Mitigating Impacts of Terrestrial lnvasive Species

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\u27 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 eastern US., and Arctic fox [Alopex lagopus] onto Aleutian Islands for development of fur industries); 3) recreation (pheasants [Phasianus colchicus] and cbukar [Afectoris chukar] introduced as game species from Asia to North America, and red deer [Cervus elaphus] introduced into New Zealand); 4) food (domestic livestock worldwide, rabbits [Oryetolagus cunniculus] into Australia, pigs [Sus scrofa] into Hawaii); 5) for biological control (mongooses [Herpestes auropunctatus] to control rats in Hawaii, fox [Vulpes vulpes] to control rabbits in Australia, and giant toad [Bufo marinus] to control cane beetles in Australia); or 6) releases from captive populations (bulbuls [Pycnonotus jocosus] in Florida and domestic ferrets [Mustela putorius] in California, mink [Mustela vison] and muskrat [Ondntra zibethicus in Europe, and horse [Equus caballus], donkey [Equus minus], and other ungulates into Australia and western North America). The majority of biological introductions fail. Of those that succeed, only a small fraction become serious pests. Many introductions, like livestock or pheasants into the US., have been generally beneficial; however, some introduced species become invasive, defined as nonnative species which cause substantial economic or ecological h m . The U.S. has at least 221 nonnative terrestrial vertebrate species[1] and New Zealand has 35 introduced birds and 33 mammals, where previously the only mammals consisted of 3 bats. [2] About 44 mammals have been introduced into Australia, of which 27 have become established, 13\u27 along with 3 species of amphibians and reptiles and numerous birds. Ten species of terrestrial mammals on the Galapagos are aliens

Efficacy of a two-ingredient fumigant on Richardson's ground squirrel

In July 1981, efficacy data were obtained on a new two-ingredient gas cartridge by field testing against Richardson's ground squirrels (Spermophilus richardsonii) in a sagebrush-rangeland pasture. The gas cartridge contained 97 g of a sodium nitrate (65%) and charcoal (35%) mixture and upon ignition generated mainly carbon monoxide with a small quantity of carbon dioxide. We live-trapped 53 (24 male and 29 female) ground squirrels, equipped each with a 164 MHz radio transmitter, and then released each at the point of capture. Later we located each ground squirrel and treated its main burrow and all burrows within 3 m by inserting ignited gas cartridges. After treatment the location of each radio-equipped ground squirrel was plotted. Ground squirrels showing no movement were presumed dead; death was confirmed by burrow excavation. Success rate was 84% as 41 of 50 (18 males and 23 females) died (82%) and 8 survived (16%). The radio transmitter on 1 (2%) failed immediately after treatment. Efficacy was estimated at 83.7%, which exceeds the 70% minimum standard established by the EPA. Thirty-eight ground squirrels died in burrows at depths ranging from 7.6 to 132.1 cm (mean = 74.7 ± SE 5.2 cm), and 3 died in nests at depths ranging from 94.0 to 182.9 cm (mean = 133.0 ±SE 26.2 cm). Seven of the eight survivors were retrapped. Factors contributing to survival are discussed, including soil porosity and moisture content, as well as squirrel body weight. Recommendations for further testing are presented

Black-footed ferret areas of activity during late summer and fall at Meeteetse, Wyoming

Black-footed ferrets (Mustela nigripes; hereafter, ferret) were formerly widespread in central North America. Their populations decreased throughout the last century to near extinction by the late 1970s as a result of extermination of prairie dogs (their main prey) and the spread of disease (Biggins and Godbey 1995; Biggins et al. 1998). In 1973 the ferret was the least known endangered mammal in the United States because of its nocturnal, semifossorial habits and the few known populations (Erickson 1973). In 1981 a small population was discovered in a complex of white-tailed prairie dog (Cynomys leucurus) colonies near Meeteetse, Wyoming. During 1983 and 1984 we used radiotelemetry to collect information on areas of activity for ferrets in this population. Our overall objective was to develop data on ferret activity and spatial use among sex and age groups. The Meeteetse population of ferrets was decimated by canine distemper (Morbillivirus) and plague (Yersinia pestis) in 1985 (Forrest et al. 1988), and 18 individuals were brought into captivity, forming the foundation for a captive-breeding program. We present data on sequential areas of activity (using minimum convex polygons) during 1983–1984 for Meeteetse ferrets monitored intensively for short periods of time between August and December. We compare the sizes of activity areas and shifts in centers of activity for male and female and adult and juvenile ferrets

The Use of Toxicants in Black-Tailed Prairie Dog Management: An Overview

Black-tailed prairie dogs pose management challenges to landowners and resource managers. They are viewed as either a pest when they cause damage to vegetation or property or pose a disease hazard or, conversely, as a valuable Akeystone@ species representative of reasonably intact prairie ecosystems. When conflicts arise with prairie dog colonies, the two main options are capture and relocation or lethal removal. There are a number of vertebrate toxicants registered for field use in the United States, but few are currently registered for prairie dog control. Only one, zinc phosphide, can be applied above ground as a grain bait. The other toxicants (aluminum phosphide pellets, fumigant gas cartridges, and acrolein) are applied in the burrow system as lethal fumigants. Most of these rodenticides are restricted use compounds and can be applied only by a certified pesticide applicator. The rodenticide label must be followed carefully to assure the safety of the applicator and to minimize non-target hazards. We present a brief summary of the toxicants registered for prairie dog control, including history and use patterns, general characteristics and mode of action, toxicity, efficacy, non-target hazards, and environmental fate

Foreword

The effects of invasive vertebrate species on agriculture, human health and safety, and the environment are a growing concern around the world. The number of incidents of invasive species causing harm continues to climb with increased worldwide travel and transportation of goods. The focus for many decades was on invasive pathogens, plants, and invertebrates because they can greatly affect human and animal health and food supplies. In recent years, invasive vertebrate species, such as rats, feral pigs, and feral cats, have garnered more attention because the magnitude of their impacts have been repeatedly highlighted in the media. In response, better methods of prevention, detection, and management of invasive species have been developed. For example, several eradications of invasive vertebrates on islands have been successful, although management on mainland settings is generally much more challenging

FLOTATION MATERIALS FOR AERIAL DELIVERY OF ACETAMINOPHEN TOXIC BAITS TO BROWN TREESNAKES

Polyvinyl chloride (PVC) tubes are effective bait stations for delivering dead neonatal mice (DNM) treated with the oral toxicant, 80 mg acetaminophen, to brown treesnakes (Boiga irregularis) in accessible jungle forest on Guam. However, PVC tubes are not practical for delivery of baits to remote areas of jungle or the forest canopy. Further, it is important that baits entangle in the canopy and not fall to the ground where they can be scavenged by non-target animals such as crabs. Data from helicopter aerial deployment of untreated DNM with radio transmitters that landed on the ground in areas of high coconut crab (Birgus latro) and hermit crab (Coenobita spp.) abundance showed that 67% of DNM were taken by crabs and 11% by monitor lizards (Varanus indicus). In contrast, in low crab abundance areas crabs took 24% of the DNM that landed on the ground. It is evident from these data that a flotation system that delivers DNM to the canopy is needed; otherwise non-target animals will remove DNM, making them unavailable for snakes. Seven aerial flotation devices were evaluated. Promising aerial devices are two types of commercial cardboard paper streamers that resulted in 75% - 85% of the DNM becoming entangled in the canopy

STATUS OF COMPOUND DRC-1339 REGISTRATIONS

Compound DRC-1339 is a restricted-use, slow-acting avicide that is registered to control a number of avian pests. It is unique because of its selective high toxicity to most pest birds, low-to-moderate toxicity to most mammals and predatory birds, and lack of known secondary hazards when used on baits. The most widely known product containing DRC- 1339 is Purina Mills’ Starlicide Complete®, a pelleted bait used to control blackbirds and starlings in feedlots. Other DRC- 1339 registrations are held by the U.S. Department of Agriculture, Animal and Plant Health Inspection Service (USDA/APHIS), for the use of nonpelletized baits at feedlots and for the control of gulls in or near their nesting colonies. Over 20 State Special Local Need 24(c) registrations have also been issued to APHIS for special DRC-1339 uses. To consolidate these registrations, APHIS has submitted data to amend its feedlot registration for blackbirds and starlings, and applied for three registrations for control of 1) raven and crow depredations on livestock and for wildlife protection, 2) pigeons in and around structures, and 3) blackbirds, starlings, and crows at preroosting staging areas. Because most of the submitted data were collected in the 1960s and 1970s, none of it was produced under the Environmental Protection Agency\u27s (EPA) Good Laboratory Practices (GLP) regulations; therefore, new data will probably be needed to support these registrations. Future data needs and procedures for collecting valid information for DRC-1339 are suggested

Nicarbazin OvoControl G Bait Reduces Hatchability of Eggs Laid by Resident Canada Geese in Oregon

Expanding populations of resident Canada geese (Branta canadensis) are resulting in increased conflicts with humans. Nonlethal and humane means are needed for managing Canada goose flocks at a variety of sites, including golf courses, industrial parks, government sites, and city parks. Decreased egg production and hatching are side effects of nicarbazin, a veterinary drug used to treat coccidiosis in chickens. Capitalizing on these effects, we developed nicarbazin as a reproductive inhibitor for Canada geese and conducted a field efficacy study. We recruited study sites in 2002 and 2003. Following laboratory testing, we conducted a field efficacy trial of nicarbazin for reducing the hatchability of Canada goose eggs in spring 2004 in Oregon, USA. The study began in February 2004 at 10 sites in Oregon, with 2 control and 3 treated sites on each side of the Cascades. We fed bait daily to resident Canada geese for approximately 6 weeks. We located and monitored nests until hatching or ≥5 days beyond the expected hatching date to determine hatchability. We completed data collection in May 2004. Geese consumed 8,000 kg of bait, with 5,100 kg of OvoControl G* (Innolytics, LLC, Rancho Santa Fe, CA) 2,500-ppm nicarbazin bait consumed among 6 treated sites and 2,900 kg of untreated bait consumed among 4 control sites. We monitored 63 nests at treated sites and 46 nests at control sites to determine hatching success of eggs. There was a 62% reduction in the percentage of nests with 100% hatchability at treated sites as compared to controls. There was a 93% increase in the percentage of nests at treated sites with 0% hatchability as compared to nests with no eggs hatching at control sites. Hatchability from treated sites versus control sites was reduced 36%(F=5.72, P=0.0622). We submitted results from this study to support Environmental Protection Agency registration of nicarbazin as a reproductive inhibitor for use in Canada geese. We have shown that treatment of resident Canada geese with OvoControl G 2,500-ppm nicarbazin bait by licensed, trained applicators immediately prior to and during the breeding season can reduce hatchability of eggs laid by treated geese, thereby reducing recruitment of goslings into problem resident Canada goose populations. ( JOURNAL OF WILDLIFE MANAGEMENT 71(1):135–143; 2007

Wildlife Damage Management: Changes over the Last 40 Years and a Look at the Future

Since becoming a wildlife biologist 40 years ago, I have seen many changes. Yet some things have remained the same, like the economic impact of wildlife damage, which was high in 1974 and even higher now. In 2014, the worldwide cost of damage by vertebrate pests to agriculture will exceed $1 billion. The world’s human population has increased at an unprecedented rate, while some wildlife populations have also burgeoned over the past 40 years due to land-use changes and effective management programs. These simultaneous human and wildlife population increases have led to increasing conflicts between humans and wildlife. Nor has the international nature of damage changed: vertebrate pest control remains vital for agricultural production everywhere. And some types of wildlife damage are unchanged, such as livestock predation, bird damage to agricultural crops, and rodent damage to crops and stored grains. What has changed over the last 40 years? I see increasing complexity in the types of problems, in the solutions, and in the political landscape under which we work. Damage problems have become more complex, with invasive species being transported around the world, and with zoonotic diseases associated with wildlife becoming more prevalent. Solutions to damage problems have also become more complex, as simpler solutions have already been employed; solutions being sought now are more scientifically difficult and require collaboration by wildlife biologists with an increasing number of other scientific disciplines, such as toxicologists, geneticists, and epidemiologists. And society itself has become more complex, demanding solutions that not only prevent damage, but that are environmentally sound and politically acceptable. What does the future bring? Human population growth will mean more wildlife damage issues. Greater travel and international shipping will bring an increase in invasive species, and global warming will bring an increase in zoonotic diseases. Solutions will need to be innovative and reflect the complexity of the problems

A Review of Prairie Dog Diet and Its Variability Among Animals And Colonies

After almost 70 years of decline, prairie dog numbers are increasing in many western states. As populations expand, it becomes increasingly important to clarify the degree of competition between prairie dogs and livestock. A review of studies on prairie dog food habits shows variable results. Prairie dogs frequently eat the same plant species as cattle and their activities may cause a decrease in grasses normally considered good livestock forage and an increase in forb cover. However, in some instances, prairie dogs may be beneficial to rangeland; plant species diversity and protein content of forage are often greater on prairie dog colonies than off. It is important to assess each area of prairie dog-cattle interaction separately because prairie dog diet (and competition with cattle) can be extremely variable among geographical areas, colonies, and even animals within colonies