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At least 1,063 records · Page 59Linked to original sources
USGS1986

Molt chronology of northern pintails in California

Intensity and chronology of molt in 10 feather groups (head, neck, breast, belly, back, rump, side, scapular, tertial, and tail) were measured using percentages of developing feathers (pinfeathers) converted to molt scores (0-100) in samples plucked monthly from northern pintails ( Anas acuta ) collected by shooting from August through March 1980-82 in the Sacramento Valley, California. Data to supplement sample size of immatures were obtained from October 1982 through January 1983. Molt scores of the prealternate molt peaked (30-40% pinfeathers) in immature and adult females and adult males in October when nearly all feather groups were molting. The prealternate molt in immature males did not peak until November. Adult males nearly completed this molt by December; no new feather growth occurred after January. Immature males were still growing new neck, side, rump, scapular, and tertial feathers in December. Molt scores of the prebasic molt among adult and immature females peaked (30-40% new growth) in February in both years. The prealternate molt of breast and belly feathers (both sexes) peaked earlier (Sep) than molt of most other feathers (Oct). Increased molt scores in peak months were a function of a disproportionate increase of molt activity within each feather group and the number of feather groups with molt. Molt scores of the prebasic molt in adult females were less during December and January of the dry (1980-81) than the wet (1981-82) winter. Restriction or delay of molt may conserve energy or other nutrients during poor habitat conditions.

California↗
USGS1986

Selenium and heavy metals in San Francisco Bay diving ducks

We analyzed for selenium (Se) and heavy metals in greater scaups ( Aythya marila ) and surf scoters ( Melanitta perspicillata ) collected from southern San Francisco Bay in March and April 1982. There were no differences (P > 0.05) between species for liver concentrations of silver (Ag), mercury (Hg), or lead (Pb). Copper (Cu) (P < 0.001) and zinc (Zn) (P < 0.01) levels were higher in scaups, whereas Se was higher in scoters (P < 0.001). Chromium (Cr) and nickel (Ni) occurred in < 50% of the samples, and there was no difference (P > 0.05) between the 2 species. The geometric mean cadmium (Cd) concentration in scoter kidneys (24.6 ppm, dry wt) was higher than in scaups (15.5 ppm) (0.1 > P > 0.05). Liver concentrations of Hg and Se were correlated (P < 0.01). The toxicological significance of some elements in these species is not known. However, Se levels in scoters (34.4 ppm, dry wt) were similar to those in livers of dabbling ducks (Anas spp.) in the nearby San Joaquin Valley where reproduction was impaired severely.

California↗
USGS1986

Trap-related injuries to gray wolves in Minnesota

Gray wolves ( Canis lupus ) captured in traps with toothed jaws offset 1.8 cm incurred fewer injuries than those captured in 3 other types of steel traps. Few wolves seriously damaged canine or carnassial teeth while in traps.

Minnesota↗
USGS1986

Influence of weather and density on lamb survival of desert mountain sheep

This report concerns the effect of weather on lamb survival in desert mountain sheep ( Ovis canadensis nelsoni ) to 6-8 months of age in the River Mountains, Nevada, and how it integrates with density to limit the population. Regression analyses were used to examine relationships between lamb survival and weather variables from 1970 to 1982. Autumn precipitation (Sep-Dec) of the preceding year (during gestation) had a significant (P < 0.05), positive effect on lamb survival. Herd density was significantly (P < 0.05) and inversely related to lamb survival. Spring winds had a positive and significant (P < 0.05) effect on lamb survival. Multiple regression revealed that 87% of the variability in lamb survival was accounted for by autumn precipitation during gestation (52%) and sheep density (35%).

Nevada↗
USGS1985

Evaluation of marked-recapture for estimating striped skunk abundance

The mark-recapture method for estimating striped skunk ( Mephitis mephitis ) abundance was evaluated by systematically livetrapping a radio-equipped population on a 31.4-km2 study area in North Dakota during late April of 1977 and 1978. The study population was 10 females and 13 males in 1977 and 20 females and 8 males in 1978. Skunks were almost exclusively nocturnal. Males traveled greater nightly distances than females (3.3 vs. 2.6 km, P < 0.05) and had larger home ranges (308 vs. 242 ha) although not significantly so. Increased windchill reduced night-time activity. The population was demographically but not geographically closed. Frequency of capture was positively correlated with time skunks spent on the study area. Little variation in capture probabilities was found among trap-nights. Skunks exhibited neither trap-proneness nor shyness. Capture rates in 1977 were higher for males than for females; the reverse occurred in 1978. Variation in individual capture rates was indicated among males in 1977 and among females in 1978. Ten estimators produced generally similar results, but all underestimated true population size. Underestimation was a function of the number of untrapped skunks, primarily those that spent limited time on the study area. The jackknife method produced the best estimates of skunk abundance.

North Dakota↗
USGS1985

Density-production characteristics of box-nesting wood ducks in a northern greentree impoundment

Nesting wood ducks ( Aix sponsa ) were studied for 7 years (1973-79) following placement of nest boxes within a 250-ha experimental greentree impoundment located at the Montezuma National Wildlife Refuge in central New York. Wood ducks filled available nesting space in the 3rd year of the study. As nesting space became saturated, density strife was reflected in dump nesting, nest desertion, and reduced hatchability. By the 5th year of study, nesting interference had reduced nesting efficiency to 22%. Discontinued flooding of the impoundment during the last 2 years of the study reduced the density of breeding pairs and restored nesting efficiency to 50 and 60%, respectively. Egg pecking by northern flickers ( Colaptes auratus ) increased as the study progressed and contributed to nest desertion. Dump nesting contributed efficiently to production under low density breeding conditions and permitted greater use of nest sites with a moderate but progressive decline in nesting efficiency as the population expanded. Total nest starts correlated negatively with nesting efficiency (r = -0.75, P < 0.05) and positively with the number of dump nests (r = +0.96, P< 0.01), number of deserted dump nests (r = +0.77, P< 0.05), and number of ducklings left in nest boxes (r = +0.77, P < 0.05). Mark-recapture estimates of day-old duckling production showed a sharp increase in production from tree cavities from 1973 to 1974, a probable result of a rapidly expanding nesting population and removal of raccoons ( Procyon lotor ) from the study area.

New York↗
USGS1985

An aerial photographic census of Chesapeake Bay and North Carolina canvasbacks

We used conventional 35-mm photography to conduct an aerial photographic census of canvasbacks ( Aythya valisineria ) throughout Chesapeake Bay (tidal Maryland and Virginia) and coastal North Carolina, 26-30 January 1981. Flock size and sex ratio characteristics were determined from examination of color transparencies of 165 canvasback flocks totaling over 95,000 birds. A sex ratio of 2.91 males/female was determined from 68,769 birds, 80% of the birds in 150 flocks. Sex ratio for the Atlantic Flyway was projected as 2.90 males/female. We recorded the greatest number of canvasbacks and the widest range of flock size in Maryland waters; the fewest canvasbacks and the smallest average flock size in Virginia; and the fewest but on average the largest flocks of canvasbacks in North Carolina. Sex ratio varied latitudinally in the flyway with a tendency for males to occupy more northern and females more southern latitudes in winter. Sex ratio (males/female) was highest in Maryland (3.98), slightly lower in Virginia (3.71), and lowest in North Carolina (1.70). Locally, sex ratio varied with flock size. In Chesapeake Bay, small flocks (<100 birds) had lower sex ratio (P < 0.05) than medium (100-1,000) or large (>1,000) flocks. By providing large- sample sex ratio information, as well as exact counts of birds, we conclude that low-level 35-mm aerial photography is the most efficient and accurate means of determining canvasback population status in eastern coastal habitats.

Maryland, North Carolina, Virginia↗
USGS1988

Duck nest success in the prairie pothole region

We estimated nest success of mallard ( Anas platyrhynchos ), gadwall ( A. strepera ), blue-winged teal ( A. discors ), northern shoveler ( A. clypeata ), and northern pintail ( A. acuta ) for 5 regions in North Dakota, South Dakota, and Minnesota, for 1-3 periods between 1966 and 1984, and for 8 habitat classes. We obtained composite estimates of nest success for regions and periods by weighting each habitat proportional to the number of nest initiations. The distribution of nest initiations was derived from estimates of breeding populations, preferences of species for nesting habitats, and availability of habitats. Nest success rates ranged from < 5 to 36% among regions, periods, and species. Rates were lowest in western Minnesota (MNW) and eastern North Dakota (NDE), intermediate in central North Dakota (NDC) and eastern South Dakota (SDE), and highest in central South Dakota (SDC). In regions with comparable data, no consistent trend in nest success was apparent from early to late periods. Gadwalls and blue-winged teal nested more successfully than mallards and pintails; the relative success of shovelers varied regionally. Ducks nesting in idle grassland were the most successful and those nesting in cropland were least successful. Mammalian predation was the major cause of nesting failure (54-85%) in all habitats, but farming operations resulted in 37 and 27% of the nesting failures in cropland and hayland, respectively. Most of the populations studied were not self-sustaining.

Minnesota, North Dakota, South Dakota↗
USGS1987

Use of urine in snow to indicate condition of wolves

Urine deposited in snow by wild gray wolves ( Canis lupus ) and by fed and fasted captive wolves was analyzed for urea nitrogen, calcium, sodium, potassium, and creatinine. Ratios of the elements with creatinine were considerably higher for fed than for fasted animals, and ratios for fed wolves compared favorably with ratios from wolf urine in snow along trails leading from kills. Thus, wolf urine in the snow can indicate whether wolves have fed recently, and a series of such urine collections from any given pack can indicate relative nutritional state.

Minnesota↗
USGS1987

Evaluation of pitfall trapping in northwestern forests: Trap arrays with drift fences

We operated pitfall arrays with 5-m drift fences at 30 stands in western Oregon and Washington for 180 days. Pitfall arrays had a pronounced removal effect on small mammals (but not on the herpetofauna) during the 1st 60 days of trapping. Conventional short (10-day) trapping periods were only adequate to detect the most common mammals. About 60 days were needed to compile a relatively complete species list (>85% of species captured) at each site. Reptiles were caught almost exclusively in the summer; amphibian captures were correlated with increased precipitation in the fall. Short (2.5-m) drift fences were less effective than the standard length of 5 m. Funnel traps captured few forest vertebrates. Pitfalls captured more insectivorous mammals than did snap traps, but snap traps were more effective for a few cricetid rodents. Pitfall arrays are adaptable to many habitats and can help assess the presence of small vertebrates, such as shrews and amphibians, that are undersampled by other techniques.

Oregon, Washington↗
USGS1987

Breeding bird response to cattle grazing of a cottonwood bottomland

We studied avian habitat relationships and the impact of grazing on breeding densities of selected migratory birds in a plains cottonwood ( Populus sargentii ) bottomland in northeastern Colorado. Five 16-ha plots served as controls and 5 were fenced and fall-grazed October-November 1982-84 following a season of pre-treatment study in the spring of 1982. We focused our analysis on bird species directly dependent on the grass-herb-shrub layer of vegetation for foraging, nesting, or both. The guild included house wren ( Troglodytes aedon ), brown thrasher ( Toxostoma rufum ), American robin ( Turdus migratorius ), common yellowthroat ( Geothlypis trichas ), yellow-breasted chat ( Icteria virens ), and rufous-sided towhee ( Pipilo erythropthalmus ). Moderate, late-fall grazing had no detectable impact on calculated densities of any of the 6 species, implying that proper seasonal grazing of a cottonwood floodplain is, at least initially (3 years), compatible with migratory bird use of a site for breeding. Habitat associations suggested that common yellowthroats and yellow-breasted chats were most unique and most likely to respond negatively to higher levels of grazing. We suggest that these latter 2 species are appropriate ecological indicators of the quality of ground-shrub vegetation as breeding bird habitats in lowland floodplains of the Great Plains.

Journal of Wildlife Management↗
USGS1987

Incorporating activity time in harmonic home range analysis

The amount of time an animal spends in particular areas is an important aspect of estimating its home range and activity pattern. Calculations of home range using the harmonic mean can be modified to reflect the amount of time or the type of activity observed at each location. The relative time spent at each location may be used to calculate a time-weighted harmonic home range and associated use pattern. This time-weighted harmonic mean approach provides a method for incorporating bursts of relocation data into a home range analysis or identifying activity areas within the home range.

Journal of Wildlife Management↗
USGS1985

An evaluation of condition indices for birds

A Lipid Index, the ratio of fat to fat-free dry weight, is proposed as a measure of fat stores in birds. The estimation of the index from field measurements of live birds is illustrated with data on the sandhill crane ( Grus canadensis) and greater white-fronted goose ( Anser albifrons ). Of the various methods of assessing fat stores, lipid extraction is the most accurate but also the most involved. Water extraction is a simpler laboratory method that provides a good index to fat and can be calibrated to serve as an estimator. Body weight itself is often inadequate as a condition index, but scaling by morphological measurements can markedly improve its value.

Journal of Wildlife Management↗
USGS1985

Organophosphate insecticide (famphur) topically applied to cattle kills magpies and hawks

A systematic field study of a black-billed magpie ( Pica pica ) population revealed that magpies and red-tailed hawks ( Buteo jamaicensis ) were killed by famphur (=famophos, Warbex®) used as a pouron to control cattle warbles ( Hypoderma sp.). Magpie mortality began on treatment day and continued for more than 3 months (38 found dead); mortality peaked between Day 5 and Day 13. Estimates of magpie density (based on transects) decreased in both the control and treatment areas, but the decrease was greater in the treatment area. A red-tailed hawk found dead on Day 10 had eaten a famphur-contaminated magpie. Another red-tailed hawk was found alive but immobilized, and a third died outside the study area. Brain cholinesterase (ChE) activity was 70-92% depressed in all dead birds examined; famphur residues were detected in all 17 magpies and the 2 hawks analyzed. The amount of famphur obtained by the dead magpies was estimated at 5.2-6.1 mg/kg (based on residue concentrations in the gizzard), which was above the acute oral LD50 for several bird species. The cow hair portion (12%) of the pooled gizzard contents from 13 other dead magpies produced extremely high famphur residues (4,600 ppm). The residues persisted on cattle hair for more than 90 days post-treatment. Magpie populations in the far western states declined between 1968 and 1979, which corresponds with widespread use of famphur, although other factors may be involved.

Washington↗
USGS1987

A decoy trap for breeding-season mallards in North Dakota

A modified decoy trap was effective for capturing wild adult male and female mallards ( Anas platyrhynchos ) during the 1980-81 breeding seasons in North Dakota. Key features contributing to the trap's success included a central decoy cylinder, large capture compartments with spring-door openings, an adjustable trigger mechanism with a balanced door attachment that was resistant to trap movement, and the use of F1, wild-stock or game-farm female decoys.

North Dakota↗
USGS1987

Microbial infections in a declining wild turkey population in Texas

A survey was conducted at 5 locations in Texas for avian pathogens that might adversely affect wild turkey ( Meleagris gallopavo ) productivity and survival. At 1 site, the Rob and Bessie Welder Wildlife Refuge (WWR), turkeys have declined precipitously in recent years. During the winters of 1983-85, 442 wild turkeys were caught with cannon and drop nets, 161 of these on WWR. Blood samples were drawn for serologic evaluation, and cloacal and tracheal swabs were collected for isolation attempts. Salmonella spp. bacteria, Newcastle disease virus (NDV), and avian influenza virus (AIV) were not detected in any samples tested. Serologic tests for antibodies to NDV and AIV also were negative. Many mycoplasma isolates were recovered from turkeys from every location. Characterization of these isolates indicated that several species were present. None were species typically associated with mycoplasmosis in domestic turkeys, such as Mycoplasma gallisepticum (MG), M. meleagridis (MM), or M. synoviae (MS), although antibodies to these pathogens were detected in turkeys at every location sampled. There was no evidence to link any of these disease causing agents to the decline observed in the population of wild turkeys on the WWR.

Texas↗