t i o n . T h e s e r e s u l t s i n d i c a t e t h a t t h e conser vation of tamaraw in the
No abstract
Fecal DNA analysis is a useful tool for the investigation of endangered species. Tamaraw (Bubalus mindorensis) is endemic to the Philippine island of Mindoro but knowledge of its genetic and ecological information is limited. In this study, we developed a species identification method for tamaraw by fecal DNA analysis. Eighteen feces presumed to be from tamaraw were collected in Mount Iglit-Baco National Park and species-known feces from domestic buffaloes and cattle were obtained from a farm. Additionally, one species-unknown fecal sample was obtained in Mount Aruyan Preserve, where the sighting of tamaraw has not been reported in recent years. Based on DNA sequence data previously reported, the genus Bubalus- and tamaraw-specific primers for PCR of cytochrome b gene were newly designed. The Bubalus-specific primer yielded a 976 bp fragment of cytochrome b for all fecal samples from tamaraw and domestic buffaloes, but not for cattle, whereas the tamaraw-specific primer yielded a 582 bp fragment for all tamaraw fecal samples and for one of the four domestic buffalo samples. PCR-RFLP (restriction fragment length polymorphism) analysis of the 976 bp PCR fragment with AvrII or BsaXI provided distinct differences between tamaraw and domestic buffalo. PCR-RFLP analysis also showed that the species-unknown sample obtained in Mount Aruyan Preserve, originates from tamaraw.
The Critically Endangered tamaraw Bubalus mindorensis is endemic to Mindoro Island, Philippines, and little is known of its ecology. During 2006-2011 we used community-based monitoring to examine the population status and ecology of tamaraw in the species' core habitat of Mount Iglit-Baco National Park. Each year, for 5 consecutive days at the end of the dry season, trained local volunteers and rangers or project staff were allocated to 18 vantage points in the study area (c. 160 km 2 ). Tamaraw were categorized as adult (. 5 years), juvenile (2-5 years) or calf (, 2 years), and sexed when possible. During the study period the population was 239-314 (mean 271), with no significant fluctuations in age structure (percentage of adults, juveniles and calves: 57.8, 21.0 and 21.3%) or estimated adult female reproductive rates (29.1%). In adults, but not in juveniles, the sex ratio was biased towards females (1 : 1.86, P , 0.01). Bulls were often solitary (32.2% of sightings), whereas the majority of cows (94.7%) formed small groups of 2-12 individuals of different ages, with or without bulls (53.4 and 46.6%, respectively). These results demonstrate that the population remained relatively stable, maintaining a constant age structure and reproductive rate, and that long-term community-based monitoring was effective for quantitative characterization of the tamaraw's social behaviour, which is critical for conservation and management of the species.
Endangered species, despite living at low population density, may undergo 2 density-dependent feed-backs in case of successful recovery or marked reduction in range. When at work, density-dependence dynamics increases extinction risks 4 and hamper conservation efforts. The last population of the critically endangered tamaraw (Bubalus mindorensis) lives on a < 3, 000ha in Mounts Iglit-Baco 6 Natural Park (MIBNP) with very limited expansion possibilities. Tamaraw abundance has been monitored on a yearly basis from animal counts by 8 Philippine authorities since the year 2000. Consistent with its protected status by law, the MIBNP tamaraw population has been increasing in size at an average 10 rate of +6% per year, which we found to be relatively low compared to other similar-sized Bovinea species. Population growth was strikingly spatially 12 structured within MIBNP with a population growth close to +16% in the core area of protection, while a reduction of abundance of −27% was measured at the 14 periphery of the species range inside MIBNP. Highly concerning is the fact that the annual population growth rate progressively decreased significantly over the 16 years since 2008, which we interpreted as an evidence of density-dependence. This isolated tamaraw population is currently experiencing a contraction of its 18 range at MIBNP, likely caused by anthropogenic pressures forcing large herbivores to live at relatively high density in the core zone of the monitoring 20 where protection is most effective. Our study highlights that beyond the encouraging results of a continuous growth over the last two decades, the 22 MIBNP tamaraw population remains subject to uncertainty of its long term viability. 24 14 is a decrease of the population growth at low population abundance (i.e. demographic component, see Stephens et al. (1999)). On the other hand, 16 classical density-dependent effects, the decrease of the population growth rate with density (Nicholson 1933), on population dynamics are often overlooked in 18 conservation because they are a priori expected to occur at high population abundance. Increasing density in populations of endangered species may, 20 however, occur incidentally following a range reduction caused by habitat loss or successful protection measures, and in turn triggers undesirable ecological 22 consequences for its conservation.Density-dependence is a pervasive demographic responses among large
Endangered species, despite often living at low population densities, may undergo unexpected density‐dependent feedbacks in the case of successful recovery or marked reduction in range. Because density‐dependence dynamics can increase risk of extinction, these effects can hamper conservation efforts. In this study, we analyze the dynamics of the largest population of the tamaraw Bubalus mindorensis, a critically endangered ungulate species endemic to Mindoro island, Philippines. The population is located within a <3000 ha area in Mounts Iglit‐Baco Natural Park, with limited expansion possibilities. We took advantage of a 22 year time series of tamaraw counts to estimate annual population growth rate and possible density‐dependence, accounting for sampling errors in the counts. The tamaraw population has been increasing at an average rate of +5% per year, as would be expected given its protected status by law. Population growth showed strong spatial structuring, with a population growth close to +10% in the core area of protection, and a reduction of abundance of −5% at the periphery of its range, inside the protected area. This range constriction is concerning because our best population dynamics model suggests significant negative density‐dependence (Bayes factor = 0.9). The contraction of tamaraw range is likely caused by anthropogenic pressures forcing the species to live at relatively high densities in the core zone where protection is most effective, creating source‐sink dynamics. Our study highlights the fact that, despite the continuous population growth over the last two decades, the long‐term viability of the Mounts Iglit‐Baco Natural Park tamaraw population remains uncertain.
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