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United States Department of Agriculture Wildlife Services: Staff Publications

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Articles 1171 - 1200 of 1529

Full-Text Articles in Physical Sciences and Mathematics

Bears Prefer Trees In The Spring, Dale L. Nolte Jul 2003

Bears Prefer Trees In The Spring, Dale L. Nolte

United States Department of Agriculture Wildlife Services: Staff Publications

As they emerge from their winter den, bears need an energy source and food is relatively scarce. Concurrently, trees are breaking dormancy and starting to generate carbohydrates. Consequently, bears commonly girdle Douglas-fir trees during the spring to feed on the available carbohydrates. Bears strip bark from a tree with their claws, then feed on the sapwood by scraping it from the heartwood with their teeth. Scattered remnants of bark strewn at the base of a tree and vertical tooth marks are characteristic indicators of bear activity. Most frequently bears forage on the lower bole of trees, girdling the bottom three …

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From Seedlings To Crowns: These Species Cover It All, Wendy M. Arjo Jul 2003

From Seedlings To Crowns: These Species Cover It All, Wendy M. Arjo

United States Department of Agriculture Wildlife Services: Staff Publications

Damage to trees in the Pacific Northwest ecosystems can occur at any point in a tree’s development. Of the three genera of voles, Microtus is the largest and most destructive to western forest ecosystems. Voles, like many small rodent species, have the ability to produce numerous litters in a single year and females are mature 30-40 days after they are born. Average litter size is three pups, and females can a produce a litter every 21 days. With this type of reproductive capability, it is easy to see why vole populations can rapidly expand in ideal habitats.

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Population Monitoring In Support Of A Rabies Vaccination Program For Skunks In Arizona, Richard M. Engeman, Kevin L. Christensen, Michael J. Pipas, David L. Bergman Jul 2003

Population Monitoring In Support Of A Rabies Vaccination Program For Skunks In Arizona, Richard M. Engeman, Kevin L. Christensen, Michael J. Pipas, David L. Bergman

United States Department of Agriculture Wildlife Services: Staff Publications

Three population monitoring methods were evaluated in support of a trap/vaccinate/release program for controlling a bat variant of rabies virus in skunks (Mephitis mephitis) in Flagstaff, Arizona (USA). Skunks were the primary species targeted for population monitoring during the program, but feral cats were also monitored as they represented an abundant secondary vector species capable of rabies transmission. Skunks were vaccinated and released, except for a subset tested for rabies. All captured cats were placed in the local animal shelter. Spotlight surveys essentially did not detect skunks, and were not able to detect reductions in the cat population. …

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Nwrc: Providing World Leadership In Science-Based Problem Management, J. Russell Mason Jul 2003

Nwrc: Providing World Leadership In Science-Based Problem Management, J. Russell Mason

United States Department of Agriculture Wildlife Services: Staff Publications

he National Wildlife Research Center (NWRC) functions as the research arm of the Wildlife Services (WS) program, an agency of the U.S. Department of Agriculture, Animal and Plant Health Inspection Service. Located on the Foothills campus of Colorado State University, WS-NWRC helps WS manage wildlife conflicts by providing scientific information on damage or threats to human health and safety, and by developing new tools and management techniques. WS-NWRC research activities emphasize economically, environmentally and socially acceptable methods that reduce or stop wildlife damage effectively without risk to humans, wildlife or the natural environment.

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Managing Ungulates To Protect Trees, Dale L. Nolte Jul 2003

Managing Ungulates To Protect Trees, Dale L. Nolte

United States Department of Agriculture Wildlife Services: Staff Publications

ig game species, such as elk and deer, inflict the most widespread form of damage to forest resources. Elk may trample or pull seedlings without well-established root systems out of the ground. Browsing elk often splinter woody stems. During the spring, the stems may be stripped of bark below where they break the stem. Deer damage inflicted on seedlings is similar to elk damage. Woody stems are often splintered and the bark is stripped from twigs. New buds are generally clipped back to the previous year’s growth. Deer do not pull seedlings as frequently as elk and their damage rarely …

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4,4'-Dinitrocarbanilide (Dnc) Concentrations In Egg Shells As A Predictor Of Nicarbazin Consumption And Dnc Dose In Goose Eggs, Randal S. Stahl, Kurt C. Vercauteren, Dennis Kohler, John J. Johnston Jun 2003

4,4'-Dinitrocarbanilide (Dnc) Concentrations In Egg Shells As A Predictor Of Nicarbazin Consumption And Dnc Dose In Goose Eggs, Randal S. Stahl, Kurt C. Vercauteren, Dennis Kohler, John J. Johnston

United States Department of Agriculture Wildlife Services: Staff Publications

Nicarbazin is being investigated as an infertility agent for the control of non-migratory Canada geese (Branta canadensis L) populations. Nicarbazin is presently registered for use as a coccidiostat for poultry. Geese fed sufficient quantities of nicarbazin will lay non-viable eggs. We established nicarbazin consumption by measuring the concentration of a component of the formulation, 4,4’-dinitrocarbanilide (DNC) in the egg contents (yolk, albumin) in non-viable eggs. To estimate the nicarbazin consumption of birds that laid viable eggs (eggs that hatched or contained an embryo), a high-performance liquid chromatography method was developed to measure the concentration of DNC in egg …

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Determination Of 4,4'-Dintrocarbanilide (Dnc), A Component Of Nicarbazin, In Canada Goose (Branta Canadensis) Eggshells Using High-Performance Liquid Chromatography, Randal S. Stahl, Kurt C. Vercauteren, Teresa L. Buettgenbach, John J. Johnston Jun 2003

Determination Of 4,4'-Dintrocarbanilide (Dnc), A Component Of Nicarbazin, In Canada Goose (Branta Canadensis) Eggshells Using High-Performance Liquid Chromatography, Randal S. Stahl, Kurt C. Vercauteren, Teresa L. Buettgenbach, John J. Johnston

United States Department of Agriculture Wildlife Services: Staff Publications

A method was developed using high-performance liquid chromatography to assay 4,4'-dinitrocarbanilide (DNC), the active ingredient in Nicarbazin, in eggshells collected from Canada geese fed a formulated feed fortified with Nicarbazin at doses of 0, 125, 250, and 500 μg/g. The method was developed using chicken eggshells fortified with DNC. The method was used to quantify DNC in both the shell-associated membranes and the calcified shell extracellular matrix. These values were compared to those obtained for a composite sample consisting of both the membranes and the calcified shell extracellular matrix. The validated method was used to quantify DNC in eggshells from …

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Cool Temperatures Elicit Reproduction In A Biologically Invasive Predator, The Brown Treesnake (Boiga Irregularis), Tom Mathies, Lowell A. Miller May 2003

Cool Temperatures Elicit Reproduction In A Biologically Invasive Predator, The Brown Treesnake (Boiga Irregularis), Tom Mathies, Lowell A. Miller

United States Department of Agriculture Wildlife Services: Staff Publications

Two different temperature regimes for eliciting reproduction in male and females of the Guam form of the brown treesnake were investigated. Males and females maintained at 24°C followed by a 60-day cool period at 19°C exhibited substantial reproductive activity, and the females that produced clutches did so during a brief period after return to 24°C. In contrast, individuals maintained at 28°C followed by an identical 19°C cooling period exhibited relatively little reproductive activity, and although some females became vitellogenic, none produced eggs. Reproductive activity was virtually absent in all individuals in both groups 7 months after the end of the …

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Longevity Of A Woodhouse's Toad, Richard M. Engeman, Melvin A. Engeman May 2003

Longevity Of A Woodhouse's Toad, Richard M. Engeman, Melvin A. Engeman

United States Department of Agriculture Wildlife Services: Staff Publications

We follow up a report on a male Woodhouse's toad (Bufo woodhousii) that had been observed since 1978 (Engeman RM, Engeman EM. 1996. Longevity of Woodhouse's toad in Colorado. Northwestern Naturalist 77:23). The toad had found its way into, and remained in, a basement window-well of a brick home in an unincorporated western suburb of Denver, Colorado. This property has recently changed hands, and access for future monitoring of the toad's survival is uncertain. Thus, we report its longevity as of 2002.

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Rodent Hunt, Dr. Ray Sterner May 2003

Rodent Hunt, Dr. Ray Sterner

United States Department of Agriculture Wildlife Services: Staff Publications

The Dryland Project is a multi-year research effort to identify no-tillage or reduced tillage, non-irrigated crop types and practices that will improve yields and soil characteristics in eastern Colorado. Left uncultivated, this is shortgrass prairie made up of blue grama, western wheatgrass, buffalo grass, prickly pear cactus, yucca shrub, plus other plant varieties, and laced with riparian stream flows. When cultivated, winter wheat has worked well here, as long as it is left idle biannually (alternated as fallow) to restore sufficient moisture for the next cycle. Alternative dryland crops and rotation schemes are being studied as a way to reduce …

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Amount And Economic Valuation Of Feral Hog Damage To A Unique Basin Marsh Wetland In Florida, Richard M. Engeman, Henry T. Smith, Robert G. Severson, Mary Ann M. Severson, Stephanie A. Shwiff, Bernice Constantin, Daniel Griffen Apr 2003

Amount And Economic Valuation Of Feral Hog Damage To A Unique Basin Marsh Wetland In Florida, Richard M. Engeman, Henry T. Smith, Robert G. Severson, Mary Ann M. Severson, Stephanie A. Shwiff, Bernice Constantin, Daniel Griffen

United States Department of Agriculture Wildlife Services: Staff Publications

Feral hogs (Sus scrofa) have been introduced into many natural habitats throughout the world, and they have adversely affected the environment in most of those places. Basin marshes are unique, but dwindling ecosystems in Florida that are especially vulnerable to damage by feral hogs. We estimated the amount of hog damage to the last remnant of a basin marsh system in Savannas Preserve State Park (SPSP), and to ecotones within the marsh. We also applied an economic valuation method for the hog damage that was based on the dollar amounts that wetland regulators have allowed permit applicants to …

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Age-Specific Reproduction By Female Laughing Gulls (Larus Atricilla), Richard A. Dolbeer, Glen E. Bernhardt Apr 2003

Age-Specific Reproduction By Female Laughing Gulls (Larus Atricilla), Richard A. Dolbeer, Glen E. Bernhardt

United States Department of Agriculture Wildlife Services: Staff Publications

The age at which female gulls first reproduce is poorly documented. We examined plumage and reproductive organs of Laughing Gulls (Larus atricilla) collected from May–August 2000–2001 at John F. Kennedy International Airport, New York, to determine age-specific reproductive effort. Each gull was classified as one year old (hatched in previous year), two years old, or ≥3 years old on the basis of color patterns of the hood and tail feathers and fifth primary flight feather. For females, each ovary was examined to determine if postovulatory follicles were present. In 2000 and 2001, the first gulls with postovulatory follicles were recorded …

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Impacts Of Small Mammals And Birds On Low-Tillage, Dryland Crops, Ray T. Sterner, Brett E. Petersen, Stanley E. Gaddis, Kenneth L. Tope, David J. Poss Apr 2003

Impacts Of Small Mammals And Birds On Low-Tillage, Dryland Crops, Ray T. Sterner, Brett E. Petersen, Stanley E. Gaddis, Kenneth L. Tope, David J. Poss

United States Department of Agriculture Wildlife Services: Staff Publications

During 2000–2001, small mammals, birds, and potential corn/soybean damage were studied at a low-tillage, non-irrigated agricultural research site in the Colorado Piedmont. A small mammal surveyinvolved four trapping sessions and 18, 12-live-trap grids each. Within years, two grids each were placed at random, fixed locations in experimental corn, fallow, millet, pea, soybean, sunflower, and wheat plots at the site; two off-plot grids each were set at random, fixed locations <100m from the north and south edge of these plots. In 2001, periodic bird observations were conducted, and damage to corn and soybean plants was assessed. Capture rates were low during all trap sessions (range 0.1%–3.3%, Χ̅ = 2:2%). Sixty-three small mammals were captured and 39 were recaptured. Captures included deer mouse (Peromyscus maniculatus), northern grasshopper mouse (Onychomys leucogaster), thirteen-lined ground squirrel (Spermophilus tridecemlineatus), and western harvest mouse (Reithrodontomys megalotis). Deer mice accounted for 56 of …

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Serologic Survey For Diseases In Free-Ranging Coyotes (Canis Latrans) From Two Ecologically Distinct Areas Of Utah, Wendy M. Arjo, Eric M. Gese, Cassity Bromley, Adam Kozlowski, Elizabeth S. Williams Apr 2003

Serologic Survey For Diseases In Free-Ranging Coyotes (Canis Latrans) From Two Ecologically Distinct Areas Of Utah, Wendy M. Arjo, Eric M. Gese, Cassity Bromley, Adam Kozlowski, Elizabeth S. Williams

United States Department of Agriculture Wildlife Services: Staff Publications

The influence of habitat and associated prey assemblages on the prevalence of canine diseases in coyotes (Canis latrans) has received scant attention. From December 1997 through December 1999, we captured 67 coyotes in two ecologically distinct areas of Utah (USA): Deseret Land and Livestock Ranch and US Army Dugway Proving Ground. These areas differ in habitat and prey base. We collected blood samples and tested for evidence of various canine diseases. Prevalence of antibodies against canine parvovirus (CPV) was 100% in the Deseret population and 93% in the Dugway population. All juveniles in both populations had been exposed. …

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Prevalence Of Antibodies To Neospora Caninum, Sarcocystis Neurona, And Toxoplasma Gondii In Wild Horses From Central Wyoming, J. P. Dubey, S.M. Mitchell, J.K. Morrow, J.C. Rhyan, L.M. Stewart, D.E. Granstrom, S. Romand, P. Thulliez, W.J. Saville, D.S. Lindsay Mar 2003

Prevalence Of Antibodies To Neospora Caninum, Sarcocystis Neurona, And Toxoplasma Gondii In Wild Horses From Central Wyoming, J. P. Dubey, S.M. Mitchell, J.K. Morrow, J.C. Rhyan, L.M. Stewart, D.E. Granstrom, S. Romand, P. Thulliez, W.J. Saville, D.S. Lindsay

United States Department of Agriculture Wildlife Services: Staff Publications

Sarcocystis neurona, Neospora caninum, N. hughesi, and Toxoplasma gondii are 4 related coccidians considered to be associated with encephalomyelitis in horses. The source of infection for N. hughesi is unknown, whereas opossums, dogs, and cats are the definitive hosts for S. neurona, N. caninum, and T. gondii, respectively. Seroprevalence of these coccidians in 276 wild horses from central Wyoming outside the known range of the opossum (Didelphis virginiana) was determined. Antibodies to T. gondii were found only in 1 of 276 horses tested with the modified agglutination test using 1: 25, 1:50, …

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Common Raven Nests In Eastern Kentucky, John J. Cox, Nathan W. Seward, Jeffrey L. Larkin, David S. Maehr Mar 2003

Common Raven Nests In Eastern Kentucky, John J. Cox, Nathan W. Seward, Jeffrey L. Larkin, David S. Maehr

United States Department of Agriculture Wildlife Services: Staff Publications

Although ravens were once widespread throughout Appalachia they are now considered threatened or endangered in many states of the region. We document a nesting pair of common ravens in an area of southeastern Kentucky nearly 50 km northwest of traditional nesting sites. Further, we suggest several factors that may have influenced the patterns of raven abundance in the state and offer management recommendations to assist their recovery.

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Mitigating Impacts Of Terrestrial Lnvasive Species, Kathleen A. Fagerstone Mar 2003

Mitigating Impacts Of Terrestrial Lnvasive Species, Kathleen A. Fagerstone

United States Department of Agriculture Wildlife Services: Staff Publications

Human beings have introduced other species around the world both accidentally and intentionally. Accidental introductions resulted from escape from captivity (monk parakeets [Myiopsitta monachus] in Florida), stowaways (rats [Ranus spp.] and house mice [Mus musculus] worldwide; brown tree snakes [Boiga irregularis] in Guam), or expansion of species' ranges. Intentional introductions occurred for various reasons including: 1) aesthetics (songbirds into Hawaii, grey squirrel [Sciurus carolinensis] into Europe, and European songbirds imported by British colonists into North America, Australia, and New Zealand); 2) economics (nutria [Myocastor coypus] introduced in the …

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Roof Rat Invasion Of An Urban Desert Island, Dale L. Nolte, David Bergman, John Townsend Mar 2003

Roof Rat Invasion Of An Urban Desert Island, Dale L. Nolte, David Bergman, John Townsend

United States Department of Agriculture Wildlife Services: Staff Publications

Roof rats have invaded the Phoenix metropolitan area. Although the desert surrounding Phoenix is formidacie to roof rats, residential and urban development has probably sufficiently altered habitat to render it suitable for roof rats. Ongoing community and government campaigns are reducing the resources necessary for rat survival and are working to suppress rat populations. Whether these efforts will be adequate to eradicate roof rats from the area is unknown. Rat activity has declined over the past several months. However, it is difficult to assess whether this reduced activity reflects decreased rat numbers or if rats have become less active during …

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Pre- And Post-Harvest Movements Of Female Rice-Field Rats In West Japanese Rice Fields, Jens Jacob, Dale L. Nolte, Rudy Hartono Mar 2003

Pre- And Post-Harvest Movements Of Female Rice-Field Rats In West Japanese Rice Fields, Jens Jacob, Dale L. Nolte, Rudy Hartono

United States Department of Agriculture Wildlife Services: Staff Publications

This study examined changes in the spatial behavior of rice-field rats (Rattus argentiventer) associated with the harvest of lowland irrigated rice. Radio-collared female rice-field rats were tracked before and after harvest in rice fields in West Java, Indonesia. The rice-field rats clearly reacted to the changes in habitat structure caused by the harvest by relocating their home ranges on average 300-400 m to piles of rice straw left on the fields and to unharvested areas. Post-harvest, there was a decrease in home-range size of 67% (0.6 ha pre-harvest: 0.2 ha post-harvest) and a decrease in range span of …

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Feasibility Of Non-Lethal Approaches To Protect Riparian Plants From Foraging Beavers In North America, Dale L. Nolte, Mark W. Lutman, David L. Bergman, Wendy M. Arjo, Kelly R. Perry Mar 2003

Feasibility Of Non-Lethal Approaches To Protect Riparian Plants From Foraging Beavers In North America, Dale L. Nolte, Mark W. Lutman, David L. Bergman, Wendy M. Arjo, Kelly R. Perry

United States Department of Agriculture Wildlife Services: Staff Publications

Beavers in North America will occupy almost any wetland area containing available forage. Wetland restoration projects often provide the resources necessary for dispersing beavers to create desirable habitats. Their wide distribution and ability to disperse considerable distances almost assure that beavers will establish themselves in new wetlands. Although beavers are a natural and desirable component of a wetland ecosystem, their foraging behaviors can be destructive. Fencing may be a feasible approach to reduce damage to small, targeted areas, and textural repellents may provide some utility to protect established trees. However, these non-lethal approaches will be marginally effective when beaver populations …

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Wariness Of Coyotes To Camera Traps Relative To Social Status And Territory Boundaries, E.S. Sequin, Michael M. Jaeger, Peter F. Brussard, Reginald H. Barrett Mar 2003

Wariness Of Coyotes To Camera Traps Relative To Social Status And Territory Boundaries, E.S. Sequin, Michael M. Jaeger, Peter F. Brussard, Reginald H. Barrett

United States Department of Agriculture Wildlife Services: Staff Publications

The primary objective of this study was to develop a better understanding of coyote (Canis latrans) wariness particularly as it related to social status. We determined that territory status (controlling alpha, resident beta, or nonterritorial transient) affected vulnerability to photo-capture by infrared-triggered camera systems. All coyotes were wary of cameras, leading to relatively low numbers of photo-captures, most of which occurred at night. Alphas were significantly underrepresented in photographs and were never photo-captured inside their awn territories. Betas were photographed inside and outside their territories, whereas transients were most often photographed on edges of territories. Both alphas and …

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Low Mitochondrial Dna Variation In Double-Crested Cormorants In Eastern North America, Juliann L. Waits, Michael L. Avery, Mark E. Tobin, Paul L. Leberg Feb 2003

Low Mitochondrial Dna Variation In Double-Crested Cormorants In Eastern North America, Juliann L. Waits, Michael L. Avery, Mark E. Tobin, Paul L. Leberg

United States Department of Agriculture Wildlife Services: Staff Publications

Double-crested Cormorant (Phalacrocorax auritus) numbers are increasing throughout eastern North America. We compared variation for five portions of mtDNA to determine if genetic differences existed among portions of the breeding range that would need to be considered when formulating management programs. Sequences for four mtDNA regions were identical across sample locations; frequencies of two haplotypes of the mitochondrial Control Region were similar across sampling locations. There is no evidence of restricted gene flow among breeding areas, or between subspecies with different migratory patterns.

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Scavenging By Vertebrates: Behavioral, Ecological, And Evolutionary Perspectives On An Important Energy Transfer Pathway In Terrestrial Ecosystems, Travis L. Devault, Olin E. Rhodes Jr., John A. Shivik Feb 2003

Scavenging By Vertebrates: Behavioral, Ecological, And Evolutionary Perspectives On An Important Energy Transfer Pathway In Terrestrial Ecosystems, Travis L. Devault, Olin E. Rhodes Jr., John A. Shivik

United States Department of Agriculture Wildlife Services: Staff Publications

Carrion use by terrestrial vertebrates is much more prevalent than conventional theory implies, and, rather than a curiosity of animal behavior, is a key ecological process that must be accounted for. Human aversion to rotted substances and difficulties associated with identifying scavenged material in studies of food habits have contributed to the relative lack of information concerning scavenging behavior in vertebrates. Several lines of evidence, however, suggest that carrion resources are more extensively used by vertebrates than has been widely assumed: 1) a substantial number of animals die from causes other than predation and become available to scavengers, 2) a …

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Characteristics Of Current And Historical Kit Fox (Vulpes Macrotis) Dens In The Great Basin Desert, Wendy M. Arjo, Tim J. Bennett, Adam J. Kozlowski Feb 2003

Characteristics Of Current And Historical Kit Fox (Vulpes Macrotis) Dens In The Great Basin Desert, Wendy M. Arjo, Tim J. Bennett, Adam J. Kozlowski

United States Department of Agriculture Wildlife Services: Staff Publications

We examined the ecological and physical characteristics of den sites for 13 adult kit fox (Vulpes macmtis) in western Utah from December 1998 to February 2001. We also compared current and historical den distribution among habitat types. The number of den sites used was not influenced by home-range size (P = 0.11) or season (P = 0.40), but was influenced by geographical area. Home-range size was smallest (P = 0.007) and the number of dens used was greatest (P = 0.009) in mountainous areas. Ecological and physical characteristics of single-use dens (n = …

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Using Color-Infrared Photography And Gis To Quantify Cattail Coverage In Wetlands, H. Jeffrey Homan, Linda B. Penry, George M. Linz Feb 2003

Using Color-Infrared Photography And Gis To Quantify Cattail Coverage In Wetlands, H. Jeffrey Homan, Linda B. Penry, George M. Linz

United States Department of Agriculture Wildlife Services: Staff Publications

Analyzing changes in habitat features at very large scales requires digital images with both high spatial and spectral resolutions. As part of an experiment to reduce blackbird (Icterinae) damage to sunflower, we used large-scale color-infrared photography to monitor regrowth of herbicide-treated cattail (Typha spp.) in wetlands used by roosting blackbirds. In this presentation we describe the methods used to collect, convert, interpret, and analyze high resolution images.

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Using Color-Infrared Photography And Gis Using Color-Infrared Photography And Gis, H. Jeffrey Homan, Linda B. Penry, George M. Linz Feb 2003

Using Color-Infrared Photography And Gis Using Color-Infrared Photography And Gis, H. Jeffrey Homan, Linda B. Penry, George M. Linz

United States Department of Agriculture Wildlife Services: Staff Publications

Analyzing changes in habitat features at very large scales requires digital images with both high spatial and spectral resolutions. As part of an experiment to reduce blackbird (Icterinae) damage to sunflower, we used large-scale color-infrared photography to monitor regrowth of herbicide-treated cattail (Typha spp.) in wetlands used by roosting blackbirds. In this presentation we describe the methods used to collect, convert, interpret, and analyze high resolution images.

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Baiting Blackbirds (Icteridae) In Stubble Grain Fields During Spring Migration In South Dakota, G. M. Linz, G.A. Knutsen, H.J. Homan, W.J. Bleier Feb 2003

Baiting Blackbirds (Icteridae) In Stubble Grain Fields During Spring Migration In South Dakota, G. M. Linz, G.A. Knutsen, H.J. Homan, W.J. Bleier

United States Department of Agriculture Wildlife Services: Staff Publications

Blackbirds (Icteridae) annually damage US$5–8 million of ripening sunflower in the northern Great Plains. Baiting blackbirds with avicide-treated rice during spring migration might reduce the regional breeding population. In March and April 1996–1997, we simulated a baiting program in eastern South Dakota to compare attractiveness of rice-baited plots placed in fields of corn and soybean stubble. Blackbirds used plots in corn stubble more often than plots in soybean stubble and chose rice-baited plots over unbaited reference plots. We conclude that blackbirds can be successfully baited with avicide-treated rice placed in corn stubble. Copyright 2002 Elsevier Science Ltd. All rights reserved.

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Predator Odours As Reproductive Inhibitors For Norway Rats, Vera V. Voznessenskaya, Sergey V. Naidenko, Natalia Yu. Feoktistova, Georgy J. Krivomazov, Lowell A. Miller, Larry Clark Feb 2003

Predator Odours As Reproductive Inhibitors For Norway Rats, Vera V. Voznessenskaya, Sergey V. Naidenko, Natalia Yu. Feoktistova, Georgy J. Krivomazov, Lowell A. Miller, Larry Clark

United States Department of Agriculture Wildlife Services: Staff Publications

We examined the influence of predator odor on reproductive output of Norway rats (Rattus norvegicus). Naive laboratory rats responded to predator chemical cues with reduced litter sire and skewed sex ratio. We found that exposure to predator urine had its greatest effect on implantation and maintenance of implantation when predator urine was applied to the bedding of rats during the first third of gestation. Based on the physical appearance of corpora lutea and uterine implantation scars, we found that the reduction in litter sire was due to resolution of the embryos during the early part of gestation. Subsequently, …

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Impact Of Blackbird Damage To Sunflower: Bioenergetic And Economic Models, Brian D. Peer, H. Jeffrey Homan, George M. Linz, William J. Bleier Feb 2003

Impact Of Blackbird Damage To Sunflower: Bioenergetic And Economic Models, Brian D. Peer, H. Jeffrey Homan, George M. Linz, William J. Bleier

United States Department of Agriculture Wildlife Services: Staff Publications

We constructed bioenergetic and economic models to estimate the potential impact of Red-winged Blackbirds (Agelaius phoeniceus), Common Grackles (Quiscalus quiscula), and Yellow-headed Blackbirds (Xanthocephalus xanthocephalus) on production yields of sunflower in the northern Great Plains of North America. The amount of sunflower consumed annually by males and females, after considering field metabolic rates, energy value and moisture content of achenes, and percentage of sunflower in diets was, respectively: Red-winged Blackbirds 277 g and 168 g; Common Grackles 267 g and 230 g; and Yellow-headed Blackbirds 248 g and 139 g. The per capita annual …

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Temporal Genetic Variation In A Coyote (Canis Latrans) Population Experiencing High Turnover, Christen Lenney William, Karen Blejwas, John J. Johnston, Michael M. Jaeger Feb 2003

Temporal Genetic Variation In A Coyote (Canis Latrans) Population Experiencing High Turnover, Christen Lenney William, Karen Blejwas, John J. Johnston, Michael M. Jaeger

United States Department of Agriculture Wildlife Services: Staff Publications

Coyotes (Canis latrans) are mobile, adaptable canids found in a wide range of habitats across North America, with range extensions into previously unoccupied areas in the western and eastern United States. Although long-distance dispersal capabilities in both sexes (Harrison 1992) and relatively large proportions of transient coyotes that do not exhibit fidelity to a single territory (typically 13–34% of a population— Andelt 1985; Windberg and Knowlton 1988) suggest that coyotes exist as a panmictic population, other aspects of coyote behavior may increase the likelihood of local population structure.

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