Hare Research Articles

Spontaneous Papillomatosis in Domestic Rabbits

Infectious papillomatosis is an enzootic virus disease of wild cottontail (Sylvilagus) rabbits. What is believed to be the first naturally occuring infection of domestic rabbits is reported, and enzootic infection of the California cottontail rabbit with this virus is suggested. Rabbit papillomatosis is an enzootic disease of cottontail rabbits (Shope, 1933). Geographically, the disease is found in the wild rabbits of Kansas, Iowa, Oklahoma, and Texas. The domestic rabbit and the jack rabbit (Lepus californieus) are also susceptible to this disease (Beard and Rous, 1935). While the virus can be obtained easily from the growths on cottontail rabbits, it is usually not recoverable from papillomas on domestic rabbits. Domestic rabbits are easily infected with the wild cottontail rabbit virus (WRV), but successive passages are usually not successful (Selbie and Robinson, 1947; Shope, 1935). The purpose of this report is to describe cases of naturally-occurring papillomatosis in domestic rabbits raised in Sout...

Effect of thermal conductance on water economy in the antelope jack rabbit, Lepus alleni.

AbstractThe heat and water balance of the antelope jack rabbit, Lepus alleni, was studied at various ambient temperatures. At high ambient temperature the animal primarily depends on evaporation for dissipation of the heat load. The use of water was, however, less than could be expected if only body size is considered.It was shown that, when the ambient temperature is below body temperature, there is a two‐ to three‐fold increase in the conductance of the animal as ambient approaches body temperature. This facilitates dry heat loss and contributes to water economy. At ambient temperatures above body temperature the direction of heat flow is reversed, now being from the environment to the body. In this situation the heat flow inwards is impeded by a decrease in conductance to minimal values, thus achieving a considerable saving in the use of water for evaporation.

Food Habits of Black-Tailed Jack Rabbits in Southern Nevada

Forage plants of black-tailed jack rabbits ( Lepus californicus deserticola Mearns) at Jackass Flat in southern Nevada were studied by microscopic analysis of stomach contents. It was determined that from spring through early summer the major forage plants are grasses, Oryzopsis, Stipa, Bromus (not native) and annuals. During the period of late summer through winter, the woody perennials, chiefly Larrea, Coleogyne, Krameria and Eurotia are eaten.

Hare's prescriptivism

Hare's prescriptivism

Hare's Prescriptivism

Hare's Prescriptivism

Occurrence of Black-Tailed Jack Rabbits in Florida

Occurrence of Black-Tailed Jack Rabbits in Florida

Tularemia in the Wildlife and Livestock of the Great Salt Lake Desert Region, 1951 through 1964

Summary The incidence of Pasteurella tularensis in wild animals and their ectoparasites from selected areas of the Great Salt Lake Desert region was determined by using bacteriological and serological techniques. Approximately 31,300 mammals, 1,700 birds, and 141,000 ectoparasites were examined from 1951 through 1964. The sera from 5,047 head of livestock of the region also were tested. Fifty-two isolates of P. tularensis were obtained, 26 from ectoparasites and 26 from animal tissues. The positive ectoparasites included three species of ticks (Dermacentor parumapertus, Dermacentor andersoni, and Ixodes kingi), a flea (Thrassis bacchi), and an anopluran louse (probably Hoplopleura hesperomydis). The tissue isolates were from black-tailed jack rabbits (Lepus californicus), an Audubon (desert) cottontail (Sylvilagus audubonii), a Great Basin pocket mouse (Perognathus parvus), Ord kangaroo rats (Dipodomys ordii), white-tailed antelope squirrels (Citellus leucurus), and beaver (Castor canadensis). Serum agglutinins at titers of 1:20 to 1:320 were found in 92 specimens of 25 species of wild mammals and birds; 31% of the cattle and 24% of the sheep had serum agglutinin titers of 1:40 or greater. Eight mammalian and seven avian species were implicated within the natural ecology of tularemia for the first time: the Western spotted skunk (Spilogale gracilis), the Western harvest mouse (Reithrodontomys megalotis), the pinyon mouse (Peromyscus truei), the Great Basin pocket mouse, the chisel-toothed kangaroo rat (Dipodomys microps), the white-tailed antelope squirrel, the cliff chipmunk (Eutamias dorsalis), the bobcat (Lynx rufus), the shrike (Lanius ludovicianus), the horned lark (Eremophila alpestris), the common mallard (Anas platyrhynchos), the California gull (Larus californicus), the prairie falcon (Falco mexicanus), the red-tailed hawk (Buteo jamaicensis), and the Great Basin screech owl (Otus asio). Four of the isolates of P. tularensis from rodents were found to be of maximal virulence (i.e., one organism was fatal for standard laboratory animals excluding the white rat), while one isolate from a desert cottontail and one from a Great Basin pocket mouse were found to be of low virulence. The latter findings are exceptions to the commonly accepted generalization that strains from North American ticks, lagomorphs, and sheep are of high virulence and those from beaver, rodents, and water are of low virulence. While the generally accepted concept is usually justified, this distinction does not exist invariably.

DIFFERENCES IN HEPATIC DRUG METABOLISM IN VARIOUS RABBIT STRAINS BEFORE AND AFTER PRETREATMENT WITH PHENOBARBITAL.

SummaryThe results of these experiments indicate that basal levels of activity of hepatic microsomal drug metabolizing enzyme systems from various rabbit strains can vary as much as 20-fold in the strains studied. This is particularly true of hexobarbital, amphetamine, and aminopyrine metabolism where the widest variations were observed. Relatively little strain variation was seen in the basal metabolism of chlorpromazine. The wild rabbits and California rabbits exhibited the greatest differences from other rabbit strains in basal hepatic drug metabolism.A wide range of variability was also observed in the response of hepatic drug metabolizing enzyme systems to in vivo pre-treatment with phenobarbital. Especially noteworthy were the 26-fold increase in hexobarbital metabolism seen with the hepatic enzyme systems of Cottontails, the 7.5-fold increase in metabolism of p-nitrobenzoic acid in Jack rabbits, and the significant increases in 3,4-benzpyrene metabolism observed only in the wild rabbits. Also inter...

Growth and Development of Black-Tailed Jack Rabbits

Growth and Development of Black-Tailed Jack Rabbits

R M Hare

R M Hare

Aesthetics and Hare's Analysis of `Good'

Aesthetics and Hare's Analysis of `Good'

Food Utilization of Snowshoe Hares on Manitoulin Island, Ontario

Food Utilization of Snowshoe Hares on Manitoulin Island, Ontario

"Freedom and Reason," by R. M. Hare

"Freedom and Reason," by R. M. Hare

Range Changes of Mammals in the Great Lakes Region

Range changes of mammals in the Great Lakes region (Minnesota, Michigan, Wisconsin, and those parts of Ontario, Ohio, Pennsylvania and New York bordering on the Great Lakes) are described, based on a review of the literature and recent data obtained by the author. Although the Great Lakes and their interconnecting rivers are a marked geographical barrier to the spread of mammals, many changes have taken place in the distribution and abundance of mammals since the last glacial period. These changes are influenced by human activities, climatic changes, and changes in biotic communities. Among these factors, the first one has been most influential. The elk (Cervus canadensis), the bison (Bison bison) and the wolverine (Gulo luscus) have become extinct since the arrival of white man. The cougar (Felis concolor) probably also disappeared, but may have reinvaded the region. Range restrictions have been recorded for the woodland caribou (Rangifer tarandus), Canada lynx (Lynx canadensis), bobcat (Lynx rufus), gray wolf (Canis lupus), black bear (Ursus americanus), marten (Martes americana), fisher (Martes pennanti), and snowshoe hare (Lepus americanus). The latter three species are reinvading formerly occupied ranges during recent years. Range extensions include the majority of species which have exhibited range changes. A distinct northward spread has been recorded for the moose (Alces americana), white-tailed deer (Odocoileus virginianus), opossum (Didelphis marsupialis), eastern cottontail (Sylvilagus floridanus), bobcat (Lynx rufus), raccoon (Procyon lotor), coyote (Canis latrans), gray fox (Urocyon cinereoargenteus), gray squirrel (Sciurus carolinensis), and fox squirrel (Sciurus niger). An eastward spread has been observed for the thirteen-lined ground squirrel (Citellus tridecemlineatus), Franklin ground squirrel (Citellus franklinii) and white-tailed jack rabbit (Lepus townsendii). The smoky shrew (Sorex fumeus) and the yellow-nosed vole (Microtus chrotorrhinus) have apparently displayed a westward spread.

RADIOIODINE UPTAKE IN NATIVE ANIMALS AT THE NRTS AND ENVIRONS.

Abstract—The National Reactor Testing Station has a fair ground cover of sagebrush, rabbit brush, and perennial grass, and a good population of native animals which are utilized in the environmental monitoring program. Research and biological monitoring are conducted in those situations where small amounts of radioiodine are released into the environment through routine operations and special reactor tests. Various species of native animals were analyzed for I131 uptake while living in their native habitat and under laboratory conditions. In each case the uptake and the biological effective half-life of I131 in the thyroid was determined with the following results: Table 1 . Species Per cent uptake at day one Effective half-life (days) Jack rabbit 29 2 Chipmunk 80 6 1/2 Kangaroo rat 80 7 Year-to-year comparisons were made of stack releases of I131 from the chemical fuel-processing plants and the amount of I131 found in the animals at different downwind distances. The quantity of radioiodine found in the animal thyroid has proven to be an extremely sensitive indicator of area contamination not only from local sources but also from nuclear weapons testing.

The hare and the tortoise: A study of the tau-effect in walking and running

The hare and the tortoise: A study of the tau-effect in walking and running

Adrenal Gland Responses in a Black-Tailed Jack Rabbit Population

Adrenal Gland Responses in a Black-Tailed Jack Rabbit Population

Periodicity of Reingestion in the Cottontail

Sylvilagus floridanus (203 individuals) was collected throughout a year. Reingestion occurred as a well-synchronized diel rhythm, coinciding with the inactive period following sunrise. During summer the reingestion period was shorter than in winter. Through a series of experiments Morot (1882) demonstrated that domestic rabbits produced two types of fecal pellets: a hard, rounded, fibrous type found wherever rabbits are common, and a smaller, softer, heavily mucous coated pellet seen only when the rabbit's stomach contents are exposed (Fig. 1). Rabbits normally take the soft pellets directly from the anus and swallow them without mastication. This type of coprophagy has been ternmed reingestion (Watson, 1954). General observations concerning reingestion in native American leporids include those of Bookout (1959) who noted fecal pellets in the stomach of a snowshoe hare (Lepus americanus) and Hamilton (1955) who found fecal pellets in the stomach of a marsh rabbit (Sylvilagus palustris), but failed to find them in the cottontail (Sylvilagus floridanus). Kirkpatrick (1955) was the first to observe a cottontail in the act of consuming pellets. Geis (1957) and Dexter (1959) reported finding fecal balls in the stomachs of cottontails. Reingestion was reported in the swamp rabbit (Sylvilagus aquaticus) by Layne (1958) and confirmed by Toll, et. al. (1960). The latter investigators also found reingestion in some cottontails. They suggested that reingestion occurred in the daytime during the resting period, and was discontinued at night during feeding. There is a great paucity of information concerning the rhythm of reingestion in American lagomorphs. The only extensive study is that of Lechleitner (1957), who noted the daily reingestion pattern of the blacktailed jack rabbit (Le pus c. californicus) in California. Virtually nothing has been published about the reingestion pattern of the cottontail. The purpose of this study was to ascertain whether there is a definite daily rhythm in cottontail reingestion; to observe individual variation in periodicity; to discern whether there is a relationship between activity and the reingestion pattern; and to discover any relationship between photoperiod and reingestion rhythm. 1 Contribution from the Missouri Cooperative Wildlife Research Unit: U. S. Fish and Wildlife Service, Wildlife Management Institute, Missouri Conservation Commission, Edward K. Love Foundation, and University of Missouri cooperating. The author acknowledges the help of William H. Elder, Rucker Professor of Zoology, University of Missouri, for direction and advice and Thomas S. Baskett, Biologist, U. S. Fish and Wildlife Service, for reading the manuscript.

Complement-Fixing Antibodies for R. Rickettsii in Serums of Black-Tailed Jack Rabbits

THE ETIOLOGICAL agent of Rocky Mountain spotted fever, Rickettsia rickettsii, is transmitted among mammals by ticks. The organism is present in numerous species of ticks including the rabbit tick Haemaphysalis leporis-palustris which is widely distributed throughout the United States (1). Antibodies for R. rickettsii may be found in rabbits infested with Dermacentor andersoni, D. variabilis, D. parumapertus, Amrblyomma amermcanum, and perhaps other species of ticks (personal communication from Dr. David B. Lackman). Although the spread of this infection from hares to man is improbable (1-), the presence of antibodies against R. rickettsii in the serums of hares is an indication that the organism is in the area. Infested hares could serve as a reservoir for the infection of additional ticks. Positive results for antibodies against R. rickettsii have been obtained by other investigators. Philip and associates (4) found complement-fixing antibodies for Rocky Mountain spotted fever in 35 of 260 serums of northern Nevada jack rabbits. Lechleitner (3) found specific complement-fixing antibodies for B. rickettsii in 10 of 142 serums tested. Stoenner and associates (5), studying the fauna of the Great Salt Lake Desert in Utah, showed that 193 of 773 jack rabbits possessed antibodies against R. riwkettsii. Since the black-tailed jack rabbit, Lepus californicus imelanotis, Mearns, is numerous near Lakin, Kans., serums of animals from that area were examined for complement-fixing antibodies against R. rickettsii.

Use of Forms by the Black-Tailed Jack Rabbit in Southwestern Kansas

Use of Forms by the Black-Tailed Jack Rabbit in Southwestern Kansas