Copyright (c) 2005 University of Nebraska - Lincoln All rights reserved. http://digitalcommons.unl.edu/vpc2 Recent documents in Proceedings of the Second Vertebrate Pest Control Conference (1964) en-us Wed, 02 Nov 2005 01:50:50 PST 3600 http://digitalcommons.unl.edu/vpc2/25 http://digitalcommons.unl.edu/vpc2/25 Mon, 31 Oct 2005 06:34:12 PST The Second Vertebrate Pest Control Conference is concluded. We hope it has been, in some measure, educational and worthwhile to each one of you. Many of you who are here attended the first conference, which was held in Sacramento two years ago. The obvious spirit displayed at that meeting, a genuine intense interest in absorbing new knowledge presented by the speakers, the warmth of making and renewing acquaintances among fellow workers and the enjoyment of the truly rare opportunity to exchange information in this special field, vertebrate pest control, has, I feel, been reenacted here. For these reasons this second conference was held, not merely for the sake of having a meeting or perpetuating an idea. Gratified as we are at this fine attendance, and it should be for the privilege of hearing these speakers, our colleagues who are not here missed a valuable opportunity; we should realize that although our own store of knowledge has been enriched we have an obligation to inform the public at large. Very often the general public is concerned with vertebrate pest- control only to the extent of wanting a solution to an individual problem. We should use those opportunities and should create others to explain the inter-related biology of pest animals in the total ecological picture, natural or man-made, and the need for sound management which is very often much more than merely removing one species from one place. There is need for a great deal more research concerning vertebrate pest species. An increased public understanding is necessary for proper evaluation, acceptance and support of vertebrate pest control, and all, resource management programs. The California Vertebrate Pest Control Committee sincerely hopes these conferences have assisted materially toward those goals, particularly the first objective, that of providing a medium of communication among us. This is a lack we all feel. Your impressions of this conference may prompt suggestions for a future conference, if there should be one. This is not an annual affair. Your suggestions will be welcomed by the Committee at any time. Maynard W. Cummings http://digitalcommons.unl.edu/vpc2/24 http://digitalcommons.unl.edu/vpc2/24 Mon, 31 Oct 2005 06:30:59 PST The purpose of this paper is to present a brief review of the research being conducted in England, France, Germany, and The Netherlands on problems caused by nuisance and depredating birds. Much of the information presented has been obtained through correspondence with collaborators. In the fall of 1962, I discussed depredating bird and bird-airport problems with research workers in these countries, and also attended the meeting of the International Union of Applied Ornithology held in Frankfurt/Main. In November 1963, I attended an international symposium about the bird-airport problem, held in Nice, France. This paper will draw attention to the current research which I think will interest American investigators, but will not report every aspect of the foreign investigations. Details appear in the publications that are listed. John L. Seubert http://digitalcommons.unl.edu/vpc2/23 http://digitalcommons.unl.edu/vpc2/23 Mon, 31 Oct 2005 06:29:47 PST Bubonic plague no longer is regarded as the dreaded black death of the middle ages. The last great plague pandemic has come to an end. In California, human cases have averaged no more than one every two years for several decades. With modern antibiotics properly administered, recovery is assured. At the same time, there is no doubt that plague is firmly entrenched in the rodent fauna and we should not be lulled even by years of quiescence into assuming that massive epizootics will not break out in the future. There is the un-measurable risk of a quick pneumonic outbreak with tragic results, or the chance that infection may transfer to urban rat populations and thus pose a markedly greater hazard. No formula can determine the magnitude of these potential hazards, or the intensity of control efforts that should be applied. Reason, both biological and fiscal, dictates that the program should be a modest one. Having reached this conclusion, it behooves us to be sure that this modest effort is applied with the fullest knowledge and understanding to secure the greatest possible benefit. Let us review briefly the history of sylvatic plague suppression in California. Early in this century, massive epizootics in California ground squirrels were discovered in the San Francisco Bay area. A great campaign of squirrel control was launched, with the purpose of eradicating the infection before it could spread. At one point an official claimed that this goal had been achieved. But new outbreaks appeared, and gradually plague was found to be present throughout most of the west. Ground squirrels of several species, chipmunks, and marmots were the animals consistently and conspicuously identified in epizootics. Not surprisingly, they were regarded as the reservoirs of plague. Occasional plague-infected mice were thought of as incidental victims. Sites where plague was found were regarded as "foci". Survey workers returned to these sites again and again in succeeding years and often found infected animals or fleas, thus reinforcing the original assumption. It naturally followed that controlling squirrels in these "foci" would control the disease itself. This led to designating a series of plague areas, subject to constant ground squirrel suppression, many of which continue to be observed as geographical control units. Current knowledge of plague ecology reveals a much different picture. Recent plague studies throughout the world show that the persistent reservoirs of infection are not those susceptible rodent species which Suffer periodic violent epizootics. Instead, they are rodents capable of maintaining a quiet state of infection, with little or no mortality. It is becoming clear that plague persists in relatively small pockets where suitable climate, flea vectors and rodent hosts occur, characteristically in cold mountainous or high plateau regions, or coastal fog belts. From these pockets of enzootic infection, plague may spread periodically through susceptible host populations in epizootic form. Even when such hosts sustain the disease for a number of years, it must follow an ever shifting epizootic path to survive. Presumably a rather high degree of crowding is required for an epizootic to be sustained. Keith F. Murray http://digitalcommons.unl.edu/vpc2/22 http://digitalcommons.unl.edu/vpc2/22 Mon, 31 Oct 2005 06:26:36 PST The specific diseases of man known to be derived from wildlife in California are: rabies, Western encephalitis, St. Louis encephalitis, Colorado tick fever, Rocky Mountain spotted fever, relapsing fever, 0. fever, plague, tularemia, murine typhus, lymphocytic choriomeningitis, psittacosis, leptospirosis, salmonellosis and toxoplasmosis. A variety of bacterial infections may be contracted from wild animals, notably those caused by Pasteurella pseudotuberculosis, Pasteurella multocida, Bacillus anthracis, Erysipelothrix rhusiopathiae, Clostridium tetani and Listerella monocyto-genes. Certain of the fungus diseases such as coccidioidomycosis and histoplasmosis are derived from exposure to wildlife habitats. California virus has been isolated from arthropods and Rio Bravo virus from bats collected in California. It has been shown by serological tests that these viruses may produce infection in man. In the course of field studies of arthropods, small mammals and birds in California and Oregon, several viruses have been isolated which may prove to be of importance as disease agents, that is, Modoc virus, Turlock virus, Kern Canyon virus, Hart Park virus and two yet unnamed viruses isolated from Microtus montanus meadow mice. The investigation of sources of diseases in wildlife must be concerned with wildlife populations and the factors which control the flora and fauna. In searching for natural foci of disease agents in wildlife, it is logical to study habitat types which have a large and relatively stable wildlife population. In such foci one does not expect to observe disease in the reservoir wildlife hosts, but if the viruses, rickettsia, bacteria or fungi set up chains of infection in aberrant hosts, this may result in epidemics of disease, sometimes having a high mortality. Harald Norlin Johnson M.D. http://digitalcommons.unl.edu/vpc2/21 http://digitalcommons.unl.edu/vpc2/21 Mon, 31 Oct 2005 06:23:25 PST There is an increasing need for new means of population control from the simplest organisms up to the larger mammalian species (include man if you wish.) A number of interesting and promising leads, such as environmental manipulation, introduction of predators, diseases, parasites, etc., and particularly antifertility agents, have been proposed for some time, but research into the latter approach in mammal control is quite recent and limited. The use of toxic agents has long been the principal method of vertebrate population conŽtrol, but the potential for the use of antiferti1ity agents to suppress reproduction may provide an important advancement. I wish I could tell you that all we have to do is to develop or discover the right antiferti1ity agent and we have the problem solved. Unfortunately this is far from the truth. Based on present knowledge of antifertility agents in vertebrate pest control, it appears that we will need a variety of agents and even more imŽportant, a wide variety of techniques of application plus the detailed knowledge of proper timing, dosage, and dispersal of bait for effective results. In many instances, the problems of application far outweigh the development of a suitable drug. At present it appears that the greatest potential lies with animals that breed once a year and secondly with birds such as pigeons. When it comes to rodents, a major problem arises; a temporary antiferti1ity agent will have to be continuously available to block reproduction throughout the year or else permanent sterility agents wi11 be needed which are apt to be so toxic they provide little advantage over a poison. Donald S. Balser http://digitalcommons.unl.edu/vpc2/20 http://digitalcommons.unl.edu/vpc2/20 Mon, 31 Oct 2005 06:21:15 PST With the help of one of your expert operators I have selected eight pesticides which I understand are widely used in vertebrate pest control, and with one exception, pose substantial safety problems for operators. These pesticides are the anticoagulants, zinc phosphide, 1080, strychnine, thallium sulfate, anhydrous ammonia, carbon disulfide, and methyl bromide. Except for the anticoagulants, it would be hard to assemble a more lethal group of chemicals. I wonder if the talents of chemical research should not be brought into this picture more actively, so that less hazardous materials could be developed for vertebrate pest control. Perhaps the economic incentives do not stimulate in this direction. Nevertheless the vertebrate pest control operators have a reasonably good record as far as acute occupational poisoning is concerned. Either you are careful, lucky, or whatever health problems which may be occurring are not being recognized. One fortunate circumstance is that a good portion of the chemicals you use are not easily absorbed through the intact skin, a property which reduces the hazard to operators considerably. On the attached table is presented a summary of the properties and hazards of the eight chemicals together with information about the protection of the operator using them. Also attached is a list of safety rules for workers handling pesticides (to be discussed in the oral presentation.) Also I'd like to present some actual cases of poisoning or other harmful effects experienced by California workers to illustrate how operators may experience difficulties. Although none of these cases occurred to operators dealing with vertebrate pests they do concern the pesticides on our list. Irma West M.D. http://digitalcommons.unl.edu/vpc2/19 http://digitalcommons.unl.edu/vpc2/19 Mon, 31 Oct 2005 06:19:05 PST New Zealand has a multiplicity of challenging animal-control problems, and all of them concern animals which man has intentionally introduced either for sport, food or fur. Since the beginning of European settlement in the 19th Century, approximately 53 species of mammals and 125 species of birds have been deliberately or accidentally introduced into New Zealand, and 34 birds and 31 mammals have become established (Wodzicki, 1950). The principal reasons the exotic big game animals (Riney, 1955), fur bearers and feral domestic livestock have been so destructive to certain habitats in New Zealand are because 1) some of the soils are highly susceptible to erosion, 2) the mountainous country often gets high intensity torrential rainfall, and 3) many of the endemic plants have little innate resistance to the heavy selective grazing or browsing pressure. The bulk of New Zealand's vegetation is composed of indigenous species. This unique flora must have evolved without the presence of browsing or grazing mammals, for New Zealand has no fossil or native land mammals, except two species of bats and a rat that was liberated a few centuries ago by the Polynesians. Consequently, natural selection did not have an opportunity to eliminate the highly palatable and non-browse-resistant plants in favor of those which were either browse-resistant or unpalatable to browsing mammals. As a result, some of the highly palatable indigenous vegetation in New Zealand is unable to withstand the heavy selective browsing and grazing pressure inflicted by the introduced mammals (Holloway, 1950, Howard MSa and MSb, Kean and Pracy, 1949, McKelvey, 1959, Riney et al., 1959, Wardle, 1961). Walter E. Howard http://digitalcommons.unl.edu/vpc2/18 http://digitalcommons.unl.edu/vpc2/18 Mon, 31 Oct 2005 06:15:55 PST This brief review of the public health importance and control of bats is oriented to Trinidad, where, during the past ten years I investigated their zoomedical importance (1). Trinidad is noted for Pawan's classic epidemiological studies of bat rabies (2,3) as well as its bat control program with which I have been associated since its inception in 1934 (4). Further, Trinidad has bat problems, in addition to rabies, which occur in other countries of the world. Although various methods of bat control have been developed in Trinidad, the field is virtually unexplored. Increasingly, bat control is a matter of paramount importance to Trinidad and other countries in Central and South America striving for self-sufficiency in meat and dairy production to feed their expanding populations. Arthur M. Greenhall http://digitalcommons.unl.edu/vpc2/17 http://digitalcommons.unl.edu/vpc2/17 Mon, 31 Oct 2005 06:13:45 PST Northern Santa Clara County, California, was historically an agricultural community with orchard culture dominating the economy. Prunes, apricots, walnuts, and cherries were the principal crops. Orchards were disced clean during most of the summer growing season, and a cover crop of mustard or horse beans was grown beneath the trees in winter. About the only "natural" year around cover on the valley floor was the brush and grass which volunteered along the several creek banks. Under such conditions, roof rats (Rattus rattus) were not numerous. An occasional rat colony could be found in a fruit processing shed or in some of the older buildings of the several small towns, but wild or feral rats were rare. Truly feral roof rat colonies are uncommon in most of the United States. Even in southwest Georgia where cover conditions would appear ideal, an intensive study of roof rat ecology failed to uncover any feral roof rat popuŽlations (Ecke-1955). On the other hand, studies on Guam by Baker in 1946; and on Hawaii by Spencer and Davis in 1950 and by Kartman and Lonergan in 1955 have shown that feral roof rat populations thrive in tropical climates, particularly where their introduction does not place them in competition with native rodent populations. This competition factor may well be an important clue to the recent rat build-up in suburbia California, including Santa Clara County. Starting in the late 1940's and continuing at an ever accelerating pace, Santa Clara County has experienced a "flood tide" immigration of people. Defense plants have attracted people and people have demanded homes. Because space was available and the weather ideal, most of these homes were designed to include spacious lots with patios and landscaping that go toward making outdoor enjoyment a part of California living. Inadvertently this trend in landscaping has greatly increased the available habitat--free of natural competition--for an increased roof rat population. In the past 10 years, beautifully landscaped yards have matured into vegetative harborages of vines and shrubs, and ornamental fruit trees together with remnants of old walnut and fruit orchards are supplying ample quantities of rat food. Such favorable habitat together with ideal climatic conditions has provided the stimulus for a roof rat population explosion in Santa Clara County. Dean H. Ecke http://digitalcommons.unl.edu/vpc2/16 http://digitalcommons.unl.edu/vpc2/16 Mon, 31 Oct 2005 06:09:36 PST I would like to discuss with you the reason why agricultural commissioners are in the poison bait business. The following are excerpts from the Agricultural Code of the State of California. Section 100 describes a pest as follows: "Pest means any of the following that is, or is liable to be dangerous or detrimental to the agricultural industry of this State" and for the purpose of this talk only part two of this section is cited which states, "any form of animal life." This is the part which covers vertebrate pests. Section 102 states, "Each commissioner is an enforcing officer of all laws, rules and regulations relative to the prevention of the introduction into or spread within the State of pests and as to such activities is under the supervision of the director." (Director means the Director of the California State Department of Agriculture.) Section 129 states, "The commissioner, whenever he deems it necessary, may enter and make an inspection of any premises, plant, conveyance or thing in his jurisdiction and if found infested or infested with a pest, etc., etc. - - -." This section and following sections provide the means by which abatement proceedings are carried out. To further facilitate the control of vertebrate pests, County Boards of Supervisors authorized their agricultural commissioners to prepare poison baits and sell them at cost and in some instances distribute them at no cost. This has been a common procedure since 1917 when the State Law prescribed rodent control as a specific function of the established agricultural regulatory set-up. Since 1917 large quantities of poison baits have been prepared. The 1920 Annual Report of the California Department of Agriculture states that counties in that year used 928,538 pounds of strychnine bait for ground squirrel control. The agricultural commissioners have prepared and distributed an average of almost a million pounds of various poison baits per year. In addition to ground squirrels, baits are prepared for Kangaroo rats, meadow mice, rats, gophers, muskrats, jackrabbits and depredating birds. Bait mixing equipment remained quite simple for a number of years and consisted primarily of a rectangular box and a square nose shovel. In recent years there has been a replacement of hand mixing to mechanical mixers. Percy F. Wright http://digitalcommons.unl.edu/vpc2/15 http://digitalcommons.unl.edu/vpc2/15 Mon, 31 Oct 2005 06:06:27 PST Common California rabbits comprise two major genera. One, the genus Sylvilagus, or true rabbit, is represented by the cottontail and brush rabbits. The second of the two major genera is the genus Lepus, or hares. These are erroneously called the jack rabbits and snow shoe rabbits. The common jack rabbit, Lepus californicus, is the most familiar one throughout California and portions of some of the other western states. Because of their size and abundance, they are by far the most destructive - so emphasis will be placed on this species throughout the balance of this report. The diet of the jack rabbit consists mostly of available vegetation. This includes a wide variety of herbs, shrubs, and succulent grasses. Food consumption studies have indicated that about 12 jack rabbits will consume the same amount of forage as 1 mature ewe, or that 60 rabbits will consume about the equivalent of a 1,000 lb. range cow. Because of frequent feedings on seedling plants of cultivated crops as well as grain, bark of young trees, and young grapevines, control measures are often necessary. Also, in recent years, high populations of rabbits in the vicinity of airports have brought about potential hazards to aircraft and a reduction of the population in these areas has been necessary. The methods of rabbit control are several - including the encouragement of natural enemies, shooting, trapping, exclusion, repellents, and poisoning. Warren V. Johnson http://digitalcommons.unl.edu/vpc2/14 http://digitalcommons.unl.edu/vpc2/14 Mon, 31 Oct 2005 05:55:19 PST As a nation we have gained world recognition for our ability to utilize our resources. In forestry our greatest accomplishments have been in the mechanization of harvest methods and in improvements in forest products. The renewal of this resource has been our greatest neglect. Though the end of the 19th Century marked the beginning of the conservation movement, it was not until a half century later that the force of economics through the demands of a growing population made forest re-establishment more than just a desire. Conservation in itself is a Utopian concept which requires other motivating forces to make it a reality. In the post-war years, and as late as the early 195O's, stocked land in the Pacific Northwest could be purchased for less than the cost of planting; the economic incentive was lacking. Only with sustained yield management and increased land values was there a balance in favor of true values. With greater effort placed on forest regeneration there was an increased need for methods of reducing losses to wildlife. The history of forest wildlife damage research, therefore, parallels that of forest land management; after rather austere beginnings, development became predominantly a response to economics. It was not until 1950 that the full time of one scientist was assigned to this important activity. The development of control methods for forest animal damage is a relatively new area of research. All animal life is dependent upon plants for its existence; forest wildlife is no exception. The removal of seed and foliage of undesirable plants often benefits the land managers; only when the losses or injuries are in conflict with man's interest is there damage involved. Unfortunately, the feeding activities of wildlife and the interests of the land managers are often in conflict. Few realize the breadth, scope, and subtilities associated with forest wildlife damage problems. There are not only numerous species of animals involved, but also a myriad of conditions, each combination possessing unique facets. It is a foregone conclusion that an understanding of the conditions is essential to facilitate a solution to any given problem. Though there are numerous methods of reducing animal damage, all of which have application under some situations, in this discussion emphasis will be placed on the role of chemicals and on western problems. Because of the broadness and complexity of the problem, generalizing is necessary and only brief coverage will be possible. However, an attempt will be made to discuss the use and limitations of various control methods. Nelson B. Kverno http://digitalcommons.unl.edu/vpc2/13 http://digitalcommons.unl.edu/vpc2/13 Mon, 31 Oct 2005 05:53:10 PST The problem of rats in our Hawaiian sugar cane fields has been with us for a long time. Early records tell of heavy damage at various times on all the islands where sugar cane is grown. Many methods were tried to control these rats. Trapping was once used as a control measure, a bounty was used for a time, gangs of dogs were trained to catch the rats as the cane was harvested. Many kinds of baits and poisons were used. All of these methods were of some value as long as labor was cheap. Our present day problem started when the labor costs started up and the sugar industry shifted to long cropping. Until World War II cane was an annual crop. After the war it was shifted to a two year crop, three years in some places. Depending on variety, location, and soil we raise 90 to 130 tons of sugar cane per acre, which produces 7 to 15 tons of sugar per acre for a two year crop. This sugar brings about $135 dollars per ton. This tonnage of cane is a thick tangle of vegetation. The cane grows erect for almost a year, as it continues to grow it bends over at the base. This allows the stalk to rest on the ground or on other stalks of cane as it continues to grow. These stalks form a tangled mat of stalks and dead leaves that may be two feet thick at the time of harvest. At the same time the leafy growing portion of the stalk will be sticking up out of the mat of cane ten feet in the air. Some of these individual stalks may be 30 feet long and still growing at the time of harvest. All this makes it very hard to get through a cane field as it is one long, prolonged stumble over and through the cane. It is in this mat of cane that our three species of rats live. Two species are familiar to most people in the pest control field. Rattus norvegicus and Rattus rattus. In the latter species we include both the black rat and the alexandrine rats, their habits seem to be the same in Hawaii. Our third rat is the Polynesian rat, Rattus exlans, locally called the Hawaiian rat. This is a small rat, the average length head to tip of tail is nine inches and the average body weight is 65 grams. It has dark brownish fur like the alexandrine rats, and a grey belly. It is found in Indonesia, on most of the islands of Oceania and in New Zealand. All three rats live in our cane fields and the brushy and forested portions of our islands. The norway and alexandrine rats are found in and around the villages and farms, the Polynesian rat is only found in the fields and waste areas. The actual amount of damage done by rats is small, but destruction they cause is large. The rats gnaw through the rind of the cane stalk and eat the soft juicy and sweet tissues inside. They will hollow out one to several nodes per stalk attacked. The effect to the cane stalk is like ringing a tree. After this attack the stalk above the chewed portion usually dies, and sometimes the lower portion too. If the rat does not eat through the stalk the cane stalk could go on living and producing sugar at a reduced rate. Generally an injured stalk does not last long. Disease and souring organisms get in the injury and kill the stalk. And if this isn't enough, some insects are attracted to the injured stalk and will sometimes bore in and kill it. An injured stalk of cane doesn't have much of a chance. A rat may only gnaw out six inches of a 30 foot stalk and the whole stalk will die. If the rat only destroyed what he ate we could ignore them but they cause the death of too much cane. This dead, dying, and souring cane cause several direct and indirect tosses. First we lose the sugar that the cane would have produced. We harvest all of our cane mechanically so we haul the dead and souring cane to the mill where we have to grind it with our good cane and the bad cane reduces the purity of the sugar juices we squeeze from the cane. Rats reduce our income and run up our overhead. William R. Smythe http://digitalcommons.unl.edu/vpc2/12 http://digitalcommons.unl.edu/vpc2/12 Mon, 31 Oct 2005 05:48:12 PST Frankly I am not sure what "Pest Control Methods and People" really means. When I asked what I should cover, I was told to give a general discussion on pesticides. I am not sure this is appropriate even though the laws and regulations that pertain to other pesticides apply equally to those materials used in vertebrate pest control; the conditions of use, the types of chemicals used, their effect upon various animal species, and the number of chemicals available are so different from the pesticides used in controlling invertebrate pests that generalizations may not cover the topic. There are, however, a few basic principles that do pertain and I will discuss these. Mr. Cummings suggested that I cover the University's policy in regards to the use of and recommendations for pesticides by our experiment station and Extension Service personnel and I will do this a little later. Looking back to your last conference in February of 1962 we find that a number of topics were discussed at that time which is being further elaborated upon during the present conference and some of these lend themselves to the discussion this morning. Dean Aldrich pointed out the importance of several bird and rodent species as enemies of our agriculture. Further, he brought out the point that many of these pests are the result of our intensified agricultural practices. When we plant certain crops over a wide area we change the environmental and ecological conditions and frequently bring about a situation that is conducive to large populations of organisms which, under the natural conditions that prevailed before the land was put into crop production, would not have occurred and, furthermore, these animals would not have been considered pests under ordinary population densities. Field mice in our orchards and sugar beet fields, gophers in alfalfa, starlings in feed lots and grapes are examples of vertebrates that fall into this category. Some imported species such as the starling have found conditions good. Others are native species which have adapted to these changed conditions. There are many such examples among insects. One striking case is that of the alfalfa butterfly. This insect is native to the United States. It lived upon various legumes and was considered a pretty but unimportant butterfly for many years. John E. Swift http://digitalcommons.unl.edu/vpc2/11 http://digitalcommons.unl.edu/vpc2/11 Mon, 31 Oct 2005 05:44:51 PST The policy of the Cape Provincial Department of Nature Conservation is based on the concept of "wise management" of wildlife resources. Where crop damage is real, control measures are essential. These, however, must be adapted to the species concerned and applied only where the damage is taking place. Blanket measures which also kill many useful species must be avoided. For this reason, the control of problem animals should be vested in the agency concerned with wildlife conservation. Douglas Hey http://digitalcommons.unl.edu/vpc2/10 http://digitalcommons.unl.edu/vpc2/10 Mon, 31 Oct 2005 05:41:42 PST The best known vertebrate pests, as the papers presented at this meeting show, are birds and mammals. Other vertebrates, however, may become pests also: sharks, lampreys, toads (they fall into swimming pools), geckos, tortoises and snakes, for example. Without considering them, however, the depredations by birds and mammals alone are so varied that no single method of pest control can ever be all-embracing. Certainly, no one would suggest that acoustical methods would be, but, with further study, acoustical pest control should be much more widely used. I hope to point out here the possibilities and a few realities in bio-acoustics as related to control of vertebrate pests. First, let us consider an aspect of acoustical pest control that seems to attract attention: the possible use of ultrasonics. Ultrasonic sounds, defined with man as reference, have frequencies above those heard by man; otherwise they are the same as other sounds. Since biologists who study the effects of liquid-borne ultrasounds on living things usually use very high intensities, causing injury by their high energies, many people believe that ultrasonic sounds have an aura of mystery. This is not so. Ultra-sounds have few special properties. Obviously, if ultrasonic sounds could be used for pest control, human beings would not hear them, and this would be advanŽtageous. However, the pests usually must hear the sounds, and this means that they must have higher ultrasonic limits than that of man. Rats, mice, and other small mammals can hear sounds that are ultrasonic for man, so acoustical stimuli for them could be inaudible to man. Birds, however, generally have ultrasonic limits lower than that of man, and for them audible sounds must be in man's sonic range. Periodically, stories appear in newspapers about the chasing of birds, usually pigeons, with ultrasonic sound. When any reasonable information is given, one usually finds that this was done with a sound source that produced ultrasonic sound well enough, but produced high intensity sonic sound as well. Invariably no effort was made to distinŽguish between the effects of different frequencies. In short, ultrasonic sounds may have advantages in pest control, but they are not likely to be somehow "mysteriously" effective. Ordinary loud noises have been used since antiquity to repel birds and mammals. These can be produced variously, from clapping hands to firing cannons. Many people believe, when they shoot at animals, that the animals flee because they fear death. It seems highly doubtful, from what we know of the conceptual abilities of birds and most mammals, that they can fear an abstraction such as death. The animals are undoubtedly frightened by the noise. Since this is the case, one is inclined to wonder why it has taken so long for firecrackers and guns to be discarded in favor of safer and cheaper mechanical noise generators or recorded shots. The latter, particularly, should be the item of choice for chasing birds, where high intensity noises can be used. Why should anyone use blanks, firecrackers, or exploders, which are expensive at best, when they can simply clap their hands in front of a microphone and produce a recorded "shot" which is infinitely reproducible? Hubert Frings http://digitalcommons.unl.edu/vpc2/9 http://digitalcommons.unl.edu/vpc2/9 Mon, 31 Oct 2005 05:37:36 PST One of the most widespread bird problems in the Western United States is damage to ripening cereal grain crops. Crops such as corn, rice, and sorghum, when grown close to favored roosting areas are often subject to serious damage from large flocks of feeding blackbirds. The redwinged blackbird is the most numerous species and causes most of the damage, but other blackbird species, including the yellow-headed blackbird, the common grackle, the brown-headed cowbird, and Brewer's blackbird, also contribute to damage problems. The Denver Wildlife Research Center is actively investigating methods to combat blackbird depredations to field corn in the vicinity of Sand Lake National Wildlife Refuge in northeastern South Dakota. This report will deal with this particular project since it is the Denver Center's most active study involving blackbird depredations. The Sand Lake project was initiated in 1960 and was planned for five years. Field work usually begins in April and ends in October. The major work period is August and September, the time of peak populations of birds and of the most acute damage. John W. De Grazio http://digitalcommons.unl.edu/vpc2/8 http://digitalcommons.unl.edu/vpc2/8 Mon, 31 Oct 2005 05:35:28 PST In 1959 Dr. Walter E. Howard, in an article printed in the Bulletin of the California Department of Agriculture, stated: "Even though the starling may be unwanted in California, it is now here and there is little chance of extirpating it". This statement is as true today as it was five years ago. At present we have in California a resident population that is increasing each year and will most probably continue to increase. Nesting starlings have been found from Imperial and San Diego Counties in the south to Modoc County in the north. To-date damage has been confined primarily to grapes and figs in the summer months and to cattle feedlots, hog farms and other concentrated feed sources during the winter months. Most of the winter communal roosts in California have been in cattail and tule areas, well away from urban situations. Because of this we have experienced very little nuisance problem, such as plagues the cities of the eastern portion of the United States. It can be expected that the damage to agriculture in California will increase as both our resident and migrant populations grow and expand. To combat this potential population increase a cooperative program has been initiated by the California Department of Agriculture, the University of California, and the Bureau of Sport Fisheries and Wildlife of the United States Department of the Interior. The agricultural commissioner's offices of the counties of the state are contributing manpower to this program. It is the function of the Department of Agriculture in this program to conduct field testing of control methods, to supervise the statewide banding program and to supply starlings to the University for research. The starling program in California logically separates itself into two distinct parts. The first is the resident breeding population and the birds fledged during the spring and summer months; damage at this time is primarily to grapes and soft fruits. The second is the migrant population that begins to arrive in November and remains until March; damage at this time is priŽmarily caused by millions of starlings congregated at feedlots and other concentrated sources of feed. Charles C. Siebe http://digitalcommons.unl.edu/vpc2/7 http://digitalcommons.unl.edu/vpc2/7 Wed, 26 Oct 2005 14:51:24 PDT As is the case in many sections of the country today, starlings are causing increasing concern in the Pacific Northwest. When these birds were first recognized in Washington, Oregon and Idaho in the early 1940's only small numbers were seen, usually with blackbirds. During the 50's, however, the number of wintering starlings increased from a few birds, to thousands, with estimated flocks of 25,000 to 50,000 in western Oregon and along the Snake River Valley in Idaho and eastern Oregon. During the past five years winter resident populations in these areas have been estimated by the 100,000's, with some observers estimating roosting concentrations as high as several million. Damage due to winter roosting of enormous numbers of starlings in western Oregon holly orchards and increasingly severe losses to cattle feedlot operations through consumption and contamination of feed resulted in the development in 1959 of a pilot program between the Oregon State Department of Agriculture and the Bureau of Sport Fisheries and Wildlife designed to develop effective, safe and economical methods of starling control. This initial investigationa1 work which began in November 1959 and terminated for the season March 20, 1960 consisted of testing frightening devices and a floodlight trap in the holly orchards and tests with lethal bait and live traps around the feedlots. H. Nelson Elliott http://digitalcommons.unl.edu/vpc2/6 http://digitalcommons.unl.edu/vpc2/6 Wed, 26 Oct 2005 14:16:13 PDT Expensive, extensive and apparently lethal control measures have been applied against many species of pest vertebrates and invertebrates for decades. In spite of this, few pests have been annihilated, and in many cases the stated goals have become progressively more modest, so that now we speak of saving foliage or a crop, rather than extermination. It is of interest to examine the reasons why animals are so difficult to exterminate, because this matter, of course, has implications for the type of control policy we pursue in the future. Also, it has implications for the problem of evaluating comparatively various resource management strategies. There are many biological mechanisms which could, in principle, enhance the performance of an animal population after control measures have been applied against it. These are of four main types: genetic, physiological, populationa1, and environmental. We are all familiar with the fact that in applying a control measure, we are, from the pest's point of view, applying intense selection pressure in favor of those individuals that may be preadapted to withstand the type of control being used. The well-known book by Brown (1958) documents, for invertebrates, a tremendous number of such cases. Presumably, vertebrates can show the same responses. Not quite so familiar is the evidence that sub-lethal doses of a lethal chemical may have a physiologically stimulating effect on population performance of the few individuals that happen to survive (Kuenen, 1958). With further research, we may find that this phenomenon occurs throughout the animal kingdom. Still less widely recognized is the fact that pest control elicits a populational homeostatic mechanism, as well as genetic and physiological homeostatic mechanisms. Many ecologists, such as Odum and Allee (1950, Slobodkin (1955), Klomp (1962) and the present author (1961, 1963) have pointed out that the curve for generation survival, or the curve for trend index as a function of last generations density is of great importance in population dynamics. Kenneth E. F. Watt http://digitalcommons.unl.edu/vpc2/5 http://digitalcommons.unl.edu/vpc2/5 Wed, 26 Oct 2005 14:14:34 PDT The National Pest Control Association, which I represent, accepts for membership those persons or firms which are actively engaged in the performance of structural pest control services for hire to the public at large and which are in sympathy with the purposes of the Association. The pest control operator in this context might be called a commercial pest control operator to distinguish him from those doing similar work but who are employed by governmental agencies or within large commercial organizations. Pest control is a growing industry with a gross annual income of 300-350 million dollars. It is estimated to contain more than 5,000 firms employing about 25,000 productive workers. Many of these servicemen, possibly 15,000, are doing vertebrate pest control every day as they combat commensal rodents. A much smaller number, usually specialists or persons normally doing superŽvisory work, are also engaged in the control of pest birds and a variety of miscellaneous vertebrates. With approximately 15,000 servicemen making at least 10 contacts a day with the public, it is readily apparent that whatever opportunity the general public has to judge the success or failure of vertebrate pest control practice is largely influenced by the work of the pest control industry. Philip J. Spear http://digitalcommons.unl.edu/vpc2/4 http://digitalcommons.unl.edu/vpc2/4 Wed, 26 Oct 2005 14:11:55 PDT In the first paper presented to you today by Dr. Spencer, an expert in the Animal Biology field and an official authority at the same time, you heard about the requirements imposed on a chemical in order to pass the different official hurdles before it ever will be accepted as a proven tool in wildlife management. Many characteristics have to be known and highly sophisticated tests have to be run. In many instances the governmental agency maintains its own screening, testing or analytical programs according to standard procedures. It would be impossible, however, for economic and time reasons to work out all the data necessary for themselves. They, therefore, depend largely on the information furnished by the individual industry which naturally has to be established as conscientiously as possible. This, among other things, Dr. Spencer has made very clear; and this is also what makes quite a few headaches for the individual industry, but I am certainly not speaking only for myself in saying that Industry fully realizes this important role in developing materials for vertebrate control and the responsibilities lying in this. This type of work - better to say cooperative work with the official institutions - is, however, only one part and for the most of it, the smallest part of work which Industry pays to the development of compounds for pest control. It actually refers only to those very few compounds which are known to be effective. But how to get to know about their properties in the first place? How does Industry make the selection from the many thousands of compounds synthesized each year? This, by far, creates the biggest problems, at least from the scientific and technical standpoint. Let us rest here for a short while and think about the possible ways of screening and selecting effective compounds. Basically there are two different ways. One is the empirical way of screening as big a number of compounds as possible under the supposition that with the number of incidences the chances for a "hit" increase, too. You can also call this type of approach the statistical or the analytical one, the mass screening of new, mostly unknown candidate materials. This type of testing can only be performed by a producer of many new materials,that means by big industries. It requires a tremendous investment in personnel, time and equipment and is based on highly simplified but indicative test methods, the results of which would have to be reliable and representative for practical purposes. The other extreme is the intellectual way of theorizing effective chemical configurations. Defenders of this method claim to now or later be able to predict biological effectiveness on the basis of the chemical structure or certain groups in it. Certain pre-experience should be necessary, that means knowledge of the importance of certain molecular requirements, then the detection of new and effective complete molecules is a matter of coordination to be performed by smart people or computers. You can also call this method the synthetical or coordinative method. G. Hermann http://digitalcommons.unl.edu/vpc2/3 http://digitalcommons.unl.edu/vpc2/3 Wed, 26 Oct 2005 14:05:37 PDT The Federal Insecticide, Fungicide, and Rodenticide Act broadly encompasses, " any substance or mixture of substances intended for preŽ venting, destroying, repelling, or mitigating...." a pest. The act includes devices as well as chemicals used in the control of pests. It is the responsibility of the manufacturer to provide authoritative evidence of the efficacy and safety of his pesticide product. Within the scope of these four brief excerpts from the act there is much about which personnel engaged in research and development of vertebrate pest control products should be informed. As stated, the coverage of the act is very complete, omitting no form of mammal, bird, amphibian, reptile, or fish whether they be wild or domestic. The chemical or device used need not be lethal or injurious to the target species and thus includes toxic agents, irritants, repellents based on odor or taste, repellents based on mechanical action such as tacky or resistant films, anesthetizing chemicals, chemosterilants, fumigants, and energy wave lengths including sound, light, and super-sonic. Donald A. Spencer http://digitalcommons.unl.edu/vpc2/2 http://digitalcommons.unl.edu/vpc2/2 Wed, 26 Oct 2005 14:02:54 PDT The purpose of this Vertebrate Pest Control Conference are several. They are to: 1. Get acquainted with other persons in the field of vertebrate pest control ; 2. Learn the best and safest methods of vertebrate pest control; 3. Hear what is going on in the various fields of research; 4. Stimulate new research; 5. Improve communications between research workers and between research workers, pest control operators and industry developers of materials used in the field of vertebrate pest control; 6. Inform the public about the true role of vertebrate pest control and why it is sometimes necessary, and 7. Attempt to eliminate misunderstandings between those of us who are engaged in vertebrate pest control and the general public. James W. Koehler http://digitalcommons.unl.edu/vpc2/1 http://digitalcommons.unl.edu/vpc2/1 Wed, 26 Oct 2005 13:51:09 PDT PROCEEDINGS SECOND VERTEBRATE PEST CONTROL CONFERENCE Charter House Hotel Anaheim, California March 4 and 5, 1964 SPONSOR:California Vertebrate Pest Control Technical Committee GENERAL CHAIRMAN OF CONFERENCE: James W. Koehler, Chief, Weed and Vertebrate Pest Control, California Department of Agriculture, Sacramento, California PROGRAM AND PUBLICITY: Maynard W. Cummings, Chairman Extension Wildlife Management Specialist, University of California, Davis James W. Koehler, Chief, Weed and Vertebrate Pest Control, California Department of Agriculture, Sacramento, California Walter E. Howard, Associate Vertebrate Ecologist, Department of Animal Physiology, University of California, Davis, California Keith F. Murray, Senior Vector Control Specialist, Bureau of Vector Control, California Department of Public Health, Berkeley, California Richard H. Dana, Vertebrate Pest Control Specialist, California Department of Agriculture, Sacramento, California Charles C. Siebe, Vertebrate Pest Control Specialist, Weed and Vertebrate Pest Control, California Department of Agriculture, Sacramento, California Adolph Zajanc, Wildlife Research Biologist, Section of Control Methods Research, Fish and Wildlife Service, U.S.D.I., University of California, Davis, California S. T. Ancell, Agricultural Commissioner, Tehama County, and President, California County Agricultural Commissioners Association, Red Bluff, California Malcolm N. Allison, District Agent, Branch of Predator and Rodent Control, Fish and Wildlife Service, U.S.D.I., Sacramento, California