Toxaphene does not affect avoidance behavior of young black ducks
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The behavior of 15 immature American woodcock ( Philohela minor ) was studied in central Maine during the summers of 1969 and 1970 using radiotelemetry. The monitored birds used a variety of nocturnal sites including old fields, bogs, powerlines, highway medians, woods roads, and fore clearings. Old fields were occupied more often than any other type of opening. Second growth-hardwoods, alders, hardwood-conifers, and conifers were utilized as diurnal cover. Diurnal locations of radio-equipped woodcock averaged 15 m from major breaks in the forest canopy. Four birds were monitored continuously during the day and night to determine periods of activity. Although the birds were active throughout the day, very little activity was recorded after they moved to nocturnal sites. No apparent difference was found in the daily patterns of movement between immature male and female woodcock. Crepuscular movements between diurnal covers and nocturnal areas averaged 332 m. A composite summer range for the 15 woodcock during 183 woodcock-days was 1060 hectares. The data suggest that immature woodcock are quite mobile during the summer and utilize most of the forest openings occurring within 1-3 km of good nesting habitat. Most of these openings are also used for singing grounds by males in the spring.
For the past 25 years estimation of mortality rates for waterfowl has been based almost entirely on the composite dynamic life table. We examined the specific assumptions for this method and derived a valid goodness of fit test. We performed this test on 45 data sets representing a cross section of banded sampled for various waterfowl species, geographic areas, banding periods, and age/sex classes. We found that: (1) the composite dynamic method was rejected (P <0.001) in 37 of the 45 data sets (in fact, 29 were rejected at P <0.00001) and (2) recovery and harvest rates are year-specific (a critical violation of the necessary assumptions). We conclude that the restrictive assumptions required for the composite dynamic method to produce valid estimates of mortality rates are not met in waterfowl data. Also we demonstrate that even when the required assumptions are met, the method produces very biased estimates of age-specific mortality rates. We believe the composite dynamic method should not be used in the analysis of waterfowl banding data. Furthermore, the composite dynamic method does not provide valid evidence for age-specific mortality rates in waterfowl.
A technique for distinguishing adult from yearling wild mallards ( Anas platyrhynchos ), from late winter through the nesting season, was developed by applying discriminant analysis procedures to selected wing feather characters of 126 yearlings and 76 adults (2-year-olds) hand-reared from wild eggs during 1974, 1975, and 1977. Average values for feather characters generally increased as the birds advanced from yearlings to adults. Black-white surface area of greater secondary covert 2 was the single most reliable aging character identified during the study. The error rate was lowest in females (3%) when discriminant functions were used with measurements of primary 1 weight and black-white area of greater secondary covert 2 and in males (9%) when the functions were used with black-white area of greater secondary coverts 1, 2, and 3. Methodology precludes aging of birds in the field during capture operations.
Three generations of mallard ducks ( Anas platyrhynchos ) were fed either a control diet or a diet containing 0.5 ppm mercury in the form of methylmercury. The levels of mercury in adult tissues and eggs remained about the same over 3 generations. The methylmercury diet had no effect on adult weights or weight changes during the reproductive season. Females fed a diet containing 0.5 ppm mercury laid a greater percentage of their eggs outside their nestboxes than did controls, and also laid fewer eggs and produced fewer ducklings. Methylmercury in the diet appeared to result in a small amount of eggshell thinning. Ducklings from parents fed methylmercury were less responsive than controls to tape-recorded maternal calls, but were hyper-responsive to a frightening stimulus in avoidance tests; there were no significant differences in locomotor activity in an open-field test.
Detailed information on the use by mallards ( Anas platyrhynchos ) of prairie pothole habitat during the nesting season is necessary to interpret habitat needs of the species during the breeding period. Many data have been collected and published relating pair counts to habitat use and water conditions (e.g., Evans and Black 1956; Smith 1971; Stoudt 1971; Stewart and Kantrud 1973, 1974). However, use of pair-count data to assess wetland use tends to emphasize individual wetland units and does not consider total wetland habitat required to sustain a breeding pair on a daily or seasonal basis. We therefore attempted to determine habitat use by individually radio marked mallards during the breeding period. This paper describes home range characteristics and habitat use of a radiomarked sample of mallard hens breeding in North Dakota during 1973-75. Time budget data are also presented for 2 marked pairs of mallard pairs of mallards.
Geese are assumed to accumulate fat on the winter range (Bent 1962, Williams 1967) to sustain them through the long northward migration and early part of the nesting season. However, there are no weights given in the literature of lesser snow geese ( Anser c. caerulescens ) on their winter ranges to compare with weights on the breeding grounds. For many years biologists relied on Kortright (1942) for weights of lesser snow geese, and more recently on Bellrose (1976). In the present study, snow geese from the Garwood Prairie, a rice growing area in Colorado County, Texas, were weighed to determine if weights increased before northward migration. The Garwood Prairie is a segment of the snow goose winter range near the Gulf Coast of Texas.
Gizzards of 934 sora rails ( Porzana carolina ) collected in Maryland (767) and Missouri (167) were examined for ingested shot. Ingested shot were found in 12.3 percent of the Maryland sample and 1.8 percent of the Missouri birds. Individual Maryland birds had ingested up to 28 pellets. None of the lead pellets examined was larger than a No. 7 1/2 shot. Maryland ingestion rates did not differ by age or sex, but significant differences between collection areas, groups of years, and collection periods within years were indicated. This exploratory work points out a potential lead poisoning problem among sora rails.
Twenty-six pregnant big brown bats ( Eptesicus fuscus ) were collected at Montpelier Barn, Laurel, Maryland, and kept in individual cages until parturition. Seven young in 5 litters were born dead; 21 litters contained only living young. Polychlorinated bipbenyl (PCB, Aroclor 1260) crossed the placenta two to three times more readily than did DDE. Concentrations of PCB were significantly greater in litters with dead young than in litters where both young were born alive. The concentration of PCB in adult females plus their litters declined with increasing age of the female.
Abstract has not been submitted
Systematic aerial searches were flown on transects to locate adult red foxes ( Vulpes vulpes ), pups, and rearing dens on 559.4 km2 (six townships) in eastern North Dakota during mid-May and mid-June each year from 1969 through 1973 and during mid-April 1969 and early May 1970. The combined sightings of foxes and fox dens from the mid-May and mid-June searches were used to identify individual fox families. The number of fox families was used as the measurement of density. Dens, highly visible during the mid-May searches, were the most reliable family indicator; 84 percent of 270 families identified during the study were represented by dens. Adult foxes second in importance, were most observable during the mid-May searches when 20 to 35 percent of those estimated to be available were sighted. Adult sightings during other search periods ranged from 4 to 17 percent of those available. Pup sightings were the most variable family indicator, but they led to the discovery of some dens. Sources of error for which adjustment factors were determined are: den moves exceeding criterion established for the spacing of dens in a single family, overestimation of the number of fox families living near township boundaries, and the percentage of fox families overlooked during the aerial searches. These adjustment factors appeared to be largely compensatory.
Osprey ( Pandion haliaetus) eggs were exchanged between Connecticut and Maryland osprey nests in 1968 and 1969 to test the hypothesis that the decline in reproductive success of Connecticut ospreys was caused by something within the external environment of the eggs. Incubation of 30 Connecticut osprey eggs by Maryland ospreys did not improve the hatching rate. Forty-five Maryland osprey eggs incubated by Connecticut ospreys hatched at their normal rate. The results of the egg exchanges and associated observations indicated that the most probable cause of the poor reproduction of Connecticut ospreys ,was related to contamination of the birds and their eggs. Residues of DDT and its metabolites, dieldrin, and PCBs were generally higher in fish from Connecticut than from Maryland. During 1968-69, average residues (on a nest basis) in osprey eggs from Maryland were: p,p'-DDE, 2.4 ppm; dieldrin, 0.25 ppm; PCB, 2.6 ppm. Average residues in eggs from Connecticut for the same period were: p,p'DDE, 8.9 ppm; dieldrin, 0.61 ppm; PCB, 15 ppm. There were no major changes in residue content of Connecticut eggs collected in 1964 compared with those collected in 1968-B9. One Connecticut osprey had a concentration of dieldrin in its brain which was in the lethal range. The average shell thickness of recently collected osprey eggs from Connecticut had declined 18 percent, and those from Maryland had declined 10 percent from pre-1947 norms. Dieldrin, DDE, and PCB are three environmental pollutants that have most likely been important factors in the greatly reduced reproductive success and rapid population decline of Connecticut ospreys.
The nutritional significance of invertebrate foods in the diet of breeding hen waterfowl during the period of egg formation is discussed. Proximate, elemental, and amino acid analyses of the principal foods consumed by hen pintails ( Anas acut ) during the nesting season indicate the animal foods selected are rich sources of protein and calcium, whereas plant foods tested were low in protein, particularly in the essential amino acids lysine and methionine. Calcium content in major plant foods was far below needs considered adequate for egg production. Studies with penned, hand-reared pintails indicated the inadequacy of wheat as the dietary staple during breeding. Egg production among pairs on the control diet differed significantly from that of the wheat plus oystershell (P < 0.05) and wheat (P < 0.01) diets. Pairs fed wheat during the breeding period experienced nearly complete reproductive failure. The poor reproductive response among hens on the diet of wheat plus oystershell suggested that calcium availability was not the only factor limiting productivity.
Digestive organ lengths, weights, and volumes in each of three groups of mallards ( Anas platyrhynchos ) were determined at the end of a 21-day period, during which one group was starter (control diet), another group was fed whole corn (low fiber content), and the third fed alfalfa pellets (high fiber content) to demonstrate the adaptive efficiency of the waterfowl diets of varying quality. Food consumption by the alfalfa-fed ducks was significantly gr 0.01) than the other two groups. All digestive organs of the alfalfa-fed ducks were significan (P < 0.01) than those of the corn- and turkey starter-fed ducks at the end of the study. It is that mallards can adapt rapidly to fibrous, relatively indigestible foods. This ability may hav value when higher quality foods are unavailable or when food habits change rapidly duritions.
The behavior of 26 adult American woodcock ( Philohela minor ) was studied in central Maine during the summers of 1971-73 using radiotelemetry. Adults used diurnal covers and nocturnal sites that were similar to those previously recorded for immature woodcock. The adults, however, were more active during the daylight hours and moved to nocturnal sites later in the evening. Adult woodcock seemed to be less susceptible than immatures to capture by banding crews at night, because adults walked more often between diurnal and nocturnal sites and remained close to the brushy edges at night. Adult birds occupied a smaller composite summer range than the immatures, did not move as far from their capture sites dunng the observation penods, and traveled shorter distances between diurnal and nocturnal sites.
We used radio telemetry to monitor the post-breeding activities of 129 mallards ( Anas platyrhynchos ) and 118 wood ducks ( Aix sponsa ) on a 932-km2 area in north-central Minnesota from 1968 to 1974. Upon completion of breeding activities and before the flightless period, all mallard drakes departed the area; this exodus peaked during early June. Of the non-brood hens 8 of 23 remained on the area, whereas 26 of 51 of the hens raising broods spent the flightless period on their breeding areas. Thirty-nine percent of the mallard hens on the area in the spring were present at the beginning of their flightless period. Fifty percent of the drake wood ducks and 41 percent of the hens left the breeding area before flightlessness. Their timing was similar to that of mallards. The flightless period began in mid-June for wood duck drakes and lasted into early October for some mallard hens. All late molting mallard and wood duck hens reared broods that same year. A minimum of 35 percent of the spring mallard hens remained on the area at the beginning of hunting season (early October). About 17 percent of the wood duck males and 42 percent of the females breeding locally remained on the area until hunting began. Eleven of 51 mallards and 4 of 25 wood ducks that reared broods were killed on the study area compared with 2 of 23 for non-brood mallards and 1 of 20 for non-brood wood duck hens. Principal habitats used by post-breeding mallards were bays of large lakes and river marshes. Wood ducks tended to use similar habitat but also frequented small woodland ponds. During the flightless period both species remained mostly in areas with abundant emergent cover.
Eggs of canvasback ducks (Aythya valisineria) from several major breeding areas were analyzed for organochlorine and mercury residues. Polychlorinated biphenyls (PCBs) were detected in 96 of 97 eggs, in concentrations up to 29 ppm (wet wt.). DDE occurred in 79 percent of the samples with a maximum residue of 12 ppm (wet wt.). DDT, DDD, dieldrin, hexachlorobenzene, cis-chlordane, heptachlor epoxide, and oxychlordane were detected less frequently. Mercury was detected in only 6 of 34 eggs analyzed. Most of the eggs contained concentrations of organochlorines and mercury below levels known to cause adverse effects on avian survival or reproduction.