Tree Swallow Contaminant Exposure Data

I.

Organochlorine Contaminants

1.

Eggs and nestlings were collected from several locations in Alberta, Canada in 1978 and 1979 (Shaw, 1984). In 1978, mean DDE concentration was 1.01 mg/g wet weight in viable eggs, 2.23 mg/g in unhatched eggs, and 0.31 mg/g in nestlings. In 1979, mean DDE concentration was 0.94 mg/g in viable eggs, and 0.86 mg/g in unhatched eggs. In 1978, mean heptachlor epoxide concentration was 0.09 mg/g in viable eggs, 0.07 mg/g in unhatched eggs, and 0.02 mg/g in nestlings. In 1978, mean PCB concentration was 0.43 mg/g in viable eggs, 0.45 mg/g in unhatched eggs, and 0.07 mg/g in nestlings.

2.

Eggs from attended nests, eggs from abandoned nests, carcasses of nestlings, live breeding females, and carcasses of dead breeding females were collected from nest boxes near Denver, Colorado between 1977 and 1980 (DeWeese et al., 1985). Geometric mean residue of DDE was 1.30 and 2.80 mg/g wet weight in attended and abandoned eggs, respectively, 0.36 mg/g in dead nestlings, 4.40 and 7.90 mg/g in carcasses of live and dead females, respectively, and 0.76 and 1.3 mg/g in brains of live and dead females, respectively. Geometric mean residue of PCBs was 0.25 and 0.33 mg/g in attended and abandoned eggs respectively, ND in dead nestlings, 0.30 and 0.37 mg/g in carcasses of live and dead females, respectively, and ND in any brains. Geometric mean residue of other organochlorines was 0.06 and 0.07 mg/g in attended and abandoned eggs respectively, ND in dead nestlings, 0.11 and 0.57 mg/g in carcasses of live and dead females, respectively, and 0.11 mg/g and ND in brains of live and dead females, respectively. Geometric mean residue of total organochlorines was 1.80 and 3.30 mg/g in attended and abandoned eggs respectively, 0.36 mg/g in dead nestlings, 5.30 and 9.30 mg/g in carcasses of live and dead females, respectively, and 1.30 mg/g in brains of both live and dead females.

3.

Carcasses were collected from Oregon, Idaho, Montana, Wyoming, South Dakota, Utah, Colorado, and New Mexico in 1980 (Deweese et al., 1986). Mean contaminant concentrations were 14.3 mg/g wet weight DDE, 0.04 mg/g DDT + metabolites, 0.42 mg/g PCB,  0.12 mg/g oxychlordane, and 0.26 mg/g heptachlor epoxide.  Hexachlorocyclohexane was not detected.  Tree swallows had higher mean organochlorine contaminants than birds in other foraging niches. Male tree swallows had higher mean organochlorine contaminants than females.

4.

Eggs and nestlings were collected from a dredge disposal site and a reference site on the Fox River, Wisconsin in 1988 (Ankley et al., 1993). Mean residue of total PCBs was 4.12 and 2.49 mg/g wet weight respectively in eggs and nestlings from the reference site, and 2.97 mg/g in nestlings from the disposal site. Mean concentrations of PCB congeners in eggs at the reference site were 42,500 pg/g congener 77, 116,000 pg/g congener 105, 1,050 pg/g congener 126, and 78.7 pg/g congener 169. Mean concentrations of PCB congeners in nestlings from the reference site were 41,200 pg/g congener 77, 47,200 pg/g congener 105, 752 pg/g congener 126, and 18.0 pg/g congener 169. Mean concentrations of PCB congeners in eggs from the disposal site were 22,500 pg/g congener 77, 66,900 pg/g congener 105, 1,180 pg/g congener 126, and 54.0 pg/g congener 169. The range of PCDD residues was ND-140 pg/g in eggs from the reference site, 2.3-56.1 pg/g in nestlings from the reference site, and ND-71.4 pg/g in nestlings from the disposal site. The range of PCDF residues was ND-39.9 pg/g in eggs from the reference site, ND-26.4 pg/g in nestlings from the reference site, and ND- 23.7 pg/g in nestlings from the disposal site.

5.

Between 1988 and 1994, tree swallow eggs were collected from southern Ontario, Canada (Bishop et al., 2000). DDE concentrations in pooled tree swallow eggs from 9 orchards and 1 pasture (a total of 2,598 eggs) were: 2.56, 0.38, 0.45, 0.78, 2.06, 0.66, 0.43, 0.54, 1.86, and 0.59 mg/g wet weight. Total organochlorine (1245- and 1234-tetrachlorobenzene, pentachlorobenzene, α-, β-, and γ-hexachlorocyclohexane, heptachlor epoxide, oxychlordane, trans- and cis-chlordane, dieldrin, photomirex, mirex, DDE, DDD, DDT, o,p’-DDE, o,p’-DDD, o,p’-DDT, endosulfan, cis-nonachlor, and total PCBs) concentrations from the same ten locations were, respectively: 3.47, 0.74, 0.86, 1.34, 2.51, 1.36, 1.21, 0.91, 2.38, and 0.98 mg/g. PCB concentrations were between 0.27 and 0.71 mg/g.

6.

Eggs and nestlings from the Fox River area and Green Bay, Wisconsin were analyzed for total PCBs and bioassayed for TCDD-EQ in 1989 (Jones et al., 1993). In addition, TCDD-EQs were also calculated for each sample based on three different toxic equivalency factors. Residue of total PCBs in a composite egg sample was 10.8 mg/g wet weight, TCDD-EQ determined by H4IIE bioassay for this sample was 170 ng/kg, and the calculated TCDD-EQs were 692, 30.3, and 67.3 ng/kg. Residue of total PCBs in a composite nestling sample was 11.3 mg/g, TCDD-EQ determined by H4IIE bioassay for this sample was 116 ng/kg, and the calculated TCDD-EQs were 430, 299, and 45.0 ng/kg. Residue of total PCBs in a carcass of an older chick was 13.1 mg/g, TCDD-EQ determined by H4IIE bioassay for this sample was 28.2 ng/kg, and the calculated TCDD-EQs were 552, 20.1, and 33.6 ng/kg.

7.

Eggs were collected from birds nesting in boxes in orchards and non-orchard forest sites in British Columbia 1990 and 1991 (Elliott et al., 1994). Mean residues of DDE ranged from 6.61 to 11.2 mg/g wet weight in orchard habitats, and from 1.09 to 5.61 mg/g in non-orchard habitats. Mean residues of PCBs ranged from 0.16 to 0.25 in orchard habitats, and from 0.13 to 0.20 mg/g in non-orchard habitats. Mean residues of all other organochlorines were lower than 0.10 mg/g in both habitats.

8.

Eggs were collected from Wye Marsh, Lake Huron, Ontario in 1991 (Martin et al., 1995). Mean residue of DDE was 0.46 mg/g wet weight. Mean residue of total PCBs was 0.26 mg/g. Mean residue of oxychlordane, OCS, HCB, dieldrin, heptachlor epoxide, b-HCH, mirex, and trans-nonachlor were 0.02 mg/g.

9.

Eggs and nestlings were collected from 4 sites on the Saginaw River, Michigan in 1991 (Nichols et al., 1995). The ranges of mean residues of PCBs in eggs and nestlings respectively were 1,707-4,600 and 445-5,850 pg/g PCB congener 77, 19,390- 39,660 and 5,810-32,160 pg/g PCB congener 101, 14,755-37,437 and 5,703-36,204 pg/g PCB congener 118, 309-685 and 87-516 pg/g PCB 126, 33,550-73,555 and 5,133-36,298 pg/g PCB congener 180, and 563-1,373 and 171-1,027 ng/g total PCBs.

10.

Eggs and nestlings were collected from several sites in the Great Lakes-St. Lawrence River basin in 1991 (Bishop et al., 1995). The ranges of mean organochlorine residues in eggs and nestlings respectively were 0.46-4.4 and 0.02-0.56 mg/g wet weight DDE, 0.01-0.06 and 0.004- 0.21 mg/g dieldrin, 0.01-0.04 and 0.002-0.12 mg/g heptachlor epoxide, 0.02-0.06 and 0.004- 0.11 mg/g oxychlordane, 0.01-0.04 and ND-0.003 mg/g mirex, and 0.25-4.0 and 0.01-0.75 mg/g total PCBs.

11.

Tree swallow eggs and nestlings were collected in 1992 from nests within the Saginaw Bay watershed in Michigan (Froese et al., 1998).  Mean PCB concentrations (summed) were similar in eggs (15.0 µg/g lipid weight, N=8) and nestlings (16.0 µg/g, N=14), and about one order of magnitude greater than total organic carbon-normalized PCB in sediments.  Concentrations of 14 individual PCB congeners were determined in both tissues.  Concentrations of PCB 136 and 138 were highest in both eggs (2500 and 730 ng/g, respectively) and nestlings (920 and 980 ng/g).  Concentrations of other PCB congeners ranged from 9-560 ng/g in eggs and 10-870 ng/g in nestlings.  Mean TEQs were 0.09 ng/g lipid weight in eggs and 0.11 ng/g in nestlings.  Results indicate that patterns of relative concentrations of PCB congeners change from eggs to nestlings, but if biota-sediment accumulation factors (BSAF) are based only on non- and mono-ortho-substituted PCB congeners or TEQs, calculated BSAFs are similar to those predicted by fugacity theory.

12.

Tree swallow eggs and nestlings were collected from seven sites along the St. Lawrence River and lower Great Lakes from 1992-1995 (Bishop et al., 1999).  Concentrations of organochlorine and chlorobenzene compounds were very low or below detection limits at all sites, with the exception of PCBs and DDE.  Mean concentrations in nestlings ranged from 0.0376-5.469 µg/g wet weight for PCBs and 0.0272-1.484 µg/g for DDE.  In eggs, mean concentrations ranged from 0.256-11.168 µg/g for PCBs and 0.625-2.567 µg/g for DDE.

13.

Eggs were collected from 4 sites on the upper Hudson River, New York in 1994 and 1995, analyzed for organochlorine residues, and TEQs were calculated based on three different toxic equivalency factors (Secord and McCarty, 1997). Mean total PCBs ranged from 4.60 to as much as 44.0 mg/g wet weight. Organochlorine pesticides were ND. Mean PCDD ranged from 0.20-38.0 pg/g, depending on sample site and congener. Mean PCDF ranged from 0.20-29.0 pg/g, depending on sample site and congener. The 3 TEQs ranged from 13-1,390 ng/g, 48-9,060 ng/g, and 36-11,100 ng/g respectively, depending on sample site.

14.

Eggs, nestlings, and adults were collected along the Hudson River, New York, between 1994-95 (Secord et al., 1999).  Mean total PCBs, at contaminated sites and at a references site on the Champlain Canal, respectively, were 9.32-29.5 µg/g wet weight and 5.94 µg/g in eggs, 3.71-62.2 µg/g and 0.72 µg/g in nestlings and 114 and 22.2 µg/g in one adult.  Mean TEQs in contaminated sites and references sites, respectively, were 1,730-12,700 pg/g and 3,060 pg/g in eggs, 1,370-25,400 pg/g and 410 pg/g in nestlings, and 57,400 and 13,200 pg/g in adults. PCB congeners 77, 81, 126, 169, 105, 118, and 156 were detected at all sites in eggs, nestlings, and adults.  Concentrations of these congeners were lower in nestlings and adults from the reference site than from the study sites, and were similar in eggs from the reference site and one study site, but lower than at two other study sites.  PCB 118 occurred at the highest mean concentration of any congener at 656 ng/g at one study site and 254 ng/g at the reference site in eggs, 1,630 ng/g at one study site and 43.1 ng/g at the reference site for nestlings, and 6,670 ng/g at one study site, and ng/g at the reference site for adults.

15.

Pipping embryos and nestlings were collected from artificial nest boxes at two polluted sites in the Fox River and Green Bay areas of Wisconsin, and from two reference sites between 1994-95 (Custer et al., 1998).  Mean DDE, at polluted and reference sites, respectively, ranged from 0.19-0.20 and 0.11-0.15 µg/g wet weight in embryos and 0.07 µg/g and 0.02-0.03 µg/g in nestlings.  Mean total PCBs ranged from 3.10-3.24 and 0.29-0.77 µg/g in embryos and from 1.87-3.29 and 0.19-0.20 µg/g in nestlings. PCB congeners 77, 105, 114, 118/106, 126, 128, 138, 156, 157, 158, 166, 167, 169, 170, and 189 were detected in embryos and nestlings from both sites.  Mean concentrations of almost all congeners were higher in embryos and pooled nestling samples from the polluted sites. PCB congener 118/106 was found in the highest mean concentrations, ranging from 68-98 and 9.24-18.6 ng/g in embryos from the polluted and reference sites respectively, and from 42-95 and 3.35-10.9 ng/g in pooled nestlings.  Mean TEQ (Kennedy) ranged from 332-589 and 85-106 ng/g in embryos and from 163-460 and 23-92 µg/g in pooled nestlings. Mean TEQ (Safe) ranged from 127-214 and 29-36 ng/g in embryos and from 62-172 and 8-31 ng/g in pooled nestlings.

16.

Tree swallow eggs were collected from pesticide-treated (4 sites) and unsprayed (3 sites) apple orchards in southern Ontario, Canada, between 1994-1997 (Bishop et al., 1998a).  Mean concentrations of DDE and total PCBs ranged from 0.36-2.29 µg/g wet weight and 0.27-2.29 µg/g, respectively, and did not vary significantly among sites.  Concentrations of all other pesticides were low (<0.06 µg/g) and did not vary among sites.

17.

From 1995-97, tree swallow eggs (4-8 per location) and nestlings (3-37 per location) were collected from six sites in Pennsylvania, two sites in Indiana, one site on the Hudson River, and a reference site in Maryland (Yorks, 1999).  Mean PCB concentrations in eggs and nestlings, respectively, were 0.9483 and 0.169 ug/g at Blue Marsh Lake, PA; 2.6 and 2.183 ug/g at the Texas Eastern Transmission Corporation in Bechtelsville, 1.8875 and 0.911 ug/g at Valley Forge National Historic Park, PA; 2.8667 and 0.743 ug/g at John Heinz National Wildlife Refuge, PA; 4.600 and 1.446 ug/g at Fort Mifflin, PA; and 0.6950 and 0.294 ug/g at the reference site at the Patuxent Wildlife Research Center.  One egg collected from the Texas Eastern Transmission Corporation in Bernville contained 9.7 ug/g PCBs.  Nestlings only were collected from other locations, with mean PCB values of 0.1305 ug/g at Goose Pond, IN; 18.46 ug/g Winston-Thomas sewage treatment plant near Bloomfield, IN; and 13.27 ug/g near Fort Edward on the Hudson River.

18.

In April 1993 and 1994 tree swallow nest boxes were set up above and below bleached kraft pulp mills that had ceased using Cl bleach in the 1990s at two locations in British Columbia, Canada: on the Fraser River and its tributaries, and on the Thompson and South Thompson Rivers (Harris and Elliott, 2000).  Nestlings (16-days-old) were collected, pooled, and homogenized (minus feathers, beaks, and feet) for each of the 4 sites.  The I-TEQs (ng/kg wet weight) for downstream and upstream nestling pools, respectively, were 11.9 and 1.9 on the Fraser River, and 15.2 and 5.3, Thompson River.  Concentrations of other contaminants, for downstream and upstream nestling pools in the Thompson River, and downstream and upstream pools in the Fraser River, respectively, were: DDD 0.9 and 1.9, <0.5 and <0.5 μg/kg; DDE 87.2 and 178.3, 164.9 and 90.2 μg/kg; dieldrin 1.2 and 0.8, 0.3 and 0.4 μg/kg; heptachlor epoxide <0.1 and 0.7, 1.1 and 0.4 μg/kg; HCB <0.5 and <0.5, <0.5 and 2.2 μg/kg; α-HCH 1.5 and 3, 1.6 and 3.1 μg/kg; γ- HCH 0.6 and <0.1, <0.1 and <0.1 μg/kg; cis-nonachlor 0.4 and 0.4, <0.1 and <0.1 μg/kg; oxychlordane 1.5 and 1.4, 1.5 and 1.3 μg/kg; tris(4-chlorophenyl)-methanol 0.6 and <0.05, <0/05 and <0.05 μg/kg; Aroclor 1260 27.7 and <0.1, 40.2 and <0.1 μg/kg; total PCBs 31.6 and <0.1,16 and <0.1 μg/kg; 1,2,3,4,6,7,8-HpCDD 1.93 and 2.2, 36.24 and 1.67 ng/kg; 1,2,3,4,6,7,8-HpCDF <1.46 and <1.87, 10.19 and <0.93 ng/kg; OCDD 2.37 and 2.69, 4.21 and 2.11 ng/kg; pentachlorophenol <1.0 and ND, 3.6 and <1.0 μg/kg; 1,2,3,7,8-PeCDD <0.69 and <0.84, 1.78 and <0.55 ng/kg; HxCDD 1.17 and <4.21, 11.14 and <1.8 ng/kg; 2,3,7,8-TCDF 3.17 and 1.29, 1.1 and 0.58 ng/kg; 1,2,3,6,7,8-HxCDF <0.73 and <0.72, 0.81 and <1.87 ng/kg; OCDF <1.51 and <2.55, 1.98 and <1.14 ng/kg; PCB-37 45.58 and 6.9, 5.64 and <2.81 ng/kg; PCB-81 3.06 and 0.92, 1.24 and <1.72 ng/kg; PCB-77 162.57 and 58.61, 79.82 and 17.67 ng/kg; PCB-126 35.44 and 9.49, 42.05 and 4.57 ng/kg; PCB-169 1.98 and 0.82, 2.81 and 1.04 ng/kg.  Of the 42 PCB congeners analyzed for total PCBs, only 101, 118, 138, 153, and 180 were detected.

19.

In 1998, tree swallow eggs (2-3 per clutch, pooled) and nestlings (12-16 days old) were collected from nest boxes on the Upper Mississippi River, Iowa (river miles 484-491), at Pigeon Creek (upriver reference site), Duck Creek (historic PCB source), and Lindsey Harbor (downstream of historic PCB source) (Custer et al., 2000).  Alpha-BHC, β-BHC, o,p’-DDD, o,p’-DDE, o,p’-DDT, and toxaphene were not detected in eggs or nestlings.  Alpha-chlordane, cis-nonachlor, mirex, p,p’-DDD, and p,p’-DDT were detected in fewer than 50% of samples, and all concentrations were < 0.07 µg/g wet weight.  Mean concentrations of total PCBs (0.28-0.54 µg/g wet weight),  p,p’-DDE (0.11-0.17µg/g), and dieldrin, oxychlordane, heptachlor epoxide, and trans-nonachlor (#0.07 µg/g for all 4) were at background levels in eggs.  Mean concentrations in eggs from Pigeon Creek and Lindsey Harbor, respectively, were 0.026 and 0.012 ng/g for 2,3,7,8-TCDD; and 0.14 and 0.22 ng/g for 2,3,7,8-TCDF.  Mean concentrations of total PCBs, p,p’-DDE, dieldrin, and heptachlor epoxide in nestlings were at or near background levels (#0.14µg/g).

20.

Nestlings from New York (N=178) and Wisconsin (N=35) were collected in 1998 (Stapleton et al., 2001). Total PCB concentration ranged from 7,600 –12,000 ng/g wet weight of body tissue in Hudson River sites. Two nestlings in Wisconsin had total PCB levels of 42 and 56 ng/g, proofing reference site.  No differences were found in swallow mutation rates in areas of relatively high or low PCB contamination.

II.

Cholinesterase-Inhibiting Pesticides

No direct exposure data available

III.

Trace Elements, Metals, and Metalloids

1.

Eggshells and embryos, and organs of pre-fledgling birds were collected from the Hackensack Meadowlands, New Jersey (Kraus, 1989). Mean concentrations of Cr, Ni, Cu, and Pb in eggshell were 174, 31.4, 2.40, 90.9, and 1.80 µg/g wet weight, respectively. Mean concentrations of Cr, Ni, Cu, and Pb in embryos were 42.2, 22.1, 54.0, 5.90 µg/g, and ND, respectively. Mean Cr in brain, liver, muscle, gizzard, and feathers was 212, 102, 56.1, 84.4, and 25.5 µg/g, respectively. Mean Ni in brain, liver, muscle, gizzard, and feathers was 27.6, 23.8, 7.60, 9.4, and 4.3 µg/g, respectively. Mean Cu in brain, liver, muscle, gizzard, and feathers was ND, ND, 1.60, 6.00, and 4.70, respectively. Mean Pb in brain, liver, muscle, gizzard, and feathers were ND, 63.6, ND, 12.5, and 4.30 µg/g, respectively.

2.

Liver and kidney of nestlings from acidified lakes and reference lakes in northwestern Ontario were collected between 1986 and 1989 (St. Louis et al., 1993). Mean Cd in nestlings from acidified lakes ranged from 0.20 to 0.36 µg/g dry weight in liver, and from 0.14 to 0.48 µg/g in kidney. Mean Cd in nestlings from reference lakes was 0.20 µg/g in liver and 0.16 µg/g in kidney. Mean Cu in nestlings from acidified lakes ranged from 12.1 to 42.6 µg/g in liver, and from 10.3 to 12.8 µg/g in kidney. Mean Cu in nestlings from reference lakes was 17.3 µg/g in liver and 10.4 µg/g in kidney. Mean Zn in nestlings from acidified lakes ranged from 70.8 to 108 µg/g in liver, and from 73.1 to 87.8 µg/g in kidney. Mean Zn in nestlings from reference lakes was 70.5 µg/g in liver and 77.1 µg/g in kidney.

3.

Eggs were collected from several sites in the Great Lakes-St. Lawrence River basin in 1991 (Bishop et al., 1995). Mean Hg ranged from 0.04 to 0.08 µg/g wet weight.

4.

Nestlings were collected from contaminated and reference sites on the Cour d’Alene river in northern Idaho in 1987 (Blus et al., 1995). Geometric mean blood Pb was 0.19 and 0.29 µg/g wet weight at the contaminated and reference sites respectively. Geometric mean hepatic Pb was 0.15 and ND at the contaminated and reference sites respectively. Mean kidney Cd was 0.07 and ND at the contaminated and reference sites respectively.

5.

Tree swallow embryos, nestling bodies and feathers, and dead adults were collected from northwestern Ontario, Canada at the Experimental Lakes Reservior Project and nearby reference lakes (Gerrard and St. Louis, 2001).  The experimental reservior was monitored in 1992 and 1993 prior to flooding and from 1994 to 1999 postflooding.  The reference lakes were monitored from 1992 to 1999. 

Between 1992 and 1999, nine dead adult tree swallows were found at the experimental reservior. Mean (range) Hg body and feather concentrations were 517 (214 to 1110) and 1690 (843 to 2740) ng/g dry weight, respectively. Total Hg body burden was 2760 to 8540 ng (mean=4760 ng).

In embryos, the mean MeHg concentration at the experimental reservior was 365±35 ng/g and was significantly higher in preflood year 1992 (518±25.9 ng/g).  At the reference lakes, the mean MeHg concentration was 270±18 ng/g, with no differences between years.  Embryo body burdens ranged from 44 to 111 ng MeHg but were not significantly different between years for the experimental reservoir or the reference lakes. 

In nestling bodies, mean MeHg concentrations increased 36.3% postflooding at the experimental reservoir from 82.8±2.2 to 130±11 ng/g.  The mean concentration of MeHg among nestling bodies for 1992-1999 was 81.6±5.1 ng/g at the reference lakes.

Nestling feather MeHg concentrations increased postflooding from 872±75 to 1210±53 ng/g at the experimental reservior.  The mean MeHg concentration in nestling feathers at the reference lakes was 747±43 ng/g, and there was no significant difference between years.

6.

Eggs were collected from 4 sites on the Upper Hudson River, New York in 1994 and 1995 (Secord and McCarty, 1997). Mean contaminants concentrations at the 4 sites ranged from 0.55 to 0.82 mg/g wet weight As, ND to 2.55 mg/g B, ND to 0.87 mg/g Ba, 0.44 to 0.48 mg/g Cu, 16.9 to 25.9 mg/g Fe, ND to 0.095 mg/g Hg, 71.6 to 72.6 mg/g Mg, 0.63 to 1.35 mg/g Mn, 1.08 to 1.83 mg/g Sr, and 14.6 to 15.6 mg/g Zn. All other metal concentrations were below detection limits.

7.

Tree swallows were collected from pesticide-treated and unsprayed apple orchards in Ontario, Canada, between 1995-96 (Bishop et al., 1998b).  Mean concentrations of Pb and As ranged from <0.03-0.1 and 0.20-0.25 µg/g dry weight, respectively, and did not vary significantly among sites.

8.

In 1998, nest boxes were placed along the North Platte River, WY (Custer et al., 2001). Eggs and nestling livers were collected from 2 sites, a refinery locale (contaminated) and 10 km further down the river (reference). Mean concentrations are recorded in µg/g dry weight. Eggs (n=7): Ba 4, B 58, Cu 2, Fe 140, Mg 330, Mn 3, Hg 0.3, Se 7, Sr 14, Zn 57. Livers (n=6): B 16, Cu 26, Fe 990, Mg 800, Mn 5, Hg 0.2, Mo 2, Se 21, Sr 0.4, Zn 88. All other metal concentrations were below detection limits.

IV.

Petroleum

No residue data available 

Tree Swallow Contaminant Response Data

I.

Organochlorine Contaminants

1.

Length, breadth, and weight of eggs collected in 1980 and 1981 in Colorado were compared among attended nests, abandoned nests, and pre-DDT era museum specimens (DeWeese et al., 1985). Mean length and breadth for pre-DDT era eggs from Colorado were 1.87 and 1.32 cm respectively. Mean weight of pre-DDT era eggs from Colorado was 0.096 g. Mean length and breadth of unattended eggs collected in 1980 ranged from 1.82 to 1.93 cm. Mean breadth of unattended eggs collected in 1980 was 1.33 cm. Mean weight of unattended eggs collected in 1980 ranged from 0.09 to 0.10 g. Mean length and breadth of attended eggs collected in 1981 were 1.80 and 1.30 cm. Mean weight of attended eggs collected in 1981 was 0.09 g. Mean length and breadth of unattended eggs collected in 1981 were 1.88 and 1.34 cm. Mean weight of unattended eggs collected in 1981 was 0.10 g. Thus, significant eggshell thinning was not observed.

2.

Between 1988 and 1994, tree swallow eggs were collected from orchards and a pasture in southern Ontario, Canada (Bishop et al., 2000). Reproduction declined in tree swallows as egg survival decreased with increased pesticide exposure.

3.

Clutch size, nest success, hatching success, and fledgling success in British Columbia in 1991 were compared between orchard habitats where organochlorine pesticides were in use, and non-orchard forest habitats (Elliott et al., 1994). No significant differences in any parameters were found between the two habitat types.

4.

Reproductive success and biochemical parameters (measured in nestlings) were monitored in tree swallows on seven sites along the St. Lawrence River and lower Great Lakes from 1991-1994 (Bishop et al., 1999).  Hatching success ranged from 50-95% and fledging success from 60-100%; neither parameter show significant differences between sites.  Hepatic porphyrins were consistently highest at Toronto Island.  Mean values ranged from 28.1-171.8 pmol/g total porphyrins, 15.7-158.0 pmol/g uroporphyrin, 2.2-18.2 pmol/g heptaporphyrin, and 3.3-26.2 hexaporphyrin, and did not differ among sites due to high individual variability.  Pentaporphyrin was detected at Toronto Island only at 9.7 pmol/g.  Concentrations of uroporphyrin and PCB 118 were positively correlated.  Retinol concentrations ranged from 0.5-2.4 µg/g in kidney and 0.6-5.3 µg/g in liver.  Retinyl palmitate ranged from 1.0-3.0 µg/g in kidney and 6.4-197.6 µg/g in liver.  Kidney retinol concentrations were negatively correlated with heptachlor epoxide in eggs.  Hepatic EROD activity was significantly higher at Cornwall Island (22.0 pmol/min/mg protein) than all other sites (1.4-13.3 pmol/min/mg), and was negatively correlated with liver retinol concentrations.

5.

During 1993-1996, tree swallows nesting in boxes located upstream and downstream from two kraft pulp mills and sewage sites in western Canada (near Grande Prairie, Alberta, and Prince Albert, Saskatchewan) were examined for dietary exposure to and effects of effluent on physiological and reproductive parameters (Wayland et al., 1998).  Aquatic insects accounted for approximately 50-60% of the diet.  Physiological responses, including EROD activity, liver somatic indices, steroid hormones levels and porphyrins did not differ between upstream and downstream locations in a manner consistent with effluent exposure with two exceptions.  In one downstream site (Grande Prairie), 17 -estradiol was lower in incubating females than the upstream site in one of two years measured.  At Prince Albert, highly carboxylated porphyrins were significantly elevated at the downstream site.  At the sewage site at Prince Albert, incubating females exhibited significantly greater androgen levels than those from the upstream site, and liver somatic indices were lower in nestlings from the downstream site compared to the upstream or sewage site, exhibiting a pattern opposite to that of fish exposed to pulp mill effluent.  At Grand Prairie, downstream nestlings had lower liver somatic indices than those upstream, but higher than those at the sewage site.  Reproduction did not differ significantly between upstream and downstream sites, though a trend existed towards enhanced reproduction at downstream sites. 

6.

Comparison of nest mass at laying, nest mass at hatching, number of nest-lining feathers at first egg, number of nest-lining feathers at last egg, and number of nest-lining feathers at hatching was made among sites in upstate New York with varying levels of PCBs in the eggs in 1994 and 1995 (McCarty and Secord, 1999a). Nest mass at laying, number of feathers at first egg, and number of feathers at last egg were significantly higher at uncontaminated sites than contaminated sites. Nest mass at hatching was significantly higher at a moderately contaminated site than at highly contaminated sites.

7.

Mean clutch size, hatching success, nestling mortality, egg abandonment and burial, and nestling mass were compared among sites in upstate New York with varying levels of PCBs in the eggs 1994 and 1995 (McCarty and Secord, 1999b). Mean clutch size did not vary significantly among locations. Hatching success and nestling mortality were lower at an uncontaminated site than at contaminated sites. Nestlings from contaminated sites had significantly higher mass than nestlings from uncontaminated sites.

8.

Pipping embryos and nestlings were collected from artificial nest boxes at two polluted sites in the Fox River and Green Bay areas of Wisconsin, and from two reference sites between 1994-95 (Custer et al., 1998).  Mean hepatic EROD activity in samples from polluted and reference sites, respectively, ranged from 78-99 and 32-53 pmol/min/mg in embryos and from 89-109 and 32-36 pmol/min/mg of nestlings.  Mean hepatic BROD activity ranged from 54-66 and 20-37 pmol/min/mg in embryos and from 53-65 and 16-20 pmol/min/mg in nestlings.  There was no significant difference in hatching success among polluted and reference sites.  Furthermore, clutches in which all eggs, some eggs, or no eggs hatched did not differ in mean concentrations of DDE or PCBs in sample eggs.

9.

Plumage color of female tree swallows nesting along the Hudson River, New York, near Hudson Falls and the Champlain Canal was monitored during the breeding seasons of 1994 and 1995 for possible alterations due to PCB contamination (McCarty and Secord, 2000).  Compared to museum specimens, sub-adult females had significantly more adult-type blue-green plumage.  No significant relationships were found between female color and reproductive parameters.

10.

Tree swallows were collected from pesticide-treated (4 sites) and unsprayed (3 sites) apple orchards in southern Ontario, Canada, between 1994-1997 (Bishop et al., 1998a).  Swallows were exposed to thiodan at 4kg/ hectare among many other pesticides.  Hepatic EROD activity ranged between 10.7 and 34.9 pg/min/mg protein and did not differ among sites.  Cell proliferation in the cortex and delayed thymic involution were positively correlated with increasing spray exposure.  Increased blastogenic response to pokeweed mitogen was found in birds from sprayed orchards.  Birds from sprayed orchards were also slightly anemic, and had smaller bursal masses and an increase in relative heterophil concentrations.  There were no significant differences in body or organ mass between sprayed and unsprayed sites. 

11.

Tree swallows were collected from pesticide-treated and unsprayed apple orchards in Ontario, Canada, between 1995-96 (Bishop et al., 1998b).  No correlations were found among DDE concentration in eggs (concentrations not reported) and testis histology, body or organ masses, or concentrations of estradiol, testosterone, or thyroid hormone (T3).

12.

From 1995-97, 12-day old tree swallow nestlings (3-49 per location) were collected from six sites in Pennsylvania, two sites in Indiana, one site on the Hudson River, and a reference site in Maryland (Yorks, 1999).  Mean BROD and EROD activity (pmol/min/mg), respectively, was 16.02 and 29.56 at Blue Marsh Lake, PA; 17.33 and 41.42 at the Texas Eastern Transmission Corporation in Bechtelsville, PA; 30.08 and 43.34 at Valley Forge National Historic Park, PA; 33.25 and 55.49 at John Heinz National Wildlife Refuge, PA; 53.58 and 92.19 at Fort Mifflin, PA; 13.00 and 37.51 near Fort Edward on the Hudson River, NY; 22.35 and 28.36 at Goose Pond, IN; 21.31 (1995 BROD), 61.72 (1996 BROD) and 60.91 (EROD) at the Winston-Thomas sewage treatment plant near Bloomfield, IN; and 21.80 (BROD), 39.14 (1995 EROD) and 28.23 (1996, 1997 EROD) at the reference site at the Patuxent Wildlife Research Center, MD.  Both BROD and EROD were positively correlated with PCB concentrations in nestlings in all sites except for the Hudson River, where no significant correlations were found.  No dramatic effects on gross and histological morphology were observed due to PCB exposure, and phenotypic gonadal morphology matched genotypic sex.

13.

In April 1993 and 1994 tree swallow nest boxes were set up above and below bleached kraft pulp mills that had ceased using Cl bleach in the 1990s at two locations in British Columbia, Canada: on the Fraser River and its tributaries, and on the Thompson and South Thompson Rivers (Harris and Elliott, 2000).  Nest success for downstream and upstream boxes, respectively was 75% and 100% on the Thompson River, and 40% and 100% on the Fraser River.  Low nest success was atrributed to nest abandonment, which may be related to contaminants, though the lack of consistency in differences in reproductive parameters associated with upstream or downstream sites makes this conclusion unlikely.

II.

Cholinesterase-Inhibiting Pesticides

1.

Brain and plasma ChE activity of nestlings and plasma ChE activity of adults were measured in tree swallows collected from nest boxes in apple orchards in Canada in 1988-89, following application of azinphos-methyl at 2.1kg/ha or phosmet at 3.75 kg/ha (Burgess et al., 1999). Plasma ChE activity in adults was depressed by 41% compared to controls after two applications of azinphos-methyl.  Plasma ChE activity in adults was depressed by 21% and 19% after a first and second application of phosmet, respectively.  Of the nestlings, only those 3-5 days old exhibited brain ChE inhibition >20%.  No significant ChE inhibition was noted in plasma of nestlings after application of either organophosphorus insecticide, although one individual from the azinphos-methyl-treated orchard and one individual from the phosmet-treated orchard exhibited 55 and 29% inhibition, respectively.  No effects on survival due to application of these pesticides were noted.

2.

Tree swallows nesting in boxes in apple orchards in southern Ontario, Canada were exposed to azinphos-methyl at 2.0 kg/ha, diazinon at 3.75 kg/ha, or carbaryl at 2.0-3.0 kg/ha (as well as many other pesticides) between 1995-96 (Bishop et al., 1998a).  Hepatic EROD activity ranged between 10.7 and 34.9 pg/min/mg protein and did not differ among sites.  Cell proliferation in the cortex and delayed thymic involution were positively correlated with increasing spray exposure.  Increased blastogenic response to pokeweed mitogen was found in birds from sprayed orchards.  Birds from sprayed orchards were also slightly anemic, and had smaller bursal masses and an increase in relative heterophil concentrations.  There were no significant differences in body or organ mass between sprayed and unsprayed sites. 

3.

Tree swallows nesting in boxes in apple orchards in southern Ontario, Canada were exposed to azinphos-methyl at 2.0 kg/ha, diazinon at 3.75 kg/ha, or carbaryl at 2.0-3.0 kg/ha (as well as many other pesticides) between 1995-96 (Bishop et al., 1998b).  Histology of testes did not vary consistently among sprayed fields and control fields except for a higher percentage of testes in control field in which Sertoli cells formed a contiguous layer over the basement membrane.   In male chicks, thyroid hormone (T3) concentration were positively correlated with increasing pesticide exposure.  No effects were found on estradiol or testosterone levels.

III.

Trace Elements, Metals, and Metalloids

1.

Hepatic metallothionein induction was compared between nestlings from acidified lakes and reference lakes between 1986 and 1989 (St. Louis et al., 1993). Metallothionein levels were higher in livers of nestling from acidified lakes than from reference lakes. Metallothionein levels were correlated with hepatic Cu and Zn concentrations.

2.

Tree swallows nesting in boxes in pesticide-treated apple orchards in southern Ontario, Canada were collected between 1995-96 (Bishop et al., 1998b).  Orchards were treated with Zn at 3.6 kg/1,000 L tank water/ha, B at 0.41 L/ha, Ca at 5.0 L/ha, and N at 5.0L/1,000 L tank water/ha.  Histology of testes did not vary consistently among sprayed fields and control fields except for a higher percentage of testes in control field in which Sertoli cells formed a contiguous layer over the basement membrane.   In male chicks, thyroid hormone (T3) concentration was positively correlated with increasing pesticide exposure.  No effects were found on estradiol or testosterone levels.

IV.

Petroleum

1.

Tree swallows nesting in boxes in pesticide-treated apple orchards in southern Ontario, Canada were collected between 1994-1997 (Bishop et al., 1998a).  Orchards were treated with oil at 20L/1,000L tank water/ha (among many other pesticides) as an insecticide.    Hepatic EROD activity ranged between 10.7 and 34.9 pg/min/mg protein and did not differ among sites.  Cell proliferation in the cortex and delayed thymic involution were positively correlated with increasing spray exposure.  Increased blastogenic response to pokeweed mitogen was found in birds from sprayed orchards.  Birds from sprayed orchards were also slightly anemic, and had smaller bursal masses and an increase in relative heterophil concentrations.  There were no significant differences in body or organ mass between sprayed and unsprayed sites. 

2.

Tree swallows nesting in boxes in pesticide-treated apple orchards in southern Ontario, Canada were collected between 1995-96 (Bishop et al., 1998b).  Orchards were treated with oil at 20L/1,000L tank water/ha (among many other pesticides) as an insecticide.  Histology of testes did not vary consistently among sprayed fields and control fields except for a higher percentage of testes in control field in which Sertoli cells formed a contiguous layer over the basement membrane.   In male chicks, thyroid hormone (T3) concentration was positively correlated with increasing pesticide exposure.  No effects were found on estradiol or testosterone levels.

3.

In 1997 and 1998, reproductive and growth parameters were measured in tree swallows nesting in reclaimed wetlands in the Athabasca River basin in Alberta, Canada, receiving oil sands mine tailings (Smits et al., 2000).  Alkylated PAHs and napathalic acid were present in the sediments.  Contaminated sites were Demonstration Pond, Shallow Wetland, Natural Wetland, and reference sites were Crane Lake (1997 only), Ruth Lake (1997 only), Poplar Creek Reservoir, and Horseshoe Lake (1998 only).  In 1997, N=62 pairs, mean nestling mass was lower at Natural Wetland than at one reference site, though there were no differences among sites for clutch size, hatching success, or nestling size, and growth and fledging success were not compromised on contaminated sites.  In 1998, N=83 pairs, swallows at Natural Wetland showed decreased hatching success, fledging rate, and nestling mass, though there were no differences among sites for clutch size, clutch mass, or nestling size.  Immune response in 9 day old nestlings (measured by change in skin thickness 24 hours after injection with phytohemagglutinin) was significantly greater in nestlings at Demonstration Pond than Natural Pond in 1997, yet no differences were detected in1998. Mean hepatic EROD activity was significantly higher in16 day old nestlings from Natural Wetland and Horseshoe Lake (52.6 and 44.8 pmol/min/mg protein, respectively) than Demonstration Pond and Poplar Creek (26.6 and 28.5 pmol/min/mg protein, respectively).

4.

In 1998, nest boxes were placed along the North Platte River, WY (Custer et al., 2001). Tree swallow and house wren eggs and nestling livers were collected from 2 sites, a refinery locale (contaminated) and 10 km further down the river (reference). Twelve different PAHs were detected in tree swallow and wren carcasses and diet samples at the refinery site, while only 1 PAH (1,2-benzanthracene) was detected in one wren carcass at the reference site. Except for 2-methylnapthalene detected in the swallow diet, all PAHs in carcasses, diet, and sediment were not methylated. Total PAHs were significantly higher at the refinery than reference, and odd-numbered aliphatic hydrocarbons were more predominant than even-numbered aliphatic hydrocarbons at the refinery and reference sites. In measuring monooxygenase activity, mean EROD (p=0.04) and BROD (p=0.048) activities in tree swallow livers were significantly higher (each more than 9 times) at the refinery than at the reference site.

V.

Other

1.

Tree swallows nesting in boxes in pesticide-treated apple orchards in southern Ontario, Canada were collected between 1994-97 (Bishop et al., 1998a).  Orchards were treated with fungicides (metiram at 6.0 kg/ha, mancozeb at 3.0-6.0 kg/ha, myclobutanil at 340 g/ha), synthetic pyrethroids (deltamethrin at 250 ml/ha, cypermethrin at 250 ml/ha), acaricides (clofentezine at 300 ml/ha), herbicides (glyphosate at 0.8-1.2 kg/ha), and growth regulators (naphthalene acetic acid at 5-20 ppm, 1,2,-dihydro-3,6-perdazinedione at 4.5 L/ha, Accel at 5-20 ppm).  Hepatic EROD activity ranged between 10.7 and 34.9 pg/min/mg protein and did not differ among sites.  Cell proliferation in the cortex and delayed thymic involution were positively correlated with increasing spray exposure.  Increased blastogenic response to pokeweed mitogen was found in birds from sprayed orchards.  Birds from sprayed orchards were also slightly anemic, and had smaller bursal masses and an increase in relative heterophil concentrations.  There were no significant differences in body or organ mass between sprayed and unsprayed sites. 

2.

Tree swallows nesting in boxes in pesticide-treated apple orchards in southern Ontario, Canada were collected between 1995-96 (Bishop et al., 1998b).  Orchards were treated with fungicides (metiram at 6.0 kg/ha, mancozeb at 3.0-6.0 kg/ha, myclobutanil at 340 g/ha), synthetic pyrethroids (deltamethrin at 250 ml/ha, cypermethrin at 250 ml/ha), acaricides (clofentezine at 300 ml/ha), herbicides (glyphosate at 0.8-1.2 kg/ha), and growth regulators (naphthalene acetic acid at 5-20 ppm, 1,2,-dihydro-3,6-perdazinedione at 4.5 L/ha, Accel at 5-20 ppm).  Histology of testes did not vary consistently among sprayed fields and control fields except for a higher percentage of testes in control field in which Sertoli cells formed a contiguous layer over the basement membrane.   In male chicks, thyroid hormone (T3) concentration was positively correlated with increasing pesticide exposure.  No effects were found on estradiol or testosterone levels. 

References for Tree Swallow

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. Arch. Environ. Contam. Toxicol. 24:332-344.

Bishop, C.A., M.D. Koster, A.A. Chek, D.J.T. Hussell, and K. Jock. 1995. Chlorinated hydrocarbons and mercury in sediments, red-winged blackbirds (Agelaius phoeniceus) and tree swallows (Tachycineta bicolor) from wetlands in the Great Lakes-St. Lawrence River Basin. Environ. Toxicol. Chem. 14:491-501.

Bishop, C.A., H.J. Boermans, P. Ng, G.D. Campbell, and J. Struger. 1998a. Health of tree swallows (Tachycineta bicolor) nesting in pesticide-sprayed apple orchards in Ontario, Canada. I. Immunological parameters.  J. Toxicol. Environ. Health, Part A, 55:531-559.

Bishop, C.A., G.J. Van Der Kraak, P. Ng, J.E.G. Smits, and A. Hontela. 1998b. Health of tree swallows (Tachycineta bicolor) nesting in pesticide-sprayed apple orchards in Ontario, Canada. II. Sex and thyroid hormone concentrations and testes development. J. Toxicol. Environ. Health, Part A, 55:561-581.

Bishop, C.A., N.A. Mahony, S. Trudeau, and K.E. Pettit.  1999.  Reproductive success and biochemical effects in tree swallows (Tachycineta bicolor) exposed to chlorinated hydrocarbon contaminants in wetlands of the Great Lakes and St. Lawrence River Basin, USA and Canada.  Environ. Toxicol. Chem.  18:263-271.

Bishop, C.A., B. Collins, P. Mineau, N.M. Burgess, W.F. Read, C. Risley. 2000. Reproduction of cavity-nesting birds in pesticide-sprayed apple orchards in southern Ontario, Canada, 1988-1994. Environ. Toxicol. Chem. 19: 588-599.

Blus, L.J., C.J. Henny, D.J. Hoffman, and R.A. Grove. 1995. Accumulation and effects of lead and cadmium on waterfowl and passerines in northern Idaho. Environ. Pollut. 89:311-318.

Burgess, N.M., K.A. Hunt, C. Bishop, and D.V. Weseloh. 1999. Cholinesterase inhibition in tree swallows (Tachycineta bicolor) and eastern bluebirds (Sialia sialia) exposed to organophosphorous insecticides in apple orchards in Ontario, Canada. Environ. Toxicol. Chem. 18:708-716.

Custer, C.M., T.W. Custer, P.D. Allen, K.L. Stromborg, and M.J. Melancon. 1998. Reproduction and environmental contamination in tree swallows nesting in the Fox River drainage and Green Bay, Wisconsin, USA. Environ. Toxicol. Chem. 17:1786-1798.

Custer, C.M., T.W. Custer, and M. Coffey.  2000.  Organochlorine chemicals in tree swallows nesting in Pool 15 of the upper Mississippi River.  Bull. Environ. Contam. Toxicol. 64:341-346. 

Custer, T.W., C.M. Custer, K. Dickerson, K. Allen, M.J. Melancon and L.J. Schmidt. 2001. Polycyclic aromatic hydrocarbons, aliphatic hydrocarbons, trace elements, and monooxygenase activity in birds nesting on the North Platte River, Casper, Wyoming, USA. Environ. Toxicol. Chem. 20:624-631.

Deweese, L.R., R.R. Cohen, and C.J. Stafford. 1985. Organochlorine residues and eggshell measurements for tree swallows Tachycineta bicolor in Colorado. Bull. Environ. Contam. Toxicol. 35:767-775.

Deweese, L.R., L.C. McEwen, G.L. Hensler, and B.E. Petersen. 1986. Organochlorine contaminants in passeriformes and other avian prey of the peregrine falcon in the western United States. Environ. Toxicol. Chem. 5:675-693.

Elliot, J.E., P.A. Martin, T.W. Arnold, and P.H. Sinclair. 1994. Organochlorines and reproductive success of birds in orchards and non-orchard areas of central British Columbia, Canada, 1990-91. Arch. Environ. Contam. Toxicol. 26:435-443.

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

Froese, K.L., D.A. Verbrugge, G.T. Ankley, G.J. Niemi, C.P. Larsen, and J.P. Giesy. 1998. Bioaccumulation of polychlorinated biphenyls from sediments to aquatic insects and tree swallow eggs and nestlings in Saginaw Bay, Michigan, USA. Environ. Toxicol. Chem. 17:484-492.

Gerrard, P.M. and V.L. St. Louis. 2001. The effects of experimental reservoir creation on the bioaccumulation of methylmercury and reproductive success of tree swallows (Tachycineta bicolor). Environ. Sci. Technol. 35:1329.

Harris, M.L., and J.E. Elliott.  2000.  Reproductive success and chlorinated hydrocarbon contamination in tree swallows (Tachycineta bicolor) nesting along rivers receiving pulp and paper mill effluent discharges.  Environ. Pollut. 110:307-320. 

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-Tetrachlorobenzo-p-dioxin equivalents in tissues of birds at Green Bay, Wisconsin, USA. Arch. Environ. Contam. Toxicol. 24:345-354.

Kraus, M.L. 1989. Bioaccumulation of heavy metals in pre-fledgling tree swallows, Tachycineta bicolor. Bull. Environ. Contam. Toxicol. 43:407-414.

Martin, P.A., D.V. Weseloh, C.A. Bishop, K. Legierse, B. Braune, and R.J. Norstrom. 1995. Organochlorine contaminants in avian wildlife of Severn Sound. Water Qual. Res. J. Canada. 30:693-711.

McCarty, J.P. and A.L. Secord. 1999a. Nest-building behavior in PCB-contaminated tree swallows. Auk 116:55-63.

McCarty, J.P. and A.L. Secord. 1999b. Reproductive ecology of tree swallows (Tachycineta bicolor) with high levels of polychlorinated biphenyl contamination. Environ. Toxicol. Chem. 18:1433-1439.

McCarty, J.P. and A.L. Secord.  2000.  Possible effects of PCB contamination on female plumage color and reproductive success in Hudson River tree swallows.  Auk  117:987-995.

Nichols, J.W., C.P. Larsen, M.E. McDonald, G.J. Niemi, and G.T. Ankley. 1995. Bioenergetics-based model for accumulation of polychlorinated biphenyls by nesting tree swallows, Tachycineta bicolor. Environ. Sci. Technol. 29:604-612.

Robertson, R.J., B.J. Stutchbury, and R.R. Cohen. 1992. Tree swallow. In A. Poole and F. Gill, eds. The Birds of North America. No. 11. 28 pp.

Secord, A.L., and J.P. McCarty. 1997. Polychlorinated biphenyl contamination of tree swallows in the Upper Hudson River Valley, New York. Draft Report to US Fish and Wildlife Service, New York Field Office, Cortland, NY. 50 pp.

Secord, A.L., J.P. McCarty, K.R. Echols, J.C. Meadows, R.W. Gale, and D.E. Tillit. 1999. Polychlorinated biphenyls and 2,3,7,8-tetrachlorodibenzo-p-dioxin equivalents in tree swallows from the upper Hudson River, New York state, USA. Environ. Toxicol. Chem. 18:2519-2525.

Shaw, G. 1984. Organochlorine pesticide and PCB residues in eggs and nestlings of tree swallows, Tachycineta bicolor, in central Alberta. Can. Field-Nat. 98:258-260.

Smits, J.E., M.E. Wayland, M.J. Miller, K. Liber, and S. Trudeau.  2000.  Reproductive, immune, and physiological end points in tree swallows on reclaimed oil sands mine sites.  Environ. Toxicol. Chem. 19:2951-2960. 

St. Louis, V.L., L. Breebaart, J.C. Barlow, and J.F. Klaverkamp. 1993. Metal accumulation and metallothionein concentrations in tree swallow nestlings near acidified lakes. Environ. Toxicol. Chem. 12:1203-1207.

Stapleton M., P.O. Dunn, J. McCarty, A. Secord and L.A. Whittingham. Polychlorinated biphenyl contamintion and minisatellite DNA mutation rates of tree swallows. Environ. Toxicol. Chem. 20:2263-2267.

Wayland, M., S. Trudeau, T. Marchant, D. Parker, and K.A. Hobson.  1998.  The effect of pulp and paper mill effluent on an insectivorous bird, the tree swallow.  Ecotoxicology 7:237-251.

Yorks, A.L.  1999.  Effects of polychlorinated biphenyls (PCBs) on reproduction, physiological processes, and biomarkers in tree swallows (Tachycineta bicolor).  Ph.D. Dissertation, University of Maryland, Baltimore, 280 pp.