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Tropical Conservation Science
December 2014 | Vol. 7 | Issue 4 | pages 597 - 828

Photo by Torrey W. Rodgers

Research Articles
    Mapping threatened dry deciduous dipterocarp forest in South-east Asia for conservation management
    pp 597-613
    Christian Wohlfart, Martin Wegmann, Peter Leimgruber
    The loss of habitat and natural ecosystems is the primary reason for species extinction, making habitat conservation an important subject for maintaining global biodiversity. Major habitat types, such as tropical evergreen forests or mangrove forests, are already well covered by conservation activities, while others remain little protected. One example is dry deciduous forests (DDF), a forest type in Asia that occurs in regions with high temperatures and a pronounced dry season. This forest type harbors a wide range of important und rare species and there is need to include DDF adequately in biodiversity conservation strategies. Currently, South-east Asia is facing an increasing socio-economic change: countries like Myanmar and Cambodia have recently become more engaged within the international community, leading to widespread changes in society, economy and also large portions of their physical environment. These countries still hold vast intact forests, but the increasing demand for timber has resulted in intense logging activities, and DDF are threatened by these trends. To effectively plan conservation activities, detailed and accurate maps are necessary. So far, no such maps for DDF throughout South-east Asia are available. This study provides a reliable distribution map of DDF for South-east Asia on continental and regional scales, assessing the extent of the forest as well as the protection status. In Myanmar, for example, we could show that large areas of DDF still exist, but fewest protected areas. To protect the remaining dry deciduous forest and conserve suitable habitat for the species living there, these countries need effective regulations and law enforcement that promote sustainable resource use.

    Invasive house (Rattus rattus) and brown rats (Rattus norvegicus) threaten the viability of red-billed tropicbird (Phaethon aethereus) in Abrolhos National Park, Brazil
    pp 614-627
    Raissa Sarmento, Daniel Brito, Richard James Ladle , Gustavo da Rosa Leal and Marcio Amorim Efe
    Red-billed Tropicbird is a tropical seabird, with a colonial behavior and late sexual maturation, which means they take a long period to become adults. Abrolhos National Park hosts the only significant breeding colony of Red-billed Tropicbird in Brazil, where the species is considered nationally threatened. Currently, Abrolhos archipelago is infested by two invasive species of rat. Both have the potential to dramatically reduce a seabird population as they eat their eggs and chicks. In this study, we conducted a population viability analysis - a widely used tool in conservation to assess extinction risk and guide conservation actions - in order to estimate the extinction probability of Red-billed Tropicbird in Abrolhos and the potential long term impacts of the rats. Our results suggest that the future of this population is uncertain due to the increasing rates of rat predation. The population faces a high risk of decline, with a probability of extinction in the next 75 years of 57.5%. In this context, we recommend the implementation of a management program to completely eradicate rats from Abrolhos. Besides direct eradication, effective conservation actions may also include sewage treatment and reduction of garbage generated by island residents and tourists, which are used as food source by rats.

    Rediscovery of the critically endangered streamside frog, Craugastor taurus (Craugastoridae), in Costa Rica
    pp 628-638
    Gerardo Chaves, Héctor Zumbado-Ulate, Adrián García-Rodríguez, Edwin Gómez, Vance Thomas Vredenburg and Mason J. Ryan
    Amphibian declines have affected populations worldwide affecting approximately 40% of the species and causing the extinction of at least 200 species. There are many examples of declines that even occurred in pristine environments, therefore which they are consider as enigmatic. These decline are characterized by its severity and rapid occurrence and became more evident during the 1980’s decade. In the tropics, most affected species are associated with riparian habitats and altitudes above 500 m. Several causes have been proposed to explain these enigmatic declines, being the most important emerging diseases and global warming. In 1987 the amphibian decline crisis reached its apex in Costa Rica when at least 17 species experienced population crashes and subsequently went undetected for decades. The emerging disease chytridiomycosis caused by a chytrid fungus has been proposed as the main cause of these disappearances. In the last few years, some affected species have recovered and some believed-to-be extinct species have been rediscovered. Here we present the rediscovery of the South Pacific streamside frog Craugastor taurus in southeastern Costa Rica, representing the first sighting after fifteen years of searching. The new populations here described occur in the driest section within the historical range, which might suggest that specific environmental conditions of this region could allow this frog to survive and coexist with the pathogenic fungus; however, more research in needed to test this hypothesis.

    Does a native grass (Imperata brasiliensis Trin.) limit tropical forest restoration like an alien grass (Melinis minutioflora p. Beauv.)?
    pp 639-656
    Ricardo Gomes César, Ricardo Augusto Gorne Viani, Milena Candido da Silva and Pedro Henrique Santin Brancalion
    About one third of all deforested areas in Brazil are occupied by low intensity pasture. Given the low opportunity costs and an increase in enforcement of environmental laws in Brazil, many restoration projects are being carried out in abandoned pastures, which are currently occupied by different grass species. Grasses are a big problem for forest restoration, since they are good at competing against planted seedlings for water, light and soil nutrients. However, little is known if different grass species affect forest restoration differently. In order to approach this question, we analyzed the effect of satintail (a native grass that naturally occurs in Brazil) and molasse grass (a widespread exotic grass used as cattle fodder) in tree seedlings in a pasture under restoration in Brazil. Our results showed that the survival and growth of planted tree seedlings and the number of tree seedlings sprouting under artificial perches were similarly affected by both grasses, regardless of being native or exotic. Additionally, the density of seedlings sprouting naturally in the pasture was also similarly affected by both grass species. However, the most interesting result was that tree seedling species in both grasses differed, indicating that there may be certain tree species that are more fit to overcome the competition with specific grass species.

    Riparian deforestation affects the structural dynamics of headwater streams in Southern Brazilian Amazonia
    pp 657-676
    Monica Elisa Bleich, Amanda Frederico Mortati, Thiago André and Maria Teresa Fernandez Piedade
    Deforestation of small streams compromises Amazonian waterways maintenance. By comparing headwater habitats of streams at Southern Brazilian Amazonia between preserved and deforested sites, it was demonstrated that streams in deforested areas have altered habitat characteristics. When Southern Brazilian Amazonian streams are not protected by forest there is lower oxygen concentration and an increase in water temperature. These results indicate alterations in habitat quality and show the influence of the surrounding forest on streams. Forest preservation contributes to streams protection, and also provides a supply of organic material, important for maintaining the aquatic ecosystem, which includes shelter and food for aquatic fauna inhabiting headwater streams in Southern Brazilian Amazonia.

    Phylogenetic position of the most endangered Chilean bird: the Masafuera Rayadito (Aphrastura masafuerae; Furnariidae)
    pp 677-689
    Javier Gonzalez
    The Masafuera Rayadito is endemic to the Pacific island Alejandro Selkirk (Juan Fernández Archipelago, Chile), a steep island of volcanic origin located 835 km west of South America. This fragile bird is declared a Critically Endangered species by the International Union for Conservation of Nature (IUCN) and was thought to be extinct in 1980, however, later estimates range from 140 (in 2002) to 500 individuals (in 2006–2007). Using mitochondrial DNA sequences obtained from blood samples, this study reports for the first time the genetic differences of the species compared to its sister species, the widespread Thorn-tailed Rayadito on the mainland. The genetic data also show that the Masafuera Rayadito colonized Alejandro Selkirk probably during the Pleistocene 600,000 years ago. Usually found in dense vegetation cover, the Masafuera Rayadito is a small, buff-brownish bird characterized by reddish spine-like tail feathers and a light superciliary stripe. The grazing of goats and cattle has increased habitat loss for the species. Other threats are lack of nesting sites, introduced species such as feral cats and rats, and increased populations of natural predators like the Masafuera Hawk. Supporting the high conservation priority of the species and coupled with its small population size and restricted distribution on a remote island, the special phylogenetic position of the Masafuera Rayadito makes this bird to contribute importantly to the diversity within the furnariids, a large family of neotropical birds

    Comparison of noninvasive genetics and camera trapping for estimating population density of ocelots (Leopardus pardalis) on Barro Colorado Island, Panama
    pp 690-705
    Torrey W. Rodgers, Jacalyn Giacalone, Edward J. Heske, Jan E. Janečka, Christopher A. Phillips and Robert L. Schooley
    For threatened and endangered species, knowledge of population density, or how many animals live in a given area, is vital for the success of conservation. Many carnivore species are elusive and difficult to observe, however, so for these species population density is often unknown. One promising method for estimating population density from elusive carnivores is the use of trace amounts of DNA left behind in their feces. This method is known as noninvasive genetic sampling. DNA from feces can be used to identify individual animals using DNA ‘fingerprinting’, and from this the number of individuals living in a given area can be estimated. This technique is relatively new, however, and its accuracy has seldom been tested in the field. To test the accuracy of this technique we conducted a study of ocelots, an elusive small cat species, on Barro Colorado Island in the republic of Panama. We estimated population density of ocelots using noninvasive genetics, while also estimating density using camera trapping, a more commonly used and trusted method. We found that population density estimated by noninvasive genetics was highly similar to population density estimated from camera trapping. As a result we conclude that noninvasive genetic sampling is a valid and accurate technique for estimating population density of elusive carnivore species. Thus noninvasive genetic methods have the potential to contribute to the conservation of threatened and endangered carnivore species worldwide. In addition, we also documented the highest density of ocelots ever recorded, at approximately 1.6 animals per square kilometer.

    Ecology and conservation of the endangered Indochinese freshwater pearl mussel, Margaritifera laosensis (Lea, 1863) in the Nam Pe and Nam Long rivers, Northern Laos
    pp 706-719
    Ivan Bolotov, Ilya Vikhrev, Yulia Bespalaya, Valentina Artamonova, Mikhail Gofarov, Julia Kolosova, Alexander Kondakov, Alexander Makhrov, Artyom Frolov, Sakboworn Tumpeesuwan, Artyom Lyubas, Tatyana Romanis, Ksenya Titova
    The freshwater pearl mussel family Margaritiferidae is small family of bivalves which inhabits rivers with fast flow, clean cold water and riffles. But only Indochinese pearl mussel, Margaritifera laosensis, inhabits tropical river systems. The species was described by Dr. Isaak Lea in 1863. Lea had only two specimens for description. It seems he had not clear information about specimen origin, and located it within “Laos Mountains, Cambodia, Siam”. First reliable data about live specimens were reported by Moris Kottelat in 2009. He obtained few individuals from Nam Long River.We detected M. laosensis in two of 10 tributaries of the Nam Ou River in 2012. As a result, first description of the habitat and ecology of M. laosensis was obtained. Specimens were found only in the Nam Long and Nam Pe rivers. Margaritifera laosensis has similar substrate and depth preferences as other Margaritiferidae including the Holarctic M. margaritifera. The presence of live small-sized mussels in the Nam Long and Nam Pe rivers suggests recent recruitment in these populations.The most significant threats to M. laosensis populations are harvest by local people and land development in the River Nam Ou Basin. As has been advocated for other Margaritiferidae, an integrative conservation strategy that identifies and sustains ecological processes and evolutionary lineages is urgently needed to protect and manage this imperiled species.The conservation measures could not only restore mussel populations but will resonate with local communities: more clear water for home needs, longer periods of navigable water and increase in fish catch.

    Evidence for an edge effect on avian nest predation in fragmented afromontane forests in the Bamenda-Banso Highlands, NW Cameroon
    pp 720-732
    Ondřej Sedláček, Martin Mikeš, Tomáš Albrecht, Jiří Reif and David Hořák
    Nest predation is the leading cause of reduced reproductive success in birds. Habitat loss and fragmentation may either directly or indirectly affect avian nest survival due to altered predation pressure on nests. In the present study we asked: (i) if the overall predation rate on nests differs between the fragmented landscape and the large continuous block of montane forest, (ii) if the artificial nests experience higher predation at forest edges than nests in the forest interior, and (iii) whether the montane forest fragmentation influences the predation rate at the edges. To address these questions, we conducted experiments using artificial nests that imitated real nests of birds confined to montane forest undergrowth in the Bamenda-Banso Highlands, the NW region of Cameroon, an endemic bird area of high conservation priority. We found equal overall predation rates in the large forest block as well as in the landscape consisting of small forest fragments. However, predation was higher close to forest edges in the small forest remnants. Since such remnants represent the majority of local montane forests, this result suggests that the edge effect on bird nest predation may reduce nest survival and the population viability of many globally endangered range-restricted birds. Conservation actions should aim to eliminate further deforestation of the area, especially due to uncontrolled bushfires, and to conserve the last larger forest patches and try to maintain their shape as circular as possible to decrease the edge-area ratio.

    Termite mound identification through aerial photographic interpretation in Lubumbashi, Democratic Republic of the Congo: methodology evaluation
    pp 733-746
    Isabelle Vranken, Marielle Adam, Basile Mujinya Bazirake, François Munyemba Kankumbi, Geert Baert, Eric Van Ranst, Marjolein Visser and Jan Bogaert
    In woodland and savannah areas, some termite species play an important environmental role because of the mounds they build. These mounds can also be used as fertilisers in agriculture and termites can be studied to evaluate the impacts of human activities on the environment because they are very sensitive to it. However, the study of termites on large areas can be very costly. The objective of our study is minimizing costs for preliminary studies and spot smaller areas that would need to be studied more deeply in the field. To do so, we propose to spot termite mounds directly on free Google Earth images. We did this in the periphery of Lubumbashi, Democratic Republic of the Congo. This city faces food insecurity, fast urban growth and nearby deforestation, so termites in the area can be useful, but also menaced. To test if our method was effective to identify termite mounds, we also visited the area and identified each termite mound and its position. We then compared the results of this field survey with the ones obtained on Google Earth images using statistical tests. We concluded that this method of aerial photography interpretation was satisfying to identify the number and general positioning of the termite mounds. This represents enough information to spot suitable areas for further study. Therefore, our method can help reduce costs for other studies on termites in woodland sand savannahs.

    Plant biomass density as an indicator of food supply for elephants (Loxodonta africana) in Waza National Park, Cameroon
    pp 747-764
    Martin N. Tchamba, Robert B. Weladji, Désiré Foguekem and Mike Loomis
    The Waza National Park (WNP) was set aside for the conservation of wildlife biodiversity, including the elephant population. Elephant population has decreased in recent years by more than 75%, indicating that the Waza elephants are facing serious threats, specifically from poaching for ivory. Moreover, persistent excursions of elephants at the beginning of the dry season, is resulting in an increase of human-elephant conflicts in areas around the park, for unknown reasons. In order to determine whether the dry season migration of elephants outside WNP is due to a lack of sufficient forage inside the park, we assessed the food supply potentially available to the elephants within the WNP during the dry season, by estimating the biomass of available potential food plants. The aboveground biomass of trees in the Woodland and Acacia seyal shrubland zones, were 16.87 tonsDM/ha and 10.99 tonsDM/ha respectively (mean 13.93 ± 4.16 tonsDM/ha). Aboveground biomass density in the herbaceous layer was 2.62, 4.21 and 6.9 tonsDM/ha, in the Woodland, Acacia seyal shrubland and Floodplain zones, respectively (mean 4.58 ± 2.16 tonsDM/ha). The overall aboveground plant biomass density of the park averaged 13.86 ± 6.4 tonsDM/ha, however the harvestable food supply for elephants was a small portion of that estimate. Our findings may partly explain the migratory status of at least some of the individuals leaving the park every year and returning to the WNP in a potentially seasonal migratory pattern. To minimize elephant encroachment into cultivated fields, it is necessary to estimate the park’s carrying capacity and regulate the population size if necessary. This however will rely on the long-term prediction of forage production in the WNP through continuous measurements of plant biomass density during the dry season.

    Local people’s attitudes and perceptions of dholes (Cuon alpinus) around protected areas in southeastern Thailand
    pp 765-780
    Kate E. Jenks, Nucharin Songsasen, Budsabong Kanchanasaka, Peter Leimgruber and Todd K. Fuller
    What is a dhole? You may never have heard of a dhole (also known as an Asian wild dog), but they are important predators in tropical forests and grasslands of Southeast Asia. Dholes are social and live in packs, working together to bring down medium to large ungulate prey. In some areas, where tigers and leopards are now gone, dholes may be the only carnivore left that is large enough to prey on deer. However, dholes are quietly disappearing too. In the past, dholes were persecuted by humans because people blamed them for killing livestock. We interviewed people living next to protected forest areas in Thailand to assess local knowledge about dholes and perceptions of dholes as “nuisance” predators. Most people had trouble identifying photographs of dholes, and consistently confused dholes with jackals. Still, we are cautiously optimistic because overall there were a large number of people who held positive attitudes towards dholes, no reports of dhole attacks on humans, and very few reports of livestock predation by dholes. This is a positive social climate to boost awareness for this endangered species.

    Local perceptions of wildlife use in Los Petenes Biosphere Reserve, Mexico: Maya subsistence hunting in a conservation conflict context
    pp 781-795
    Malena Oliva, Salvador Montiel, Ana García and Laura Vidal
    In this study, we analyze the conservation conflict associated with subsistence hunting in two Maya communities located in the zone of influence of Los Petenes Biosphere Reserve, Mexico. Perceptions and expectations of stakeholders regarding subsistence hunting in the reserve were recorded through ethnographic techniques as semi-structured and in-depth interviews, applied to peasant-hunters and reserve authorities. We also carried out participant observation in each community. Peasant-hunters identified in both communities acknowledged hunting for family subsistence and expressed the conviction to continue hunting in the region. They also mentioned their enthusiasm for hunting white-tailed deer and perceived a recent reduction in prey locally. Although the law in Mexico does not prohibit subsistence hunting, external authorities stated that they have announced a generalized ban on hunting based on the precautionary principle to simplify enforcement both inside and outside the reserve. The de facto restriction on wildlife use, even for subsistence purposes, conflicted with the local need and expectation of the contemporary Maya hunters to continue subsistence hunting in the region. Our study provides valuable information for managing this conservation conflict in Los Petenes Biosphere Reserve and for decision-making in other protected areas of Mesoamerica, where natural resources management and conservation involve traditional practices for subsistence of local populations.

    Short-term success in the reintroduction of the red-humped agouti Dasyprocta leporina, an important seed disperser, in a Brazilian Atlantic Forest reserve
    pp 796-810
    Bruno Cid, Luiza Figueira, Ana Flora de T. e Mello, Alexandra S. Pires and Fernando A. S. Fernandez
    Agoutis are considered forest gardeners due to their habit of burying large seeds for later consumption; some of these seeds are not recovered and originate new trees. In many localities, however, these animals have disappeared due to habitat fragmentation and hunting, compromising the regeneration of these trees. In these localities, the reestablishment of this process can be achieved through the release of individuals of the species. We have reintroduced the agouti Dasyprocta leporina in Tijuca National Park, Rio de Janeiro city, Brazil, where the species had been locally extinct for several decades. We captured individuals from a semi-captive population and after a quarantine period in the Zoo, they were acclimatized to the forest in a fenced pen previously to release. Additionally, food supplementation was provided after animals leave the pen. We released four males and seven females, all equipped with radio-transmitter collars. The survival of released individuals was high, animals established home ranges and 10 nature-born cubs were observed. Thus the reintroduction was considered successful in the short-term. Besides, animals consumed fruits and seeds of 10 species and buried seeds of three of them. The buried seeds are from animal-dispersed large-seeded trees, thus helping to restore plant reproduction in this impoverished forest. We suggested several improvements in the procedures, which can be useful to replicate reintroductions elsewhere, as a tool to restore ecological process in the beleaguered Atlantic Forest biome.

    The value of including intraspecific measures of biodiversity in environmental impact surveys is highlighted by the Amazonian brilliant-thighed frog (Allobates femoralis)
    pp 811-828
    Pedro Ivo Simões, Adam Stow, Walter Hödl, Adolfo Amézquita, Izeni P. Farias and Albertina P. Lima
    In recent years, large infrastructure projects such as roads and new power plants have been developing rapidly in Brazilian Amazonia. At the same time, environmental legislation has been amended in order to provide guidelines to studies targeting at assessing environmental impacts of these developments on wild species and reporting potentially vulnerable ones. However, despite their immense value for protecting endangered and endemic species, these new regulations still overlook important components of biodiversity, such as the variability in genetic and behavioral traits that exist among groups of individuals of species that occupy wider geographic ranges. As many authors support, such variability might be crucial to a species ability to survive and to thrive in the face environmental change. In this study, we discuss the shortcomings of not updating environmental licensing legislation, while reporting that areas soon to be impacted by damming of one the Amazon’s largest tributaries, the Xingu River, are inhabited by genetically unique populations of a diurnal amphibian, the brilliant-thighed frog (Allobates femoralis). Frogs inhabiting these areas also emit calls that are very distinct from the ones heard among individuals of the same species recorded in other parts of the Amazonian lowlands. Additionally, we show that other large tributaries of the Amazon River also separate brilliant-thighed frogs which are genetically distinct, despite identical in terms of their repertoire of calls. We suggest that Brazilian environmental licensing regulations should be amended in a way that guarantees that such cases of intraspecific diversity is protected or, at least, acknowledged.

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