We examine the abundance and distribution of Sumatran tigers (Panthera tigris sumatrae) and nine prey species in Bukit Barisan Selatan National Park on Sumatra, Indonesia. Our study is the first to demonstrate that the relative abundance of tigers and their prey, as measured by camera traps, is directly related to independently derived estimates of densities for these species. The tiger population in the park is estimated at 40-43 individuals. Results indicate that illegal hunting of prey and tigers, measured as a function of human density within 10 km of the park, is primarily responsible for observed patterns of abundance, and that habitat loss is an increasingly serious problem. Abundance of tigers, two mouse deer (Tragulus spp.), pigs (Sus scrofa) and Sambar deer (Cervus unicolor) was more than four times higher in areas with low human population density, while densities of red muntjac (Muntiacus muntjac) and pigtail macaques (Macaca nemestrina) were twice as high. Malay tapir (Tapirus indicus) and argus pheasant (Argusianus argus), species infrequently hunted, had higher indices of relative abundance in areas with high human density. Edge effects associated with park boundaries were not a significant factor in abundance of tigers or prey once human density was considered. Tigers in Bukit Barisan Selatan National Park, and probably other protected areas throughout Sumatra, are in imminent danger of extinction unless trends in hunting and deforestation are reversed.

Global change is impacting forests worldwide, threatening biodiversity and ecosystem services including climate regulation. Understanding how forests respond is critical to forest conservation and climate protection. This review describes an international network of 59 long-term forest dynamics research sites (CTFS-ForestGEO) useful for characterizing forest responses to global change. Within very large plots (median size 25 ha), all stems ≥1 cm diameter are identified to species, mapped, and regularly recensused according to standardized protocols. CTFS-ForestGEO spans 25°S-61°N latitude, is generally representative of the range of bioclimatic, edaphic, and topographic conditions experienced by forests worldwide, and is the only forest monitoring network that applies a standardized protocol to each of the world's major forest biomes. Supplementary standardized measurements at subsets of the sites provide additional information on plants, animals, and ecosystem and environmental variables. CTFS-ForestGEO sites are experiencing multifaceted anthropogenic global change pressures including warming (average 0.61°C), changes in precipitation (up to AE30% change), atmospheric deposition of nitrogen and sulfur compounds (up to 3.8 g N m À2 yr À1 and 3.1 g S m À2 yr À1), and forest fragmentation in the surrounding landscape (up to 88% reduced tree cover within 5 km). The broad suite of measurements made at CTFS-ForestGEO sites makes it possible to investigate the complex ways in which global change is impacting forest dynamics. Ongoing research across the CTFSForestGEO network is yielding insights into how and why the forests are changing, and continued monitoring will provide vital contributions to understanding worldwide forest diversity and dynamics in an era of global change.

The monitoring and management of species depends on reliable population estimates, and this can be both difficult and very costly for cryptic large vertebrates that live in forested habitats. Recently developed camera trapping techniques have already been shown to be an effective means of making mark-recapture estimates of individually identifiable animals (e.g. tigers). Camera traps also provide a new method for surveying animal abundance. Through computer simulations, and an analysis of the rates of camera trap capture from 19 studies of tigers across the species' range, we show that the number of camera days/tiger photograph correlates with independent estimates of tiger density. This statistic does not rely on individual identity and is particularly useful for estimating the population density of species that are not individually identifiable. Finally, we used the comparison between observed trapping rates and the computer simulations to estimate the minimum effort required to determine that tigers, or other species, do not exist in an area, a measure that is critical for conservation planning.

Vultures (Accipitridae and Cathartidae) are the only known obligate scavengers. They feed on rotting carcasses and are the most threatened avian functional group in the world. Possible effects of vulture declines include longer persistence of carcasses and increasing abundance of and contact between facultative scavengers at these carcasses. These changes could increase rates of transmission of infectious diseases, with carcasses serving as hubs of infection. To evaluate these possibilities, we conducted a series of observations and experimental tests of the effects of vulture extirpation on decomposition rates of livestock carcasses and mammalian scavengers in Kenya. We examined whether the absence of vultures changed carcass decomposition time, number of mammalian scavengers visiting carcasses, time spent by mammals at carcasses, and potential for disease transmission at carcasses (measured by changes in intraspecific contact rates). In the absence of vultures, mean carcass decomposition rates nearly tripled. Furthermore, the mean number of mammals at carcasses increased 3-fold (from 1.5 to 4.4 individuals/carcass), and the average time spent by mammals at carcasses increased almost 3-fold (from 55 min to 143 min). There was a nearly 3-fold increase in the mean number of contacts between mammalian scavengers at carcasses without vultures. These results highlight the role of vultures in carcass decomposition and level of contact among mammalian scavengers. In combination, our findings lead us to hypothesize that changes in vulture abundance may affect patterns of disease transmission among mammalian carnivores.

Investments to prevent tropical deforestation and to limit wildlife trade will protect against future zoonosis outbreaks

The remarkable large‐mammal fauna of the Indonesian island of Sumatra is one of the most endangered on Earth and is threatened by rampant deforestation. We used remote sensing and biological surveys to study the effects of deforestation on populations of endangered large mammals in a Sumatran landscape. We measured forest loss and created a predictive model of deforestation for Bukit Barisan Selatan National Park and an unprotected buffer area based on satellite images between 1985 and 1999. We used automatic cameras to determine the distribution and relative abundance of tigers (   Panthera tigris sumatrae ), elephants (  Elephas maximus ), rhinoceros (  Dicerorhinus sumatrensis ), and tapirs (  Tapir indicus ). Between 1985 and 1999, forest loss within the park averaged 2% per year. A total of 661 km 2 of forest disappeared inside the park, and 318 km 2 were lost in a 10‐km buffer, eliminating forest outside the park. Lowland forest disappeared faster than hill/montane forest (  by a factor of 6  ) and forests on gentle slopes disappeared faster than forests on steep slopes (  by a factor of 16  ). Most forest conversion resulted from agricultural development, leading to predictions that by 2010 70% of the park will be in agriculture and that by 2036 lowland forest habitat will be eliminated. Camera‐trap data indicated avoidance of forest boundaries by tigers, rhinoceroses ( up to 2 km ), and elephants ( up to 3 km ). Classification of forest into core and peripheral forest based on mammal distribution suggests that, by 2010, core forest area for tigers and rhinoceros will be fragmented and reduced to 20% of remaining forest. Core forest area for elephants will be reduced to 0.5% of remaining forest. Halting forest loss has proven one of the most difficult and complex problems faced by Indonesia's conservation agencies today and will require a mix of enforcement, wise land‐use strategies, increased education, capacity to manage, and new financing mechanisms.

We studied spatial and temporal variation in a population of Sulawesi Redknobbed Hornbills (Aceros cassidix) in relation to availability of fruit resources over a twoyear period in the Tangkoko DuaSudara Nature Reserve, North Sulawesi, Indonesia. Fruit production did not show any discernable patterns over 22 months of study, in spite of the strong seasonality of rainfall. Figs were available in all months of the year, and fig biomass exceeded ripe nonfig-fruit biomass in 10 of 22 months. Hornbill densities fluctuated dramatically over time (2 = 51 birds-km-2, range 9.3-82.7) and among habitats. Spatial and temporal variation in hornbill numbers was best explained by habitat selection and the abundance and distribution of figs. Hornbill numbers were higher in those areas with greater densities of fig trees, and monthly hornbill densities and mean flock size increased with increasing fig biomass. Because Sulawesi Red-knobbed Hornbills appear to track fig production over potentially large distances, and include a mix of other rainforest tree species in their diet, we hypothesize that they may play an important role as agents of rainforest regeneration.

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