Quiscalus Quiscula Research Articles

Mitochondrial DNA Variation, Population Structure, and Evolution of the Common Grackle (Quiscalus quiscula)

Mitochondrial DNA Variation, Population Structure, and Evolution of the Common Grackle (Quiscalus quiscula)

Comparison of Roost Use by Three Species of Communal Roostmates

Our previous studies of communally roosting European Starlings (Sturnus vulgaris) revealed that each bird fed daily for months on its own diurnal activity center (DAC) and commuted to a variety of nearby and distant roosts. Since these observations contrast sharply with the predictions of most foraging explanations for communal roosting, we wanted to determine if this DAC-centered roosting pattern occurred in other communally roosting species. In this study we used radiotelemetry to monitor feeding and roosting sites used by starlings, Common Grackles (Quiscalus quiscula), and American Robins (Turdus migratorious), three species that share communal roosts in central New Jersey. Our goals were to determine (a) whether avian species that roost together use the roosts in similar ways, and (b) when and why individuals change roosts. Foraging patterns were similar in all three species; individuals fed daily on their DACs for many weeks. Roosting patterns were similar for grackles and starlings; individuals switched among nearby and distant roosts. In contrast, robins always roosted near their DACs, changing both roosts and DACs at the end of the breeding season. Predation rates at roosts were extremely low and did not explain the use patterns of large and small roosts. We argue that (a) DACs and DAC-centered roosting are probably widespread among communally roosting species, and (b) DAC-based individuals select roosts primarily on the basis of their proximity to good sources of food.

Alternate-row treatment with the repellent methiocarb to protect cherry orchards from birds

An alternate-row treatment of the bird repellent methiocarb (CA chemical name 3, 5-dimethyl-4-(methylthio)phenyl methylcarbamate; Mesurol® was evaluated for protecting entire cherry orchards from damage by European starlings, American robins, house finches, common grackles and other birds. Half of each orchard was randomly selected for treatment with methiocarb (1·7 kg/ha) applied to trees in every other row. The other half of each orchard was used as a control. Estimated loss of cherries to birds at the time of damage assessment was significantly lower in the six partially sprayed blocks (6·5%) than in the six unsprayed, control blocks (8·8%) ( P = 0·03). However, the level of bird damage and the magnitude of the reduction were insufficient to provide a favourable benefit:cost ratio: there was a return of only $0·80 in cherries saved for every $1·00 spent on application and chemical costs. The overall lower damage in the partially sprayed blocks appeared to result primarily from reduced feeding by birds in the sprayed trees, which averaged 4·6% loss compared with 8·4% loss for unsprayed trees within the same block ( P = 0·22). That this difference was not statistically significant indicates that birds had to sample a substantial number of berries before discriminating between sprayed and unsprayed fruit. It is not clear how birds detected berries sprayed with the repellent. Suggestions for evaluating other partial treatments of bird repellents in cherry orchards are discussed.

The Use of Banding Recovery Data to Estimate Dispersal Rates and Gene Flow in Avian Species: Case Studies in the Red-Winged Blackbird and Common Grackle

Dispersal resulting in gene flow strongly affects the evolution of genetic structure in populations. This report describes statistical estimators of dispersal parameters based on USFWS banding recovery records. Finite-area studies of avian species yield estimates of root-mean-square (RMS) dispersal along a transect of about 1 km per generation. In contrast, estimates of RMS dispersal for the Red-winged Blackbird (Agelaius phoeniceus) and Com­ mon Grackle (Quiscalus quiscula), based on USFWS banding recovery records, are 94.6 and 111.4 km per generation, respectively. Distributions for both species are extremely lepto­ kurtic, and confidence intervals based on jackknife statistics are large because the estimators are sensitive to outlying values. Dispersal rates can also be estimated from gene frequency data. Although all three kinds of data are not available for any one avian species, genetic­ based estimates for several species are consistent with our estimates for Red-winged Black­ birds and Common Grackles in inferring that gene flow is generally high in North American birds-probably closer to 100 km than 1 km per generation. High' gene flow also implies that where geographic variation is observed, such as plumage patterns across hybrid zones, selection plays a role in maintaining the pattern of geographic variation.

Avian response to a turf application of triumph® 4E

AbstractA field study was conducted to assess the hazard presented by Triumph® 4E insecticide applied to turf at 5 kg a.i./ha to free‐ranging birds during the breeding season. The occurrence, distribution, activity and habitat use of birds were monitored on treated and untreated portions of a golf course before and after chemical application. In addition, avian mortality and nesting success were recorded. Residues of Triumph 4E were measured in water, turf and invertebrate samples. Six bird species were more frequently observed following application. Triumph 4E‐contaminated mole crickets (Scapteriscus vicinus) (mean, 0.32 ppm, a.i.) that surfaced after treatments were a food source for the birds. At least three of the six species whose numbers increased on the treated field (common grackle, Quiscalus quiscula: boat‐tailed grackle, Quiscalus major; and northern mockingbird, Mimus polyglottus) appeared to be attracted to dead or impaired mole crickets. No increases in bird mortality or other adverse effects in reproductive performance were evident.

Physiological Correlates of Preference and Aversion for Sugars in Three Species of Birds

We studied preferences of red-winged blackbirds, common grackles, and European starlings for the disaccharide sucrose and the monosaccharides glucose and fructose. We also tested the hypothesis that sucrose preference is correlated with activity of sucrase, the intestinal enzyme that hydrolyzes sucrose. All species preferred a 1:1 mixture of glucose and fructose over water at concentrations > 0.75 M. Starlings rejected concentrated solutions of sucrose and lacked sucrase activity. Red-winged blackbirds preferred sucrose solutions at intermediate concentrations (0.35 M) but rejected concentrated ones, whereas common grackles preferred sucrose at all the concentrations offered. Sucrase activity was higher in grackles than in red-winged blackbirds. Blood glucose levels were measured after a meal of a mixture of glucose and fructose or of sucrose. Blood glucose concentration increased in all species after the monosaccharide meal and peaked after about 30 min. In starlings the concentration of glucose in blood...

Angiotensin converting enzyme in brush-border membranes of avian small intestine.

Angiotensin converting enzyme activity was identified in brush-border membranes purified from the small intestinal epithelium of the common grackle, Quiscalus quiscula. Angiotensin converting enzyme was enriched 20-fold in the membrane preparation, compared with intestinal epithelial cell scrapes, and was coenriched with the brush-border markers, alkaline phosphatase and aminopeptidase N. The kinetics of hydrolysis of N-[3-(2-furyl)acryloyl]-L-phenylalanylglycylglycine (FAPGG) gave a Vmax of 907 +/- 41 units g-1 and a Km of 55 +/- 6 mumol l-1. The avian intestinal angiotensin converting enzyme was inhibited by the antihypertensive drug, Ramipril, with a median inhibitory concentration (IC50) of 1 nmol l-1. In the light of previous studies on angiotensin converting enzyme in mammalian epithelia, these results may implicate a physiological role for angiotensin converting enzyme in regulating electrolyte and fluid uptake in bird small intestines.

Lead poisoning in six captive avian species.

Red-winged blackbirds (Agelaius phoeniceus), brown-headed cowbirds (Molothrus ater), common grackles (Quiscalus quiscula), mallards (Anas platyrhynchos), northern bobwhites (Colinus virginianus), and eastern screech-owls (Otus asio) were poisoned with a concentration of lead (Pb) acetate in the diet which was increased by 60% each week until half of the birds in each treatment group died; surviving birds and all control birds except screech-owis were then killed by euthanasia. An additional group of mallards was poisoned with Pb shot. The gizzards of mallards poisoned either way usually were stained with bile; some of these birds also had proventricular impaction. Most poisoned birds of the other species were emaciated but lacked other gross lesions caused by Pb poisoning. In birds other than mallards, Pb poisoning could not be diagnosed without histological or hematological examinations or analysis of tissues. Poisoned birds of all six species could be reliably separated from control birds by an increase in the protoporphyrin concentrations in the blood and by a decrease in the activity of delta-aminolevulinic acid dehydratase (ALAD) in red blood cells. Hepatic iron (Fe) concentrations varied so much among individual birds that even though median hepatic Fe concentrations increased in poisoned birds, hepatic Fe concentrations were not useful in identifying poisoned birds. Renal intranuclear inclusion bodies occurred in 83% of all birds dying from Pb poisoning. Nephrosis, myocardial necrosis, and arterial fibrinoid necrosis were occasionally present. Median hepatic Pb concentrations varied from 20 ppm (wet wt) in male red-winged blackbirds to 111 ppm in female northern bobwhites. Median renal Pb concentrations varied from 22 ppm in redwinged blackbirds to 190 ppm in female northern bobwhites. Hepatic and renal Pb concentrations varied substantially among birds within each species. Median hepatic and renal Pb concentrations of birds that died were not statistically different (p > 0.05) from those of birds that were killed. Lead shot and Pb acetate affected mallards similarly.

Predation on Waterhyacinth Weevils and Other Aquatic Insects by Three Wetland Birds in Florida

Common moorhens (Gallinula chloropus), boat-tailed grackles (Quiscalus major) and red-winged blackbirds (Agelaius phoeniceus) were collected monthly from September 1984 to August 1985 at a waterhyacinth (Eichhornnia crassipes) infested lake in northcentral Florida. Contents of esophagi and gizzards were examined to assess predation on waterhyacinth weevils, Neochetina eichhorniae and N. bruchi, and other aquatic insects. Waterhyacinth weevils were rarely found in stomach contents of common moorhens, whose herbivorous diet consisted largely of coontail, hydrilla and duckweed. Although diets of the other two bird species varied seasonally, both consumed significant proportions of aquatic insects. Adults of Donacia leaf beetles were found to be very abundant in stomach contents of grackles and blackbirds (aggregate percent: @?x = 17.2, @?x = 26.9, respectively). Neochetina weevils were frequently found in gizzards of boat-tailed grackles and red-winged blackbirds (percent occurrence: @?x = 52.5, @?x = 41.5, respectively), but accounted for a relatively small proportion of the total diet (aggregate percent: @?x = 1.0, @?x = 6.3, respectively). Implications for biological control of waterhyacinth are discussed.

Secondary Sex Ratios and Egg Sequence in Herring Gulls

Variation in the secondary (hatching) sex ratio has been documented for many bird species. Significant deviations from the 1:1 ratio have led to theoretical speculation about adaptive facultative manipulation of the sex ratio (Trivers and Willard 1973). Seasonal changes in the nestling sex ratio of the Common Grackle (Quiscalus quiscula; Howe 1977) and the Redwinged Blackbird (Agelaius phoeniceus; Fiala 1981) and the biased production of male Zebra Finches (Poephila guttata; Burley 1981) by females mated with highquality males provide some support to the TriversWillard hypothesis. Recently, Ankney (1982) found that in newly hatched Lesser Snow Geese (Chen caerulescens) the first two eggs of 4-egg clutches produced more males (64%) than females and the last two eggs produced more females (72%) than males. Similarly, Ryder (1983) reported in Ring-billed Gulls (Larus delawarensis) the first-laid eggs of 3-egg clutches hatched predominantly more males (66%) than females and the second-laid eggs hatched more females (61 %) than males. This phenomenon suggested a facultative manipulation of the sex produced, although the adaptive significance is unexplained. Weatherhead (1985) examined the occurrence of a sex-sequence relationship in the Red-winged Blackbird after Fiala's (1981) documentation that the last-laid egg of this species produced significantly more females than males. Although Weatherhead (1985) found a sex-sequence relationship, the pattern was not consistent among different clutch sizes. Stimulated by these studies, we examined the secondary sex ratio in relation to laying sequence in newly hatched Herring Gull (L. argentatus) chicks on Granite Island (48?43'N, 88?29'W) in Black Bay, northern Lake Superior (see Ryder 1976 for a description of the colony). During the 1983-1986 nesting seasons, newly constructed Herring Gull nest sites were marked numerically with spray paint and the nests checked daily for the presence of new eggs. Each egg in a clutch was marked in sequence laid by placing dots of nail enamel on the blunt end of the egg (1 dot = first egg laid, 2 dots = second, 3 dots = third). The latest date we arrived at Granite Island was 11 May in 1983. We thus used 11 May as the standard date to compare the progress of Herring Gull egg laying in the three nesting seasons (1984 data were not available). Close to the expected time of hatching, nests were checked twice daily for signs of pipping eggs. Chicks hatched from 3-egg clutches were collected and their sex determined by gonadal inspection. We used only those clutches from which all eggs hatched and where the position of each chick in the sequence laid was known for statistical analyses. We compared clutch sizes using ANOVA and Scheffe a posteriori tests. The sex-ratio data were analyzed using Chi-square and G-tests (Sokal and Rohlf 1981). Significance was accepted at P < 0.05. Upon our arrival at Granite Island each year, laying in several nests had already commenced. The difference in the proportions of initiated and completed clutches by 11 May each year (Fig. 1) indicates that Herring Gulls breeding in 1983 did so later in the season than those nesting in 1985 and 1986. The proportion of nests with 3 eggs was much lower in 1983 than in the other years (Table 1). This low 3-egg clutch-size frequency was manifested in the significantly lower average clutch size for 1983 (F = 5.02, P < 0.05). The secondary sex ratio favored females in 1983 and 1985 and males in 1984 and 1986 (Table 2). The deviation from a 1:1 sex ratio, however, was not significant in any of these years. The G-statistic also indicated no significant relationship between sex and sequence for any year. Similar results were obtained from the combined data. Our results suggest that the allocation of sex chromosomes by the heterogametic female Herring Gull is a random process. A late season, lower average clutch size and hatch of 12% more females than males occurred in 1983. Although it was tempting, at first, to invoke the predictions of the Trivers-Willard (1973) hypothesis, whereby the later-starting females may have been in relatively poor physiological condition

Relationships between Sex of Gosling and Position in the Laying Sequence, Egg Mass, Hatchling Size, and Fledgling Size

The sex of Canada Goose (Branta canadensis) goslings was not correlated with the position in the laying sequence, egg mass, or size of goslings at hatching. However, male goslings were larger at fledging than female goslings. This suggests that sex determination in Canada Geese and probably in other Anserinae occurs randomly over the laying sequence and that parental allocation of resources is equal for male and female goslings. Received 19 February 1986, accepted 25 August 1986. SEX of offspring may be of unequal value to the fitness of parents if the sex ratio of the breeding population varies or if the costs of producing each sex differs (Maynard Smith 1984). If parents provide more care to one sex or if the female can control the sex ratio of her progeny to increase survival of one sex, paren- tal fitness will increase also. The possibility that a female bird can control the sex of her off- spring has been suggested (Ankney 1982, Ry- der 1983, Weatherhead 1985). Theoretically, this would be adaptive under specific circum- stances (Trivers and Willard 1973, Myers 1978). The sex ratio of offspring varies through the breeding season in Red-winged Blackbirds (Agelaius phoeniceus; Fiala 1981, Blank and No- lan 1983) and Common Grackles (Quiscalus quis- cula; Howe 1977), and varies with position in the laying sequence in Snow Geese (Chen caeru- lescens; Ankney 1982; but see Cooke and Harm- sen 1983), Ring-billed Gulls (Larus delawarensis; Ryder 1983), and Red-winged Blackbirds (Fiala 1981, Weatherhead 1985). I report on the relationships between the sex of Canada Goose (Branta canadensis) goslings and four variables: position in the laying sequence, egg mass, hatchling size, and fledgling size. The purpose was to determine whether females controlled the sex of their offspring in relation to the position in the laying sequence and to examine if parental allocation of resources, as determined by egg mass, hatchling size, and fledgling size, was equal in the two sexes. STUDY AREA AND METHODS

Tissue specific isozyme expression in three species of icterinae (Aves: Emberizidae)

Tissue specific banding patterns were examined for ten enzyme systems in three species of the subfamily Icterinae, family Emberizidae — Quiscalus quiscula, Agelaius phoeniceus and Molothrus ater. Ten tissues were compared. Generally, tissue specific patterns observed were remarkedly similar as compared to other taxa, across the three species over all enzyme systems examined, indicating low levels of divergence in regulatory genes. This concurs with other observations of conservative avian protein evolution as indicated by small comparative electrophoretic distances between species.

Yersinia enterocolitica and related species isolated from wildlife in New York State.

Fecal specimens for Yersinia screening were obtained from a variety of wild mammals, birds, reptiles, fish, and invertebrates throughout New York State. One specimen from each of 1,426 animals was examined. A total of 148 isolates of Yersinia enterocolitica and related species were obtained from 133 (9.3%) of the animals. Y. enterocolitica was isolated from 100 (7%) of the animals tested, including 81 (10%) of 812 mammals and 19 (3.3%) of 573 birds. Y. intermedia, Y. frederiksenii, and Y. kristensenii were isolated from 39 (2.7%), 5 (0.35%), and 4 (0.28%) animals, respectively. The 81 Y. enterocolitica isolates from mammals belonged to 15 serogroups and included three pathogens: two isolates of typical serogroup 0:8, the "American strain," one from a gray fox (Urocyon cinereoargenteus) and one from a porcupine (Erethizon dorsatum); and one isolate of serogroup 0:3, bacteriophage type IXb, the "Canadian strain," from a gray fox. The most prevalent serogroups recovered from mammals were 0:6,31 (16 isolates) and 0:5,27 (6 isolates). The 19 isolates of Y. enterocolitica from birds belonged to nine serogroups and included one serogroup 0:6,31 isolate from a common grackle (Quiscalus quiscula) and two serogroup 0:5,27 isolates from great horned owls (Bubo virginianus).

Resistance of Sweet Corn to Damage by Blackbirds and Starlings

Abstract Twenty-five cultivars of sweet corn were evaluated for resistance to bird damage in an aviary during 1983 and 1984. A free-choice test was used in which red-winged blackbirds (Agelaius phoeniceus L.), common grackles (Quiscalus quiscula L.), and starlings (Sturnus vulgaris L.) could select from among 8 cultivars at a time. In addition, no-choice conditions in which red-wings were presented with only one cultivar at a time were tested. In the free choice test, there were significant differences among bird species and corn cultivars in the amount of damage. The most damaged cultivar had 4.8 times the damage of the least damaged cultivar. Starlings did the most damage and grackles the least, but all bird species damaged the cultivars in the same approximate order. Differences in damage among cultivars were diminished in the no-choice tests; however, the damage ranking of cultivars was similar to that of the free-choice test. Husk weight, length of husk beyond kernels, and weight of husk extension were the best correlates (all negative) with damage. The incorporation of these characteristics into sweet corn lines should increase cultivar resistance to damage by birds.

Shrinkage and Growth Compensation in Common Sunflowers: Refining Estimates of Damage

Shrinkage and growth compensation of artificially damaged common sunflowers (Helianthus annuus) were studied in central North Dakota during 1981-82 in an effort to increase accuracy of estimates of blackbird damage to sunflowers. In both years, as plants matured damaged areas on seedheads shrank at a greater rate than the sunflower heads themselves. This differential shrinkage resulted in an underestimation of the area damaged. Sunflower head and damaged-area shrinkage varied widely by time and degree of damage and by size of the seedhead damaged. Because variation in shrinkage by time of damage was so large, predicting when blackbird damage occurs may be the most important factor in estimating loss. Yield/occupied area was greater (P < 0.05) for damaged than undamaged heads and tended to increase as degree of damage inflicted increased, indicating growth compensation was occurring in response to lost seeds. Yields of undamaged seeds in seedheads damaged during early development were higher than those of heads damaged later. This suggested that there was a period of maximal response to damage when plants were best able to redirect growth to seeds remaining in the head. Sunflowers appear to be able to compensate for damage of -<15% of the total head area. Estimates of damage can be improved by applying empirical results of differential shrinkage and growth compensation. J. WILDL. MANAGE. 50(3):513-520 Sunflowers, grown primarily for the oil seed market, have become an increasingly important cash crop in the United States in recent years. In North Dakota, South Dakota, and Minnesota about 21,450 km2 of sunflowers were harvested in 1979. Production losses occur when birds, especially red-winged blackbirds (Agelaius phoeniceus), yellow-headed blackbirds (Xanthocephalus xanthocephalus), and common grackles (Quiscalus quiscula) damage ripening sunflower heads. In 1980, sunflower losses to blackbirds in North Dakota, South Dakota, and Minnesota were estimated to be 32,100 metric tons (R. L. Hothem, pers. commun.) worth $7.9 million. Estimates of damage losses generally are conducted near harvest by measuring the damaged (vs. undamaged) areas on a sample of sunflower heads. Sunflower heads shrink as they mature, and recently, investigators have discovered that d maged areas on heads shrink more than undamaged areas, resulting in underestimates of damage (J. L. Guarino and D. F. Mott, pers. commun.). To more accurately assess sunflower eed loss to blackbirds, refinements of damage estimation techniques are necessary. Yet even when differential shrinkage between damaged and undamaged areas of sunflower heads is taken into account, damage estimates may not reflect true yield loss by weight. Because blackbird damage peaks before seeds are fully mature (Cummings and Marsh 1980), damaged plants may be able to direct energy to the remaining undamaged seeds, compenThis content downloaded from 157.55.39.223 on Wed, 24 Aug 2016 05:11:15 UTC All use subject to http://about.jstor.org/terms 514 SUNFLOWER DAMAGE ESTIMATES * Sedgwick et al. J. Wildl. Manage. 50(3):1986 sating for part or all of the loss in yield caused by blackbirds. This apparently occurs to some extent in corn (Woronecki et al. 1976, 1980), where low levels of damage do not result in a decrease in yield. If sunflowers can compensate for blackbird damage, it may be necessary to adjust estimates of losses downward. The objectives of this study were to provide information to refine assessments of sunflower loss to blackbirds. To do so we evaluated the effects of differential shrinkage between damaged and undamaged sunflower head areas on damage estimates and determined how shrinkage varies with time of damage, head size, and degree of damage. We also investigated the extent of growth compensation in sunflowers and determined the effects of sunflower time of damage, head size, and amount of damage on growth compensation. We would like to thank P. Y. Sweanor, L. J. Barrie, and S. A. Boyle for their assistance in the field and laboratory and N. P. Groninger for computer programming advice. We thank R. T. Sterner and J. L. Cummings (Denver Wildl. Res. Cent.) for their field and technical assistance. We also gratefully acknowledge Denver Wildl. Res. Cent. biologists J. L. Guarino, C. E. Knittle, T. L. Burst, J. F. Besser, and G. M. Linz for technical assistance and manu-

On the filarioid nematodes (Splendidofilaria spp.) from the pulmonary arteries of birds

Splendidofilaria caperata Hibler, 1964 was found in the pulmonary arteries of 1 of 7 red-winged blackbirds (Agelaius phoeniceus (L.) (Icteridae)), 2 of 30 common grackles (Quiscalus quiscula versicolor Vieillot (Icteridae)), and 1 of 2 American robins (Turdus migratorius L. (Muscicapidae)) collected near Guelph, Ontario, Canada. All are new host records and their epizootiologic importance in Ontario is discussed. Two of the three species of filarioids described from the pulmonary arteries of birds can be readily distinguished by cuticular morphology: S. caperata has a thick, striated cuticle which often appears wrinkled and inconspicuous lateral alae, whereas S. algonquinensis (Anderson, 1955) (= S. passerina Koch and Huizinga, 1971) has only a thin striated cuticle. A third species, S. periarterialis (Caballero, 1948), requires additional study.

The effects of bird predation on an estuarine stickleback (Pisces: Gasterosteidae) community

Eight species of birds fed on a community of sticklebacks living in salt marsh pools along the southern shore of the St. Lawrence estuary in May and June when the fish breed. Three birds, the black-crowned night heron (Nycticorax nycticorax), the bronzed grackle (Quiscalus quiscula), and the ring-billed gull (Larus delawarensis) accounted for 80% of the estimated captures. Bird predation removed about 30% of the sticklebacks in the marsh. Significantly more male than female Gasterosteus aculeatus and G. wheatlandi were eaten, indicating selective predation is playing a role in structuring this fish community.

Common Grackles Anting With Marigold Flowers

Common Grackles Anting With Marigold Flowers

4-Aminopyridine baits on baiting lanes protect sunflower fields from blackbirds

4-Aminopyridine baits, applied by hand in 6.6-m swaths from baiting lanes, were evaluated in 1981 for protecting ripening sunflower from blackbird damage in six test fields in North Dakota, U.S.A. Paired experimental untreated units lost 4 902 kg of sunflower seed to birds during the 6-day treatment period whereas baited units lost 2 332 kg of seed or 52% less. However, untreated units also had somewhat more damage during pretreatment periods and therefore, based on ratios of pretreatment losses, observed losses on baited units were only 43.3% less than expected. Peak numbers of blackbirds damaging individual fields ranged from 5 000 to 31 000 during the test period. The species composition of feeding flocks was estimated to be 73% red-winged blackbirds ( Agelaius phoeniceus), 20% yellow-headed blackbirds ( Xanthocephalus xanthocephalus), and 7% common grackles ( Quiscalus quiscula). The estimated kill of 169 blackbirds was similar in composition. However, 30 of 34 birds seen giving distress displays were yellow-headed blackbirds. We found evidence that many red-wings broke the chopped corn baits before consuming them, thereby lengthening response times and contributing to lower bait effectiveness. The benefits of baiting were calculated to be only $1.75 for each $1 of cost (exclusive of labor). Nevertheless, growers would have saved about $25 worth of sunflower seed for each hour spent baiting and creating lanes.

Effects on Wildlife of At-Planting Corn Applications of Granular Carbofuran

Application, at planting, of a granular formulation of the insecticide carbofuran to 195 ha of corn resulted in wildlife mortalities in Frederick County, Maryland, in April and May 1980. Systematic field searches within 96 hours of treatment revealed six dead songbirds (order Passeriformes), five of which contained residues of carbofuran ranging from 1.6 to 17.0 ppm (gastrointestinal tract and liver combined). An American robin (Turdus migratorius) and a mallard (Anas platyrhynchos) were observed exhibiting symptoms consistent with carbofuran poisoning. A dead white-footed mouse (Peromyscus leucopus) found 24 hours posttreatment contained 15.1 ppm carbofuran. The pesticide was detected in 10 of 12 common grackles (Quiscalus quiscula) shot at the site (gastrointestinal tract and liver: f = 0.75 ppm, SE = 0.19), suggesting extensive sublethal exposure among birds feeding in treated fields. Captive house sparrows (Passer domesticus) and red-winged blackbirds (Agelaius phoeniceus) were orally administered carbofuran granules; doses as low as one granule resulted in fatalities with both species. Given the extensive annual use of granular carbofuran (>4 x 106 ha) in the United States, numerous wildlife mortalities are likely. J. WILDL. MANAGE. 48(4):1353-1359 Toxic pesticides are applied to large areas of farmland annually. The corn crop in the United States, for example, amounts to approximately 34 million ha with 11 million ha treated with insecticides (Eichers et al. 1978). When pesticides are applied in populated areas, as occurred in Dutch elm disease treatments (Hickey and Hunt 1960) or, more recently, in pesticide treatments to turf (Stone 1979), wildlife mortalities are observed and reported. Most agricultural land in the United States, however, occurs in sparsely populated areas. With few people searching for dead wildlife in treated fields and considering the rapidity with which carcasses disappear (Rosene and Lay 1963), even if kills were common they would seldom be observed and reported. The objective of our study was to investigate the effects on wildlife of at-planting corn applications of granular carbofuran (Furadan? 10 Granul s), a widely used corn insecticide (Eichers et al. 1978). We thank S. D. Palmeteer and J. A. McCann of the Terrestrial and Aquatic B ol. Lab., U.S. Environ. Prot. Agency, Beltsville, Maryland, for laboratory space and equipment. C. E. Grue, U.S. Fish and Wildl. Serv., Patuxent Wildl. Res. Cent., generously supplied the red-winged blackbirds. We thank C. Bushong, K. R. Barbehenn, and R. R. Stevens for commenting on an earlier draft of this paper. STUDY AREA AND METHODS The study area was in northwestern Maryland (Frederick County), a rural agricultural region. Cropland at the site (405 ha) is privately owned. Corn was the only c op planted at the time of the study, but in previous years some alfalfa and soybeans were grown. Fifteen fields totaling 195 ha were selected for study. The fields J. Wildl. Manage. 48(4):1984 1353 This content downloaded from 157.55.39.223 on Wed, 24 Aug 2016 05:40:50 UTC All use subject to http://about.jstor.org/terms 1354 EFFECTS OF CARBOFURAN ON WILDLIFE * Balcomb et al. were not contiguous but were interspersed with woodlots, hedgerows, fallow fields, turf, and roads. A stream bisected the area. Fieldwork was conducted from 22 April to 16 May 1980. Pesticide Applications Furadan? 10 Granules (10% carbofuran: 2,3-dihydro-2,2-dimethyl-7-benzofuranyl methylcarbamate) were applied at planting at the rate of 11.2 kg of product/ ha (1.12 kg active ingredient [a.i.]/ha) to control corn rootworm. Two common methods of planting were used: (1) the soil surface was plowed and disked prior to planting (115 ha), and (2) a no-till technique was used such that planting proceeded over existing soil conditions and surface litter without plowing or disking (80 ha). A White (model 543) six-row planter was used. This apparatus simultaneously plants the corn seed and applies fertilizer and insecticide (the planter opens a narrow furrow [1.5 x 4 cm], and the seed, insecticide, and fertilizer are metered in and a presswheel closes and compacts the furrow). These methods adhere to label directions and are considered typical of most corn in-furrow treatments. The pre-emergent herbicides atrazine (2.24 kg a.i./ha) and metolachlor (2.8 kg a.i./ha) were applied to plowed fields within a few hours of planting. The postemergent herbicide paraquat (0.28 kg a.i./ ha) was similarly applied to no-till areas.