Thomas Custer (Former Employee)
Science and Products
Filter Total Items: 166
Within- and among-clutch variation of organochlorine residues in eggs of black-crowned night-herons Within- and among-clutch variation of organochlorine residues in eggs of black-crowned night-herons
Within-clutch variability of DDE and PCB residues in eggs from 62 clutches of black-crowned night-herons (Nycticorax nycticorax) was small (12% and 17%) compared to among-clutch variability (88% and 83%). Significant correlations between concentrations of DDE (median r=0.8885) and of PCBs (median r=0.8244) occurred when 501 correlations were run on two randomly selected eggs from within...
Authors
T. W. Custer, G. Pendleton, H. M. Ohlendorf
Organochlorine contaminants in eggs of common terns from the Canadian Great Lakes, 1981 Organochlorine contaminants in eggs of common terns from the Canadian Great Lakes, 1981
To determine if contaminant levels in Common Terns had changed over the last decade, we collected and analyzed eggs from four nesting colonies on the three lower Great Lakes during 1981. DDE and PCBs were detected in every egg from the four colonies. Dieldrin, mirex and trans-nonachlor were detected in more than 45% of the eggs. Seven other organochlorine contaminants (DDD, DDT...
Authors
D. V. Weseloh, T. W. Custer, B. M. Braune
Brain cholinesterase activity of nestling great egrets, snowy egrets, and black-crowned night-herons Brain cholinesterase activity of nestling great egrets, snowy egrets, and black-crowned night-herons
Inhibition of brain cholinesterase (ChE) activity in birds is often used to diagnose exposure or death from organophosphorus or carbmate pesticides. Brain ChE activity in the young of altricial species increase with age; however, this relationship has only been demonstrated in the European starling (Sturnus vulgaris). Brain ChE activity of nestling great egrets (Casmerodius albus)...
Authors
T. W. Custer, H. M. Ohlendorf
Organochlorine contaminants in white-faced ibis eggs in southern Texas Organochlorine contaminants in white-faced ibis eggs in southern Texas
White-faced ibis eggs collected from 2 colonies in southern Texas in 1985 had low mean concentrations of DDE. DDD, the only other organochlorine contaminant detected, was found in only 1 of 20 eggs. DDE concentrations in eggs were not significantly correlated with eggshell thickness. Mean DDE concentrations were significantly higher in eggs collected from nests where not all of the...
Authors
T. W. Custer, C. A. Mitchell
Brain cholinesterase activity of nestling great egrets snowy egrets and black-crowned night-herons Brain cholinesterase activity of nestling great egrets snowy egrets and black-crowned night-herons
Inhibition of brain cholinesterase (ChE) activity in birds is often used to diagnose exposure or death from organophosphorus or carbamate pesticides. Brain ChE activity in the young of altricial species increases with age; however, this relationship has only been demonstrated in the European starling (Sturnus vulgaris). Brain ChE activity of nestling great egrets (Casmerodius albus)...
Authors
T. W. Custer, H. M. Ohlendorf
Organochlorine contaminants in white-faced ibis eggs in southern Texas Organochlorine contaminants in white-faced ibis eggs in southern Texas
White-faced Ibis (Plegadis chihi) eggs collected from two colonies in southern Texas in 1985 had low mean concentrations of DDE (0.14-0.27 ppm wet weight). DDD, the only other organochlorine contaminant detected, was found in only 1 of 20 eggs. DDE concentrations in eggs were not significantly correlated with eggshell thickness. Mean DDE concentrations were significantly higher in eggs...
Authors
T. W. Custer, C. A. Mitchell
Organochlorines and mercury in eggs of coastal terns and herons in California, USA Organochlorines and mercury in eggs of coastal terns and herons in California, USA
In San Franciso Bay, California, USA, concentrations of DDE and mercury in eggs differed among Caspian Tern, Forster's Tern, Black-crowned Night-Heron, and Snowy Egret in 1982. Geometric mean DDE concentrations were higher (P 0.05) in Caspian Tern eggs (6.93 ppm, wet weight) than in eggs of other species (1.92-2.84 ppm). Mean mercury concentrations were significantly greater in Caspian...
Authors
H. M. Ohlendorf, T. W. Custer, Roy W. Lowe, M. Rigney, E. Cromartie
Organochlorine contaminants and reproductive success of black skimmers in south Texas, 1984 Organochlorine contaminants and reproductive success of black skimmers in south Texas, 1984
Ninety-four Black Skimmer (Rhynchops niger) nests on a dredged-material island colony near Laguna Vista, Texas, were fenced and monitored in 1984 from early incubation until 21 d after the last egg hatched. The daily probability of success was greater during the nestling (99.7%/d/nest) period than during the incubation (98.5%) or hatching (98.5%) periods. By contrast, the success of eggs...
Authors
Thomas W. Custer, Christine A. Mitchell
Nesting by pomarine jaegers near Barrow, Alaska, 1971 Nesting by pomarine jaegers near Barrow, Alaska, 1971
An estimated 5.7 pairs of pomarine jaegers km -2 (14.8 mi -2) nested near Barrow, Alaska, in 1971. Hatching success of 67 eggs (34 nests) was 57%. Fledging success of 44 nestlings (26 nests) was 32%. An estimated 0.4 young survived to 25 d of age per nesting attempt. Low fledging success is explained by an abrupt decline in lemming abundance.
Authors
Thomas W. Custer, Frank A. Pitelka
Exposure to insecticides of brushland wildlife within the Lower Rio Grande Valley, Texas, USA Exposure to insecticides of brushland wildlife within the Lower Rio Grande Valley, Texas, USA
Brushland wildlife within the Lower Rio Grande Valley of south Texas were studied following applications of eleven insecticides to nearby sugarcane or cotton fields. During the study no wildlife were found dead. Mean brain acetylcholinesterase (AChE) activity of great-tailed grackles (Quiscalus mexicanus) and mourning doves (Zenaida macroura) was significantly lower than controls...
Authors
T. W. Custer, C. A. Mitchell
Energy budget and prey requirements of breeding lapland longspurs Calcarius lapponicus near Barrow Alaska, U.S.A. Energy budget and prey requirements of breeding lapland longspurs Calcarius lapponicus near Barrow Alaska, U.S.A.
Breeding Lapland longspurs, Calcarius lapponicus, near Barrow, Alaska, have relatively constant energy demands throughout the summer; the average estimated daily energy budgets (DEBs) were 132 and 118 kJ for the male and female. Thermoregulation accounted consistently for one-quarter to one-third of the total DEB. Flight in the male and incubation in the female were major components of...
Authors
T. W. Custer, R. G. Osborn, F.A. Pitelka, J.A. Gessaman
Hatching success of Caspian terns nesting in the lower Laguna Madre, Texas, USA Hatching success of Caspian terns nesting in the lower Laguna Madre, Texas, USA
The average clutch size of Caspian Terns nesting in a colony in the Lower Laguna Madre near Laguna Vista, Texas, USA in 1984 was 1.9 eggs per nest. Using the Mayfield method for calculating success, one egg hatched in 84.1% of the nests and 69.8% of the eggs laid hatched. These hatching estimates are as high or higher than estimates from colonies in other areas.
Authors
C. A. Mitchell, T. W. Custer
Science and Products
Filter Total Items: 166
Within- and among-clutch variation of organochlorine residues in eggs of black-crowned night-herons Within- and among-clutch variation of organochlorine residues in eggs of black-crowned night-herons
Within-clutch variability of DDE and PCB residues in eggs from 62 clutches of black-crowned night-herons (Nycticorax nycticorax) was small (12% and 17%) compared to among-clutch variability (88% and 83%). Significant correlations between concentrations of DDE (median r=0.8885) and of PCBs (median r=0.8244) occurred when 501 correlations were run on two randomly selected eggs from within...
Authors
T. W. Custer, G. Pendleton, H. M. Ohlendorf
Organochlorine contaminants in eggs of common terns from the Canadian Great Lakes, 1981 Organochlorine contaminants in eggs of common terns from the Canadian Great Lakes, 1981
To determine if contaminant levels in Common Terns had changed over the last decade, we collected and analyzed eggs from four nesting colonies on the three lower Great Lakes during 1981. DDE and PCBs were detected in every egg from the four colonies. Dieldrin, mirex and trans-nonachlor were detected in more than 45% of the eggs. Seven other organochlorine contaminants (DDD, DDT...
Authors
D. V. Weseloh, T. W. Custer, B. M. Braune
Brain cholinesterase activity of nestling great egrets, snowy egrets, and black-crowned night-herons Brain cholinesterase activity of nestling great egrets, snowy egrets, and black-crowned night-herons
Inhibition of brain cholinesterase (ChE) activity in birds is often used to diagnose exposure or death from organophosphorus or carbmate pesticides. Brain ChE activity in the young of altricial species increase with age; however, this relationship has only been demonstrated in the European starling (Sturnus vulgaris). Brain ChE activity of nestling great egrets (Casmerodius albus)...
Authors
T. W. Custer, H. M. Ohlendorf
Organochlorine contaminants in white-faced ibis eggs in southern Texas Organochlorine contaminants in white-faced ibis eggs in southern Texas
White-faced ibis eggs collected from 2 colonies in southern Texas in 1985 had low mean concentrations of DDE. DDD, the only other organochlorine contaminant detected, was found in only 1 of 20 eggs. DDE concentrations in eggs were not significantly correlated with eggshell thickness. Mean DDE concentrations were significantly higher in eggs collected from nests where not all of the...
Authors
T. W. Custer, C. A. Mitchell
Brain cholinesterase activity of nestling great egrets snowy egrets and black-crowned night-herons Brain cholinesterase activity of nestling great egrets snowy egrets and black-crowned night-herons
Inhibition of brain cholinesterase (ChE) activity in birds is often used to diagnose exposure or death from organophosphorus or carbamate pesticides. Brain ChE activity in the young of altricial species increases with age; however, this relationship has only been demonstrated in the European starling (Sturnus vulgaris). Brain ChE activity of nestling great egrets (Casmerodius albus)...
Authors
T. W. Custer, H. M. Ohlendorf
Organochlorine contaminants in white-faced ibis eggs in southern Texas Organochlorine contaminants in white-faced ibis eggs in southern Texas
White-faced Ibis (Plegadis chihi) eggs collected from two colonies in southern Texas in 1985 had low mean concentrations of DDE (0.14-0.27 ppm wet weight). DDD, the only other organochlorine contaminant detected, was found in only 1 of 20 eggs. DDE concentrations in eggs were not significantly correlated with eggshell thickness. Mean DDE concentrations were significantly higher in eggs...
Authors
T. W. Custer, C. A. Mitchell
Organochlorines and mercury in eggs of coastal terns and herons in California, USA Organochlorines and mercury in eggs of coastal terns and herons in California, USA
In San Franciso Bay, California, USA, concentrations of DDE and mercury in eggs differed among Caspian Tern, Forster's Tern, Black-crowned Night-Heron, and Snowy Egret in 1982. Geometric mean DDE concentrations were higher (P 0.05) in Caspian Tern eggs (6.93 ppm, wet weight) than in eggs of other species (1.92-2.84 ppm). Mean mercury concentrations were significantly greater in Caspian...
Authors
H. M. Ohlendorf, T. W. Custer, Roy W. Lowe, M. Rigney, E. Cromartie
Organochlorine contaminants and reproductive success of black skimmers in south Texas, 1984 Organochlorine contaminants and reproductive success of black skimmers in south Texas, 1984
Ninety-four Black Skimmer (Rhynchops niger) nests on a dredged-material island colony near Laguna Vista, Texas, were fenced and monitored in 1984 from early incubation until 21 d after the last egg hatched. The daily probability of success was greater during the nestling (99.7%/d/nest) period than during the incubation (98.5%) or hatching (98.5%) periods. By contrast, the success of eggs...
Authors
Thomas W. Custer, Christine A. Mitchell
Nesting by pomarine jaegers near Barrow, Alaska, 1971 Nesting by pomarine jaegers near Barrow, Alaska, 1971
An estimated 5.7 pairs of pomarine jaegers km -2 (14.8 mi -2) nested near Barrow, Alaska, in 1971. Hatching success of 67 eggs (34 nests) was 57%. Fledging success of 44 nestlings (26 nests) was 32%. An estimated 0.4 young survived to 25 d of age per nesting attempt. Low fledging success is explained by an abrupt decline in lemming abundance.
Authors
Thomas W. Custer, Frank A. Pitelka
Exposure to insecticides of brushland wildlife within the Lower Rio Grande Valley, Texas, USA Exposure to insecticides of brushland wildlife within the Lower Rio Grande Valley, Texas, USA
Brushland wildlife within the Lower Rio Grande Valley of south Texas were studied following applications of eleven insecticides to nearby sugarcane or cotton fields. During the study no wildlife were found dead. Mean brain acetylcholinesterase (AChE) activity of great-tailed grackles (Quiscalus mexicanus) and mourning doves (Zenaida macroura) was significantly lower than controls...
Authors
T. W. Custer, C. A. Mitchell
Energy budget and prey requirements of breeding lapland longspurs Calcarius lapponicus near Barrow Alaska, U.S.A. Energy budget and prey requirements of breeding lapland longspurs Calcarius lapponicus near Barrow Alaska, U.S.A.
Breeding Lapland longspurs, Calcarius lapponicus, near Barrow, Alaska, have relatively constant energy demands throughout the summer; the average estimated daily energy budgets (DEBs) were 132 and 118 kJ for the male and female. Thermoregulation accounted consistently for one-quarter to one-third of the total DEB. Flight in the male and incubation in the female were major components of...
Authors
T. W. Custer, R. G. Osborn, F.A. Pitelka, J.A. Gessaman
Hatching success of Caspian terns nesting in the lower Laguna Madre, Texas, USA Hatching success of Caspian terns nesting in the lower Laguna Madre, Texas, USA
The average clutch size of Caspian Terns nesting in a colony in the Lower Laguna Madre near Laguna Vista, Texas, USA in 1984 was 1.9 eggs per nest. Using the Mayfield method for calculating success, one egg hatched in 84.1% of the nests and 69.8% of the eggs laid hatched. These hatching estimates are as high or higher than estimates from colonies in other areas.
Authors
C. A. Mitchell, T. W. Custer