WILDLIFE MANAGEMENT AND ECOLOGICAL DYSBIOSIS: TOWARD STEWARDSHIP OF BIODIVERSITY AND ONE HEALTH: A NEW PARADIGM FOR NATURAL RESOURCE MANAGEMENT By Michael W. Fox BVetMed, PhD, DSc, MRCVS Abstract The fostering of high White-tailed deer densities as a revenue-generating form of wildlife farming by private land owners and various State wildlife management agencies has resulted in significant ecological dysbiosis and wildlife diseases. This practice, considered a cultural tradition by deer hunters, is coupled with decades of shooting, trapping and snaring small and large carnivores, some almost to the point of extinction. This has helped create an abundance of mice and other rodents as well as deer. Lead from hunters’ shot poisoning raptors that prey on small rodents, and ground-feeding birds that consume ticks being killed in large numbers by licensed small game hunters have helped create a perfect ecological storm for the proliferation of Lyme and other disease- transmitting ticks. A revision of wildlife and natural resource management practices is called for from the perspectives of optimizing biodiversity and public, animal and environmental health. This review is based on estimated animal numbers, alive and killed annually, documented by the Minnesota Department of Natural Resources to support the thesis that a new paradigm for wildlife management is urgently called for based on ecological science and health.
The One Health concept that human, animal and ecosystem health are interconnected, adopted by the American Medical Association, American Veterinary Medical Association and other health organizations (1) (www.onehealthinitiative.com and www.onehealthcommission.org ) is becoming a significant movement since its acceptance as a resolution by the National League of Cities (2) (www.nci.org/influence-federalpopicy/resources) and by the Centers for Disease Control and Prevention (3) ( https://www.cdc.gov/onehealth/index.html ) An illustrative review presented below applies this One Health concept to a public health issue in Minnesota that is relevant to all states and countries where Borreliosis (Lyme disease) and other insect-transmitted and animal-harboring diseases are an increasing public health concern (4). This animal and public health issue is connected to human activities variously condoned and legally protected by local and state authorities, the Department of Natural Resources in particular. Ecosystem manipulations that increase deer numbers, coupled with the selective harvesting of other species that control Lyme disease by consuming ticks and rodents, are of particular concern.
Lyme and other tick-borne diseases on the rise in Minnesota (more than 1,200 cases per year) and in other states. According to the Minnesota Conservation Volunteer (5), published by the Minnesota Department of Natural Resources ( MN DNR)“Multiple factors have caused the increase, ( in Lyme disease) including warmer winters, that allow ticks to stay out longer; habitat changes that allow ticks to flourish, and an increase of host populations, such as deer and mice..” As this review documents, this increase in host populations is, in part, anthropogenic due to current wildlife management practices. It is also notable that more cases of Lyme disease in dogs are being diagnosed by veterinarians in Minnesota (6). The Blacklegged or Deer tick feeds primarily on small rodents during its larval stages of development, moving to larger species, notably deer, as reproducing adults. In contrast the winter tick Dermacentor albipictus spends all stages on its primary host, deer and moose, often causing severe anemia and endangering the latter species in Minnesota.
Annual “Harvests” of Carnivores and Other Species
From available postings provided by the MN DNR ( 7) the following numbers of carnivores were trapped or snared in Minnesota during the 2015-2016 season: 657 Bob cat, ( 109 also shot ), 756 Fisher,877 Pine marten, 7,746 Mink, 1,083 Short-tailed weasels, 734 Long-tailed weasels, 4,061 Red fox, 1,161 Grey fox, 10,084 Coyotes. These estimates may be low since not all trappers respond to voluntary mail surveys and non-target animals, including Wolves and Lynx, caught in traps and snares are rarely reported.
The “Small Game” hunter harvest of carnivores for 2015-2016 was 3,780 Red fox, 816 Gray fox and 35,123 Coyotes (8). There is no bag limit on Red and Grey fox. There is no closed season, bag limit or license needed to hunt Coyotes and Weasels that also kill small rodents. An incalculable number of Coyotes are killed by hunters and not reported since there is an open season on them and no license is required to shoot them, and in some counties there are bounties and killing contests.
The consequences of “harvesting” all these carnivores, the total killed that were recorded in the 2015-2016 being some 71,599 animals, even if the take is ostensibly “sustainable,” it nevertheless must significantly reduce biodiversity and related predator control of small rodent populations. This is one anthropogenic aspect of the rising incidence of Lyme and other tick-borne diseases. Significantly, the number of licenses given out to trappers has risen from 925 in 1982-83 to 9,540 for the 2014-2015 season which parallels the rise in Lyme disease diagnosed in-state. Gophers, Porcupines and Striped skunks that compete with rodents for food, as do Raccoons, Opossums. Prairie dogs and Badgers are also hunted. Some 29,963 Raccoons, 6,349 Striped skunks,1,814 Opossums, 376 Badgers were trapped during the 2015-2016 season. No license is needed to kill Woodchucks and Crows any time of year. In this same 2015-2016 season hunters shot 149 Badgers, 38,387 Raccoons,742 White-tailed jack rabbits, 41,716 Eastern cotton tail rabbits, 6,374 Snowshoe hare, 46,383 Fox Squirrels and 96,400 and Gray squirrels—all controllers of mice and other smaller rodent species in part through food-resource competition. All these carnivores, omnivores, insectivores and carrion-eaters, along with various raptors and snakes, consume or compete with mice and other small rodents and help control the rodent population, including White-footed and other mice, shrews, voles and chipmunks, that is the main reservoir for tick-borne diseases like Lyme, as well as babesiosis, anaplasmosis and other diseases. In one field study it was reported that “the strongest predictors of a current year’s risk of Lyme disease were the prior year’s abundance of mice and chipmunks and abundance of acorns 2 years previously. In no case did inclusion of deer or climate variables improve the predictive power of models based on rodents, acorns, or both” (9) Government predator control agents exterminate “troublesome” coyotes and also trap and kill 150-200 “problem” wolves annually. Wolves have been caught in snares set to capture Coyotes, Bobcats and Foxes. (10). These predator species are the main deer population control agents in healthy, well-managed ecosystems, along with Bobcats and Black bear. Hunters killed 4,612 Black bear 2015-2016. The Minnesota Pollution Control Agency estimated that 2,610,720 pounds (1,184 metric tons) of lead shot were used annually in Minnesota in hunting and shooting ranges (11).This accumulating poison gets into the food chain, paralleling the accumulation of mercury from the state’s coal- fired power plants which contaminate fish in the great lakes, children and other consumers. Lead has been found in Woodcock, and may be an issue in other ground-feeding, insect-consuming birds that may or may not play a significant role in controlling ticks, notably pheasants, grouse, turkeys, partridge and crows. But many ground-feeding bird species certainly help indirectly suppress rodent numbers through food-competition. Permitting hundreds of thousands of these birds to be killed annually by state licensed small game hunters may be imprudent from an environmental and public health perspective. (11,854 Turkeys, 171,883 Ring-neck pheasants and 285,180 Ruffed grouse were shot in the Spring 2017 season.). White-tailed Deer A large White-tailed deer population, estimated at approximately one million, supports an annual, seasonal harvest generating $725 million economic value according to the MN DNR, some 184,963 deer being taken by hunters in 2018..The MN DNR has set an annual take of 200,000 deer, but fear of possible human infection with the prion causing Chronic Wasting disease in deer across the State may mean fewer hunters in the future and problems of biosecurity in the disposal of diseased deer, elk and moose. White tailed deer carry a parasite that is a factor in the decline of moose and caribou. The Brain worm Parelaphostrongylus tenuis is a nematode that naturally parasitizes white-tailed deer and several species of gastropods (snails and slugs) throughout central and eastern North America. White-tailed deer are the natural hosts of adult P. tenuis and survive infection with few ill effects. Moose however, are incidental hosts of the adult worms and infection can lead to death. Minnesota’s forest land area is currently estimated at 16.2 million acres or roughly 32 percent of the land area of the State. The pre-settlement area of forest land was estimated to be 31.5 million acres. White-tailed deer have a negative impact on conifer and oak forests, limiting regeneration by consuming saplings. (12). Several studies have shown that abundance and distribution of deer ticks are correlated with deer densities.(13, 14) When the deer population was reduced by 74% at a 248-acre (100 ha) study site in Connecticut the number of nymphal ticks collected at the site decreased by 92%..The relationship between deer and tick abundance, and human cases of Lyme disease was documented in the Mumford Cove Community in Groton, CT, from 1996 to 2004. The deer population in Mumford Cove was reduced from about 77 deer per square mile to about 10 deer per square mile (4 deer per square kilometer) after 2 years of controlled hunting. After the initial reduction the deer population was maintained at low levels. Reducing deer densities to 10 deer per square mile (4 deer per square kilometer) reduced the risk of humans contracting Lyme disease in by more than 90% (15). But reducing the deer population in small areas may lead to higher tick densities resulting in more tick-borne infections in rodents leading to a high prevalence of tick-borne encephalitis and creating a tick “hot-spot.” (16). This finding confirms the importance of DNR wildlife management practices encouraging thriving populations of smaller carnivore species to help control rodent numbers, especially as a ‘buffer’ when there is over-harvesting of deer in some hunting zones and seasons. Diseases and Ecological Dysbiosis Urbanization and other anthropogenic factors can be implicated in the spread of the Lyme disease organism ( Borellia burgdorferi sensu lato) to humans (17). Human interferences and practices that do not foster optimal biological diversity in ecosystems, (such as the rattle snake roundups in the South West), cause rodent population imbalances. These are associated with increased incidence of various zoonotic (animal-to human) diseases such as documented outbreaks of Sylvatic plague and Hanta virus in the U.S. southwest. Rodent populations can also harbor leptospirosis and tularemia, carry other tick-borne diseases such as Tick paralysis, Rocky mountain spotted fever, Colorado tick fever, and Ehrlichiosis, and be the reservoirs for mosquito transmitted St. Louis, La Crosse and California encephalitis viruses, Eastern and Western equine encephalitis and West Nile fever. Midges, controlled in part by insectivorous birds and bats, can proliferate in their absence and decimate deer herds with epizootic hemorrhagic disease which can also infect cattle. Municipal, agricultural and wildlife/natural resource management activities that disrupt terrestrial and aquatic ecosystems and consequentially reduce indigenous populations of insectivorous birds, bats and other vertebrates and invertebrate species that variously help control tick and mosquito numbers give an anthropogenic edge to the emergence of zoonotic diseases. The widespread broadcasting of pellets containing Bacillus thuringiensis to control mosquito larvae removes a food-source for other insectivorous aquatic and terrestrial species is illustrative of the biodiversity-damaging consequences of many current wildlife, environmental and public health management policies and practices that are integrated neither ecologically nor economically.
Notable are two studies that underscore the Lyme-disease promoting consequences of human depredation on carnivores that indirectly control this disease be reducing rodent numbers and which should lead to tighter restrictions and prohibitions of them being hunted, trapped, snared and poisoned. (!8, 19). Rewilding, where changes in management of public and private lands allow the recovery of biodiversity and ecological complexity would do much to improve environmental, animal and public health. But world-wide, human encroachment and the monocultures of industrial agriculture, agroforestry, plantations and livestock ranching are responsible for biodiversity loss and habitat change. (20). Compounded by widespread pesticide use and other lethal methods of pest and predator control wildlands are encroached and converted into biological deserts and bio-industrial wastelands. Rewilding, analogous in many ways to the organic, eco-farming practices of optimizing sustainable biodiversity, fallowing the land to improve soil quality (microbiome diversity) and productivity, calls for no hunting or trapping for one or more years in designated areas. Monitoring and culling of White-tailed deer in some areas may be needed to prevent environmental damage and spread of Chronic wasting and other diseases until population control by non-human predators is established and enduring. Private land owners should have conservation-status compensation for participation in captive and wild White-tailed deer population reduction. In other states this would apply to other over-stocked and managed game species, notably Elk, also now afflicted with Chronic wasting disease. The science-based ecological and ethical management/stewardship of natural resources and wildlife is in accord with the One Health concept. Since healthy ecosystems with optimal biodiversity interface with public and animal health, all state, federal and private business activities that adversely impact the functional integrity of the natural environment need to be called to question from the perspective of One Health. The control and prevention of endemic zoonotic diseases and new emerging diseases that threaten both the human and domestic animal populations call for an inter-agency and inter-disciplinary approach with public involvement (21, 22), the effectiveness of which would be enhanced by a shared vision of the One Health concept (23). One illustration of vested interests in protecting certain species for hunters by eliminating perceived competitors is South Dakota’s April 2019 giving $10 to trappers for every raccoon, striped skunk, badger, opossum or red fox they kill because these predators raid the nests of waterfowl and upland game birds (24). For similar reasons hunters of large game ( deer and elk) have joined with livestock keepers and trappers for decades to eliminate wolves and cougars. Conclusions The One Health vision shared by the veterinary and medical professions and allied specialists in epidemiology, conservation biology and other sciences calls for a diplomatic and ultimately collaborative engagement with other stake holders and responsible parties including: state and federal regulatory agencies, politicians, legislators, the business community, farmers and hunters, non-profit conservation and animal protection organizations. A civil society initiative to examine how natural resource and wildlife management practices can help play a critical role in the reduction and prevention of zoonotic diseases such as Babesiosis and Borreliosis (Lyme disease), along with improved protection of predator species, is long overdue. Rewilding golf courses, parkways and corporate and private lawns would mean improved air and water quality and less chemical and noise pollution in our communities and also help save bees and other pollinators. Replenishing and purifying our lakes, rivers and drinking water, water security and quality being a critical concern in many communities around the world, calls for an ecological and ethical revolution in agriculture. Nitrates and pesticides in community drinking water from corn production to feed pigs, along with antibiotics to boost growth and profits that contribute to the antibiotic resistant bacteria infecting humans, are unacceptable. The rising global demand for meat is non-sustainable. The loss of an estimated 1,200 square miles of land set aside under the Conservation Reserve Program in Minnesota by farmers raising GMO corn and soy to feed farmed animals at home and abroad is part of a much bigger issue than loss of pheasant and other upland game for hunters. (Star Tribune, Oct 13⁄19). This loss of biodiversity and the global demand for meat are recognized as major contributing factors to the Climate Crisis. This means that our appetites as well as farming practices must change. But this is unlikely without a full cost accounting of the “externalities” or hidden costs and a carbon tax be applied to all consumables and industries, especially high-input commodity crop farming with its over-reliance on fossil fuels. These times of environmental and economic concern could be the turning point in American agriculture to adopt more sustainable practices such as the development and planting of more perennial grains to feed ourselves and restoration of grasslands and wetlands to better accommodate the rains and purify our drinking water now contaminated by agrichemicals. Such initiatives would put the U.S. first in the Americas to rectify agriculture’s contribution to climate change and polluted rivers. This agricultural and socio-economic revolution should be in concert with state wildlife, animal health and natural resource management authorities under the banner of One Earth, One Health. As utopian as this paradigm may seem as corrective for dystopian times, it is based on science, reason and concern for the suffering of billions of animals, wild and domesticated, we need not cause; and also to ourselves. END NOTE: Wildlife management practices protecting and restoring biodiversity—indigenous plant and animal species and microorganisms—is essential for the health of aquatic and terrestrial ecosystems (which are models of how our industrial economy should function sustainably). This will help secure life-giving and health-sustaining “ecological services” including air and water purification, flood and drought control, nutrient cycling, pollination of crops and wild plants plus control of invasive pests and diseases.
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