Effects of Trophy Hunting on Lion and Leopard Populations in Tanzania

Abstract: Tanzania holds most of the remaining large populations of African lions (Panthera leo) and has extensive areas of leopard habitat (Panthera pardus), and both species are subjected to sizable harvests by sport hunters. As a first step toward establishing sustainable management strategies, we analyzed harvest trends for lions and leopards across Tanzania's 300,000 km² of hunting blocks. We summarize lion population trends in protected areas where lion abundance has been directly measured and data on the frequency of lion attacks on humans in high‐conflict agricultural areas. We place these findings in context of the rapidly growing human population in rural Tanzania and the concomitant effects of habitat loss, human‐wildlife conflict, and cultural practices. Lion harvests declined by 50% across Tanzania between 1996 and 2008, and hunting areas with the highest initial harvests suffered the steepest declines. Although each part of the country is subject to some form of anthropogenic impact from local people, the intensity of trophy hunting was the only significant factor in a statistical analysis of lion harvest trends. Although leopard harvests were more stable, regions outside the Selous Game Reserve with the highest initial leopard harvests again showed the steepest declines. Our quantitative analyses suggest that annual hunting quotas be limited to 0.5 lions and 1.0 leopard/1000 km² of hunting area, except hunting blocks in the Selous Game Reserve, where harvests should be limited to 1.0 lion and 3.0 leopards/1000 km².     

Monitoring Mammal Populations in Costa Rican Protected Areas under Different Hunting Restrictions

Abstract: It is necessary to assess whether the management of protected areas is achieving the objectives set for them. In particular, changes and trends in wildlife populations should be documented. We compared the 1990 abundance of mammals in two Costa Rican protected areas, Corcovado National Park (CNP) and Golfo Dulce Forest Reserve (GDFR), with similar environmental characteristics but different hunting restrictions and levels of protection. We also monitored the abundance of mammals in CNP over a 4-year period. We also devised an inexpensive method of monitoring tropical rainforest mammal populations in a timely and efficient manner. The method is based on the use of mammal track records and arboreal mammal sightings and requires little effort. With this method 20 mammal species were recorded at CNP and 15 at GDFR. Species were consistently less abundant in GDFR than in CNP, principally those species preferred by hunters. Species were grouped according to whether or not they are used as food and whether they are locally or globally threatened or not threatened. The abundance of all these groups of species in GDFR was 6–28% the abundance in CNP. During 1990–1994, overall mammal abundance in CNP remained relatively stable, but there was considerable variability among species. As a group, both species used for food and globally threatened species declined in abundance during that period in CNP. The abundance of all groups of species declined from 1992 to 1994, coinciding with a reduction in hunting vigilance at CNP. Evidence suggests that the main factor differentiating the abundance of mammals in the two protected areas, and at CNP during the study period, was the level of hunting. Golfo Dulce Forest Reserve seems to be achieving only partial success in protecting wildlife, whereas Corcovado National Park seems to be considerably more effective, although not entirely successful.     

Microsatellite Analysis of Population Structure in the Endangered Hawaiian Monk Seal

Abstract: The endangered Hawaiian monk seal breeds at six locations in the northwestern Hawaiian Islands. To determine whether significant genetic differentiation exists among these sites, we used microsatellite loci to examine the monk seal population structure at the five largest breeding colonies. Of 27 loci isolated from other seal species, only 3 were polymorphic in an initial screening of one individual from each breeding site. Only two alleles were found at each of these 3 loci in samples of 46–108 individuals. This extremely low variation is consistent with other measures of genetic variability in this species and is probably the result of a recent severe population bottleneck, combined with a long-term history of small population sizes. Although the smallest monk seal subpopulation in this study ( Kure Atoll) showed some evidence of heterozygote deficit, possibly indicative of inbreeding, the next smallest ( Pearl and Hermes Reef) had an apparent excess of heterozygous individuals. Genetic differentiation was detected between the two subpopulations at extreme ends of the range ( Kure and French Frigate Shoals). This trend was significant only at the microsatellite locus for which we had the largest sample size ( Hg6.3: R _ST = 0.206, p = 0.002; allelic goodness of fit G _h = 15.412, p < 0.005). French Frigate Shoals is the source population for translocated animals that have been released primarily at Kure Atoll. Differentiation between these sites consisted of allele frequency differences (with the same allele predominant in each location at all three loci), rather than the preservation of alternative alleles. Although the translocations have had positive demographic effects, we recommend continued genetic monitoring of both the source and recipient populations because translocated individuals are now entering the breeding population.     

Bayesian Small Area Models for Assessing Wildlife Conservation Risk in Patchy Populations

Abstract:  Species conservation risk assessments require accurate, probabilistic, and biologically meaningful maps of population distribution. In patchy populations, the reasons for discontinuities are not often well understood. We tested a novel approach to habitat modeling in which methods of small area estimation were used within a hierarchical Bayesian framework. Amphibian occurrence was modeled with logistic regression that included third-order drainages as hierarchical effects to account for patchy populations. Models including the random drainage effects adequately represented species occurrences in patchy populations of 4 amphibian species in the Oregon Coast Range (U.S.A.). Amphibian surveys from other locations within the same drainage were used to calibrate local drainage-scale effects. Cross-validation showed that prediction errors for calibrated models were 77% to 86% lower than comparable regionally constructed models, depending on species. When calibration data were unavailable, small area and regional models performed similarly, although poorly. Small area estimation models complement wildlife ecology and habitat studies, and can help managers develop a regional picture of the conservation status for relatively rare species.     

The Sustainability of Subsistence Hunting in the Neotropics

Hunting is an important component of native subsistence strategies in Amazonia. It is also a serious threat to biodiversity in some areas. We present data on the faunal harvests of two native Neotropical subsistence hunting peoples, Machiguenga bow-hunters and Piro shotgun hunters of Peru. The rate of annual harvest per square kilometer of catchment is estimated and compared to rates of sustainable harvest calculated by Robinson and Redford (1991). We used indicators of prey abundance to test for the depletion of species that hunters killed in numbers greater than what the model predicts to be sustainable. As predicted, we found the strongest evidence for local depletion of the large primates at the Piro site. The woolly monkey ( Lagothrix lagothricha) harvest at the Machiguenga village and the deer ( Mazama americana) and collared peccary (Tayassu tajacu) harvests at both sites were not predicted to be unsustainable and we found no evidence for depletion. Machiguenga bow hunters killed spider monkeys (Ateles paniscus) in quantities that were slightly above what the model predicted to be sustainable, yet we found no evidence for depletion. Differential species vulnerability, catchment size, and consumer population size could be important factors in determining sustainability.     

Radioactivity in the Baltic Sea

The Baltic Sea is, like the Mediterranean, a marginal sea, which with the Black Sea, were marine environments contaminated from the Chernobyl accident.

Radiocaesium and plutonium isotopes were studied in water, sediment and macroalgae in the Baltic Sea since 1982. the inventory of ¹³⁷Cs in the Baltic increased from 0.65 PBq to 5.85 PBq following the Chernobyl accident. the corresponding increase for ^{239 + 240}Pu was less significant and yielded 1.5 TBq to a total value of 16.5 TBq.

For plutonium, 98% is trapped in the sediment and the net-exchange of this element through the Baltic straits is very small (1 GBq/year), while for radiocaesium, 45% is in the water phase and there is a net-loss of 60 000 GBq annually into the adjacent water (Kattegatt).     

Effect of Hunting in Source-Sink Systems in the Neotropics

Abstract: Previous studies of the sustainability of wildlife hunting in the Neotropics have not considered the potential dispersal of animals into hunted areas. A literature review of studies of subsistence hunting in the Neotropics suggests that hunting is often conducted in areas adjacent to relatively undisturbed habitat that may act as sources of animals for the hunted sites. We compared studies of tapir (   Tapirus terrestris ) hunting at different sites to illustrate the potential bias of sustainability evaluations based on local productivity. The limited information available suggests that dispersal could have a key role in rebuilding animal populations depleted by hunting. Thus, factors that strongly affect dispersal—such as spatial distribution and size of areas with and without hunting, population size in source areas, and social behavior—should be considered when the sustainability of hunting is evaluated in areas with heterogeneous hunting pressure. We suggest the application of two models that use spatial controls (recognizing the potential source-sink nature of some hunted systems and protecting unhunted refugia) to avoid wildlife overexploitation when biological data and enforcement capabilities to regulate harvests are limited. This approach may produce more reliable evaluations of sustainability, provide information on the dynamics of hunting systems, and help local communities and policymakers conserve key areas (including protected areas) that may act as game sources.     

Trophy Hunting and Wildlife Conservation in Zambia

For wildlife conservation to succeed in developing countries, people who live in or near protected areas must receive benefits that offset the costs of their reduced access to natural resources. International trophy hunting is currently generating significant economic benefits for residents of game management areas in Zambia. This has been made possible through a revolving fund and an administrative program that direct revenues from trophy hunting to local wildlife management and community development projects. Benefits might be enhanced by better biological information for management, greater local participation in the allocation and operation of hunting concessions, and the promotion of ecological and ethical standards for trophy hunting. An international system of certification for trophy hunting operations could foster these improvements.     

Hunting for Sustainability in Tropical Secondary Forests

Abstract:  The interaction between land-use change and the sustainability of hunting is poorly understood but is critical for sustaining hunted vertebrate populations and a protein supply for the rural poor. We investigated sustainability of hunting in an Amazonian landscape mosaic, where a small human population had access to large areas of both primary and secondary forest. Harvestable production of mammals and birds was calculated from density estimates. We compared production with offtake from three villages and used catch-per-unit-effort as an independent measure of prey abundance. Most species were hunted unsustainably in primary forest, leading to local depletion of the largest primates and birds. The estimated sustainable supply of wild meat was higher for primary (39 kg · km⁻²· yr⁻¹) than secondary forest (22 kg · km⁻²· yr⁻¹) because four species were absent and three species at low abundance in secondary forests. Production of three disturbance-tolerant mammal species was 3 times higher in secondary than in primary forest, but hunting led to overexploitation of one species. Our data suggest that an average Amazonian smallholder would require ≥3.1 km² of secondary regrowth to ensure a sustainable harvest of forest vertebrates. We conclude that secondary forests can sustainably provide only 2% of the required protein intake of Amazonian smallholders and are unlikely to be sufficient for sustainable hunting in other tropical forest regions.     

Hunting and the Likelihood of Extinction of Amazonian Mammals

Species inhabiting tropical forests are thought to be on the verge of mass extinction. Much work has focused on extinction rates caused by deforestation; however, many of the recorded extinctions that have occurred since 1600 were a result of overhunting. We collected data on the relative abundance of large-bodied mammals in the northeastern Peruvian Amazon in areas with persistent hunting pressure and in areas with infrequent hunting pressure. We quantified the effects of hunting by calculating the change in abundance of species between the infrequently and persistently hunted sites. We report that in Amazonian mammals weighing more than 1 kg the degree of population declines caused by hunting is correlated with the species' intrinsic rate of natural increase (r_max  ), longevity, and generation time. Our results show that species with long-lived individuals, low rates of increase, and long generation times are more vulnerable to extinction than species with short-lived individuals, high rates of increase, and shorter generations.     

Incentivizing Monitoring and Compliance in Trophy Hunting

Conservation scientists are increasingly focusing on the drivers of human behavior and on the implications of various sources of uncertainty for management decision making. Trophy hunting has been suggested as a conservation tool because it gives economic value to wildlife, but recent examples show that overharvesting is a substantial problem and that data limitations are rife. We use a case study of trophy hunting of an endangered antelope, the mountain nyala (Tragelaphus buxtoni), to explore how uncertainties generated by population monitoring and poaching interact with decision making by 2 key stakeholders: the safari companies and the government. We built a management strategy evaluation model that encompasses the population dynamics of mountain nyala, a monitoring model, and a company decision making model. We investigated scenarios of investment into antipoaching and monitoring by governments and safari companies. Harvest strategy was robust to the uncertainty in the population estimates obtained from monitoring, but poaching had a much stronger effect on quota and sustainability. Hence, reducing poaching is in the interests of companies wishing to increase the profitability of their enterprises, for example by engaging community members as game scouts. There is a threshold level of uncertainty in the population estimates beyond which the year‐to‐year variation in the trophy quota prevented planning by the safari companies. This suggests a role for government in ensuring that a baseline level of population monitoring is carried out such that this level is not exceeded. Our results illustrate the importance of considering the incentives of multiple stakeholders when designing frameworks for resource use and when designing management frameworks to address the particular sources of uncertainty that affect system sustainability most heavily. Incentivando el Monitoreo y el Cumplimiento en la Caza de Trofeos     

Space-time modeling for the Missouri Turkey Hunting Survey

The Missouri Turkey Hunting Survey (MTHS) is a postseason mail survey conducted by the Missouri Department of Conservation. The 1996 MTHS provides information concerning the number of turkeys harvested by hunters on each day and the total number of trips made to the counties by these hunters on each day of the hunting season. The success rates are then found from this information. Small sample sizes produce large standard errors for the estimates at the county level. We use a Bayesian hierarchical generalized linear model to estimate daily hunting success rates at the county level. The model includes an autoregressive process for the days of the hunting season and spatially correlated random geographic effects. The computations are performed using Gibbs sampling and adaptive rejection sampling techniques. Results show that there are significant spatial corelations between counties and correlations between days of the hunting season. The estimates are close to the frequency estimates at the state level and much more stable at the county level.     

New indicator species in the Baltic zooplankton in 1972

The occurrence of zooplankton species, indicating a salinewater influx from the North Sea into the Baltic Sea in 1972, is described. Particular attention is paid to 8 species so far unknown in this region (Ectopleura dumortieri, Rosacea plicata, Tomopteris kefersteini, Aetideus armatus, Centropages typicus, Eucalanus elongatus, Metridia lucens, Electra pilosa). The appearance of these zooplankters in the Southern Baltic Sea is discussed in relation to the hhdrographic changes taking place in this area in 1972. Based on these data, assessments are made regarding the intensity of dynamic exchange processes in the Baltic and North Atlantic waters in 1972.