Overhunting of mammals may negatively affect plant populations though indirect impacts on mammal-plant interactions such as herbivory. In this paper, we examined how hunting of terrestrial mammals impacts the survival...Overhunting of mammals may negatively affect plant populations though indirect impacts on mammal-plant interactions such as herbivory. In this paper, we examined how hunting of terrestrial mammals impacts the survival of seedlings and juveniles of the palm Astrocaryum gratum. To determine A. gratum seedling survivorship patterns, an experiment with seedlings in 25 × 250-m plots exclosures and different levels of mammal species presence was conducted: all mammals, only Tayassu peccari potentially a major seedling predator and no animals excluded. More than 50,600 non-adults were measured for 27 months. We replicated these treatments in three forest categories: 1) no hunting, with an intact mammal community, 2) a lightly hunted region and 3) a heavily hunted area. Seedling survivorship under natural non-experimental conditions was highest in the heavily hunted (S(T) = 0.72), lower in moderate and lowest in unhunted forests. Experiments revealed that T. peccari was the main agent of palm seedling mortality and the most important factor determining seedling and juvenile survivorship, for example they caused the 84.61% deaths of the seedlings in unhunted forests. Thus, T. peccari feeding habits can influence forest dynamics and forest structure. T. peccari was also susceptible to hunting pressure and as the main seed and seedling predator in the system, its extinction should affect the survivorship and distribution of A. gratum in forests.展开更多
The white-lipped peccary (Tayassu pecari) is facing range-wide declines throughout the Neotropics. It has been eliminated from about 89% of its historical range in Costa Rica. Corcovado National Park, in the Osa Penin...The white-lipped peccary (Tayassu pecari) is facing range-wide declines throughout the Neotropics. It has been eliminated from about 89% of its historical range in Costa Rica. Corcovado National Park, in the Osa Peninsula of Costa Rica, is the last remaining stronghold for the white-lipped peccary in the country. In 2013, the Park experienced a sudden gold rush that brought with it a wave of 250 miners and vigorous hunting pressures on the population. Given that the species is endangered and is susceptible to hunting due to its herding behavior and tendency to cohere and attack when threatened rather than flee, it is important to assess its probability of extinction under various hunting scenarios. Incorporating data from studies on the life history of the species throughout its range in the Neotropics and in Corcovado, I used the population viability analysis software VORTEX to simulate the population trajectories and probabilities of extinction of the species under current hunting pressures and under various management scenarios. The results of this study revealed that under the 2013 scenario where 250 miners were present in the Park, the population of white-lipped peccaries has a about a 40% chance of extinction within five years and about a 99% chance of extinction within 10 years. Moreover, there is an “extinction threshold” for the population between the presence of 100 and 150 miners hunting in the Park. At this threshold, the population growth rate, r, drops from a positive growth rate (r = 0.09, SD = 0.08) to a negative one (r = -0.07, SD = 0.29). I suggest that anti-mining and anti-poaching laws be enforced immediately, and that the number of miners be reduced to 100 at a minimum, if not completely, in order to ensure that the population of white-lipped peccaries becomes viable and evades a local extinction.展开更多
The trade creation and conservation of wild species in Amazon, including collared peccaries （Pecari tajacu）, may be favored by artificial insemination, but the time of semen storage may lead to reduced fertility in ...The trade creation and conservation of wild species in Amazon, including collared peccaries （Pecari tajacu）, may be favored by artificial insemination, but the time of semen storage may lead to reduced fertility in sperm of some wild animals. Thus, the aim of this research was to evaluate the influence of semen storage at 17 ℃ over time on seminal features of peccaries in captivity. Eight adult males were sedated and underwent electroejaculation. The ejaculates （n = 65） were evaluated for volume, concentration, pH, sperm motility, vigor, and cell with intact plasma membrane intact （IPM） and sperm morphology. Selected ejaculates （n = 21） were diluted （1：1） in Beltsville Thawing Solution and kept during 48 hours under controlled temperature （17 ℃）. Assessments were made after dilution （TO）, after 24 hours （T24）, and 48 hours after the onset of cooling （T48）. The storage impacted on sperm survival （P 〈 0.05）. Semen characteristics changed throughout the storage period studied and after 48 hours storage. The decline of sperm motility was of 55.2% for 10.9%, vigor was 2.3 for 0.5 and IPM cells were of 59.0% for 15.8%. Primary defects sperm increased of 19.8% for 32.2%, secondary defects of 9.8% for 10.4% and total defects of 29.4% for 42.7%. However, within 24 hours of preservation, chilled semen peccaries presented sperm motility average rate and IMP cells levels indicative to use in assisted reproductive events. These results indicate chilled semen for 24 hours could be used in experimentally artificial insemination of peccaries, technology that still has not been performed before.展开更多
文摘Overhunting of mammals may negatively affect plant populations though indirect impacts on mammal-plant interactions such as herbivory. In this paper, we examined how hunting of terrestrial mammals impacts the survival of seedlings and juveniles of the palm Astrocaryum gratum. To determine A. gratum seedling survivorship patterns, an experiment with seedlings in 25 × 250-m plots exclosures and different levels of mammal species presence was conducted: all mammals, only Tayassu peccari potentially a major seedling predator and no animals excluded. More than 50,600 non-adults were measured for 27 months. We replicated these treatments in three forest categories: 1) no hunting, with an intact mammal community, 2) a lightly hunted region and 3) a heavily hunted area. Seedling survivorship under natural non-experimental conditions was highest in the heavily hunted (S(T) = 0.72), lower in moderate and lowest in unhunted forests. Experiments revealed that T. peccari was the main agent of palm seedling mortality and the most important factor determining seedling and juvenile survivorship, for example they caused the 84.61% deaths of the seedlings in unhunted forests. Thus, T. peccari feeding habits can influence forest dynamics and forest structure. T. peccari was also susceptible to hunting pressure and as the main seed and seedling predator in the system, its extinction should affect the survivorship and distribution of A. gratum in forests.
文摘The white-lipped peccary (Tayassu pecari) is facing range-wide declines throughout the Neotropics. It has been eliminated from about 89% of its historical range in Costa Rica. Corcovado National Park, in the Osa Peninsula of Costa Rica, is the last remaining stronghold for the white-lipped peccary in the country. In 2013, the Park experienced a sudden gold rush that brought with it a wave of 250 miners and vigorous hunting pressures on the population. Given that the species is endangered and is susceptible to hunting due to its herding behavior and tendency to cohere and attack when threatened rather than flee, it is important to assess its probability of extinction under various hunting scenarios. Incorporating data from studies on the life history of the species throughout its range in the Neotropics and in Corcovado, I used the population viability analysis software VORTEX to simulate the population trajectories and probabilities of extinction of the species under current hunting pressures and under various management scenarios. The results of this study revealed that under the 2013 scenario where 250 miners were present in the Park, the population of white-lipped peccaries has a about a 40% chance of extinction within five years and about a 99% chance of extinction within 10 years. Moreover, there is an “extinction threshold” for the population between the presence of 100 and 150 miners hunting in the Park. At this threshold, the population growth rate, r, drops from a positive growth rate (r = 0.09, SD = 0.08) to a negative one (r = -0.07, SD = 0.29). I suggest that anti-mining and anti-poaching laws be enforced immediately, and that the number of miners be reduced to 100 at a minimum, if not completely, in order to ensure that the population of white-lipped peccaries becomes viable and evades a local extinction.
文摘The trade creation and conservation of wild species in Amazon, including collared peccaries （Pecari tajacu）, may be favored by artificial insemination, but the time of semen storage may lead to reduced fertility in sperm of some wild animals. Thus, the aim of this research was to evaluate the influence of semen storage at 17 ℃ over time on seminal features of peccaries in captivity. Eight adult males were sedated and underwent electroejaculation. The ejaculates （n = 65） were evaluated for volume, concentration, pH, sperm motility, vigor, and cell with intact plasma membrane intact （IPM） and sperm morphology. Selected ejaculates （n = 21） were diluted （1：1） in Beltsville Thawing Solution and kept during 48 hours under controlled temperature （17 ℃）. Assessments were made after dilution （TO）, after 24 hours （T24）, and 48 hours after the onset of cooling （T48）. The storage impacted on sperm survival （P 〈 0.05）. Semen characteristics changed throughout the storage period studied and after 48 hours storage. The decline of sperm motility was of 55.2% for 10.9%, vigor was 2.3 for 0.5 and IPM cells were of 59.0% for 15.8%. Primary defects sperm increased of 19.8% for 32.2%, secondary defects of 9.8% for 10.4% and total defects of 29.4% for 42.7%. However, within 24 hours of preservation, chilled semen peccaries presented sperm motility average rate and IMP cells levels indicative to use in assisted reproductive events. These results indicate chilled semen for 24 hours could be used in experimentally artificial insemination of peccaries, technology that still has not been performed before.
