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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.


The year of ecology

The keynote speaker comments on the advent of the “Year of Ecology,” with concerns that some of the current environmental rhetoric fails to understand the science behind pest control and the current practices of food production and food processing. In regard to pests, 4tThroughout history man has always made value judgements about other organisms that share our world, and always decides in favor of himself. It is a concern that we will almost certainly lose some of the more useful chemical tools used in pest control, as a result of the emotional concern about pollution, and it is already becoming increasingly difficult to get registration and residue tolerance for new pesticides. All pest control measures are going to continue to be under attack. The solution is to continue to depend up on the scientific method: do basic research, get the facts, and leave emotions out of our decisions, and lastly, speak out.

Outlook for rodenticides and avicides registration

The history of pesticide regulations is presented. Major emphasis is on federal regulations. The evaluation of avicides and rodenticides Is discussed and related to regulations. Currently registered avicides and rodenticides are described along with a listing of efficacy criteria requirements. The future of registration of avicides and rodenticides is projected.

New factors controlling populations of land vertebrates in Great Britain

The vertebrate fauna of Britain is impoverished by nature. Further, virtually the whole land surface has been altered radically by man, and all vertebrate species have been profoundly affected both unconsciously and consciously by man. The rate of change during the last quarter of a century has been far greater than at any other time; new deleterious factors - increased habitat destruction, increased human pressure and motor traffic, myxomatosis, and a vast increase In pesticide use have coincided in this period. The public's attitude to several common species (e.g. rabbit, woodpigeon, fox, and birds of prey) has been equivocal and has altered in time. In Britain the cost of effective population control of most vertebrate pest species would be far greater than the value of the damage done by them; but local control operations are often necessary. Pest control and conservation are seen as different sides of the same coin; in thickly populated industrial countries with rapidly changing environments such as Britain, the emphasis is likely to shift from pest control to conservation in the future.

The pharmacology of rodenticides

The essential mechanisms of some common rodenticides are described. With the category of organic agents, these include the anticoagulants, alpha-naphthylthiourea (ANTU), sodium fluoroacetate (1080), fluoroacetamide (1081), methyl fluoroacetate, strychnine sulfate, red squill, and norbormide. Within the inorganic rodenticides are included zinc phosphide, thallium sulfate, barium carbonate, yellow phosphorus, and arsenic trioxide. The fumigants carbon monoxide, methyl bromide, and hydrogen cyanide are also summarized. Included is brief mention of chemical sterilants, as well as chlorinated insecticides that are toxic to mice.

Notes on the ecology of sewer rats in St. Louis

A study of Norway rat populations in the combined storm drains and sewers of St. Louis, Missouri is described and results are reported. Initially, packets of grain were provided to rats in sewers and drains and checked at two-week intervals during a two-year period. A rather pronounced annual cycle of sewer rat activity was documented, which was rather synchronous around the city. Prevalence of active manhole site via bait take increased from February through June, and then began a gradual but irregular decline to a low point in January. It was postulated that seasonal difference in surface runoff following summer rains may have flushed out the “surplus” rat population that was not attached to stable home ranges containing refugia. Further, winter weather may have led to a sharp decline in active sites during two successive winters. Changes in baiting strategy were initiated, which indicated either that many sewer rats were transient, or that some locations lie outside the regular travel path of rats with stable home ranges. It was also determined that rats hoarded cracked corn, and to a lesser degree, cornmeal; this is important, as bait consumption when seen in pest control operations may not be a reliable indication of rat abundance. Observations of rat behavior, coupled with an analysis of physical factors in the environment, are important in developing an effective control strategy.

The role of the coyote in an infection of man and animals

As part of epidemiological studies on hydatid disease in the central valley of California, a survey was made of seven counties of possible infections with Echinococcus granulosus in the coyote (Canis latrans). Of 173 animals examined, seven (4.0 percent) were found infected, six of them from Tehama County.

The importance of wildlife rabies control

Rabies in animals has been known In North America for over two centuries, and whether the disease was initially present in wild species or was introduced by dogs, it has been known in skunks for almost a century and a half. Today more rabies cases in wild animals are reported than in domestic animals, and a considerable proportion of both human and domestic animal exposures to the disease are the result of wild-animal contact. The most useful techniques for controlling wild animal rabies today are methods that reduce contact between infected individuals and susceptible individuals; these involve the manipulation of populations, most often by direct reduction methods. Such techniques have proved effective in controlling or eliminating the disease; they are most effective when the area involved is small and/or isolated by barriers. The effectiveness of animal reduction programs on rabies is limited by the range of the animals involved, of ingress from surrounding areas for animals incubating the disease, and the continuity of the program; at least two maximum incubation periods of the disease must have elapsed as insurance that incubating animals are not left to serve as a new nucleus of infection. Rabies control programs for wild species have not yet threatened any species with extinction, nor are they likely to in the future.

Current status of plague and plague control in the United States

During the first quarter of the 20th century, massive rat-borne plague epidemics occurred in port cities of the United States in conjunction with the last world-wide pandemic which originated in China in 1893. By 1950, plague was found to be firmly established in wild rodent populations in states west of the 100th meridian. Presumably because of improved sanitation coupled with retreat of the world-wide pandemic, there have been no human cases in this country associated with urban rats since 1924. However, sporadic cases, fewer than 10 per year, are reported as due to contact with wild rodents, lagomorphs, rural rats, and/or their fleas. Recent observations suggest that: a) in the current decade there has been an increase in human plague cases; b) there continues to be a serious potential of a single undiagnosed and untreated case, which possibility is intensified by the very paucity of human cases decreasing the likelihood of a correct diagnosis and by changing patterns of life exhibited by members of our society (e.g., hippie communes and a generally increased mobility); and c) the apparent distribution of plague only in the area west of the 100th meridian might be found to represent an unrealistic generalization if adequate surveillance were carried out. At the present time human plague cases from wild animal sources tend to be isolated events both spatially and temporally and often cannot be attributed to confined and definable epizootic sources amenable to effective control programs. Improved means for epizootic control and long-term management of enzootic plague sources must be sought aggressively. These measures should include development of: a) a surveillance network to detect plague activity in rodent and lagomorph populations throughout the western United States; b) effective, yet ecologically sound, means of ectoparasite control, including suitable materials and methods of application; c) methods for management of plague-susceptible wild animal populations, particularly where they exist in contact with high use recreation and residential areas; and d) more extensive knowledge of enzootic plague and the factors that bring about epizootic plague and potential human contact.

The rats in Hawaiian sugarcane

Heavy losses In Hawaiian sugarcane are caused by Polynesian rats (Rattus exulans), Norway rats (R. norvegicus), and black rats (R. rattus). Relative population levels, movement patterns, damage to sugarcane, and suggested timing of control during five stages of the 2-year crop cycle are described. The progress toward the registering of zinc phosphide for use in crops and the development of other rodenticides are mentioned.

Rodent control in the Hawaiian sugar industry

Past and present concepts of rodent control at the 24 sugar plantations of Hawaii are reviewed with particular attention being given to the research efforts of the Experiment Station of the Hawaiian Sugar Planters Association in improving operational rodent control in sugarcane. Hawaii offers a unique set of conditions: a 2-year crop cycle, a production of over 100 tons of sugarcane per acre, countless numbers of gulches and wasteland bordering crop fields, and a year-long growing season, all having an effect on rat population and habitat.

Vampire bat control: A review and proposed research programme for Latin America

In Latin America, paralytic rabies transmitted by vampire bats is a major cause of death in cattle. This problem becomes more acute as countries attempt to increase livestock production to feed rapidly expanding human populations. Vaccination has been the principal weapon against rabies, however this offers no protection to domestic animals and poultry against dally predation of vampire bats. Established methods of vampire bat control, though limited, have proved effective and should be continued while more effective methods are being developed and tested. Existing methods are discussed in some detail. Of the approximately 200 kinds of bats found in Latin America all could be potential vectors of rabies. The 12 species most frequently found infected with rabies (including the three types of vampires) should receive close ecological study for possible control. They have certain attributes in common: they have been reported rabid; are found in association with vampires; are widely distributed; are found in buildings near domestic animals and people; live in groups; have sharp teeth; fly considerable distances; frequently change their roosts; do not hibernate and are biologically or economically Important. Improved vampire bat control must be based on an ecological approach in which all available techniques are combined into an integrated control which will not affect other species of bats. Such an approach could use biological, chemical, physical, and regulatory techniques. These cannot be fully developed until basic information Is available on two points. First, there must be a thorough understanding of the ecosystem in which the bats live, including population dynamics. Second, the population levels which cause damage must be determined. This information is lacking for vampire bats. Two other questions must also be answered: first, what are the host preferences of vampire bats throughout their range from Mexico to Argentina? And second, how many vampires inhabit any given area? A precise technique for measuring these numbers is essential to evaluate any control measure. All the countries in Latin America are discussed on a regional rather than a political basis, listing special problems to be solved. The vampire bat problems throughout Latin America should be defined. FAO could, if requested, assist these countries in carrying out presently known methods of vampire bat control which could provide immediate relief in limited areas. It could also help to establish priorities of research based on the financial and manpower capabilities of these countries to conduct such research.

Chemosterilants as an approach to rodent control

Capitalizing on research directed toward oral contraceptives for humans, a wide variety of compounds are now under study for their practical value in inhibiting rodent reproduction to suppress detrimental populations. This paper discusses the specifications of ideal rodent chemosterilants and the advantages of chemosterilants over other methods of control and compares the potential values of chemosterilants acting on females, males, and both sexes. Specific situations are detailed where chemosterilants will be most valuable in rodent control, together with proposed methods of application. Chemosterilants are not expected to become a panacea for control, but since they are based on sound biological principles they should be a safe and effective approach to regulation of rodent populations.

Olfaction in rodent control

A brief survey is presented of current knowledge on olfaction in rodents and the various roles that odors may play in modifying rodent behavior. Some species at least utilize olfactory cues: to locate food items; to recognize their mother and mates; to mark territory; as an involuntary population density regulator; possibly to recognize predators; as a warning cue against a repellent or toxic substance (poison-bait shyness); and probably, for many other behavioral purposes. The value of using artificial odors in rodent baits to increase bait acceptance Is not yet well documented. The addition of attractive natural odors may increase detection of low-preference foods, but there is little evidence that a strange odor can improve palatability for any prolonged period. Much more research is needed before rodent control methodology can fully exploit the olfactory acuity of wild rodents.

Mole control

Four kinds of moles are found In the Pacific Coast states but only the Townsend mole (Scapanus townsendii) in Washington and Oregon and the broad-handed mole (Scapanus latimanus) in California are considered economically important. Damage in agricultural areas is caused by mole mounds and burrow systems which reduce pasture production, make harvesting difficult by breaking or plugging machinery, contaminate hay and silage thus retarding proper curing, contribute to soil erosion, and make ready-made homes for invading meadow mice, pocket gophers, and other rodent pests. Holes also damage lawns, gardens, flower beds and occasionally eat or destroy valuable seeds and bulbs. Control methods reviewed include traps, poisoned baits, gases, soil fumigants, natural enemies, and miscellaneous methods such as mole wheels, mole plants, nest digging, and flooding.

Destruction of conifer seed and methods of protection

Agents responsible for losses of conifer seed and methods for seed protection are reviewed. Published information indicates that much seed is destroyed, especially by seed-eating rodents and birds. Improvement of existing protective methods and development of new chemical means are necessary to overcome the problem.

Studies in microencapsulation of rodenticides

Warfarin, zinc phosphide, norbormide and alphachloralose have been microencapsulated by the technique of coacervation and fed to laboratory rats (R. norvegicus) and mice (M. musculus). Results are given of experiments in which the concentration of rodenticide, wall material, and phase ratio have been varied separately and in combination. Experiments are also reported in which normal and encapsulated rodenticide have been fed together in the same test diet. Microencapsulation can increase the intake of rodenticides, appreciably, whether or not alternative food is simultaneously available. Nevertheless, significantly higher kills from higher intakes of poison have not been achieved, indicating difficulties in optimizing the characteristics of the capsule wall to achieve the desired release of ingested active ingredient.

A permanent type poison station for porcupine control

A method has been devised to protect the poison strychnine-salt blocks used in controlling porcupines, Erethizon dorsatum, from the weather, killing of non-target animals, and vandalism. An aluminum poison bait station has been developed which is lightweight, durable, camouflaged, and safe. These structures are easily constructed and are relatively inexpensive when longevity ls considered. Porcupines are controlled effectively and economically using this method.

Trapping - the oldest profession

While trapping is probably the oldest pursuit of man, predating hunting and agriculture, it has not undergone many drastic changes since the first primitive attempts. An arbitrary classification of traps [improvised traps, snares and nets, cage traps, spring traps and glues] is discussed and examples of each group given. As the behavioral and physical characteristics of vertebrate animals vary so much, it is impossible to discuss trapping procedures in any detail, but certain principles apply to most situations. These are: (1) need for an understanding of the target species' habit patterns, (2) selection of a trap size and design suitable for a given situation, (3) recognition of the need for a more humane approach, (4) maintaining traps in satisfactory mechanical condition, (5) proper placement, (6) attractive bait, (7) adequate concealment, and (8) a sufficient number of traps for a project.

Methods of controlling jackrabbits

Since 1963, biologists of the Denver Wildlife Research Center have been investigating methods of alleviating agricultural damage by the black-tailed jackrabbit (Lepus californicus). Of the several approaches to control, most biological methods (predation, habitat manipulation, disease and parasites, and chemosterilants) appear impractical with present knowledge. Mechanical control except for fence barriers, usually has limited effectiveness. Currently, the most useful approach is still chemical control. Improved baiting techniques and several chemical control agents, including an experimental toxicant highly selective for jackrabbits, are described.

A vehicle mounted bait dispenser

A 3-inch-diameter plastic tube mounted on a truck was designed for distributing bait (cut carrots or grain) for mammal control. Baits are fed into the tube by an operator standing in the truck bed. The device is light-weight and detachable and permits rapid, accurate placement of bait along a line on the ground or in a plowed furrow.

Pocket gopher problems and control practices on national forest lands in the Pacific Northwest region

A survey of animal-reforestation problems by the Pacific Northwest Forest and Range Experiment Station and the Forest Service placed pocket gophers high on the list of problem animals on National Forest lands in Oregon and Washington. Gophers ranked equally with porcupines as second to deer in importance. Lack of basic information on pocket gopher ecology and damage control is preventing prompt reforestation on large acreages. Most control methods are effective in limited situations, but the only technique proven useful over a wide range of conditions is baiting with rodenticides. Hand baiting and mechanical baiting using the burrow-builder machine are described and were evaluated in recent forestry applications; costs and efficacy achieved are reported. Some apparent areas of forest-gopher ecology needing study are: population dynamics, movement patterns, seasonal activity, food habits, habitat preferences, and effects of forest management programs on populations. As basic facts become available, it will be possible to integrate habitat modification, silvicultural practices, and direct control to provide necessary conifer protection. If research productivity lags, we will continue on a hit and miss basis and much needed timber production will be lost.

Rodenticides - problems and current research

Regarded from both the economic and health aspects, the control of rodents is a pressing worldwide problem. Continued improvements in food storage facilities, crop husbandry, and environmental control are likely to do much in the long term to help reduce rodent populations and damage. Looking ahead again, it is possible that biological control methods involving for example the use of reproduction inhibitors or rodent predators or diseases may ultimately be developed for rodent control purposes. In the immediate future, however, it is likely that rodent control operations will continue to be based on the use of rodenticides. The rodenticides in current use are either of the single dose, acute type or of the multiple-dose, chronic-acting anticoagulant type. The relative paucity and shortcomings of existing acute poisons and the emergence, particularly In Europe, of anticoagulant resistant rodent populations emphasizes the need for alternative rodenticides of both the acute and chronic types. A search for new rodenticides is now being conducted at the Infestation Control Laboratory, Tolworth, U.K. in cooperation with various chemical and pharmaceutical companies and in collaboration with the World Health Organization. Candidate rodenticides provided by Industry are evaluated in a programme employing laboratory and wild rats Rattus norvegicus and mice Mus musculus. The test procedures developed and the rodenticidal performance of standard and candidate compounds are considered.

Control of freshwater fish with chemicals

Fish toxicants have been used for nearly 60 years by sport fishery managers to remove predaceous or competing fishes from gamefish waters. The reclamation of lakes and streams by poisoning unwanted fish is considered to be one of the better management tools, and the demand for reclamations is increasing as more waters come under intensive management. Many chemicals have been tried as fish toxicants, but the insecticides rotenone and toxaphene have been most widely used despite their disadvantages of non-selectivity between wanted and unwanted fishes, persistence in water, and toxic effects on aquatic invertebrates. Research In the past 20 years led to the development of toxicants specific to fish and formulations better suited to aquatic applications. Further progress is noted in the search for safe, more selective controls for pest fishes in the wide variety of aquatic environments.

Standardization of procedures for developing vertebrate control agents

In research to develop methods for controlling damage by vertebrates, chemical evaluation procedures vary with every investigator, so that data cannot be meaningfully compared. Toxicology is one common area where standardization Is both applicable and desirable. It is recommended that standard guidelines be developed through an international body recognized by the members of the discipline.

Rodent control problems in developing countries

None of the so-called developing countries has an adequate rodent control program at present. In only a few of these countries is any rodent control research occurring despite the fact that rodent problems are actually quite serious in many regions and potentially so in others. Expertise, techniques, and materials from the developed countries are of limited usefulness because of major differences in rodent species involved, standards for food handling and sanitation, and in the cultural contexts in which rodent control must occur. Trained personnel, both for control work and the basic research needed, are in very short supply. In addition, rodent control is frequently a low priority Item in the generally meager budgets of developing countries. To date, international agencies, foreign aid programs, and foundations have had very limited success in altering this situation, although at present there is an upsurge of interest in rodent control problems.

The outlook for vertebrate pest control

Because of the increased concern for the environment and the public's positive action toward preservation of all forms of plant and animal life, future control methods for pest animals will require a greater degree of specificity than in the past. Vertebrate pest control does not face a very promising future unless the independent and cooperative effort of both industry and government is expanded. The time has passed when one could use a chemical simply because it was a good poison or repellent. Now, especially when food or feed crops are involved, it is necessary to know a lot more about a chemical than just its effect on the target species. Our knowledge now must include: 1) chemical and physical properties, including chemical structure, 2) micro-analytical methods for detecting or measuring the chemical, 3) degradation rates and resultant by-products, 4) oral and dermal toxicity (acute and chronic) to target and non-target animals, 5) efficacy as toxicant or repellent, 6) phytotoxicity, 7) pharmacology, and 8) secondary hazards. At present there is need for more chemists and pharmacologists in the field of vertebrate pest control research. Due to the comparatively small market for chemicals used in vertebrate pest control, most chemical companies are reluctant to spend the large sums necessary for their development. Also, a potential source of personnel for increasing this type of research is available at many state universities and experiment stations. Support from these institutions should be encouraged.

The Pocatello Supply Depot

The history and purpose of the Pocatello Supply Depot, operated by Division of Wildlife Services, Bureau of Sport Fisheries and Wildlife, U.S. Dept. of the Interior, is described. Begun in 1926, the facility manufactures and supplies rodent and predator control materials, which are not available to the general public, to cooperating Federal, State, and private agencies. Approximately 70% of the effort is devoted to rodent control materials, and 30% to predator control. This is done on a non-profit basis, and the Depot’s work has made possible large-scale control programs. Materials produced have led to more effective cooperative control measures.

Some vertebrate pest problems in Japan

The wildlife in Japan does more damage in outbreaks in forestry than in agriculture. Hares annually damage in excess of 250 thousand acres. Voles annually damage 50 to 100 thousand acres; in some areas great damage may occur suddenly. The giant flying squirrel damages areas of replanted trees in southern areas of Japan. The Himalayan black bear strips the bark on tree trunks. In agriculture, the sparrow and the duck do an excessive amount of damage in rice fields, and the boar does conspicuous harm in the plowed fields of mountain villages. In Okinawa, sugar cane is attacked by Rattus rattus, and in some years the loss is severe. Of even greater concern Is the damage done by introduced vertebrates. The gem-faced civet was imported from Taiwan. Similarly introduced from Taiwan, the tree squirrel increased on Izu-Oshima. The nutria was introduced in 1940; they escaped from cages in Southern Honshu and have increased.

The role of the wildlife refuge in relief of vertebrate pest damage in agriculture

Wildlife refuges in the upper Sacramento Valley of California play a very significant role in the relief of wildlife damage problems affecting agriculture. The history, management, and effectiveness of Gray Lodge Wildlife Area near Gridley, CA, are described as a case study representative of the refuges within this region. The refuge functions as a multipurpose recreational use are with objectives as follow: to provide a marshland-wildlife environment with particular concern for waterfowl using the Pacific Flyway; to provide wildlife food crops including desirable aquatic, as well as agricultural cereal crops, to lessen waterfowl crop depredation and to maintain health wildlife populations; to provide recreational opportunities including controlled public hunting; and to provide a site for pertinent wildlife research projects. The refuge’s management strategy and functions are described in some detail, including the economic value of crops produced, and wildlife taken during sport hunting and depredation hunts.

Surfactants as blackbird stressing agents

Applications of wetting-agent solutions produce mortality in birds. The exact cause of death is undetermined, but it is believed that destruction of the insulating qualities of the plumage permits ambient cold temperatures and evaporation to lower the body temperature to a lethal level. The original concept of using these materials as bird-control tools was developed in 1958 at the Patuxent Wildlife Research Center, Bureau of Sport Fisheries and Wildlife, Laurel, MD. Early field trials by personnel of the Division of Wildlife Services and the Denver Wildlife Research Center indicated that ground-application techniques had promise but limitations of the equipment precluded successful large-scale roost treatments. In 1966, Patuxent Center personnel began using tanker-type aircraft to evaluate high-volume aerial applications of wetting agents. The success of these tests led to the use of small aircraft to make low-volume, high-concentration aerial applications just prior to expected rainfall. Recent trials of the low-volume method show that, with some limitations, it is effective, inexpensive, and safe to the environment. Current research emphasizes the screening of new candidate materials for efficacy, biodegradability, and toxicity to plants and non-target animals, as well as basic investigations of the avian physiological mechanisms involved. Field trials to develop more effective application techniques will continue.

Bird damage problems in Latin America

In 1968 and 1969, biologists of the Denver Wildlife Research Center made field surveys in six Latin American countries to obtain information on bird damage problems in agriculture, under an agreement with the Agency for International Development. Species of icterids, fringillids, psittids, columbids, and anatids caused most of the damage. Grain sorghum, corn, and rice were damaged most heavily. Other crops such as soybeans, wheat, cacao, and mangoes were also damaged, but seldom seriously. Resident post-breeding populations of birds in Latin America cause some damage to crops in summer, the tropical wet season; however, migrants from the United States and Canada greatly swell these problem populations in winter, the tropical dry season, when smaller acreages of mostly irrigated crops are available. Problems also intensify in October when the largest numbers of migrants descend upon ripening crops and, again, in April when many crops are being planted. Bird damage problems in Latin America are similar to those in the United States, involving many of the same types of crops and genera of birds. Therefore, research conducted in one area should be beneficial for the other, and cooperative work is recommended.

Reproduction inhibitors for bird control

Reproduction inhibitors are Intended to maintain or control a population at a desired level; toxicants aim at elimination of the population. Azocosterol hydrochloride (SC-12937; 20,25-diazocholestenol dihydrochloride) is a long-acting inhibitor of ovulation in the pigeon (Columba livia) by interfering with cholesterol synthesis and egg yolk formation. Corn impregnated with SC-12937 at the 0.1% level by weight and fed for 10 days has been found to inhibit or diminish reproduction for 5-6 months. Population turnover rate, mortality, and longevity of the feral urban pigeon is also discussed.

Carbamate baits discourage blackbirds from using feedlots

Red-winged blackbirds (Agelaius phoeniceus) have been discouraged from using cattle feedlots near Denver, Colorado, by baiting alleys with cracked corn treated with an aversion-producing immobilizing agent, DRC-736 [4-(methylthio)-3,S-xylyl N-methylcarbamate]. In three studies, large populations of redwings were reduced 70% - 98% within a few days and protection lasted about a month. In a fourth study, simultaneous baiting of three heavily used feedlots reduced redwing use by more than 90% within hours and was apparently responsible for these birds abandoning their roost and relocating in areas where they caused little trouble. Mortality was low (less than 5% of affected redwings in the fourth study), and few birds of nontarget species were affected.

House finch (linnet) control in California

The house finch or linnet, Carpodacus mexicanus frontalis (Say) is a protected migratory nongame bird indigenous to California and found abundantly in all but the northern and mountainous areas. These finches attack more than twenty different crops and damage is demonstrated by fruit pecks, seed removal, and disbudding. When house finches cause agricultural damage, control measures must be carried out under the general supervision of a county agricultural commissioner. Control practices involve the use of toxic baits, trap-decoy stations, and bio-acoustical devices. Most importantly, these control methods have been demonstrated to be safe, selective, and successful when employed by persons properly trained in the ecology of the species.

Importation of wildlife

The importation of live birds, mammals, reptiles, fish and amphibians into the United States is a growing problem to law enforcement agencies of the Federal and State governments. Importation of the above types of animals into the U.S. is supervised by the Bureau of Sport Fisheries and Wildlife of the U.S. Department of the Interior. The function is of a regulatory nature: 1) to insure that no prohibited species enter the United States; 2) to enforce compliance with certain Federal Acts such as a) the Migratory Bird Treaty Act, b) the Lacey Act, Title 18 USC, Sec. 42, 43 and 44, c) the Bald and Golden Eagle Act; 3) to assist in the enforcement of State laws and regulations concerned with entry of undesirable species of wildlife not afforded Federal prohibition. Restricted species of birds and mammals prohibited entry into the U.S. by Federal laws are: Birds: java sparrow, Padda oryzivora; Sudan dioch, Quelea quelea; rosy pastor, Sturnus roseus; and the red-whiskered bulbul, Pycnonotus jococus; Mammals: mongoose; any species of the genera Atilax, Cynictis, Helogale, Herpestes, Ichneumia, Mungos, and Suricata; bats of the genus Pteropus; multimammate rat of the genus Mastomys; the East Indian wild dog of the genus Cuon. The abovenamed birds and mammals were declared undesirable for entry into the U.S. because of their destructive habits to agriculture and our native wildlife.

Current work on bird hazards to aircraft

Collisions between birds and aircraft have caused loss of human life and millions of dollars worth of property damage. The advent of even larger planes may reduce airframe damage, but it seems doubtful that engine damage will be significantly reduced. Dealing with the problem biologically involves combatting the hazards caused both by birds on or near the ground at airfields, and by birds on mass migrations at altitudes up to several thousand feet above ground. Airports can be designed or altered to minimize their attraction to birds. The chance arrival of a flock of birds must be treated as an emergency with all available equipment and personnel used to ensure quick dispersal. The hazards caused by birds aloft must be dealt with by making it possible for aircraft to avoid the main bird flocks. Warnings of the immediate presence of birds can be given by air traffic control operators trained to recognize birds on their radar. The ability to forecast the probable presence of flocks of birds on migration is now being developed.

The organisation of rabbit control (Oryctolagus cuniculus) in Western Australia

Under Western Australian legislation, landholders have an obligation to control rabbits on their properties; local authorities the responsibility to supervise their work whilst the Agriculture Protection Board has a Statewide supervisory and co-ordination role. Prior to 1950 (when the Agriculture Protection Board was formed) the central role was in the hands of a government department which, through lack of staff and money, was unable to provide adequate supervision, and rabbits were in plague proportions. Since 1950, the Board has actively engaged in a vigorous policy aimed at tighter control and supervision. To enable this, the Board has entered into a voluntary scheme with local authorities whereby the role of local supervision of landholders is passed to staff employed by the Board, but jointly financed by the local authority and the Board. A contract poisoning service is also provided by the Agriculture Protection Board to any landholder who is unable or unwilling to meet his obligations in this area. Both services are subsidised. Two of the major reasons for the poor level of control existing before 1950 have thereby been minimised. Soon after Its formation, the Board set up a research section which has devoted nearly all of its activities to applied research on control of the State’s many vertebrate pest problems. In the rabbit control area, poisoning has received most attention. The “One-Shot” method of poisoning was developed after years of research. Fumigation is at present being closely studied as is the economics of complete eradication from some areas of the State. Greatest needs in the applied rabbit research field at present are: 1) a selective poison, or poisoning regime, which will not harm stock, and 2) a more complete understanding of the economics of control and eradication. The serious rabbit problem which existed in 1950 has been reduced to very small proportions by organisational development using local research findings. These organisational developments have been implemented by circumvention rather than confrontation.