Geology topics
Milton Friend
Publications and source records attributed to Milton Friend.
Increased avian diseases with habitat change
Changes in disease patterns and trends reflect changing relationships between the affected species (host) and the causes of disease (agent). Host-agent interactions are closely linked to environmental factors that either enhance or reduce the potential for disease to occur. As a result, wildlife disease patterns and trends are, to a substantial extent, indicators of environmental quality and changing host-agent interactions within the environment being evaluated. The types, distribution, and frequency of diseases causing major avian die-offs have changed greatly during the 20th century. Too little is known to assess the changes of most avian diseases that result in chronic attrition rather than major die-offs, or about those that affect reproductive success, reduce body condition, or affect survival in other indirect ways. Nevertheless, the changing patterns and trends in highly visible avian diseases provide notice of problems needing attention. Information on the status of disease in wild birds was obtained from National Wildlife Health Center (NWHC) evaluations of the cause of death for more than 30,000 carcasses from across the United States during the past two decades, reports of avian mortality received from collaborators, the scientific literature, and NWHC field investigations of bird mortality. Comprehensive assessments of causes of wild bird mortality, magnitude of losses, and geographic distribution of specific diseases are not possible from these data, although we can identify general relationships for waterfowl and some other species.
Control of avian influenza: Philosophy and perspectives on behalf of migratory birds
Aquatic birds are considered the primary reservoir for influenza A viruses (Nettles et al., 1987). However, there is little concern about avian influenza among conservation agencies responsible for the welfare of those species. IN contrast, the poultry industry has great concern about avian influenza and view aquatic birds as a source for infection of poultry flocks. In some instances, differences in these perspectives created conflict between conservation agencies and the poultry industry. I speak on behalf of migratory birds, but philosophy and perspectives offered are intended to be helpful to the poultry industry in their efforts to combat avian influenza.
Introductory remarks: Disease ecology and the conservation of avian species
No abstract available.
Lead poisoning: The invisible disease
Lead poisoning is an intoxication resulting from absorption of hazardous levels of lead into body tissues. Lead pellets from shot shells, when ingested, are the most common source of lead poisoning in migratory birds. Other far less common sources include lead fishing sinkers, mine wastes, paint pigments, bullets, and other lead objects that are swallowed.
Avian cholera: a major new cause of waterfowl mortality
No abstract available.
Avian botulism: geographic expansion of a historic disease
Avian botulism is a paralytic, often fatal disease of birds resulting from ingestion of toxin produced by the bacterium Clostridium botulinum. Waterfowl die-offs from the botulism are usually caused by type C toxin; sporadic die-offs among fish-eating birds, such as common loons (Gavia immer) and gulls, have been caused by type E toxin.
Disease control operations
Individual disease outbreaks have killed many thousands of animals on numerous occasions. Tens of thousands of migratory birds have died in single die-offs with as many as 1,000 birds succumbing in 1 day. In mammals, individual disease outbreaks have killed hundreds to thousands of animals with, for example, hemorrhagic disease in white-tailed deer, distemper in raccoon, Errington's disease in muskrat, and sylvatic plague in wild rodents. The ability to successfully combat such explosive situations is highly dependent n the readiness of field personnel to deal with them. Because many disease agents can spread though wildlife populations very fast, advance preparation is essential in preventing infected animals from spreading disease to additional species and locations. Carefully though-out disease contingency plans should be developed as practical working documents for field personnel and updated as necessary. Such well-designed plans can prove invaluable in minimizing wildlife losses and costs associated with disease control activities. Although requirements for disease control operations vary and must be tailored to each situation, all disease contingency planning involved general concepts and basic biological information. This chapter, intended as a practical guide, identifies the major activities and needs of disease control operations, and relates them to disease contingency planning.
Avian botulism
What is avian botulism? Avian botulism, or Western duck sickness, is one of the three most important disease problems of wild migratory birds. Each year, many birds are paralyzed or die after exposure to a toxin produced by the botulinum bacterium. Two of the seven toxin types that have been identifies cause mortality in wild birds; one of these types, type C, is most often associated with dieoffs of ducks, while type E primarily affects gulls and loons.
Inhibition of mallard salt gland function by DDE and organophosphates
The effects of selected environmental pollutants on avian salt gland function were studied in the mallard duck, Anas pZatyrhynchos . DDE and several organophosphates were found to have an inhibitory effect on the ability of these glands to concentrate and secrete salt from the body. DDE significantly reduced secretion rates from the salt glands. More severe effects were observed following exposure to organophosphate insecticides; reduction in gland size, reduced ability of the birds to secrete Na+ via the salt glands, and reductions in cholinesterase activities in the salt gland and hypothalamus all contributed to elevated mortality levels in treatment birds over controls.