, 30).   Concentrations of Hg were below detection limits in all chick blood.  The mean Hg content of blood cells collected from adult loons on low pH lakes was significantly greater than the clot Hg content of adult loons collected on neutral/alkaline pH lakes. The mean male and female serum clot Hg concentrations were not statistically different. Mean feather Hg concentrations were not significantly different between adult loons captured on low vs. neutral pH lakes, however males had significantly greater levels than did females. Serum clot Se concentrations were also greater in adults captured on low pH lakes, however, the linear relationship between blood cell Hg vs. blood cell Se concentrations was not significant. The mean serum clot Ca content of adult loons captured on low pH lakes was significantly less than the clot Ca content of adult loons sampled on neutral pH lakes, with male and female Ca levels being similar. 

17.

Blood and feather samples were collected from 35 adult common loons and 30 chicks captured on 22 lakes in northern Wisconsin during July 1991 (Meyer et al., 1992). The following mean concentrations (mg/g) were found in blood serum clots and listed as a comparison of lake acidity (low pH lake / neutral pH lake): Adult males, n=7 for each lake type: Hg (5 / 2), Se (3 / 2), Ca (23 / 31). Adult females, n=6 for low pH lakes and n=4 for neutral pH lakes: Hg (4 / 1), Se (4 / 2), Ca (16 / 28). All adults: Hg (5 / 2), Se (3 / 2), Ca (20 / 30), Pb from whole blood (50 / 30).  The following mean concentrations (mg/g) were found in feathers and listed as a comparison of lake acidity (low pH lake / neutral pH lake): Adult males, n=7 for low pH lakes and n=6 for neutral pH lakes: Hg (14 / 11), Al (10 / 8), Ca (300 / 487). Adult females, n=7 for low pH lakes and n=5 for neutral pH lakes: Hg (8 / 7), Al (10 / 11), Ca (325 / 549). All adults: Hg (12 / 9), Al (10 / 9), Ca (338   / 512).  The Hg content of serum clot samples from adult loons on low pH lakes was significantly greater than the clot Hg content of adult loons collected on neutral pH lakes, with no difference between males and females. Conversely feather Hg concentrations were not different for loons captured on different lake types. However, male feathers had significantly more Hg than females.

18.

From 1991 to 1996 feather (n=455) and blood (n=381) samples from adult loons were collected between June and September in five regions of North America (Evers et al., 1998). The following mean Hg concentrations (mg/g) were found in blood samples: Alaska female (n=14, 0.60), Alaska male (n=9, 0.75), Northwest female (n=6, 0.83), Northwest male (n=4, 1.50), Great Lakes female (n=141, 1.41), Great Lakes male (n=149, 1.78), New England female (n=11, 1.85), New England male (n=19, 2.57), Canadian Maritimes female (n=14, 3.60), Canadian Maritimes male (n=13, 3.45).  The following mean Hg concentrations (mg/g fresh weight) were found in feather samples: Alaska female (n=14, 5.2), Alaska male (n=9, 5.6), Northwest female (n=6, 8.3), Northwest male (n=4, 9.9), Great Lakes female (n=174, 9.6), Great Lakes male (n=196, 13.0), New England female (n=15, 10.2), New England male (n=20, 15.4), Canadian Maritimes female (n=8, 10.9), Canadian Maritimes male (n=9, 10.3).  Adult and offspring blood Hg concentrations were correlated and exposure in adults and juveniles significantly increased from western to eastern North America. The geographic order and significant differences of the 5 study regions were identical for both adults and juveniles. A significant difference was found between blood and feather Hg concentrations between sexes, males having higher concentrations, and adults had significantly higher Hg concentrations than juveniles in both blood and feathers.

     19.

Blood and feather samples were collected from common loon families (mating pairs and chicks) in south-central Ontario, Canada during July 25 and August 7, 1992 (Scheuhammer et al., 1998a). The following mean Hg concentrations were found: Adult blood (n=22, 2.06 mg/ml), chick blood (n=35, 0.142 mg/ml), adult feather (n=20, 13.3 mg/g dry weight), chick feather (n=17, 2.32 mg/g dry weight). Adult males had significantly greater Hg concentrations in blood and feathers than their mates (adult females), these differences being related to the male’s larger size. Chick blood Hg concentrations were significantly correlated with that of their parents, with adults having about an order of magnitude higher concentrations. Blood and feather Hg concentrations were significantly correlated in both adults and chicks.  In addition, a significant positive correlation was found between adult blood Hg and fish Hg, and between chick blood Hg and fish Hg (fish are those known to be eaten by the loons).

20.

Livers were collected from common loons that had ingested lead sinkers and found dead or moribound throughout New England (Pokras and Chafel, 1992).  The mean Pb concentration for the livers of loons ingesting sinkers was 11.51 mg/g wet weight, and for those not ingesting sinkers was 0.06 mg/g.  

21.

Adult loons (n=99) and chicks (n=56) were captured from 45 lakes during 1992 and 1993, each individually color marked with plastic leg bands, and blood and feathers were collected for Hg analysis (Meyer et al., 1998). Adult return rates to breeding territories and reproductive outcome were recorded for the 45 lakes from 1993 to 1996. The following four blood concentration ranges for adult loons reveal no significant differences in return rates to territorial breeding sites (Number of adults present/Number of adults absent): A) 0.55 to 0.90 mg/g (15/6), B) 0.91 to 1.34 mg/g (15/6), C) 1.35 to 1.85 mg/g (17/4),  D) 1.86 to 4.20 mg/g (15/5).  The following four feather concentration ranges for adult loons show no significant differences in return rates to territorial breeding sites (adults present/adults absent): A) 3.0 to 9.6 mg/g (16/4), B) 9.6 to 11.0 mg/g (14/6), C) 11.0 to 13.0 mg/g (14/6), D) 13.0 to 21.0 mg/g (13/6). Chick blood Hg concentrations are nearly an order of magnitude less than those of adults. There was a significant negative linear relationship between lake pH and log (adult blood Hg) for both males and females, but the same relationship was not observed with log (adult feather Hg).

22.

Kidney samples from common loons found dead or moribund were collected between August 1992 and November 1995 from Nova Scotia, New Brunswick, and Prince Edward Island (Daoust et al., 1998). The following Hg concentrations (mg/g wet weight) were found: Emaciated birds (n=23, 18.80), Healthy birds (n=8, 3.07). One immature loon with encephalitis had a concentration of 0.85 mg/g Hg in a brain sample. The average amount of renal Hg in emaciated loons of all ages was significantly higher than in healthy loons of all ages. In ten emaciated loons for which data were available, concentrations of Hg were significantly higher in kidneys (28.8 mg/g) than brain (1.13 mg/g). Six loons in poor body condition had renal concentrations of Pb compatible with poisoning (91.6 mg/g), and gizzards of four of these birds contained remnants of Pb sinkers. Renal Pb concentrations in other emaciated birds and eight healthy birds were below detection limit, save for one emaciated adult loon with 0.6 mg/g Pb in liver.

23.

In April 1993 adult common loons (n=23) were found dead in North Carolina (Spitzer, 1995).  The liver contained a geometric mean of 10.9 mg/g Hg and 10.4 Se (n=15). The concentration of Hg exceeded 20 mg/g in 6 of 23 samples and exceeded 30 mg/g in 3 samples. 

24.

In April 1993 adult common loons recovered dead as part of a large die-off in North Carolina were analyzed for metal contamination from liver and feather samples and compared to reference samples from loons collected from the same area in 1993 and 1994 with known causes of death (Augspurger et al., 1998).  The following geometric mean concentrations (mg/g wet weight) were found in liver samples: 1993 Die-Off: Hg (n=23, 10.9), Se (n=15, 10.4), As (n=15, 0.96), Pb (n=15, <0.10);  Reference: Hg (n=10, 8.25), Se (n=10, 6.80), As (n=10, 0.63), Pb (n=10, <0.15).  The Hg content of feathers was 5.44 (n=23) and 9.66 (n=10). Selenium concentrations from die-off specimens were significantly higher than reference loons and the Hg concentrations in feathers were significantly lower in die-off birds than in reference loons. Liver Hg significantly correlated with liver Se. 

25.

Feathers were collected from adult (n = 15) and immature (n= 13) common loons found dead in Maine, Vermont and Massachusetts (Burger et al., 1994). The following arithmetic mean concentrations (ng/g dry weight) were (adult,immature): Pb (1314,1116), Cd (80, 83), Hg (20245, 9677), Se (1055, 1176), Cr (7600, 9242), Mn (2758, 1913), Cu (35066, 34723).  Adults had significantly higher concentrations of Hg than juveniles, and immature female loons had significantly higher Hg concentrations than males (12430 females, 7660 males).

26.

Common loon carcasses (n=85) were found dead and/or emaciated (n=50), or shot (n=35) for research projects, in Ontario, Quebec, and Atlantic Canada (Scheuhammer et al., 1998b). The following mean concentrations (mg/g dry weight) were found: Kidney Hg (15, n=31), Liver Hg (19, n=30), Breast muscle Hg (2.9, n=36), Kidney Se (15, n=31), Liver Se (15, n=30), Breast muscle Se (2.8, n=36). Liver generally had the highest total Hg concentrations followed by kidney, thenh breast muscle. Selenium concentrations were similar in kidney and liver tissues and in breast muscles were lowest. Mean total Hg and Se concentrations were significantly higher in tissues of emaciated loons than in tissues of apparently healthy birds.

B.

Concentrations in eggs

1.

Between 1968 and 1980, 98 common loon eggs were collected from active nests at locations in Ontario, Canada (Algonquin, Kinoje Lake, Algonquin Parry Sound (Frank et al., 1983). The following are the years and mean Hg concentrations (mg/g wet weight): 1970, n = 34, (0.92); 1972, n = 15, (1.11); 1978, n = 12, (0.81).

2.

Common loon eggs were collected from 1974 to 1976 at various lakes in northwestern Ontario, Canada (Barr, 1986). The 34 lakes within the Wabigoon-English River watershed, were grouped in 4 classes according to proximity to Hg contamination sources. C1 lakes are directly downstream of Hg contamination source, C2 lakes are not within the flow of contaminated waters but contain contaminated fish, C3 are upstream of the contamination source, and C4 are independent, control lakes. The following concentrations of total Hg and MeHg (mg/g wet weight) were found in the eggs listed as (Hg/MeHg): C1 lakes (n=5, 1.39/1.34), C2 lakes (n=6, 0.72/0.71), C3 lakes (n=10, 0.54/0.53), C4 lakes (n=13, 0.59/0.58). A significant correlation was found between total Hg concentrations in the brains of nesting females and their eggs. Almost 100% of the Hg transferred from adult loons through eggs to chicks was organic, with no net loss of MeHg in chick tissue to suggest effective demethylation by the developing embryo. Concentrations of MeHg in eggs and in the brain of newly hatched chicks frequently exceeded concentrations in the female parent’s brain.

3.

From 1974 to 1975 common loon eggs (n=31) were collected from Hanson Lake, Saskatchewan (Fox et al., 1980).  The geometric mean Hg concentration found was 0.35 mg/g wet weight. This value was compared with 0.26 mg/g Hg, found in 7 eggs from Ontario, Canada.

4.

Non-viable common loon eggs were collected from 15 locations on six New Hampshire lakes and from 28 lakes in the Adirondacks of New York from 1978 to 1986 (McIntyre et al., 1992). The following mean concentrations (mg/g wet weight) were found and are listed in the order of years (1978 n=10, 1979 n=5, 1980 n=3, 1982 n=2, 1983 n=5, 1984 n=12, 1985 n=14, 1986 n=9): Al (0.32, NA, 0.34, 0.22, NA, 0.73, 0.56, ND) ; Cr (0.05, NA, 0.08, 0.27, NA, 0.08, 0.08, 0.02) ; Cu ( 1.13, NA, 0.74, 1.11, NA, 1.25, 1.41, 0.90) ; Fe (30.36, NA, 19.69, 17.32, NA, 23.71, 29.41, 30.88) ; Hg (1.53, 0.64, 0.84, 0.63, 0.75, 0.86, 0.62, 1.18) ; Mg (150.05, NA, 79.01, 121.47, NA, 144.42, 160.87, NA) ; Se (0.98, NA, 0.59, 0.74, 0.28, 0.96, 0.87, 0.82) ; Zn (11.86, NA, 8.20, 13.16, NA, 13.54, 15.79, 12.55)

5.

Non-viable common loon eggs were collected from Stillwater reservoir, New York  from 1978 to 1986 (McIntyre et al., 1992).  The following mean concentrations (mg/g wet weight) were found and listed as (1978 n=8 / 1986 n=9): Al (0.32 / ND); Cr (0.05 / 0.02); Cu (1.11 / 0.90); Fe (32.32 / 30.88); Hg (2.14 / 1.18); Mg (168.73 / NA); Se (1.00 / 0.82).  Individual total mercury concentrations were found as follows: 1978 (1.70, 2.00, 2.20, 2.80, 2.60, 2.40, 1.60, 2.10); 1980 (1.80, 1.50, ND); 1982 (0.63); 1984 (1.40, 1.40); 1985 (1.20, 1.40); 1986 (0.89, 1.15, 0.76, 2.06, 1.42, 1.05, 1.19, 1.01, 1.54).

6.

Failed eggs were collected from New Hampshire common loon nests in 1979 (n=15) and 1981 (n=21) (Haseltine et al., 1983). The following geometric mean concentrations (mg/g wet weight) were found, listed in order of (1979, 1981): Pb (0.22, NA), Zn (7.2, NA), Cd (ND, NA), Cr (0.15, NA), Hg (0.44, 0.53), Se (0.42, NA)

7.

Common loon eggs (n=12) collected at Turtle-Flambeau Flowage in Iron County, Wisconsin from 1986 to 1987 contained 0.64 mg/g wet weight Hg (Belant and Anderson, 1990).

IV.

Petroleum

1.

In March 1937, a 2.7 million gallon crude oil spill occurred just outside of the Golden Gate, San Francisco from the tanker Frank Buck (Moffitt and Orr, 1938).   Subsequently, three oiled common loons were found alive at Tomales Bay which was unaffected by the spill. It was reasoned that these loons flew in from a contaminated area. Few loons were oiled within the 55 mile spill affected area from Pt. Reyes south to below Half Moon Bay, mainly owing to their protected estuarine habitat. In Bolinas Bay, however an uncounted number of loons were observed among a group of beached seabirds severely oiled and struggling to clean themselves. On March 23 two common loons were among the dead oiled birds found and counted at Bolinas Bay.

2.

During early March 1956 the mortality of seabirds per lineal mile caused by oil pollution was monitored along measured parts of the western beaches of the Avalon Peninsula, Newfoundland (Tuck, 1960). Oiled common loons were found at Angels Cove at the measure of 8 loons per lineal mile. These loons represented 2% of all seabirds found dead and oiled at Angels Cove.

3.

On September 6, 1956 the freighter Seagate ran aground on rocks near Pt. Grenville, Washington spilling fuel oil (Richardson, 1956). Stretches of beaches between Grays Harbor and Ruby Beach were examined for oiled birds. Only two oiled common loons were found, one of which had a broken wing and was severely oiled. Inspection of the digestive tracts of the loons revealed internal oiling, i.e. oil-stained gizzards and oily masses in the intestine. 

4. 

On 18 March 1967 the MV Torrey Canyon ran aground near western England spilling crude oil (Bourne, 1967). Of the thousand of seabirds killed as a result of oiling from this spill,19 oiled common loons were recovered and taken to stations for cleaning and rehabilitation. 

5.

A crack developing in the hull of the Tank Duchess allowed 87 tons of Venezuelen crude oil to be released in the Tay Estuary, UK on February 29, 1968 (Greenwood and Keddie, 1968). Of the 1300 birds killed by oiling, 5 common loons were found dead near the Fife ness.

6.

On April 30, 1969 the tanker Hamilton Trader released about 700 tons of heavy fuel oil into Liverpool Harbor, England after a collision (Hope-Jones et al., 1970).  Among approximately 2,400 oiled seabirds found (both alive and dead) there was only a single common loon, which was found dead.

7.

During the winter of 1969-1970 among frequent oil spills noted in Florida was a spill near Tampa Bay where the species killed in greatest number from oiling included ‘many hundreds’ of common loons (Stevenson, 1970). One observer noted that there were few, if any, survivors among the many birds captured, washed, and released.

8.

From 1970 to 1994 common loons found dead (n=434) on beaches of Florida were examined for cause of death (Forrester et al., 1997). Oiling was the second most important mortality factor and affected loons from both Atlantic (n=71) and Gulf Coasts (n=5). The majority (n=69) of the oiled loons were found on beaches between St. Augustine and Flagler Beach, the consequence of an offshore oil spill from an unidentified source in January of 1974. 

9.

On February 4, 1970 the tanker Arrow ran aground in Chedabucto Bay, Nova Scotia spilling 2.5 million gallons of Bunker C fuel oil, of which 450,000 gallons came ashore in the bay (Brown at al., 1970). Oiled common loons were found between February 9 and 16 at Chedabucto Bay (n=1), and also between March 11 and 13 (n=1) and May (n=4) at Sable Island. The estimated minimum mortality caused by the oil slick was 2300 birds (non-specific) at Chedabucto Bay and 4800 birds (non-specific) at Sable Island. On February 14, the oil barge Irving Whale spilled between 3,000 and 7,000 gallons of Bunker C fuel oil off the SE coast of Newfoundland. Slicks from this spill caused a minimum estimated mortality of 7000 birds (non-specific). Only 2 oiled common loons were found on beaches in Newfoundland following the spill.

10.

Two tankers collided in the mouth of San Francisco Bay on January 18, 1971 spilling 840,000 gallons of bunker C fuel oil (Smail et al., 1972). This oil spread over 17 miles out to sea and along the coast from Drake’s Bay south to Pt. Ano Nuevo during the following days.  An estimate of 6,000 oiled birds passed through cleaning stations, while an estimated minimum mortality of 20,000 birds may have resulted. Birds were censused at four cleaning stations along the coast of California. The following are numbers of oiled common loons delivered to the stations: Bolinas 10, Tiburon 9, Pacifica 9.  

11.

During a study of the causes of mortality of 105 common loons found from 1972 to 1999 in New York one oiled common loon was found dead (Stone and Okoniewski, 2001).

12.

A survey of beached birds along the Atlantic and Gulf coasts of North America from December 1975 to November 1983 revealed that 17.7 % of dead common loons found were oiled (Simons, 1985). Of the 789 common loons found dead on the beaches, 140 were oiled.

13.

At least 4572 seabirds were confirmed killed by oiling as a result of the super-tanker ‘Amoco Cadiz’ oil spill (220,000 tons of light Iranian and Arabian crude oils) in northwest France and the Channel Islands in March 1978 (Hope-Jones et al., 1978). Among the 33 species affected, the following numbers of oiled common loons, both dead and alive, were observed in the areas listed: Finistere north (43), Cotes du Nord (9), Manche west coast (0), Channel Islands (14). These 66 loons represented close to one fifth of the 300 breeding pairs in the Palearctic region at that time.

14.

A spill of 1,174 tons of heavy fuel oil from the tanker ‘Esso Bernicia’ at the Sullom Voe oil terminal (Shetland Isles, UK) on 31 December 1978 polluted an estimated 105 km of the shoreline of Sullom Voe and Yell Sound (Heubeck and Richardson, 1980). Over 3,702 birds of 49 species were killed and particularly affected were six species including 149 common loons found dead and oiled.

15.

A continuous survey of 665 km of German North Sea coastline was conducted from August 1983 to April 1986 focusing on oiled birds (Vauk et al., 1989). During the survey a single common loon was found dead without external oiling, but had internal oiling where the stomachs and intestines were filled with a brownish-black viscous substance identified chemically as oil and oil derivatives picked up from feathers during preening. An oil spill on January 3, 1986 (300 tons of heavy fuel oil at entrance of Kiel Canal) was estimated to have greatly impacted the survey, though no formal estimate of losses from this spill was computed. 

16.

On 19 March 1984 the tanker Mobiloil ran aground spilling 170,000 to 230,000 gallons of heavy residual oil, No. 6 fuel oil, and an industrial fuel oil into the Columbia River near St. Helens, Oregon (Speich and Thompson, 1987). Of the 450 live oiled birds retrieved from the vicinity of the spill, 2 or <1% of the total  were oiled common loons. Oiled birds retrieved during 23 March to 23 April 1984 were cleaned at a treatment center and 284 birds were released. Species identities of released birds were not recorded.

17.

On 21 December 1984 an unidentified vessel released around 5000 gallons of No. 6 fuel oil into Puget Sound near Whidby Island, Washington (Speich and Thompson, 1987).  Common Loons (n=10) were among over 447 oiled birds of various species retrieved and taken to a cleaning station.

18.

Approximately 148 common loons were among oiled seabirds found dead on beaches after the barge Apex Houston discharged up to 25,800 gallons of crude oil from Point Reyes to Monterey, California during February 1986 (Page et al., 1990). Between 1–8 February 1986, a total of 128 loons were found oiled, but alive and were taken to a cleaning station for treatment.

19.

Between August 1992 and November 1995, five severely oiled common loons were collected from maritime Atlantic provinces of Canada (Daoust et al., 1998). The five loons consisted of one adult male, two adult females, one immature male, and one immature female. 

20.

Approximately 15 miles of San Mateo County, California beaches were affected by the release of an estimated 3,000 gallons of Intermediate Bunker fuel oil from the M/T Command on September 26, 1998 (USFWS, 2002). A single oiled common loon was collected dead. 

Common Loon Contaminant Response Data

I.

Organochlorine Contaminants

A.

Eggshell thinning and reproduction

1.

Between 1968 and 1980, 98 common loon eggs were collected from active nests at locations in Ontario, Canada (Algonquin, Kinoje Lake, Algonquin Parry Sound) and analyzed for organochlorine residues and Hg (Frank et al., 1983). Eggshell thicknesses were also taken from eggs in 1978 and 1979-1980. The following mean thicknesses (mm) were found:  Pre-1947 (n = 39, 0.64);  1969 (n = 14, 0.54);  1970 (n = 34, 0.58).

2.

A common loon egg was collected from each of 15 clutches in the Lac La Biche- St. Paul region of Alberta, Canada during 1972 (Vermeer, 1973).  Individual eggshell thickness measurements for the fifteen eggs (in microns) were: (594, 529, 582, 435, 561, 636, 617, 579, 607, 544, 581, 635, 577, 549, 565).  No correlation was found between DDE concentrations and shell thickness in the common loon eggs.

3.

From 1974 to 1975 common loon eggs (n=31) were collected from Hanson Lake, Saskatchewan (Fox et al., 1980).  There was a negative correlation between eggshell thickness and DDE content; however, the mean thickness of these loon eggs was not significantly different from archived eggs dating back to pre-1947. In addition, of 200 loons nesting on the lake studied for breeding performance, no relationship was found between reproductive performance and concentrations of DDE, dieldrin, PCBs or Hg,.

4.

Common loon eggs (n=51) from 3 New Hampshire lakes were collected from 1975 to 1976 after they had either been abandoned following disturbance, abandoned  after prolonged incubation, or knocked into the water by an incubating adult (Sutcliffe, 1978). The geometric mean value of shell thicknesses of all 51 eggs was 0.58 mm. Of the 51 eggs collected, 14 were measured for shell thickness and egg contents analyzed for organochlorines  (mg/g wet weight) with the following geometric means recorded: Thickness (0.59), DDE (5.88), DDT (2.44), dieldrin (0.105), PCB total (24.6), DDD (<0.05), PCB as arochlor 1254 (n=8, 18.30). Both DDT and DDE residue concentrations were significantly correlated with shell thickness.

5.

Non-viable common loon eggs were collected from Stillwater reservoir, New York from 1978 to 1986 (McIntyre et al., 1992). Eggshells had a mean thickness of 0.598 mm (n=56). A trend in lower organochlorine levels at Stillwater reservoir between 1978 and 1986 was reflected in thicker eggshells, although, due to small sample size, a significant relationship between organochlorine residue concentrations and shell thickness was not shown. However, pooled shell thickness were significantly thinner than pre-1946 shells measured in a separate study.

6.

A study of contaminants from failed loon eggs collected in 1979 (n=15) and 1980 (n=21) and productivity of common loon nests revealed that organochlorine contaminants did not seem, at that time frame, to have an effect on loon survival or productivity (Haseltine et al., 1983).

7.

Failed eggs werevcollected from New Hampshire common loon nests in 1979 (n=15) and 1981 (n=21) (Haseltine et al., 1983). The two principal contaminants of loon eggs, DDE and PCBs, decreased significantly between sampling periods. Mean eggshell thicknesses of 0.66 mm in 1979 and 0.65 mm in 1981 were comparable to pre-DDT shell thicknesses from the same region.

B.

Biochemical and Morphological Responses

1.

A moribund common loon (female, subadult weighing 4 lbs.) was found in Madison County, Mississippi in December 1973 (Prouty et al., 1975). After dying, the loon was found to have 1400 mg/g wet weight DDD in carcass and 200 mg/g in whole brain. The cause of death was presumed to be DDD poisoning based on earlier studies showing that DDD residues of > 65 mg/g in brains of cowbirds caused death.

II.

Cholinesterase-Inhibiting Pesticides

No response data available

III.

Trace Elements, Metals, and Metalloids

1.

Common loons and their eggs collected from 1974 to 1976 at various lakes in northwestern Ontario, Canada were analyzed for total Hg and MeHg contamination, the lakes were examined for physical characteristics, and the breeding success for the residing loons was investigated (Barr, 1986). The 34 lakes sampled within the Wabigoon-English River watershed were grouped in 4 classes according to proximity to Hg contamination sources. There was a strong negative correlation between the successful use of territories by breeding loons and levels of Hg contamination in lakes for 160 km downstream from the source of industrial pollution on the Wabigoon River. The correlation was weaker beyond 160 km downstream, being masked by deleterious effects of extensive, unpredictable water-level changes and turbidity. However, prey species and loons and their eggs from this area contained concentrations of Hg high enough to result in reduced egg production, physical and behavioral dysfunction, and increased mortality. Reductions in egg laying, and in nest site and territorial fidelity were associated with mean Hg concentrations ranging from 0.3 to 0.4 mg/g in prey, and from 2 to 3 mg/g in adult loon brain and loon eggs. Loons established few territories, laid only one egg, and raised no progeny in waters where mean contamination of small prey species exceeded 0.4 mg/g. 

2.

No significant correlation was found between Hg contamination in failed loon eggs collected in 1979 (n=15) and 1980 (n=21) and loon productivity (Haseltine et al., 1983).

3.

Of 31 adult loons (17 female, 13 male, 1 unknown) collected in New England from 1989 to 1990, Pb toxicosis from the ingestion of fishing sinkers and hooks caused deaths of 9 males, 6 females, and the one unknown loon (Pokras et al., 1991). The livers of adult loons that had ingested Pb sinkers were analyzed and found to have a concentration range between 5 to 18 mg/g wet weight. Of loons analyzed for blood lead content, birds without ingestion of lead sinkers ranged from 0.01 to 0.05 mg/g. One loon that ingested a Pb sinker had 0.78 mg/g Pb in the blood sample.

 4.

During the 27-year period investigated (1972-1999), 22 of 105 common loons recovered had ingested Pb fishing sinkers and the subsequent Pb poisoning was determined to be the cause of morbidity of a number of these loons (Stone and Okoniewski, 2001). The hepatic Pb concentrations of these loons often exceeded the 5 to 6 mg/g diagnostic thresholds for lethality in waterfowl. Some values of Pb (mg/g) in livers of loons with ingested Pb fishing sinkers that had died of Pb toxicosis were given as: 3.24, 4.18, 1.57, 4.9.  The geometric mean of lead in livers of common loons without indication of ingestion of Pb fishing sinkers was 0.07 mg/g.  

5.

From 1976 through 1991, 222 common loon carcasses were examined at the National Wildlife Health Research Center, Madison, Wisconsin to determine cause of death (Franson and Cliplef, 1992). Lead toxicosis was determined to be the cause of death of 14 loons, all of which were emaciated or in poor body condition. Fishing weights (Pb) were found in the stomachs of 11 of the 14 loons. Liver Pb concentrations for the 14 loons ranged from 4.7 to 46.1 mg/g wet weight.  

6.

Liver and kidney from common loons submitted to Rose Lake Wildlife Research Center between 1988 and 1992 were analyzed for 23 metals (Poppenga et al., 1992). Based on post mortem examinations and tissue Pb concentrations, 15 of 38 loons died from Pb intoxication, primarily due to ingestion of Pb objects. Tissue Hg and Se concentrations were also elevated in a large percentage of loons. There was a significant positive correlation between tissue Pb and Hg concentrations in both liver and kidney samples. It is hypothesized that elevated tissue Hg concentrations result in sublethal neurotoxic effects that alter normal loon behavior and predispose affected birds to lethal Pb intoxication secondary to ingestion of Pb objects.

7.

Common loons (n=124) found dead or moribund from 1989 to 1992 throughout New England were examined for trace element and metals (Pokras et al., 1992).  Liver and bone Pb concentrations were compared for 8 loons as follows (liver Pb / bone Pb): Loons with Pb toxicosis n = 5, (13.20 / 22.50) (11.60 / 16.42) (10.60 / 19.09) (15.80 / 9.64) (11.40 / 8.11).  Loons without Pb toxicosis n = 3, (22.60 / 0.77) (<0.49 / 0.60) (<0.49 / 1.25).  Loons diagnosed with Pb toxicosis (n=13) were further evaluated and the following symptoms were listed: Clinical signs for a few birds (birds appeared to wretch or vomit, fishing line protruding from mouth, head tilt or ‘kinked neck’, convulsions, green stained vent area, emaciation), Clinical signs for more than 25% of birds: (Depression and coming onto land for rest, weakness and the inability to fly or escape, gaping and open mouth breathing), Radiographic signs include: (Increased density of air sacs in a few birds, enlarged cranial digestive tract silhouette in proventriculus and esophagus in more than 25 % of birds, and round or oval metallic density objects in gizzard seen in more than 90% of birds). Gross necropsy findings in a few birds: (Fluid in pericardium, decrease or absence of abdominal fat, swollen pancreas, enlarged spleen, granulomatous air sac thickening). Gross necropsy findings in 25 % of birds: (Digestive tract distended with food from pylorus cranially, and enlarged gall bladder). Small, well worn or disk-like lead in gizzard was seen in over 90% of birds. Histopathic necropsy findings for a few birds: (splenic hemosiderosis, and Aspergillus air saculitis. More than 90 % of birds showed moderate to severe hemosiderosis of hepatic Kupffer cells. 

8.

Adult loons (n=99) and chicks (n=56) were captured from 45 lakes during 1992 and 1993, each was individually color marked with plastic leg bands, and blood and feathers were collected for Hg analysis (Meyer et al., 1998). Adult return rates to breeding territories and reproductive outcome were recorded for the 45 lakes from 1993 to 1996. No relationship was observed between levels of adult Hg exposure and annual return rates or reproductive performance. Chick blood Hg concentrations explained 29 % of the variability in loon productivity on 26 study lakes from 1993 to 1996. Fewer chicks hatched or survived to 8 weeks of age on lakes where elevated chick blood Hg concentrations were measured. However, we found no evidence of a relationship between adult Hg exposure and reproductive performance. Adult loons with elevated blood or feather Hg concentrations were as likely to raise chicks to 8 weeks of age as were loons with low Hg exposure.

9.

Common loon eggs (n=14) were taken from abandoned nests within a study area of northern Wisconsin from 1992 to 1993 (Meyer et al. 1998). The range of Hg concentrations found within Wisconsin loon eggs (range, 0.5 to 1.6 mg/g fresh weight, mean 0.9 mg/g) is comparable to levels associated with reduced hatching success or reduced survival of embryos or hatchlings in pheasants and in Ontario loons. Chick production was lower at lakes where chick blood had elevated Hg concentrations, a negative linear relationship was found between chick blood Hg and the number of chicks surviving > 8 weeks for a three year period of 1993 to 1996.

10.

Blood samples from common loon chicks and adults collected from 11 territories within Kejimkujik National Park, Nova Scotia, Canada and the Lepreau watershed, New Brunswick, Canada were analyzed for Hg and behavioral observations were made on these loons from May to September in both 1996 and 1997 (Nocera and Taylor, 1998). During observations, time activity budgets were collected and event behavior recorded to catalog pre-/post-hatch and pre-/post-nesting behavioral states of 12 breeding pairs. The blood samples were taken from chicks from 6 of the 11 territories and from adults at 7 of the 11 territories. A set of analysis on TABs of chicks at all developmental stages revealed a relationship between Hg burdens in chick blood (0.15 – 1.29 mg/g) and TABs patterns of downy young <12 days old. Additional analyses show that this was manifest as a significant negative effect of chick blood Hg burden on time spent by chicks in back-riding, i.e. brooding by riding on parents back, and a positive effect on time spent preening. Loon chicks with the highest Hg exposure (1.29 mg/g) spent no time being brooded by parents.

IV.

Petroleum

1.

In early February 1986 the oil barge Apex Houston lost about 20,000 gallons of San Jaoquin Valley crude oil while under tow off the central California winter feeding grounds of the common loon and other sea-birds (Fry and Addiego, 1987). It is estimated that more than 10,000 birds were affected by the oil spill, including 3 individual common loons treated at a rehabilitation center and whose blood was monitored with the following mean values: hematocrit 39% mean with a range of 30 to 40%, and total plasma protein mean value of 3.2 gm/dl with a range of 1.7 to 4.7 gm/dl.  These blood values represent a condition of hemolytic anemia, which is associated with ingestion of oil.