Christine A. Mitchell

Parathion alters incubation behavior of laughing gulls

SummaryOne member of each pair of incubating laughing gulls at 9 nests was trapped, orally dosed with either 6 mg/kg parathion in corn oil or corn oil alone, and marked about the neck with red dye. Each nest was marked with a numbered stake and the treatment was recorded. A pilot study with captive laughing gulls had determined the proper dosage of parathion that would significantly inhibit their brain AChE activity (about 50% of normal) without overt signs of poisoning.After dosing, birds were released and the nests were observed for 21/2 days from a blind on the nesting island. The activities of the birds at each marked nest were recorded at 10-minute intervals. Results indicated that on the day of treatment there was no difference (P>0.05, Chi-square test) in the proportion of time spent on the nest between treated and control birds. However, birds dosed with 6 mg/kg parathion spent significantly less time incubating on days 2 and 3 than did birds receiving only corn oil. By noon on the third day, sharing of nest duties between pair members in the treated group had approached normal, indicating recovery from parathion intoxication. These findings suggest that sublethal exposure of nesting birds to an organophosphate (OP) insecticide, such as parathion, may result in decreased nest attentiveness, thereby making the clutch more susceptible to predation or egg failure. Behavioral changes caused by sublethal OP exposure could be especially detrimental in avian species where only one pair member incubates or where both members are exposed in species sharing nest duties.

Ticks as a factor in nest desertion of California brown pelicans

first became intense during the 1920’ s as birds began to shift from aquatic habitat to cropland to feed. Wheat and other cereal grains are now an integral part of the diet of this species particularly during autumn. Agricultural tillage has also affected diet composition in wetland habitat. Krapu (197413) reported that wild millet (barnyard grass) formed 71% of the diet of breeding Pintail hens feeding in tilled basins. This annual grass is a dominant species in annually tilled wetland basins. Grains of wild millet are eaten from spring through fall during periods when tilled basins are flooded. We thank Mavis I. Meyer for assistance in preparing food habits data and Jerome R. Serie for critically reviewing the manuscript.

Herbivory on shoalgrass by wintering redheads in Texas

An estimated 80% of redheads (Aythya americana) winter on the Laguna Madre of south Texas and Mexico and feed almost exclusively on shoalgrass (Halodule wrightii) rhizomes. Shoalgrass abundance has decreased by 60% over the past 30 years, and because the effects of shoalgrass loss on wintering redheads are unknown, we initiated a study to define habitat selection criteria and document the effect of wintering redheads on shoalgrass in the lower Laguna Madre, Texas. Redheads consumed an average of 75% of shoalgrass rhizome biomass at collection sites each winter. When rhizome biomass was grazed to a mean biomass of ≤0.18 g dry mass/core (approximately 10 g dry mass/m 2 ), shoalgrass did not recover to its previous level the following growing season

Temporal accumulation of Organochlorine pesticides in shorebirds wintering on the south Texas coast, 1979–80

Organochlorine pesticide residues were determined in 168 shorebirds of three species collected at approximate bimonthly intervals during the fall and winter months of 1979–80 near Port Mansfield on the south Texas coast. The study was conducted to determine if shorebirds wintering on mudflats at the outlets of agricultural drains in Texas accumulated pesticides during this period. The predominant Organochlorine residues detected in shorebirds were DDE, dieldrin, and toxaphene. Ninety-five % of the skinned carcasses analyzed contained detectable levels of DDE, 13% contained dieldrin, and 22% contained toxaphene. DDE significantly increased in all species of shorebirds from October to December, with potentially dangerous levels accumulating in some long-billed dowitchers (Limnodromus scolopaceus) and American avocets (Recurvirostra americana), but DDE residues seldom exceeded 0.5 ppm in carcasses of western sandpipers (Calidris mauri). After about two months on the study area, no further residue increases were documented. The high levels of DDE detected in a large proportion of the dowitchers, and to a lesser extent in the avocets, are near or within the range known to inhibit reproduction in some avian species. This study demonstrates that certain aquatic areas near agricultural lands on the south Texas coast may be potential threats to waterbirds eight years after the use of DDT was banned in the United States.

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 following application of some organophosphorous insecticides. Brain AChE activity varied significantly among chemicals, days after exposure and application rates. Mean brain AChE activity of white-winged doves (Zenaida asiatica) and three small mammal species was not significantly different than their respective controls following application of insecticides. Mean brain AChE activity of grackles was inhibited significantly more than white-winged doves after application of Bolstar, EPN-methyl parathion, and Azodrin and significantly more than that of mourning doves after applications of Bolstar and EPN-methyl parathion. Our data indicate that there were no adverse effects on most brushland wildlife. Exposure was probably dependent upon use of the agricultural fields as feeding or resting sites and only grackles and mourning doves were regularly present in the fields.

PARATHION POISONING OF WILD GEESE IN TEXAS

On the mornings of 24 and 25 February 1981, 60 Canada geese (Branta canadensis), six snow geese (C/zen caerulescens), four white-fronted geese (Anser albifrons), and two Ross’ geese (C/zen rossii) were found dead on the south shore of 1..ake Texoma within the boundaries of the Hagerman National Wildlife Refuge near Sherman, Texas. Al! th,e specimens were fresh. The birds were not observed in the area on the afternoon of 23 February, therefore they were assumed to have died during the next two days. Six specimens (four Canada geese, one snow goose, and one white-fronted goose) were sent on wet ice to the National Wildlife Health Laboratory (NWHL), Madison, Wisconsin, for necropsy and pathological examination. Additionally, six specimens (four Canada geese, one snow goose, and one white-fronted goose) were kept frozen until brain assays for cholinesterase activities and chemical analyses of proventricu!ar contents could be performed. Nine apparently healthy specimens (five Canada geese, two snow geese, and two white-fronted geese) collected in January and April 1981 near Hereford, Texas, and Lake Charles, Louisiana, served as controls in the analyses.

Trace elements and organochlorines in the shoalgrass community of the lower Laguna Madre, Texas

Our objectives were to measure concentrations of seven trace elements and 14 organochlorine compounds in sediment and biota of the shoalgrass (Halodule wrightii) community of the lower Laguna Madre of south Texas and to determine whether chemicals associated with agriculture (e.g. mercury, arsenic, selenium, organochlorine pesticides) were highest near agricultural drainages. Arsenic, mercury, selenium, lead, cadmium, and organochlorines were generally at background concentrations throughout the lower Laguna Madre. Nickel and chromium concentrations were exceptionally high in shrimp and pinfish (Lagodon rhomboides), which is difficult to explain because of no known anthropogenic sources for these trace elements. For sediment and blue crabs (Callinectes sapidus), mercury was highest near agricultural drainages. Also, DDE was more frequently detected in blue crabs near agricultural drainages than farther away. In contrast, selenium concentrations did not differ among collecting sites and arsenic concentrations were lowest in shoalgrass, blue crabs, and brown shrimp (Penaeus aztecus) near agricultural drainages.

Azodrin® Poisoning of Waterfowl in Rice Fields in Louisiana

Received for publication 27 April 1983. Although infestations of sarcoptic mange have sometimes occurred concomitantly with lice infestations (Gier et a!., 1978, In Coyotes: Biology, Behavior, and Management, Bekoff (ed), Academic Press, New York, 384 pp.; Pence and Custer, 1981, In Worldwide Furbearer Conf. Proc., Vol. II, Chapman and Pursely (eds.), Worldwide Furbearer Conf., Inc., Frostburg, Maryland, pp. 760-845), there was no evidence of mange mites on the four hide samples examined in our study. Trichodectes canEs has not been previously identified on wild canid populations in Alaska, although it is found occasionally on dogs according to a statewide survey of veterinarians. Although no additional morbidity or mortality was observed, it seems obvious that severely infested wolves have a higher probability of contracting other diseases associated with stress or possibly suffer increased mortality from exposure during severe winters. In addition, the extreme hair loss associated with heavy lice infestations reduced the commercial value of pelts. Hides of most pup wolves and the coyote were worthless, while those of the adult wolves were worth one-third of their normal market value. If the prevalence of infestation on wolves from the Kenai Peninsula persists or increases, the commercial value of their hides and possibly those of coyotes will decrease significantly. We thank S. Mersch who originally isolated and identified the louse; Dr. R. Zarnke for examining scalp samples for mange; T. Spraker, Game Biologist, for collecting lice specimens from sealed wolves; trappers J. Cook, W. Sather, C. Bierdaman, E. Jordan, and A. Horwath for providing samples of lice from harvested wolves; E. Bangs, Kenai National Wildlife Refuge Biologist, for data on physical condition of harvested wolves, B. Taylor for data on louse density and information from his statewide survey of veterinarians concerning T. canEs occurrence on domestic dogs; and K. Schneider, A. Franzmann, W. Ballard, and S. Peterson for reviewing the manuscript.

Contaminant exposure of willets feeding in agricultural drainages of the Lower Rio Grande Valley of South Texas.

Willets (Catoptrophorus semipalmatus) were collected in June and August 1986 at the outlets of two agricultural drainages into the Lower Laguna Madre of South Texas and at two other Texas coastal sites. Mean liver concentration of arsenic was higher in August than June. Over 20% of the livers had arsenic concentrations elevated above a suggested background level of 5.0 ppm dry weight (DW), but concentrations (maximum 15 ppm) were below those associated with acute toxicity. Selenium concentration in livers varied from 2.3 to 8.3 ppm DW for all locations and represented background levels. Mercury concentrations in livers for all locations (means = 2.0 to 3.4, maximum 17 ppm DW) were below those associated with avian mortality and similar to levels found in other estuarine/marine birds. DDE in carcasses was higher in adults (mean = 1.0 ppm wet weight) than juveniles (0.2 ppm), and higher in August (1.0 ppm) than June (0.5 ppm); however, DDE concentrations were generally at background levels. Based on brain cholinesterase activity, willets were not recently exposed to organophosphate pesticides.

Seasonal brain acetylcholinesterase activity in three species of shorebirds overwintering in Texas.

ConclusionsThere was no seasonal variation in average brain AChE activity for the 3 species of wild birds collected between October and February. Further work needs to be done, however, covering an even broader time frame which includes the reproductive cycle. It appears that some birds feeding at the mouth of an agricultural drain, at some distance from the nearest pesticide applications, were affected by AChE inhibitors.