The puma (Felis concolor) has the most extensive range of any terrestrial mammal in the Western Hemisphere, covering over 100° latitude. Food habits of different puma subspecies vary with latitude. Subspecies from temperate habitats generally eat larger prey and specialize on a smaller number of prey taxa, whereas, in tropical habitats, they prey on smaller, more varied prey. In North America, ungulates (primarily deer) represented 68% of the puma's diet by frequency of occurrence. Mean weight of vertebrate prey (MWVP) was positively correlated (r=0.875) with puma body weight and inversely correlated (r=-0.836) with food niche breadth in all America. In general, MWVP was lower in areas closer to the Equator. Patterns of puma prey selection are probably influenced by prey availability and vulnerability, habitat characteristics, and potential competition from the jaguar (Panthera onca).

No abstract

JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact support@jstor.org.

JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact support@jstor.org.. American Society of Mammalogists is collaborating with JSTOR to digitize, preserve and extend access to Journal of Mammalogy. (Cabrera, 1957;Ximenez, 1975). In 1980, this spotted cat became the most commonly traded felid species in the world (MacMahan, 1986) with more than 450,000 skins exported from 1976 to 1980 from Argentina alone (Fujita and Calvo, 1982). Despite its economic importance, almost nothing is known about the biology and ecology of the species, especially in its native South American habitat. In Chile, where Geoffroy's cat is classified as endangered, research on this species is considered to be a priority (Glade, 1988). The only published field study was the report of the home range of one subadult female in Paraguay based on 12 radiotelemetry relocations (Berrie, 1978). Geoffroy's cat (Felis geoffroyi) is distributed from southern Bolivia and the Parana Basin of southern Brazil to the southern tip of Patagonia in Chile and ArgentinaThe goal of our study was to obtain basic ecological information on Geoffroy's cat in the southern portion of its distribution. Specific objectives were to describe home-range sizes and distribution patterns, habitat use, activity patterns, and food habits of Geoffroy's cat.The study was conducted from 1986 through 1989 in the eastern part of Torres del Paine National Park (51*3'S, 72*55'W), an International Man and Biosphere Reserve located in the eastern foothills of the Andean mountain range in southern Chile. The park encompasses 2,400 km2 and provides almost undisturbed habitat for wildlife. The park has a high heterogeneity of plant associations and habitats from glacier-covered mountains to dense Nothofagus deciduous forest and grassland. Approximately 70% consists of a steppe biome, or pre-Andean, dry-shrub association, and the remainder is a mosaic of lakes, forests, and aridmountain alpine zones. The steppe is characteristic of the pampa of southern South America, found in Chile and Argentina at elevations <500 m (Pisano, 1973(Pisano, , 1974. The locally dominant species of this biome (or association) is mata barrosa (Mulinum spinosum), a spiny, dome-shaped shrub, common in thin, rocky upland, and rapidly draining soils and mata negra (Verbena tridens), a 1-to 1.5-m shrub covering large areas. Other common species are senecio (Senecio patagonicus), calafate (Berberis buxifolia), and paramela (Adesmia boronoides). The woodland areas are dominated by two medium-sized species of trees, fiirre (Nothofagus antarctica) and lenga (N. pumilio). The dominant grass species in the study area are Festuca gracillina, Anarthrophyllum patagonicum, and F. palliscens, in order of decreasing cover (Ortega and Franklin, 1988;Pisano, 1973Pisano...

The activity patterns, home-range use, and habitat utilization of sympatric South American grey fox (Dusicyon griseus) and culpeo fox (Dusicyon culpaeus) in eastern Torres del Paine National Park, Chile, were studied to determine how the two species were distributed. Both species were primarily nocturnal. Mean percent daily activity did not differ between species or among seasons, but the grey fox had a greater daily activity rate in summer and fall and the culpeo fox in winter and spring. Seasonal and annual home ranges of culpeo foxes were larger than those of grey foxes, but did not differ between sexes or among seasons. Home ranges of grey and culpeo foxes were interspersed in a mosaic-like arrangement and did not overlap. Grey foxes were located more often in upland shrub transition habitat and in areas of medium cover density. Culpeo foxes were found more often in thickets of trees and in areas of high cover density. Within their home range, matorral shrubland or Nothofagus thicket habitat was selected by all culpeo foxes and by 60% of grey foxes monitored. Interference competition by the culpeo fox may have been important in determining fox distribution.

JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact support@jstor.org.. American Society of Mammalogists is collaborating with JSTOR to digitize, preserve and extend access to Journal of Mammalogy.

Summary1. The Chilean National Forestry and Park Service is striving to implement a guanaco management programme of sustained-yield use. To achieve this, the rate, variation and causes of juvenile guanaco mortality must be understood thoroughly. Therefore, we monitored the survival of 409 radio-collared juvenile guanacos in Torres del Paine National Park, Chile, from 1991 to 1996. 2. The Kaplan±Meier product limit estimator of survival for staggered entry was calculated, and survival rates between juvenile males and females and among years were compared using the LIFETEST procedure in SAS. The Cox proportional hazards model was used to relate mortality rate to explanatory variables such as juvenile sex, birth weight, adult female aggression towards researchers during the capture and tagging of newborns, population density, and mean monthly winter snowfall. 3. Mean juvenile survival rate (S Ã ) was 0´38, but varied between 0´31 and 0´55. Survival rates between the sexes were not signi®cantly dierent, although male survival was lower than that of females. Mortality rate was highest during the ®rst 14 days after birth. Most deaths occurred between birth and 7 months of age. 4. The risk of mortality increased by almost 6% with every 1 cm increase in winter snowfall, whereas the risk of mortality decreased by almost 24% as adult female aggression increased towards researchers. 5. Current management objectives are aimed at the implementation of a rational harvest of guanacos on the Chilean side of the island of Tierra del Fuego. Our results provide improved and updated estimates of juvenile guanaco survival and will aid in the modelling of harvest rates of guanacos in southern Chile. Future proposed harvests from wild populations in southern Chile need to consider the rate and variation of this critical life-history parameter.

Two colonies of black-tailed prairie dogs (Cynomys ludovicianus) in Wind Cave National Park, South Dakota, were compared during 1979 and 1980 to investigate the effects of (1) the age of the population and (2) the availability of resources on specific demographic parameters. The younger colony was surrounded by, and expanding into, unused available habitat. The older colony had little available habitat for expansion. At the younger colony (1) there was a greater proportion of successful pregnancies; (2) the litters were larger; (3) the juveniles grew faster; (4) yearlings were more likely to reproduce; (5) survivorship of adults and juveniles was greater, and (6) the density was more than 2X that of the older colony. Individuals at the younger colony showed a distinct feeding preference for vegetation growing at the colony periphery. Because this peripheral vegetation had only recently been modified from surplus habitat, we hypothesize that surplus habitat available to the younger colony accounted for the observed demographic differences.