Sustainability of hunting, population densities, intrinsic rates of increase and conservation of Papua New Guinean mammals: A quantitative review

New Guinea’s mammalian fauna consists of a unique assemblage of relatively small sized (0.5-13.5 kg) marsupial mammals, the hunting of which provides a major source of protein for local communities. However, the impact of hunting and the influence of the marsupial life-history strategies on the sustainability of hunting are unknown. Anthropological studies of subsistence hunting and published life-history data for Australasian marsupial mammals were quantitatively reviewed to determine the major sources of game and annual harvest, and estimate intrinsic rates of population increase (r_max) and population densities. These data were used to estimate extraction versus maximum sustainable production (MSP) and make a preliminary estimate of the sustainability of hunting. There were significant negative relationships between increasing body size and decreasing r_max and decreasing population densities, which were further influenced by phylogeny and diet, and appear very similar to relationships found for placental mammals in Afrotropical and Neotropical forests. The estimated biomass of mid-sized marsupial mammals (923 kg/km²) in Papua New Guinea is also comparable with densities of placental mammals in other evergreen tropical forests. Intrinsic rates of increase ranged from 0.28 for tree-kangaroos (Macropodidae) and 0.29 for cuscus (Phalangeridae), up to 5.14 for bandicoots/echymipera (Peroryctidae). Estimated population densities ranged from 0.4-4.0 animals/km² for long-beaked echidna (Zaglossus sp.) to 150-340 animals/km² for ringtails (Pseudocheridae). Extraction rates of game in three studies averaged 23.5 ± 9.9 kg/km²/year, with cuscus and bandicoot species numerically comprising the main game, although cuscus are the most important source of protein. Rates of extraction in Papua New Guinea versus rates of production demonstrate that long-beaked echidna, tree-kangaroos and cuscus are likely to be hunted unsustainably. In contrast hunting of bandicoots and ringtails was lower than maximum production levels, and the high intrinsic rate of increase of bandicoots means that they can potentially provide a sustainable source of protein, in preference to scarcer and intrinsically slower breeding species.     

Savanna herbivore dynamics in a livestock-dominated landscape: I. Dependence on land use, rainfall, density, and time

Ecosystem processes in African savannas can be better conserved if management is based on a mechanistic understanding of wildlife dynamics in livestock-dominated landscapes. For Laikipia District, a non-protected savanna region in northern Kenya, we used spatially explicit estimates of density to characterize factors influencing the dynamics of large herbivores on three land-use types: commercial ranches that favor wildlife, communal ‘group ranches’ practicing pastoralism, and the remainder (‘transitional’ properties). For 21-year time series of nine wild and two domestic species, linear model selection was used to ascribe between 45% (Grant’s gazelle) and 95% (plains zebra) of observed variation in biomass density to land use, rainfall-dependence, density-dependence, and trends over time.Strongly opposing patterns of variation across the landscape in wildlife and livestock densities affirmed the primacy of land use among factors influencing wildlife abundance in non-protected areas. Rainfall limited densities of only the dominant grazing species throughout the monitoring period (plains zebra and cattle), and of most other species while their densities were high. Regulating effects of density were detected only for the dominant wild grazing and browsing species (zebra and giraffe). All but two wild species (zebra and Grant’s gazelle) declined on at least one land-use type, for reasons that varied among land uses.Where favored, diverse and abundant wild herbivores (mean of 1.7 t km⁻² on pro-wildlife ranches) can thrive even when sharing the landscape with a slightly higher biomass density of livestock (mean of 2.7 t km⁻²). Where not favored, only a few resilient wild species (e.g. gazelles and plains zebra) persist with high densities of livestock (mean of 4.6 t km⁻² on transitional ranches). Maintaining higher wild species diversity in the landscape will depend on the creation of a network of unfenced conservation areas in which livestock densities are persistently low or zero, which are sufficiently large to act as ‘sources’ of wild species that are prone to displacement by humans and livestock, and which generate benefits to community members that exceed opportunity costs.     

Getting to grips with the magnitude of exploitation: Bushmeat in the Cross-Sanaga rivers region, Nigeria and Cameroon

Wild meat harvests in African moist forests are presumed to exceed production, even in the case of traditional societies still using rudimentary hunting methods. Though some approximations do exist of the volume of bushmeat harvested in some Central African moist forest areas, estimates based on extensive and simultaneous sampling, within a large geographical region, are not available. Here, we present the results of the first reported study of this kind. During a period of 5 month, we counted bushmeat carcasses deposited in 89 urban and rural markets in a 35,000 km² area between the Cross River in Nigeria and the Sanaga River in Cameroon. We used these data to calculate annual bushmeat volume traded by site, species and overall in the study area.Mammals represented >90% of the bushmeat carcasses sold in all sites. Reptiles were also abundant, but birds and amphibians were relatively scarce. Estimates of carcasses extracted and crude biomass per site varied significantly between countries. In Nigeria, biomass (kg) extracted for sale per km² per year, was three times greater (600 kg/km²) than in Cameroon. Conservative estimates for the entire study area indicate that >900,000 reptiles, birds and mammals are sold each year by the rural and urban population, corresponding to around 12,000 tonnes of terrestrial vertebrates. We also assessed the relationship between bushmeat harvested for sale and distance of the study settlements from the main protected areas (Cross River and Korup National Parks). The number of carcasses and biomass sold was negatively related to the proximity to the national parks in >50% of species in Nigeria, and in 40% of species in Cameroon.Our cross-site comparison documents the staggering volume of wild species affected by hunting in the region. We also conclude that species within the main protected areas in both countries are likely to be negatively affected by the current and future demand for bushmeat in the surrounding areas.     

Extent and conservation of tropical dry forests in the Americas

This paper shows the results of an assessment on the current extent of Neotropical dry forests based on a supervised classification of MODIS surface reflectance imagery at 500-m resolution. Our findings show that tropical dry forests extend for 519,597 km² across North and South America. Mexico, Brazil and Bolivia harbor the largest and best-preserved dry forest fragments. Mexico contains the largest extent at 181,461 km² (38% of the total), although it remains poorly represented under protected areas. On the other hand, Brazil and Bolivia contain the largest proportion of protected tropical dry forests and the largest extent in continuous forest fragments. We found that five single ecoregions account for more than half of the tropical dry forests in the Americas (continental and insular) and these ecoregions are: the Chiquitano dry forests, located in Bolivia and Brazil (27.5%), the Atlantic dry forests (10.2%), the Sinaloan dry forests in Mexico (9.7%), the Cuban dry forests (7.1%) and the Bajio dry forests in Mexico (7%). Chiquitano dry forests alone contain 142,941 km² of dry forests. Of the approximately 23,000 km² of dry forest under legal protection, 15,000 km² are located in just two countries, Bolivia and Brazil. In fact, Bolivia protects 10,609 km² of dry forests, where 7600 km² are located within the Chiquitano dry forest ecoregion and protected by a single park. Low extent and high fragmentation of dry forests in countries like Guatemala, Nicaragua, Ecuador, Costa Rica and Peru means that these forests are at a higher risk from human disturbance and deforestation.     

Degradation of tropical forest in Hainan, China, 1991-2008: Conservation implications for Hainan Gibbon (Nomascus hainanus)

The Hainan gibbon (Nomascus hainanus) is one of the most endangered primates in the world, confined to mature natural forest in Hainan Island, China. We assessed changes in habitat condition on the island between 1991 and 2008, using vegetation maps generated by remote-sensing images. We defined forest suitable for gibbons based on composition, tree size and canopy cover. During the 17-year period, the area of suitable gibbon forest decreased by 540 km² (35%) across the whole island, and by 6.3 km² (7%) in the locality of the sole remaining gibbon population at Bawangling National Nature Reserve. The forest patches large enough (>1 km²) to support a gibbon group decreased from 754 km² to 316 km² in total area, and from 92 to 64 in number. Suitable natural forest was mainly replaced by plantations below 760 m, or degraded by logging, grazing and planting of pines above 760 m. Meanwhile, forests in former confirmed gibbon areas became more fragmented: mean area of patches decreased by 53%. We mapped the patches of natural forest in good condition which could potentially support gibbons. We recommend a freeze on further expansion of plantations between core patches at Bawangling, Jiaxi-Houmiling and Yinggeling Nature Reserves in accordance with forest protection regulations; establishment of nature reserves in currently unprotected natural forest patches elsewhere in line with the local government’s nature reserve expansion policy; and active natural-forest restoration between remaining fragments at Bawangling.     

Estimating the density of a jaguar population in the Brazilian Pantanal using camera-traps and capture-recapture sampling in combination with GPS radio-telemetry

The jaguar (Panthera onca) is the largest feline in the Americas and third largest world-wide, smaller in size only to the tiger (P. tigris) and lion (P. leo). Yet, in comparison, relatively few studies on jaguar population densities have been conducted and baseline data for management purposes are needed. Camera trapping and capture-recapture sampling methods were used to estimate the size of a jaguar population in the Pantanal’s open wet grassland habitat, an important area for the long-term survival of the species. This study is the first jaguar population estimate conducted in co-operation with a GPS-telemetry study providing an important opportunity for comparing different methods of density estimation. An accessible area within a 460 km² privately-owned ranch was sampled with equal effort during the dry seasons of 2003 and 2004. Thirty-one and twenty-five individual jaguars were identified in 2003 and 2004, respectively. Estimates of jaguar abundance were generated by program CAPTURE. Density estimates were produced according to different methods used to calculate the effectively sampled areas which ranged from 274 to 568 km². For 2003, the currently-used mean maximum distance moved (MMDM) method produced a density of 10.3 jaguars/100 km², while GPS-telemetry-based calculations produced a mean density of 6.6 jaguars/100 km². For 2004, the MMDM method produced an estimate of 11.7 jaguars/100 km² while GPS-telemetry calculations produced a density of 6.7 jaguars/100 km². Our results suggest that the widely-used MMDM method used to calculate effectively sampled areas is significantly under-reflecting maximum distances moved by jaguars and their range-use and, thereby, considerably inflating cat density estimates. This overestimation could place a population in a difficult situation by lengthening the time taken to initiate protection measures because of underestimating the risk to that population.     

How does human exploitation affect impala populations in protected and partially protected areas? - A case study from the Serengeti Ecosystem, Tanzania

Human exploitation can have severe conservation implications for wildlife populations. In the Serengeti ecosystem, Tanzania, illegal hunting is a serious concern for wildlife management, and in this study we investigated if density, demography and behaviour can be used as indicators of human exploitation. We used impala (Aepycerus melampus) as a model species to study human exploitation inside and outside a strictly protected area. Over a six month period, a total of 2050 km of transects were driven in the different protected areas (National Park, Game Reserve, Open Area). Densities were estimated by using distance sampling and the partially protected areas were found to have significantly lower densities (4.3 ind/km²) than the National Park (15.3 ind/km²). A variation in density between different sections within the National Park was also found. However, we found no differences in group sizes. Moreover, the sex-ratio was more skewed towards females in the partially protected areas and in sections within the National Park close to villages. In addition, impalas showed higher alertness levels, and longer flight initiation distance to an approaching human in the partially protected areas compared to the National Park. The present harvest levels by illegal hunting in the study area are most likely the cause of the observed differences. Our results suggest that density, demography and behaviour can be used as indicators of human exploitation, but that this probably varies according to local hunting pressure. Furthermore, it could be expected that the results obtained in this study might reflect the state of other ungulates in the area, which raises concern whether management objectives for the buffer zones of Serengeti National Park are met.     

Biotic homogenization of the California flora in urban and urbanizing regions

Biotic homogenization, driven by native species losses and invasive species gains was investigated for the flora of California. Data from a variety of available databases were aggregated at the county level to examine patterns in county population density and growth in relation to floristic change. Based on population, California was divided into three zones: high (n = 9; 257-1320 people/km²), medium (n = 25; 28-177 people/km²), and low (n = 24; 1-24 people/km²) density counties. Examining patterns of rare plant occurrences among these counties revealed that high and medium density counties contained, on average, as many or more rare and endemic species than low density counties. The largest pool of these species, 48 percent of the 962 highly threatened taxa in California, is restricted to high and medium density counties. Thus, urban and urbanizing counties play a strategic role in maintaining a part of California’s flora that is both globally significant and threatened with extinction. Examining species losses and noxious weed additions across high density counties, reveals a consistent pattern of low similarity among species that have been extirpated from high density counties and a high similarity among noxious weeds that these counties now share. The consequence is that California’s urban county floras appear to be homogenizing. Examining homogenization using the entire flora for urban counties demonstrates that less similar counties become more similar. The effect of loss of rare species could outweigh the gain in exotics, under an assumption of strong extinction. Finally, a strong negative relationship between population density and the proportion of county land in public ownership suggests that high and medium density counties are in a poor position to protect rare plant populations on a localized basis.     

Hunting reduces recruitment of primate-dispersed trees in Amazonian Peru

Hunting with firearms decimates primates of large and medium body size (>2 kg) that disperse the seeds of large-seeded trees. In continuous, un-fragmented forests of southeastern Peru regularly hunted with firearms for 30-40 years, large primates are extirpated and medium-sized (medium) primates are reduced 61% compared with protected forests. At hunted sites seedlings and small juveniles (<1 m height) of trees dispersed by primates heavier than 2 kg are reduced 46%, a loss of one species m⁻², and abiotically-dispersed plants are 284% more common, adding eight individuals m⁻², compared with protected forests. Here we provide evidence consistent with the long-held prediction that commercial hunting changes plant communities. We show that the composition of seedling and small juvenile tree communities that ultimately regenerate future forests differs markedly in forests hunted with firearms compared with protected forests. This opens the possibility of shifts in tree species composition, even in hunted forests that are not logged or fragmented, towards forests dominated by trees dispersed by wind or non-game animals.     

Habitat fragmentation and the desiccation of forest canopies: A case study from eastern Amazonia

Across the deforestation frontier in eastern Amazonia, we examined the relationship between edge-related forest desiccation and deforestation patterns using remote-sensing techniques. Canopy-moisture levels were estimated over an eight-year period in three study sites that encompassed ∼100,000 km² in area. We found four main effects of deforestation on dry-season canopy desiccation. First, intact forests showed no detectable change in canopy water content whereas forests adjacent to clearings showed significant water loss. Second, the distance to which edge-related desiccation penetrated into forest interiors varied among landscapes with differing forest loss and fragmentation. In moderately fragmented landscapes (with 65% and 51% remaining forest cover), canopy desiccation extended 1-1.5 km into forest interiors, whereas in heavily fragmented landscapes (20% forest cover) desiccation penetrated up to 2.7 km into forests. Third, the magnitude of edge-related desiccation varied among landscapes with differing fragmentation. Moderately fragmented landscapes exhibited a greater magnitude of change in canopy-water loss over the first 1 km from an edge than did heavily fragmented landscapes. Finally, forest desiccation penetrated further into forests over time in the moderately fragmented landscapes, but not in the heavily fragmented landscape, where edge-related desiccation had evidently ‘saturated’ remaining forests. We conclude that protracted dry seasons will have far more serious effects on fragmented than intact rainforests, with the former becoming highly vulnerable to destructive fires. With ∼30,000 km of new forest edge being created annually in Brazilian Amazonia, these finding have serious implications for forest conservation.     

Uneven regional distribution of protected areas in Finland: Consequences for boreal forest bird populations

The significance of reserves in maintaining forest bird species of conservation concern (N = 36) was studied by large-scale quantitative line transect bird censuses in Finland, which stretches 1100 km through the boreal zone from the hemiboreal to the subarctic. Altogether 12 245 km of line transect was carried out in 1981-2004 in reserves covering 28 910 km². Bird census data in protected areas were combined into 100 km × 100 km squares. As a group the studied bird species were rather evenly distributed throughout the reserve network. The present reserve network is particularly significant for species having their highest densities in northern Finland, because large proportions of the populations of these species occurred in protected areas. However, over half of the studied species were concentrated in protected areas of southern and central Finland, and only small proportions of their populations were included in the present reserve network. In contrast to the whole species pool of conservation concern, the studied individual forest bird species were not distributed evenly throughout the whole reserve network. This suggests that for most individual species a regionally concentrated network is a preferred option, but for the whole species group the reserve network should clearly be regionally complementary and representative even in the boreal zone, where species have rather wide ranges. Thus, only some species and their habitats can be preserved in a spatially uneven reserve network in boreal forests.     

Conservation status of tigers in a primary rainforest of Peninsular Malaysia

This study provided the first reliable density estimate of tigers based on photographic capture data in Taman Negara National Park, Peninsular Malaysia's most important conservation area. Estimated densities () of adult tigers ranged from 1.10 ± 0.52 to 1.98 ± 0.54 tigers/100 km² (X²=1.56, df=2, P=0.46) with the overall mean of 1.66 ± 0.21 tigers/100 km². The tiger population in the 4343-km² park was estimated to be 68 (95% CI: 52-84) adult tigers. Prey biomass estimates ranged from 266 to 426 kg/km², and wild boar were the most important potential prey species in terms of abundance, biomass, and occupancy, followed by muntjac. Both tigers and leopards were more diurnal than nocturnal, which corresponded with the activity patterns of wild boar and muntjac. No evidence of poaching of large mammals was found in the 600-km² study sites and overall human impacts on the tiger-prey community appear to be minimal, but in the long run its viability needs to be evaluated in a greater landscape context.     

Spatial fields’ dispersion as a farmer strategy to reduce agro-climatic risk at the household level in pearl millet-based systems in the Sahel: A modeling perspective

The rainfall pattern in the Sahel is very erratic with a high spatial variability. We tested the often reported hypothesis that the dispersion of farmers’ fields around the village territory helps mitigate agro-climatic risk by increasing yield stability from year to year. We also wished to evaluate whether this strategy had an effect on the yield disparity among households in a village. Based on a network of approximately 60 rain gauges spread over 500 km² in the Fakara region (Southwest Niger), daily rainfall was interpolated at 300 m × 300 m resolution over a 12-year period. This data was used to compute, by means of the APSIM crop simulation model, millet biomass and grain yields at the pixel scale. Simulated yields were combined with the land tenure map of the Banizoumbou village in a GIS to assess millet yield at field and household level. Agro-climatic risk analysis was performed using linear regression between a spatial dispersion index of household fields and the inter-annual (instability) and inter-household (disparity) millet yield variability of 107 households in the village territory. We find that the spatial variability of annual rainfall induces an even higher spatial variability of millet production at pixel, field and household levels. The dispersion of farm fields reduces moderately but significantly the disparity of millet yield between households each year and increases the inter-annual yield stability of a given household. The less the household fields are scattered, the more the presence of a fertility gradient around the village enhances the inter-annual stability but also the disparity between households. Our results provide evidence that field dispersion is an effective strategy to mitigate agro-climatic risk, as claimed by farmers in the Sahelian Niger. Although the results should be confirmed by further research on longer term rainfall spatial data, it is clearly advisable that any land reforms in the area take into account the benefits of field dispersion to mitigate climatic risk.     

Forest fragmentation and edge effects from deforestation and selective logging in the Brazilian Amazon

Forest fragmentation results from deforestation and disturbance, with subsequent edge effects extending deep into remaining forest areas. No study has quantified the effects of both deforestation and selective logging, separately and combined, on forest fragmentation and edge effects over large regions. The main objectives of this study were to: (1) quantify the rates and extent of forest fragmentation from deforestation and logging within the Brazilian Amazon, and (2) contextualize the spatio-temporal dynamics of this forest fragmentation through a literature review of potential ecological repercussions of edge creation. Using GIS and remote sensing, we quantified forest fragmentation - defined as both increases in the forest edge-to-area ratio and number of forest fragments - and edge-effected forest occurring from these activities across more than 1.1 million km² of the Brazilian Amazon from 1999 to 2002. Annually, deforestation and logging generated ∼32,000 and 38,000 km of new forest edge while increasing the edge-to-area ratio of remaining forest by 0.14 and 0.15, respectively. Combined deforestation and logging increased the edge-to-area ratio of remaining forest by 65% over our study period, while generating 5539 and 3383 new forest fragments, respectively. Although we found that 90% of individual forest fragments were smaller than 4 km², we also found that 50% of the remaining intact forests were located in contiguous forest areas greater than 35,000 km². We then conducted a literature review documenting 146 edge effects and found that these penetrated to a median distance of 100 m, a distance encompassing 6.4% of all remaining forests in our study region in the year 2002, while 53% of forests were located within two km of an edge. Annually deforestation and logging increased the proportion of edge-forest by 0.8% and 3.1%, respectively. As a result of both activities, the total proportion of edge-forest increased by 2.6% per year, while the proportion within 100-m increased by 0.5%. Over our study period, deforestation resulted in an additional ∼3000 km² of edge-forest, whereas logging generated ∼20,000 km², as it extended deep into intact forest areas. These results show the large extent and rapid expansion of previously unquantified soft-edges throughout the Amazon and highlight the need for greater research into their ecological impacts.     

The sustainability of subsistence hunting of peccaries in the Argentine Chaco

Subsistence hunting practiced by poor rural and indigenous people in Latin America differentially affects the three species of peccaries (Artiodactyla: Tayassuidae). Sustainability of subsistence hunting of peccaries in the Argentine semi-arid Chaco, where the three species coexist, was unknown. My objectives were to determine the importance of peccaries for the local people, describe the current pattern of hunting and its impact on the three species of peccary and identify the factors that affect hunting sustainability. I found that many rural (70%) and village people (40%) consumed peccaries. White-lipped and chacoan peccaries were more susceptible to overharvesting than collared peccary. Current rates of hunting of white-lipped and chacoan peccaries are likely not sustainable because: (a) density of both species was between two to three times higher inside a protected area than outside; (b) populations have declined near larger villages and in older settlements; (c) herds sizes were small in comparison with other regions; (d) large number of juveniles less than one year old were harvested; (e) hunting did not discriminate based on sex or reproductive status and (f) The unified harvest model indicated unsustainable harvest because more than 40% of the reproductive production was taken and populations densities were less than 60% carrying capacities. In contrast, harvest of collared peccary seems sustainable at the current rates of hunting by rural peasants. Other threats such as forest exploitation, however, are accelerating, and are likely to reduce sustainability.     

Three decades of deforestation in southwest Sumatra: Have protected areas halted forest loss and logging, and promoted re-growth?

Much of the forest cover in southern Sumatra, Indonesia has been cleared since the early 1970s, but accurate estimates of the scales and rates of loss are lacking. This study combined high-quality remote sensing applications and extensive field surveys, both to provide an accurate picture of deforestation patterns across an area of 1.17 million ha in southwest Sumatra and to assess whether southwest Sumatra’s Bukit Barisan Selatan National Park (BBSNP) has halted forest loss and logging, and promoted re-growth, since its creation in 1984. Of the single large (692,850 ha) contiguous area of forest standing across our study area in 1972, nearly half (344,409 ha) has been cleared from 1972 to 2002, at an average rate per original forest cover of 1.69% y⁻¹. In Gunung Raya Wildlife Sanctuary (GRWS) and Hydrological Reserves (HR), forests have shrunk by 28,696 ha and 113,105 ha, at an average rate of 2.74% y⁻¹ and 2.13% y⁻¹, respectively. In contrast, forests in BBSNP have reduced four times more slowly than those in GRWS and HR, and have shrunk by 57,344 ha, at an average rate of 0.64% y⁻¹. Nevertheless, the forests within BBSNP were cleared almost as rapidly during the post-establishment, as during the pre-establishment, period (0.65% y⁻¹ and 0.63% y⁻¹, respectively) despite the introduction of protection measures during the post-establishment period, following the government’s pledge to expand and protect Indonesia’s network of Protected Areas (PAs) at the 1982 Bali World Parks Congress. While these protection measures failed to slow down rates of forest loss caused by agricultural encroachments they reduced large-scale mechanised logging by a factor of 4.2 and stabilized some 8610 ha of agricultural encroachments, enabling forest re-growth.     

Movements and activities of snow leopards in Southwestern Mongolia

Four adult (2M:2F) snow leopards (Uncia uncia) were radio-monitored (VHF; one also via satellite) year-round during 1994-1997 in the Altai Mountains of southwestern Mongolia where prey densities (i.e., ibex, Capra siberica) were relatively low (∼0.9/km²). Marked animals were more active at night (51%) than during the day (35%). Within the study area, marked leopards showed strong affinity for steep and rugged terrain, high use of areas rich in ungulate prey, and affinity for habitat edges. The satellite-monitored leopard moved more than 12 km on 14% of consecutive days monitored. Home ranges determined by standard telemetry techniques overlapped substantially and were at least 13-141 km²in size. However, the satellite-monitored individual apparently ranged over an area of at least 1590 km², and perhaps over as much as 4500 km². Since telemetry attempts from the ground were frequently unsuccessful , we suspect all marked animals likely had large home ranges. Relatively low prey abundance in the area also suggested that home ranges of >500 km²were not unreasonable to expect, though these are >10-fold larger than measured in any other part of snow leopard range. Home ranges of snow leopards may be larger than we suspect in many areas, and thus estimation of snow leopard conservation status must rigorously consider logistical constraints inherent in telemetry studies, and the relative abundance of prey.     

Hunting habitat selection by hen harriers on moorland: Implications for conservation management

We examine habitat use by hunting hen harriers Circus cyaneus at three study sites in Scotland to evaluate whether foraging patterns differ between sexes, sites, and stages of the breeding period. We modelled time spent hunting in focal plots as a function of habitat and nest proximity. Male hunting intensity (time spent hunting per hour of observation and km²) varied between sites and breeding periods, being lower during the nestling than the incubation period. Habitat use patterns were mostly consistent among study sites, which is important for developing species management recommendations applicable over the species’ range. Males avoided improved grassland, and selected areas of mixed heather and rough grass (with an optimum at ca. 50% heather cover). The effect of nest proximity was small. In contrast, females hunted mainly within 300-500 m of the nest, with a small additive effect of vegetation cover, areas of fragmented heather being preferred. Habitat management to benefit foraging harriers will involve creating (or maintaining) mosaics of heather/grassland around nest areas. Additionally, it might be possible to manipulate habitat to reduce conflict in areas where harrier predation on red grouse is important by segregating areas holding highest grouse densities (with high heather cover) from those favoured for harrier foraging (heather-grass mosaics). However, it would be necessary to test whether these manipulations might also influence harrier nest distribution, an effect which could negate any benefits from this strategy.     

Conserving tigers Panthera tigris in selectively logged Sumatran forests

The response of most large carnivores to selective logging is poorly understood. On the one hand, selective logging may represent loss of important habitat, yet, on the other hand, selective logging may increase browse availability for a terrestrial ungulate prey base, thereby indirectly benefiting large carnivores. Using a camera trap-based sampling method, we estimate tiger density in two primary-selectively logged forest areas that straddle Kerinci Seblat National Park, Sumatra. We then investigate potential differences between the habitat use of tigers: within these study areas and forest types; and, within the finer-scale landscape features associated with these covariates. Across the mixed forest study areas, tiger density estimates (adult individuals/100 km² ± S.E.) of 2.95 ± 0.56 and 1.55 ± 0.34 were produced. However, within these areas, tigers showed a preference for primary over degraded forest, and this was related to the greater accessibility of degraded forest sites to people, e.g., through their proximity to roads. Presently, the majority of Sumatran tigers occur within large tracts of primary forest, but these extend outside of the island’s protected area borders, and these unprotected forests are especially at risk from the high levels of deforestation in Sumatra. As forest is cleared, previously remote, and therefore safer, tracts of primary forest become accessible and, eventually, degraded. Yet, from our study, degraded forest in combination with primary forest supported sufficiently high tiger densities and can, therefore, make an important contribution to tiger conservation. It is therefore essential to lessen the detrimental effects of accessibility through increasing law enforcement and destroying ex-logging roads.     

The impact of trophy hunting on lions (Panthera leo) and other large carnivores in the Bénoué Complex, northern Cameroon

In West and Central Africa large carnivores have become increasingly rare as a consequence of rapid habitat destruction and lack of resources for protected area management. The Bénoué Complex (23,394 km²) in northern Cameroon is a regionally critical area for large mammal conservation. In the complex lions (Panthera leo), leopards (Panthera pardus) and spotted hyenas (Crocuta crocuta) are formally protected in three national parks and 28 hunting zones. Over-hunting may be having a strong additive effect precipitating declines in large carnivore numbers across the complex. We used a coarse level track index method to estimate the relative abundance of these three species both in hunting zones and national parks. The results were interpreted with respect to ungulate abundance, and hunting impact. There was no significant difference between the densities of medium to larger species of ungulates in the hunting zones and the national parks, and no difference in leopard and spotted hyena densities in the respective areas. However, lions occurred at significantly lower densities in the hunting zones, and even in the national parks occurred at significantly lower densities than prey biomass would predict.