Melvin E. Sunquist

Jaguars, pumas, their prey base, and cattle ranching: ecological interpretations of a management problem

Jaguar and puma depredation on livestock may be influenced by (1) innate and learned behavior; (2) health and status of individual cats; (3) division of space and resources among jaguar and puma; (4) cattle husbandry practices; and (5) abundance and distribution of natural prey. Our study in Los Llanos of Venezuela aimed to establish how all these elements related to cattle being lost to cat depredation. Prey distribution was influenced by forest composition, topographical characteristics, and degree of habitat interspersion. The biomass of natural prey in the study area was adequate to support the resident large cats without a subsidy of livestock. Selective rather than opportunistic hunting by the cats reinforced that conclusion. Puma were responsible for more attacks on livestock than jaguar, frequently in maternity pastures in upland areas of relatively low prey availability. Management recommendations are discussed that may be relevant to other savanna/forest mosaics of South America.

Population structure, density and biomass of large herbivores in the tropical forests of Nagarahole, India

We studied the population structure, density and biomass of seven ungulate and two primate species in the tropical forests of Nagarahole, southern India, using line transect sampling and roadside/platform counts, during 1986–87. The estimated ecological densities of large herbivore species in the study area are: 4.2 muntjac km −2 , 50.6 chital km −2 , 5.5 sambar km −2 , 0.8 four-horned antelope km −2 , 9.6 gaur km −2 , 4.2 wild pig km −2 , 3.3 elephant km −2 , 23.8 hanuman langur km −2 and 0.6 bonnet macaque km −2 . Most ungulates have female-biased adult sex ratios. Among common ungulate species, yearlings and young of the year comprise about a third of the population, suggesting relatively high turn-over rates. Three species (muntjac, sambar and four-horned antelope) are solitary, while others form groups. The study area supports a wild herbivore biomass density of 14,744 kg km −2 . Among the three habitat types within the study area, biomass is lower in dry deciduous forests when compared with moist deciduous or teak plantation dominant forests. Using our results, we have examined the factors that may contribute towards maintenance of high ungulate biomass in tropical forests.

Foraging ecology of jaguar (Panthera onca) and puma (Puma concolor) in hunted and non‐hunted sites within the Maya Biosphere Reserve, Guatemala

Subsistence hunting and commercial exploitation directly influence wildlife populations in many regions of Central and South America. Where prey populations are exploited, the foraging ecology of top-level predators can be effected negatively. This study assessed the food habits and prey selection of jaguar Panthera onca and puma Puma concolor within hunted and non-hunted segments of the Maya Biosphere Reserve (MBR), Guatemala. Food habits were determined from analysis of 76 jaguar and 145 puma scats collected within hunted and non-hunted areas of the MBR from February 2000 to August 2001. Diets of jaguar and puma were compared (1) within species between areas with and without hunting to evaluate effects of subsistence hunting, and (2) between species to evaluate resource partitioning between these sympatric carnivores. Origin of predator scats was determined from mitochondrial DNA, diets were determined from prey remnants found within scats, and frequency of prey in scats was compared to expected values based on prey density estimates to test the hypothesis that diets of jaguar and puma were selective. Densities of major prey species were estimated using line-transect sampling. White-lipped peccary Tayassu pecari , collared peccary Tayassu tajacu and brocket deer Mazama sp. were less abundant, and coatis Nasua nasua more abundant, in the hunted area than in the non-hunted area. Jaguar and puma in both hunted and non-hunted sites obtained similar dietary contributions from large prey to their respective diets despite differences in the abundance of these prey species. Diets of jaguar and puma, as measured by percentage biomass occurrence of prey species, did not differ between hunted and non-hunted areas. Jaguar diets were dominated by medium-sized prey, particularly armadillos Dasypus novemcinctus and coatis, in both hunted and non-hunted areas. Medium-sized mammals also were prominent in puma diets, but large mammals constituted approximately 50% of prey biomass in both hunted and non-hunted areas. Deer Odocoileus virginianus and Mazama sp. and large rodents Agouti paca and Dasyprocta punctata were the most important prey of puma. Dietary overlap between jaguar and puma in both hunted and non-hunted areas was low.

The influence of landscape, patch, and within-patch factors on species presence and abundance: a review of focal patch studies

Understanding the influence of large and small-scale heterogeneity on species distribution and abundance is one of the major foci of landscape ecology research in fragmented environments. Although a large number of studies have addressed this issue individually, little effort has been made to synthesize the vast amount of literature published in the last decade. We reviewed 122 focal patch studies on 954 species published between 1998 and 2009 to determine the probability of species responding significantly to landscape, patch, and within-patch variables. We assessed the influence of taxonomic, life history, and methodological variables on probability of response to these 3 levels. Species in diverse taxa responded at high rates to factors at all three levels, suggesting that a multi-level approach is often necessary for understanding species response in patchy systems. Mammals responded at particularly high rates to landscape variables and therefore may benefit more than other taxa from landscape-level conservation efforts in fragmented environments. The probability of detecting a species response to landscape context, patch, and within-patch factors was influenced by a variety of methodological aspects of the studies such as type of landscape metric used, type of response variable, and sample size. Study design issues rarely are discussed by authors as reasons why a particular study did not find an effect of a variable, but should be given more consideration in future studies.

The relative influence of habitat loss and fragmentation: Do tropical mammals meet the temperate paradigm?

The relative influence of habitat loss vs. habitat fragmentation per se (the breaking apart of habitat) on species distribution and abundance is a topic of debate. Although some theoretical studies predict a strong negative effect of fragmentation, consensus from empirical studies is that habitat fragmentation has weak effects compared with habitat loss and that these effects are as likely to be positive as negative. However, few empirical investigations of this issue have been conducted on tropical or wide-ranging species that may be strongly influenced by changes in patch size and edge that occur with increasing fragmentation. We tested the relative influence of habitat loss and fragmentation by examining occupancy of forest patches by 20 mid- and large-sized Neotropical mammal species in a fragmented landscape of northern Guatemala. We related patch occupancy of mammals to measures of habitat loss and fragmentation and compared the influence of these two factors while controlling for patch-level variables. Species responded strongly to both fragmentation and loss, and response to fragmentation generally was negative. Our findings support previous assumptions that conservation of large mammals in the tropics will require conservation strategies that go beyond prevention of habitat loss to also consider forest cohesion or other aspects of landscape configuration.

Food habits and activity patterns of the Asiatic golden cat (Catopuma temminckii) and dhole (Cuon alpinus) in a primary rainforest of Peninsular Malaysia

12 2008 33 4737 Received 3.3.2007 ; a cepted 7.8.2008 Copyright

Ecology of small mammals in tropical forest habitats of southern India

Five species of rodent ( Rattus rattus wroughtoni, Mus platythrix, Funambulus tristriatus, Cremnomys blanfordi and Golunda ellioti ) were live-trapped over a period of eight months in three different habitat types (moist evergreen forest, moist deciduous forest and teak plantation) in Anaimalais Wildlife Sanctuary, Tamil Nadu, India. Small mammal densities ranged between 16.3 individuals ha −1 and 20.7 ha −1 for the natural forest sites and were 10.4 ha −1 in the teak plantation. Moist deciduous forest had the highest species richness and diversity scores. Although the teak plantation site had the same mammal species richness as the moist evergreen forest, numbers of individuals and overall small mammal biomass in the plantation was far lower than on the natural forest sites. Compared to moist deciduous forest, species richness and diversity were significantly lower on the teak plantation. R. r. wroughtoni and M. platythrix were the two most common species captured on all three sites. R. r. wroughtoni was the most common small mammal species captured, reaching densities of 14.5 ha −1 in moist evergreen forest. G. ellioti was the least common species, present only in moist deciduous forest. Demographic patterns and microhabitat selection were examined for R. r. wroughtoni, M. platythrix , and F. tristriatus . Only M. platythrix appeared to show any distinct seasonality in reproduction, with an increase in capture of breeding individuals towards the end of the wet season. Discriminant analysis did not reveal any distinct microhabitat preferences for any of the species. However, R. r. wroughtoni showed a significant association with bamboo, and F. tristriatus was associated with areas of higher canopy height and density in moist deciduous forest.

Response of large galliforms and tinamous (Cracidae, Phasianidae, Tinamidae) to habitat loss and fragmentation in northern Guatemala

The potential conservation value of fragmented or countryside landscapes in the tropics is being increasingly recognized. However, the degree to which fragmented landscapes can support species and the key patch and landscape features that promote population persistence remain poorly understood for elusive species such as ground-dwelling birds. We examined the presence/absence of seven species of galliforms and tinamous in 50 forest patches of 2.9–445 ha in northern Guatemala using camera traps and audiovisual surveying. After accounting for differences in detectability among species we found great variation in patterns of vulnerability of these species to habitat loss and fragmentation, with the three largest species being the most vulnerable. Distribution patterns of species among patches was influenced more strongly by measures of landscape context, such as the amount and configuration of habitat in the surrounding landscape, than within-patch variation in vegetation structure or disturbance. Our results indicate that large-bodied game birds may be particularly sensitive to habitat loss and fragmentation and emphasize that management efforts for these species need to go beyond consideration of local, within-patch factors to consider the impact of processes in the surrounding landscape. Our findings also demonstrate the utility of camera traps as a methodology for surveying large terrestrial bird species in fragmented landscapes.

Density dependence or climatic variation? Factors influencing survival, recruitment, and population growth rate of Virginia opossums

Abstract Mesopredators play an increasingly important role in ecosystems where apex predators have been eliminated, but population ecology of these midsized mammalian carnivores remains poorly understood. We applied Pradels temporal symmetry models to > 6 years of monthly capture–mark–recapture data and investigated factors influencing apparent survival, recruitment, and realized population growth rate of the Virginia opossum (Didelphis virginiana), an important mesopredator with unique life-history characteristics. Apparent survival did not vary temporally; monthly survival probabilities were 0.86 ± 0.01 (SE) for females and 0.76 ± 0.02 for males. Recruitment rate varied monthly, with the highest recruitment in December (0.32 ± 0.12 for females and 0.57 ± 0.22 for males). Realized population growth rate varied monthly and was also highest in December (1.30 ± 0.17). Both recruitment and population growth rate were positively influenced by the monthly coefficient of variation of precipitation. There was no evidence of density-dependent influences on opossum population dynamics, nor was there evidence of competition from the raccoon (Procyon lotor), a sympatric and abundant mesopredator. Our study is the 1st to simultaneously report survival, recruitment, and population growth rate of Virginia opossums and to investigate factors influencing these rates. In doing so, we provide important insights into the population dynamics of an increasingly influential mesopredator. Resumen Los meso-depredadores juegan un papel cada vez más importante en los ecosistemas donde los depredadores ápice han sido reducidos o eliminados; sin embargo, se conoce poco sobre la ecología poblacional de estos mamíferos carnívoros de tamaño mediano. Nosotros aplicamos modelos simétricos temporales de Pradel a datos mensuales de marcaje, captura y recaptura (de más de 6 años) e investigamos los factores que influencian la sobrevivencia aparente, el reclutamiento y la tasa de crecimiento poblacional de la zarigüeya de Virginia (Didelphis virginiana); el único marsupial que habita al norte de la frontera Mexicana y un importante meso-depredador con características de historia de vida únicas. La sobrevivencia aparente fue diferente entre sexos y no presentó variación temporal, con probabilidades de sobrevivencia mensual de 0.86 ± 0.01 (EE) para hembras y 0.76 ± 0.02 para machos. La tasa de reclutamiento fue diferente entre sexos y varió mensualmente, con un mayor reclutamiento en diciembre (0.32 ± 0.12 para hembras y 0.57 ± 0.22 para machos). La tasa de crecimiento poblacional también varió mensualmente y fue mayor en diciembre (1.30 ± 0.17). Las tasas de reclutamiento y crecimiento poblacional fueron influenciadas positivamente por los coeficientes de variación mensual de la precipitación. No hubo evidencia de un efecto de la densidad sobre la dinámica poblacional de esta zarigüeya, ni evidencia de competencia con el mapache (Procyon lotor), un meso-depredador simpátrico y abundante. Nuestros resultados sugieren que la dinámica poblacional de esta zarigüeya es más fuertemente influenciada por la variación climática que por la competencia inter o intra-específica. Nuestro estudio es el primero en reportar simultáneamente las tasas de sobrevivencia, de reclutamiento y de crecimiento poblacional para la zarigüeya de Virginia, y en investigar los factores que influencian estas tasas con un análisis riguroso de datos de campo tomados sobre un largo periodo tiempo. De esta manera, aportamos información importante sobre la dinámica poblacional de un meso-depredador cada vez más influyente.

Patterns of vertebrate abundance in a tropical mosaic landscape

Multi‐faceted field sampling in a mosaic landscape in Venezuela generated insights on how topographical characteristics, forest composition, degree of habitat interspersion, and paleoecology influenced the abundance and distribution of vertebrates. Physical heterogeneity resulted in distinct vegetation types and a very uneven distribution of medium to large‐sized vertebrates. Variations in forest composition resulted in dramatic contrasts in primate densities. White‐tailed deer densities varied an order of magnitude between vegetation types. Yellow‐knobbed curassow densities peaked in moist forest. Similar chachalaca densities were encountered in dry forest. Although there was spatial overlap between jaguars and pumas, from a large‐scale perspective pumas made more use of drier habitats. In select habitats the abundance and biomass of red‐footed tortoises exceeded that of multiple species of large native mammals combined. This variation in animal abundance highlights the significance of scale in the interpretation of ecological data.