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Open Access Publications from the University of California


The concept of the Vertebrate Pest Conference originated in early 1960 from discussions among representatives of the University of California; the California Dept. of Fish & Game; the California Dept. of Agriculture; the California Dept. of Public Health; and the Branch of Predator and Rodent Control, Bureau of Sport Fisheries and Wildlife, U.S. Fish & Wildlife Service. The original participants recognized that few published documents on vertebrate pest control were available, as such information was typically contained within in-house reports of the various agencies that were largely unavailable and unable to be cited. Dr. Walter E. "Howdy" Howard of UC realized that having a conference would permit a Proceedings to be published, in which this information could be made widely available.

To plan such a conference, the organizing group, chaired by Dr. Howard, became the Vertebrate Pest Control Technical Committee, which arranged and hosted the first "Vertebrate Pest Control Conference" held in Sacramento on February 6 & 7, 1962. The planning committee formally became an incorporated non-profit entity in 1975, and the Vertebrate Pest Conference is now held in late winter or early spring every two years. It is the most widely-recognized conference of its kind worldwide.

Detailed histories of the development of this Conference are found in these publications:

Salmon, Terrell P. 2012. VPC: Fifty Years of Progress? Proc. Vertebr. Pest Conf. 25:3-6.

Marsh, Rex E. 2008. A History of the Vertebrate Pest Conference. Proc. Vertebr. Pest Conf. 23:310-326.

Gorenzel, W. Paul. 2004. Opening Remarks - A Retrospective Look at the Vertebrate Pest Conference. Proc. Vertebr. Pest Conf. 21:1-2.

Howard, Walter E. 1982. Twentieth Anniversary of Vertebrate Pest Conferences in California. Proc. Vertebr. Pest Conf. 10:235-236.

Howard, Walter E. 1962. Opening Remarks – Vertebrate Pest Control. Proc. Vertebr. Pest Conf. 1:1-7.


Vertebrate pest animals in the Province of the Cape of Good Hope, Republic of South Africa

The keynote speaker describes the fauna of Southern Africa, renowned for its wealth of wildlife. Here, representatives of 51 mammalian families occur, a greater diversity than are found in any other zoogeographical region on earth. No less than 12 families are endemic and include 30 species of antelope. In terms of conflicts with human interests, carnivores are the most important order, including the large cats, jackals and hyenas, the aardwolf, civets, genets, mongooses, meerkats, the honey-badger, otters, and weasels. Many mammals came into conflict with humans, including the Bushmen and Hottentots tribes, from the earliest times. Following the first European white settlement in 1652, wild animal depredations suffered losses of livestock and of crops. As colonization continued, all larger forms of wildlife, considered “vermin,” were exterminated in the vicinity of settlements. Today, the Department of Nature Conservation in the Province of the Cape of Good Hope strives to find balance between conflicting interests of human endeavors, including agriculture, and conservation of wildlife. Techniques employed to control vertebrate pest animals today include use of trained hounds to hunt predators; use of the coyote getter to kill jackals that prey on livestock and poultry; use of fencing; live traps; and poisons. Poisons should be used as selectively as possible and by trained personnel; eggs treated with malathion have been used extensively to control crows and small mammalian predators, and Telodrin has been successful in poisoning baboons that can do extensive damage to crops and livestock. Among birds causing damage are the red-billed quelea, the red bishop bird, and the Cape sparrow. As early as 1957, the Department recognized the important role of predatory birds in nature by giving protection to all eagles, hawks, and owls. Today all predatory birds are protected in the Cape Province, but a farmer who loses livestock to eagles can obtain a permit to destroy the birds responsible. There appears to be a marked improvement in the attitude of farmers toward predatory birds, although some species are now classed as endangered. Problems with introduced rodents such as Norway and black rats are handled by public health authorities. In their desire to enhance sport fishing, anglers in the past introduced species form both Europe and North America, including trout and bass, which have practically eliminated indigenous fishes. European carp have destroyed aquatic vegetation, rendering ecosystems unable to support native species. Other problem species, whose introduction is said to be blamed on Cecil John Rhodes, include the American gray squirrel, Himalayan tahr, ring-necked pheasant, European goldfinch, and the European starling.

Small animals census and control on a hardwood plantation

For centuries, man has been at conflict with and has suffered untold crop losses to ubiquitous small mammals. Such losses may range from unnoticed removal of vegetation in hay and grain fields to 95 - 99 percent losses in unprotected orchards or forest plantations. A most dramatic and conspicuous type of damage occurs where large numbers of meadow voles cause excessive tree girdling damage to a wide variety of plantation grown trees. Surveys of small mammal populations carried out on a hardwood plantation in southern Ontario during 1971-72-73 indicated the magnitude of the rodent problem. Control measures using broadcasting of anticoagulant-treated grain proved extremely effective but of temporary duration. Rapid reinvasion and high rate of reproduction soon brought the population number to former levels or higher. A poisoned bait feeder station developed and field tested by the writer proved extremely effective in providing an inexpensive long-term means of rodent control on the study area.

Urbanized wildlife

Man, with his continual movement and his need to construct, has devastated the wilderness. Provided with man's year-round lush vegetation, his sheltered and protected area, wildlife has adapted to urbanization. Urbanized wildlife is not always tolerated by man. Management of vertebrate pests in urban areas is specialized. Toxic baits or hazardous techniques are avoided to prevent exposure to people, pets, and other non-targets. Birds, as woodpeckers, crows, and hawks, which are urbanized wildlife in wooden and other structures of parks, residences, and airports, can be controlled by wire screens, topping trees, or removing their food source. Rodents, as rabbits and ground squirrels, can be controlled by proper placement and safe management of toxic baits. If uncontained, their predators, as snakes, also migrate to urban districts. Other reptiles, as lizards, are also intolerable to some human urbanites. Like migratory skunks disrupting turf in urban areas, control of insects will reduce lizard and skunk populations. By live trapping racoons and opossums and moving them away from urbanization, undue harm can also be avoided to these occasional visitors. Humane control methods compatible with all life -- the vertebrate pest, man and his pets, and non-targets, should be considered especially when dealing with urbanized wildlife.

A safe approach to natural home ranges, as applied to the solution of edge effect subjects, using capture-recapture data in vole populations

Capture-recapture work was performed in 1970 and 1971 with Microtus montebelli seeking to disclose the edge effect subjects. For the purpose, in principle, it is needful for us to approach the reality of home range in size and shape. As the result of these studies, it has been established that the method using observed range length and width is highly available for searching after natural ranges and that the natural range of the voles (Microtus and Clethrionomys) is ordinarily on the order of 0.05 for females and of 0.10 for males in acres and generally oblong in shape such as its eccentricity is about 0.80. Several tentative means have been thus far presented for determining the area of effect by sampling, but the process of Dice's assessment line has proved to be most useful in its sureness and simplicity; its empirical validity could be confirmed through mediation of Marten's notion (1972) and Wlerzbowska's (1972).

Environmental impact statements

The National Environmental Policy Act of 1969 (NEPA) became law January 1, 1970, while the California Environmental Quality Act was adopted on September 18 of the same year. NEPA established specific action-forcing procedures for implementing the policy; created the Council on Environmental Quality (CEQA); fostered development of indices of environmental quality; and provided for an annual CEQA report of progress. Section 102(2)(C) is the most renowned portion of NEPA. It requires the preparation of detailed written statements of environmental impacts, including alternative actions and their impacts. Section 102(2)(A) requires federal agencies to implement the integrated use of natural and social sciences and environmental design arts in reviewing environmental problems. The California Environmental Quality Act of 1970 was amended substantially in 1972 as a result of the Friends of Mammoth Decision by the State Supreme Court. CEQA requires that guidelines for the preparation of environmental impact reports shall be adopted by the State Resources Agency and followed by all state and local government entities regulating activities of private individuals, corporations, and public agencies which are found to affect the quality of the environment. CEQA defines environment as the physical conditions within the area which will be affected by a proposed project, including land, air, water, minerals, flora, fauna, noise, objects of historic or aesthetic significance.

Pest management in relation to human health

Vector-borne disease prevention and control strategies, aside from those associated with domestic rodents, have rarely involved management of vertebrate populations, even though in many cases such management would appear to represent the most effective and economical long-term approach. Prevention of a long list of arthropod transmitted diseases ls often at best a stop-gap procedure undertaken only after substantial disease hazard is detected in reservoir populations. More often, control actions await the detection of human cases, at which time short-term emergency control measures may be conducted, usually involving the use of toxicants against arthropod vectors and occasionally vertebrate reservoirs. In some cases, action is not taken because techniques are not available, but more often the decisive factors in action versus inaction are economic, jurisdictional, and/or organizational. Often, public health problems proceeding from unmanaged vertebrate populations are (justifiably) given low priority on the basis of costs versus benefits. If the same populations constitute a problem for health, economic, wildlife, or recreational interests, it may behoove us to pool our priorities, skills, and resources in collaborative management program designed for the greatest overall benefit rather than to proceed only on those programs that can be justified on the basis of one special Interest.

The association of the roof rat (Rattus rattus) with the Himalayan blackberry (Rubus discolor) and Algerian ivy (Hedera canariensis) in California

The roof rat (Rattus rattus) utilizes Algerian ivy and the Himalayan blackberry for food and cover, often living Independent of man. Algerian ivy is the most popular ornamental and ground cover plant in California and is used extensively for landscaping, particularly in southern California. The Himalayan blackberry, inhabited by feral roof rats, grows abundantly in northern California along inland creeks and in pastureland of the Sacramento Valley and in the foothills of the Sierra Nevada. Rats construct platform nests on or within the dense layer of canes that accumulate within the thickets. Information on distribution and recommendations for the control of the roof rat within the blackberry habitat are presented. A potential human plague threat exists where rodent cohabitants of the berry thickets may become involved in epizootics.

The potential value of genetically sterile Norway rats in regulating wild populations

Recognition of a gene in Norway rats, a result of mutation, that produces male sterility linked to white pelage on the head or abdomen, has been studied at the University of Oklahoma. At the age of 120 days, mutant males show no spermatogenic activity. In a controlled laboratory test situation, use of sterile males has been demonstrated to reduce population growth. Results from subsequent fields tests conducted thus far do not allow us to say that the Norway rat can be eradicated by introduction of sterile males; we do not yet have an adequate basis for devising a formula for release rates of sterile males. In future research, other heritable characters may be discovered that can be combined with the sterility gene to improve the sterile males’ competitive performance.

An overview of ASTM's activities in establishing standards for vertebrate pest control materials

Given the new authority for pesticide registration now within the U.S. Environmental Protection Agency, there is a need for develop pesticide standards. A large group of representatives of those involved with pesticides including academia, consumers, and pesticide producers met in early 1973 with the American Society for Testing and Materials (ASTM) to discuss the possibility of developing a committee on pesticide standards. ASTM standards have frequently been upheld in court, as they are based on objective scientific principles and do not represent bias of any particular group. Thus far, a subcommittee on Terrestrial Vertebrate Control Agents has been formed, which has divided into four Task Forces: Rodenticides, Predacides, Avicides, and Terminology. The focus of each Task Force is described, with anticipation that draft publications may occur within the present year to define tentative standards, which will be subject to subsequent review over a period of two to three years, resulting in workable permanent standards.

A new series of selective rodenticides

A new series of target-specific, single-dose rodenticides has been discovered by Rohm and Haas Company (Peardon 1972; Peardon et al. 1972). One compound, RH-787, best exemplifies the balance of desirable qualities of a good rodenticide. It is effective against a broad spectrum of pest rodents, has a desirable margin of safety in non-target animals, is well accepted in baits, causes no secondary hazard problems and is effective against ''Warfarin-resistant" (anticoagulant-resistant) rats. This material will become commercially available upon receipt of registration from the EPA.

Laboratory testing of albino rats with anticoagulant rodenticides

The results of testing dry anticoagulant baits at the Animal Biology Laboratory are evaluated in this paper. Overall, 14,940 rats were committed to these tests resulting in a mortality rate of 91.8 percent. The five chemicals tested and their mean mortality per test are: Diphacinone (93.5 percent), Pival (87.5 percent), Warfarin (93.9 percent), Prolin (91.2 percent), and Fumarin (92.8 percent). The data indicates that 77.4 percent of the tests conducted resulted in a mortality of 90 percent or greater, but only 11.9 percent of them resulted in acceptance of 33 percent or greater and mortality of 90 percent or greater.

The role of W.H.O. in the study and control of rodent-borne disease

While little information is available on the distribution and incidence of most of the diseases with rodent reservoirs, many of them are known to be widespread and may have considerable public health importance in some of the foci in which they are found. The World Health Organization Is carrying out investigations on the epidemiology of several diseases with rodent reservoirs and on the biology and ecology of the rodent reservoir species themselves. These investigations are being carried out both at WHO research units and with collaborating laboratories. Based on the ecological information the organization is attempting to develop effective and economically acceptable methods and materials to control rodent populations to a point where transmission of disease no longer occurs.

The significance of preference in laboratory bait acceptance studies

Measurement of palatability and rodent acceptance of oral baits is a controversial subject. Particularly with anticoagulants, effectiveness requires the bait be consumed by the target species, and this is of increasing interest to the industry as well as to regulatory agencies. This paper explores the role of sex of the test animal, the significance of difference between assay methods, and the number of observations during an assay. Factors affecting bait palatability are discussed, including the toxicant, formulation and mixing methods, and shelf life.

Animal Damage Control Research -- 'Are present priorities based on actual need?'

Priorities regarding Bureau of Sport Fisheries and Wildlife vertebrate damage control research are in most cases based on actual need. Need is influenced by economic, political, legislative, and biological incentives. These incentives affect private industry, state and local governments, academia, and the federal government but in different ways. The Bureau of Sport Fisheries and Wildlife has 24 percent of its wildlife research budget invested in vertebrate damage control research. Its programs deal with predators, birds, and small mammals and research programs are problem oriented. Priorities are generally developed within the organization and are usually determined by biological need.

Muskrat control and damage prevention

Although the muskrat, Ondatra zibethicus, is native throughout most of the United States and has been a mainstay of the fur business, in recent years it has become a serious pest causing extensive damage to some specific crops, as well as to earthen water-holding structures. Damage caused by muskrats to rice crops, food fish, and bait fish reservoirs In Arkansas was estimated in 1967 to be almost $900,000. A control program begun in October 1967, directed principally at muskrat control, proved a significant aid in reducing damage. This program provided Arkansas farmers and landowners with practical, effective methods and techniques which could be utilized by them or their labor force to control or eliminate damage attributable to muskrat depredation.

The effects of a chemosterilant (Mestranol) on population and behavior in the Richardson's ground squirrel (Spermophilus richardsonii) in Alberta

A chemosterilant, mestranol, was administered to three populations of Richardson's ground squirrel in southeastern Alberta. Mestranol was given to all squirrels in one plot, to only 50 percent in another plot, while a third plot remained as control. In all plots social behavior and population dynamics were followed over two seasons by live trapping and visual observations. Mestranol sterilized all females who received the drug shortly before or in early pregnancy; accordingly the birth rates were reduced. Levels of total aggression were also reduced but increased survival and immigration rates nullified the effects of the treatment during the first season. During the second season, low birth rates due to repeated treatment in one plot and to adult emigration and unknown causes in the other, were not compensated for by immigration. As a result of the repeated mestranol treatment and in one case also of adult emigration, the numbers of squirrels were reduced in the vicinity, thus limiting potential immigration in the treated plots. As a consequence, both treated populations crashed, demonstrating the effectiveness of mestranol.

Oregon's nutria problem

The nutria or coypu, Myocastor coypus, is a large semi-aquatic rodent that superficially resembles an overgrown muskrat or a stunted beaver. They were introduced into Oregon from about 1930 to the 1950's. At one time Oregon had more than 600 fur farmers raising these animals for fur; now there are none. Some animals escaped and many others were released into the wild when it became apparent that pelt values were nonexistent and production costs greatly exceeded profits. Being prolific and quite mobile, the nutria quickly spread through much of western Oregon. By the 1960's damage to agricultural crops was common to severe in western Oregon. Crops damaged included seed, grain, forage, hay and trees. Burrowing damage to stream banks, field borders, and farm ponds was reported in many areas. Growth and reproduction data for Oregon nutria are included. Methods for controlling feral nutria including the use of prolin, red squill, strychnine alkaloid, and zinc phosphide are reported. Fur trapping and adverse weather as factors in population reduction are discussed.

The European rabbit problem in New Zealand

Although in much smaller numbers now than previously, the European rabbit (Oryctolagus cuniculus) is still a major pest and a significant threat to agriculture, particularly sheep farming. The total cost of rabbit control is about NZ$5 million and the net annual return due to increased agricultural production has been calculated at about NZ$60 million. Aerial poisoning using 1080 (sodium fluoroacetate) on carrot baits is the most effective means of controlling the European rabbit currently used In New Zealand. Approximately 600,000 acres are treated annually at a cost of about NZ$300,000. Due to the extremely rapid replacement of losses, kills of at least 90 percent are required before a significant long-term reduction occurs.

Dual role of forbs and rodenticides in the ground spray control of pine mice

Highly effective controls for the pine mouse (Pitymys pinetorum) were obtained for three years in apple orchards by means of herbaceous ground cover sprays of [(chloro 4 phenyl) 1 phenyl] acetyl 2 dioxo 1-3 indane at a rate of 0.2 lb. per acre of actual orchard. This toxicant from Europe is designated there as chlorophacinone. The spray residue persists for a maximum of about 30 days and was not found to be translocated to fruits nor was it detected in runoff water. Ingestion of the lethal agent is markedly enhanced by an adequate presence of forbs in the treated greenery. Too little attention has been directed to the basic differences in control between herbaceous type feeders and the seed consumers. CPN is now reported to give excellent results from large-scale applications by growers.

Rodent control activities when direct seeding forest lands in Northern California

The author reviews the changing use of rodenticides for deer mouse control over the past decade. He summarizes the operational procedures associated with direct seeding of forest lands by helicopter and the related practices of forest rodent control as they exist in the north coastal region of California. A description of the various field studies on Peromyscus baits and seed repellents presented to indicate the extent of local research activity in this increasingly important area of forest regeneration.

A review of rodent control programs in New York State

The history of rodent control programs in New York State is reviewed, beginning with state-funded efforts in August 1967. In 1969, Federal rodent control grant funds were used to establish four Model Cities programs. At its peak in 1970, programs were active in 18 counties, eight cities and villages, and in six Model Cities areas. The program encompasses all the major metropolitan areas of the state, serving some nine million persons. As part of the state program, the Rodent Control Evaluation laboratory was established to investigate chemosterilants as a means of rodent control and to develop knowledge of pest rodent biology. Since then, the investigations program has turned to the problem of rodent resistance to anticoagulant rodenticides both in New York and other states in the eastern United States. Initial rat infestations, which ran 24.4 percent statewide in 1969, have been decreased 84 percent by late 1973. Similarly, in the same time period, unapproved refuse storage deficiencies were decreased 55.6 percent and exposed garbage conditions declined 44.7 percent. Rat bites showed a 40 percent decrease during these same years. By all measures, then, the program has been a success. Most programs have relied heavily upon anticoagulant rodenticides in the chemical control or rodent populations. Zinc phosphide, red squill, and norbormide are also used. Harborage removal and environmental improvement are stressed through active cleanups and educational efforts. During the four-year period 1969-1972, some 177,000 tons of rat harborage were removed from 66,000 premises in the state.

Vertebrates...and the conflicts in public image

The author explores human perceptions, as influenced by words and the images they conjure in the human brain. People worldwide have formed strong images relating to our environment, both positive and negative: beauty and splendor vs. struggle, plague, and ills. Such a conflict is just beginning between two opposing philosophies concern vertebrates: one, their management completely for the benefit of man; the other, quoting civilization’s threat to the beauty and even existence of high animals. Both viewpoints are unacceptable. When these two viewpoints meet, pest control will be under the giant floodlights of public opinion.

The role of F.A.O. in vertebrate pest problems

Since 1947, when FAO began its involvement in vertebrate pest problems, its role has gradually expanded. Through short-term Consultants, Experts, Regional and Headquarters Officers, it advises Member Countries about vertebrate pest control needs and opportunities, fulfills requests for assistance suggesting needed modifications, and guides and reports on assistance rendered. Assistance may involve one or more international specialists for a few weeks up to national and regional projects of several years' duration. In cooperation with WHO it sponsors meetings of specialists, develops rodenticide specifications for international commerce, and has published rodent bibliographies covering 1950 to 1969.

Trapping: A continuous integral part of a rodent control programme

Trapping is usually considered a rodent control technique of minor importance. Due to the economic situation in the Dumaguete, Philippines programme from which this report is drawn, regular trapping was a biological necessity. Four species of rodents and a shrew were of concern. A continuing daily trapping programme was developed from a field study of trap bait acceptability. Trap baits were reused every 23 days. Alternate baits were selected. Trap usage techniques were designed to optimize the results. Trap-bait shyness and trap shyness effects were observed but were not a major problem.

Rabies vector control in Alberta

Following the last serious outbreak of rabies in 1952-57, the province of Alberta remained virtually free of the disease for 13 years. In 1970 a sudden increase occurred with 16 cases in various species. The Alberta Central Rabies Control Committee was reactivated to cope with the situation. Pre-immunization of high-risk personnel and domestic pets was Initiated along with supportive research to monitor infection rates in various species. Vector control programs were established to stop the spread of rabies by known wildlife vectors, particularly skunks (Mephitis mephitis) which had brought rabies across the great plains to the Alberta-Saskatchewan border by 1970. By the use of a buffer zone and radial depopulation, the spread of rabies westward into Alberta has been essentially prevented over the last three years.

A review of coyote control research

Research on coyote control has lagged behind operational control for several decades. With the current controversy over toxicants and control of coyotes, attention has suddenly been given to the research needs of the problem. In the past research on annual damage problems, particularly predators, was concentrated on coming up with new lethal methods. The picture has changed with a definite need to study the entire problem, including the measurement of losses, the ecology of predators and prey, their behavior, and means of solving loss problems by nonlethal methods or mechanical protection. In any lethal control research, selectivity must be emphasized. The ultimate solutions lie in a greater understanding of all phases of the problem, particularly on ecological and economic considerations, and do not depend solely on the development of one or two more control methods.

Reptiles and amphibians -- a management dilemma

Reptiles and amphibians, despite general public revulsion, have a more positive than negative potential. On the positive side are food, scientific, and educational benefits, biological control of pests, medicine, ornamentation, carrion cleanup, pets, and aesthetic values. On the negative side are predation, human confrontation, and health. Where control is deemed a necessary management procedure, it can be achieved to some degree by cultural controls, repellents , trapping, and reductional methods such as hand capture, den hunting, electric fence, and pesticides (though none are currently registered for this purpose).

Rabbit behaviour research in Australia and its relevance in control operations

Research in Australia on the behaviour of wild rabbits has provided a basis for improvements in the tactics and strategy of control. As the warren is a central focus for growth and survival of a population, a program for effective control or eradication should aim at making the warren unavailable to rabbits. Enclosure studies of behaviour suggested that poisoning would be much more effective when carried out in the non-breeding season. This has been confirmed in field trials. The behavioural importance of the odour-producing inguinal, submandibular, and anal glands is emphasized. It is suggested that further studies of these glands may provide insights for the development of repellents or attractants.

Rare and endangered wildlife problems and solutions

Worldwide concern over vanishing species prompted a World Wildlife Conference in Washington, D.C. on February 12 - March 2, 1973 which resulted in a Convention of lnternational Trade in Endangered Species of Wild Fauna and Flora. Enactment of the Endangered Species Conservation Act of 1973 by Congress places all endangered species native to United States under jurisdiction of the Federal Government. The California Endangered Species Conservation and California Species Preservation Act enacted by the California Legislature in 1970 has resulted in a listing of 49 California animals declared rare or endangered. Efforts to protect and enhance threatened species are being directed to determine the current status of these animals and seeking stewardship over the habitat critical to their survival. Identity of problems and development of solutions to remove these animals to a nonendangered status is of immediate necessity. Such can be accomplished through a program of interagency cooperation.

Emergency rabid skunk control in Montana

A maximum of 500 strychnine eggs were placed in designated skunk habitat within a three-mile radius where rabid skunks were diagnosed as an emergency control method to reduce or prevent the spread of rabies in striped skunk (Mephitis mephitis) populations in northeastern Montana. The effects of strychnine on skunk and other non-target species populations were evaluated. When placed in primary skunk habitat, the toxicant eggs were selective in removing striped skunks. Scent post surveys indicated that skunk populations were reduced, while non-target species populations remained stable or increased in control areas. The effects of the toxicant egg program in reducing the incidence of rabies in striped skunks in northeastern Montana is not clear after only one year of data. Close surveillance of the emergency skunk control areas in succeeding years may indicate the need for continuation or expansion of similar programs.

Feral burros and wildlife

Feral burro have caused devastating damage to the vegetation and soil which has resulted in a deterioration of the entire biota. Wildlife numbers have declined where there is competition with burro for food, water, or space. The Department of Fish and Game made a burro survey in conjunction with bighorn investigations. There are an estimated 3,400 free-roaming wild burro In California. They are found in 7 of the 14 bighorn study areas and have caused problems in each of these areas.

Feral hogs -- boon or burden

Feral hogs (Sus scrofa L.) have long been considered a pest by most land managers because of the potential range and pasture damage that can result from their feeding habits. In recent years however, second only to deer, feral hogs have become the most sought-after big game animal in California. Their great reproductive capacity coupled with the ruggedness of their preferred habitat has allowed the California State Fish and Game Department to set liberal seasons and bag limits. The freedom to work within the state's liberal framework has prompted some private land managers to look at controlled harvest programs with several objectives in mind. Using paid hunting as the main means of control, thus providing additional revenue for the landowner, such programs would aim at keeping the herds within the carrying capacity of the range, so that minimal damage is done to the vegetation and soil as well as keeping interspecific competition in check. Reviewed here is a description of how such a program is carried out on the Dye Creek Preserve.

Activities of the rodent branch of the European and Mediterranean Plant Protection Organization (EPPO)

The European and Mediterranean Plant Protection Organization (EPPO/OEPP) is a regional, governmental body, which has 33 member countries in Europe, North Africa, and Middle East. Its former activities were mainly concentrated on phytosanitary problems, but recently more attention has been paid on coordinating research activities and, especially, on problems associated with the use of pesticides in plant protection. On the Rodent Branch EPPO has at present three working units: 1. The Working Group on Field Rodents, concentrated primarily on biological aspects of the control of Microtines and other injurious rodents causing damage on field crops, horticulture, and forestry; 2. The Rodenticide Panel, which simultaneously with other expert panels of the Working Party on Pesticides in Plant Protection, has the development of standard methods for rodenticide tests as its main task; and 3. A Working Party for Muskrat Problems. As one of its main initiatives the Working Group on Field Rodents has started a critical mapping out of the economic importance as well as geographical and ecological range of the most prominent rodent problems in the member countries.

Experiments with sounds in repelling mammals

Since its introduction for use in repelling birds, a number of people have found that Av-Alarm is effective for control of certain mammals. This includes not only those familiar to North Americans (deer, elk, coyotes), but also various less familiar species, even anthropoids (baboons) and bats. A number of example cases are described. A concept theory is presented in order to explain why certain sounds are more effective than others, and why sounds originally meant for bird control are also effective with mammals. The theory helps to predict untested situations, and also suggests when complex repelling sounds can profitably be augmented by other sounds or by visual harassment.

The detection of exotic vertebrate pests in California

Numerous exotic vertebrates are imported into California each year for use in scientific research, zoological gardens, the commercial pet trade, and private collections. Certain of these imported species are known within their native range to depredate agricultural commodities, compete with other species of wildlife, and facilitate the spread of diseases detrimental to humans or other animals. The California Department of Food and Agriculture, in cooperation with other governmental agencies and conservation-oriented societies, is active in the exclusion, detection, and eradication of these detrimental species. Exclusion procedures include inspections of air cargo, truck, and postal terminals in addition to private automobiles. Detection procedures involve surveying urban areas, cropland, entryways, rangeland, and high hazard situations. The results obtained indicate these preventative procedures are both efficient and effective.

Recent changes in federal bird control

Recent regulatory changes at the federal level have expanded the reach of the Migratory Bird Treaty Act and the Fish and Wildlife Act of 1956. Now, almost all birds found in North America are classed as Migratory Birds. The only exceptions are the English sparrow starlings, psittacines, and the families of birds covering grouse, pheasants, turkeys, quail, etc. Bird permit requirements are virtually the same; no permit is needed for control of yellow-headed, bicolored or tricolored redwing blackbirds, or for Brewer’s blackbirds, cowbirds, grackles, crows and magpies. The special coverage in California in regard to County Agricultural Commissioners states that no permit is necessary to kill meadowlarks, horned larks, crowned sparrows, goldfinches, hose finches, acorn woodpeckers, Lewis woodpeckers, and flickers if this must occur to safeguard any agricultural or horticultural crop. Additional changes and adjustments to federal and state law are explained.

Modelling for research on chemical control of mammals in New Zealand

Development of predictive formulae or qualitative statements about the probable outcome of control campaigns entails knowledge of bait quality and distribution, behaviour, vagaries of weather at the time of the control campaign, and other factors which govern the probability that the target animals will accept bait. This paper collates experience in recognising, estimating and using some of these variables for predicting the outcome of large-scale poisoning, and discusses possible approaches to the solution of some hard-core problems.

The relationship of quelea migrations to cereal crop damage in the Lake Chad Basin

Quelea quelea and some other species of weaverbirds (Ploceidae) cause severe damage to cereal crops in sahelian zones of Africa. Recent observations of weaverbird damage to cereals in the Lake Chad Basin show that crops grown in certain places at particular times are more likely to be damaged than others. Timing of harvest by varying planting times and selection of short-cycle cereals may avoid damage in some situations.

Nesting success of Quelea quelea with one parent removed and observations on roosting behavior, with implications for control

Avicidal sprays are likely to continue to be a major tool in controlling Quelea quelea nesting colonies when they are found in cereal producing areas. New observations on nesting behavior indicate that a single parent cannot successfully care for the nest if the other parent is destroyed before the eggs have hatched. During the incubation period, Quelea return earlier in the evening and males are more concentrated in night roosting areas than after the eggs have hatched. These factors indicate that for the most efficient control, the best time to spray nesting colonies is before hatching begins.

Bird damage appraisal methods in some agricultural crops

Bird damage appraisal methods that have been developed and published are reviewed. For sprouting field crops, they exist for corn and for rice. For mature field crops, published appraisal methods are available for corn, peanuts, and rice. For fruit crops, appraisal methods are cited for cherries (control evaluation; and extensive survey) and for blueberries.

Bird damage to wine grapes in central California, 1973

Bird damage to wine grapes was surveyed in nine counties in the coastal area of central California in 1973. Damage to 90 bunches of grapes in each of 140 randomly selected plantings was visually estimated according to seven damage classes. Results indicated that birds damaged or destroyed 1.99%± 1.08% (95% confidence interval) of the crop, or about 1,547 to 5,219 tons of grapes worth more than $0.75 million. Napa, San Benito, and Sonoma Counties had the highest dollar losses. Upper bunches on grapevines were more heavily damaged than lower ones, and dark-colored varieties were more heavily damaged than light-colored ones. Early-maturing and late-maturing varieties were not differentially damaged. Of the birds observed in the sampled plantings, 51.5% were house finches (Carpodacus mexicanus) and 25.8% were starlings (Sturnus vulgaris); 16 other species made up the remaining 22.7%. Modifications of the survey methods are suggested for similar surveys of bird damage to grapes and for surveys where higher accuracy is desired.

The monk parakeet: A potential threat to agriculture

Small flocks of monk parakeets, Myiopsitta monachus, were recently sighted and reported In Southern California. This avian species, native to Argentina, Brazil, Uruguay, Paraguay, and Bolivia, substantially damages grain, fruit, and vegetable crops grown within its native habitat. Overall crop losses in those areas range from two percent to 15 percent, with some as high as 45 percent annually. Because of its known ability to breed successfully in California and other states and to survive adverse climatic conditions, the possible effects of M. monachus on California's agricultural industry must be examined. This study evaluates the pest potential of this exotic avian species.

Feral pigeon control

Feral pigeons, descendants of the rock dove that is native to North Africa and Europe, were brought to North America by the first European settlers as domestic poultry, and subsequently escaped. Their biology and control are reviewed, including their potential threats to public health. Description of control techniques and trials involving experimental use of Starlicide®, and utilization of an improved pigeon live trap design are discussed in detail.

Use of chlorophacinone in the struggle against the common vole (Microtus arvalis Pallas) and against the muskrat (Ondatra zibethicus L.)

Use of the anticoagulant rodenticide chlorophacinone was largely developed in France during the past decade. Laboratory and field trials of this compound’s development for control of the common vole (Microtus arvalis) and the introduced muskrat (Ondatra zibethica) are described. Efficacy and risk to nontarget game species were evaluated, as are other candidate anticoagulants that were investigated.

Mestranol as a repellent to protect Douglas-fir seed from deer mice

Mestranol [3-Methoxy-19-nor-17α-pregna-1,3,5 (10)-trien-20-yn-17-ol (C21H2602)] was tested at 2 percent (active) as a repellent for protecting Douglas-fir (Pseudotsuga menziesii) seed from deer mice (Peromyscus maniculatus). In 5-day laboratory bioassays, deer mice consumed 61 to 66 percent fewer mestranol-treated seeds than control seeds; these results were about equal to those with a standard 0.5 percent (active) endrin seed treatment. Deer mice showed a progressive aversion to the mestranol seed treatment from 24 percent to 76 percent in 5 days. Thereafter, with minimal reinforcement, avoidance was maintained at 90 to 99 percent for 6 months. In six field trials in Washington, Oregon, and California, areas seeded with 2 percent mestranol-treated Douglas-fir seed yielded 1.6 to 5.9 times more germinants than areas seeded with control seed. In three of these areas, endrin seed treatments were included; they yielded 1.2 to 3.4 times more germinants than the mestranol treatment and 1.9 to 17.3 times more germinants than the control seed. Although the endrin treatments yielded higher numbers of germinants, the mestranol treatments in these tests generally resulted in acceptable numbers of germinants for first-year stocking. Mestranol's nontoxic, nonpersistent properties plus the aversion shown by deer mice to mestranol in our tests makes it a leading candidate as a Douglas-fir seed protectant in western United States.

Alpha-naphthylthiourea as a conditioning repellent for protecting conifer seed

The object of this study was to find an alternative rodent repellent to take the place of endrin when direct seeding to regenerate coniferous forests. Compounds with aversive conditioning repellent attributes were screened. Even though still falling far short of endrin, which also acts as a lethal rodenticide, alpha-naphthylthiourea (ANTU) treated seed produced about twice as many seedlings as did the untreated seed. Both the laboratory and field evaluation procedures and results are discussed. It is hoped that with more research the efficacy of ANTU as a seed protectant can be further improved. The compound is much too promising to abandon as a candidate repellent for deer mice and possibly other rodent species.