William L. Franklin

Biogeographic variation of food habits and body size of the America puma

SummaryThe 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 pumas 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).

Behavioral Ecology of Dispersal in the Black-Tailed Prairie Dog

An investigation of black-tailed prairie dogs ( Cynomys ludovicianus ) was conducted in Wind Cave National Park, South Dakota, between May 1979 and May 1982 to study factors affecting dispersal. Dispersing prairie dogs were radiotracked to determine distance of movements and survivorship, and a study colony was monitored intensively to determine proximate factors that caused dispersal. Exchange of individuals between coteries (family groups) within the study colony (intracolony dispersal) occurred throughout the year, whereas dispersal away from established colonies (intercolony dispersal) occurred only during a predictable period in late spring. Both males and females dispersed. Dispersing males were predominantly yearlings whereas dispersing females also included older individuals. Intercolony dispersers appeared to be in good physical condition, moved an average distance of 2.4 km from points of capture, and survivors immigrated into existing colonies; no new colonies were established by radiocollared animals. The mortality rate of intercolony dispersers was significantly greater than that among residents of the study colony. Prairie dogs select new vegetative growth at colony peripheries. Coterie density per ha of edge vegetation was inversely related to the exchange of individuals between coteries during the dispersal season. There was no relationship between absolute coterie density and change in animal numbers. Other factors promoting dispersal included shortage of unrelated females in the coterie, harassment of females by juveniles, and possible genetic influences.

Ecology of the Patagonia puma Felis concolor patagonica in southern Chile

The ecology of the Patagonia puma was studied in Torres del Paine National Park, Chile. Thirteen pumas were captured from 1986 to 1989 and equipped with radio transmitters. During the winter of 1988 there was one puma per 17 km 2 in the 200 km 2 study area. Home ranges varied from 24 to 107 km 2 . Female home ranges overlapped with those of other males and females extensively, but male ranges overlapped each other for only short time periods. Seven adult pumas had home ranges extending outside the park boundaries and at least three preyed on sheep. Guanacos Lama guanicoe, especially young animals, were the puma’s most important prey item by biomass, but European hares Lepus capensis were preyed upon more than expected relative to available biomass. Of 731 guanaco skulls collected from 1979 to 1988, 33% showed clear evidence of having been killed by pumas. Over the past decade puma numbers are believed to have increased in the park, perhaps in response to an increase in guanaco numbers and continued protection. With decreased hunting pressure and harassment by horses and dogs, pumas have habituated to people and are being observed more often by park visitors. # 1999 Elsevier Science Ltd. All rights reserved.

Demographic Differences Between an Old and a New Colony of Black-tailed Prairie Dogs (Cynomys ludovicianus)

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.

Spatial distribution of guanaco mating sites in southern Chile: conservation implications

We investigated the distribution, habitat characteristics and conservation value of mating areas in a wild population of guanacos in Torres del Paine National Park, Chile. Copulating guanacos were observed directly during December–January 1994–1995, 1995–1996 and 1997–1998. The timing of the breeding season was homogeneous across years. Copulation sites occurred in vega (ephemeral wetland) habitats (48.6%) greater than expected based on their relative availability (12.6%). A multivariate habitat analysis revealed that habitat composition of breeding habitats differed significantly from non-breeding areas (P < 0.001). Availability of trees and shrubs (breeding=5.5%; non-breeding=35.6%; P < 0.001) and grassland (breeding=34.6%; non-breeding =9.5%; P < 0.001) contributed most to the variation in habitat types among areas. Relative occurrence of pumas was significantly lower in breeding areas (P=0.04). The spatial arrangement of mating sites was similar among years suggesting that adult female and male guanacos exhibited site fidelity to breeding sites. Since vegas were important habitats for mating it is critical that natural resource managers consider the importance of these ephemeral wetland resources to ensure for proper reproduction and viability of local guanaco populations. # 2002 Elsevier Science Ltd. All rights reserved.

Forced dispersal of juvenile guanacos (Lama guanicoe): causes, variation, and fates of individuals dispersing at different times

We examined adult-juvenile conflict in the guanaco (Lama guanicoe). During spring, territorial males become increasingly aggressive toward all juveniles born the previous year and begin expelling them from family groups. In an apparent effort to reduce aggression, juveniles display submissive crouches when being observed, approached, or attacked by the territorial male. Therefore, we assessed the influence of juvenile submissive behavior on the timing of dispersal and also examined if dispersal time was related to survival and reproductive performance as adults. We also evaluated hypotheses regarding the evolution of juvenile mammalian dispersal in the context of if and how each may favor the forced dispersal of juvenile guanacos by territorial males. Juveniles generally dispersed in late spring and early summer, and a nearly equal proportion of females (n=46; 48%) and males (n=49; 52%) dispersed. More-submissive animals generally dispersed later than less-submissive animals. Juvenile sex and dispersal time were not related to survival. In contrast, juvenile sex and dispersal time were related to reproductive performance. The probability of reproducing was highest when juveniles dispersed early and decreased with increasing time in family groups prior to dispersal. The largest proportion of juveniles was forced to disperse during a 2-week interval following the peak of the breeding season. Competition for food resources is likely very intense at this juncture and territorial males may force older juveniles to disperse in order to divert food resources to younger neonates. Additionally, juveniles may be forced to disperse after territorial males mate their mothers to prevent lost mating opportunities, because females leave territories when their offspring disperse and possibly prior to mating with males. We conclude that the forced dispersal of juvenile guanacos by territorial males is ultimately driven by competition for food resources on territories. The timing of dispersal, however, may be tempered by the chronology of matings between territorial males and particular adult females, and/or genetic relatedness between territorial males and juveniles.

Predation of guanacos (Lama guanicoe) by southernmost mountain lions (Puma concolor) during a historically severe winter in Torres del Paine National Park, Chile

The effects of mountain lion Puma concolor predation on guanaco Lama guanicoe mortality was investigated during the historically severe winter of 1995 in Torres del Paine National Park, Chile. The 45 guanaco carcasses located represented 3% of the entire guanaco population of which 74% were mountain lion kills, 13% died from malnutrition, 2% died from fence entanglement and 11% died from unknown causes. Depleted bone marrow fat was observed in 20% of all carcasses. The number of guanaco deaths differed among sex and age classes, particularly in juveniles (< 1 year of age), which died more often than expected (P < 0.001). Fresh guanaco carcasses (n= 19) killed by mountain lions were located in tree and shrub habitats 79% of the time and were significantly greater than expected values based on the relative availability of these habitats (P < 0.001). Observations of the spatial distribution of mountain lion kills and guanaco mixed-sex groups were similar (P= 0.10), suggesting that mountain lions responded to winter migratory movements made by guanacos. Overall, adult guanacos experienced surprisingly lower levels of mortality (adult male = 1%, adult female = 2%) than expected, despite the severe winter conditions, while juveniles experienced higher levels of mortality (13%) than expected. In comparison to other years (1991–96), the severe winter of 1995 (i.e. this investigation) had the greatest total mortality for juveniles, although the proportion of deaths caused by mountain lion predation for juveniles was greatest during other winters.

rPatterns of mtDNA and microsatellite variation in an island and mainland population of guanacos in southern Chile

The archaeological record indicates that guanacos inhabited the Patagonia of Chile and Argentina about 13,600 years ago, but were unable to migrate further south owing to the presence of glacial and water barriers that covered much of southern South America including the island of Tierra del Fuego. As environmental and ecological conditions improved, guanacos, along with other large mammals including horses, colonized the area. As a result of continued world-wide glacial melting, ocean levels rose and Tierra del Fuego became isolated from the mainland approximately 8000 years ago. Although island populations generally exhibit lower levels of genetic variation than their counterpart mainland populations, it is difficult to predict how much less variation island populations will exhibit. An analysis of mitochondrial cytochrome b and ATPase-8 sequences and 15 nuclear microsatellite loci revealed that both populations retained appreciable genetic diversity. The island population, however, exhibited much less variation than the mainland population. Measures of genetic variation revealed modest, but significant genetic differentiation, consistent with separation of the two populations approximately 8000 years ago. The assessment of levels of genetic diversity and population differentiation among populations of the wild South American camelids is becoming increasingly important as interest mounts in their utilization as a renewable resource.

TERRITORIAL FIDELITY OF MALE GUANACOS IN THE PATAGONIA OF SOUTHERN CHILE

Abstract We investigated site fidelity of territorial male guanacos (Lama guanicoe) in Torres del Paine National Park, Chile. The study took place over a 10-year period, with intensive work in the final years, 1997–1999. Guanacos have a social system of resource-defense polygyny with fluid movement of females between male territories. After the annual winter migration, males establish and maintain their territories from mid-spring until late autumn. Territorial males are classified as solo or family-group territorial males. We collected data on type, location, size, and usage of territories for tagged, known-age males. We compared male territorial fidelity between mating (8 December–11 January) and nonmating periods within the 6-month territorial season each year (1 October–15 March) and between multiple years. Males used the same area within the 1997 and 1998 territorial seasons (n = 47). Most males (73%; n = 60) also returned to the same territory location from year to year. Males (27%) that shifted territorial locations showed no clear patterns in changes between solo territorial males and family-group territorial males. High predictability of male territory sites within a given year and between years has short- and long-term benefits for management and conservation efforts.

Activity and population characteristics of Andean Condors in southern Chile

Se recolectaron datos sobre los patrones generales de actividad y caractersticas de la poblacion del Condor Andino Vultur gryphus. El estudio se realizo en el Parque Nacional Torres del Paine, Chile, entre julio 1992 y junio de 1994, totalizando 3680 horas de observacion. Durante el estudio fueron evidentes diferencias estacionales en los patrones de actividad y abundancia relativa de estas aves. El numero promedio de condores por observacion durante el otono y el invierno fue significativamente diferente al promedio observado durante la primavera y el verano. Hubo una disminucion significativa desde la primavera - verano hacia el otono - invierno en el porcentaje de observaciones de condores solitarios y tambien hubo un aumento significativo en el numero de grupos de condores. El promedio mensual maximo del tamano de grupo fue significativamente mas alto en el otono - invierno que en la primavera - verano. La proporcion entre los sexos (machos:hembras ) en la poblacion juvenil favorecio significativamente a las hembras, mientras que en la poblacion adulta favorecio a los machos. Esta diferencia en la proporcion entre condores adultos y juveniles posiblemente esta relacionada con diferencias en la distribucion y el uso de habitat y/o bajas tasas de reproduccion. Diferencias en las tasas de mortalidad juvenil al igual que diferencias en las tasas de dispersion tambien pudieron contribuir a las diferencias en proporciones entre los sexos y las edades, pero se necesitan mas investigaciones al respecto. La actividad de los condores en el parque parecio ser dependiente de la fuerza del viento. Observamos mayores cantidades de condores durante dias con vientos de intensidades bajas y menos durante dias con vientos de intensidades altas. La temperatura ambiental tambien parecio influir en la actividad aerea de los condores ; fue mas comun observar a estas aves volar durante los dias con temperaturas mas calidas. Hubo una correlacion debil entre la intensidad del viento y la temperatura ambiental.