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Tropical Conservation Science - Summaries for the December 2013 issue

Conservation Letter
    Biodiversity persistence in highly human-modified tropical landscapes depends on ecological restoration
    pages 705-710
    Pedro H. S. Brancalion, Felipe P.L. Melo, Marcelo Tabarelli, Ricardo R. Rodrigues
    Tropical forests are recognized for harboring a great variety of plants and animals threatened to disappear forever as a result of human negative interventions on natural ecosystems. The intense and recent process of deforestation for expanding agriculture and cities has beleaguered biodiversity to very small forest fragments, with insufficient size for the survivorship of many native species. To aggravate the problem, a large portion of these species have difficulties to move to other forest fragments to seek partners, shelter, and food, since these species are not adapted for crossing the agricultural fields and cities that separates these fragments. Thus, there is an imminent risk of extinction of many species in the future. In this context, we suggest that the recuperation of native forests by humans, which can be attained by several methods such as tree seedling plantings and active encouragement of naturally regenerating seedlings, can be an alternative to support the maintenance of native species in regions dominated by agriculture and cities. Although forests recuperated with the assistance of men are not equivalent to those generated by nature in the last centuries, they can ease the mobility of biodiversity from one fragment to the other and increase the quality of these fragments by establishing protective barriers. Thus, we need to consider the restoration of native forests in degraded lands, and not only the conservation of existent forests, in order to keep biodiversity in regions dominated by men.

Research Articles
    Tree cavity-using wildlife and the potential of artificial nest boxes for wildlife management in New Guinea
    pages 711-733
    Diat Warakai, Daniel Solomon Okena, Paul Igag, Muse Opiang, and Andrew L. Mack
    Tree hollows provide an important resource to many birds and mammals as nest and den sites. In New Guinea this relationship has not been studied, so there is little information on what species used cavities, how common cavities are, and whether animals will use artificial nest boxes as an alternative to natural cavities. We found about 24% of terrestrial mammals and 18% of terrestrial birds are known to use cavities. In a detailed survey of two hectares of forest where every tree was felled and examined, we found 26 cavities in primary forest and none in secondary forest. Cavities were predominantly in large, older trees. Thus logging is likely to greatly reduce availability of nest and den sites. A few mammal species, particularly cuscuses and sugar gliders, readily occupied artificial nest boxes among 190 boxes monitored. This study indicates that more research is needed to assess impacts of logging on cavity using species and that further experimentation with artificial nest boxes is needed to ascertain if they can be used to assist conservation of some species. The best conservation measures would be to ensure more large trees with cavities are retained for wildlife during logging operations.

    Spatial and temporal variation in hornbill densities in Namdapha Tiger Reserve, Arunachal Pradesh, north-east India
    pages 734-748
    Rohit Naniwadekar and Aparajita Datta
    Asian hornbills are threatened by hunting and habitat loss. Five of the 32 Asian hornbills occur in north-east India, but there is limited information on their abundance in the region. It is important to know the variation in densities of different hornbill species in space and time to understand population trends. Namdapha Tiger Reserve is considered to be an important area for hornbills. We estimated densities of four of the five species in the reserve by walking line-transects during the non –breeding season between 2009 and 2012. We had 458 sighting of the Rufus-necked, Great, Wreathed and White- throated Brown hornbill. Our study provides the first density estimates of the White-throated Brown hornbill (8 birds/km2). The density of the Rufus-necked hornbill (7 birds/km2) was higher than those reported elsewhere. Great (3.9 birds/ km2) and Wreathed Hornbill (16.1 birds/km2) densities were similar to other sites. The combined densities (100 birds/km2) of four hornbill species in November-December are among the highest recorded for any site in Asia. Wreathed hornbill densities declined considerably from November (69 birds/km2) to April (1.3 birds/km2). This is likely to be due to seasonal movements by this species to low-elevation forests outside the reserve. Our study showed that hornbill distribution also varies in the Great and White-throated Brown hornbills occurring in low densities in higher elevations in the reserve. Namdapha Tiger reserve is likely to harbor significant populations of the Rufus-necked, Great, Wreathed and White-throated Brown hornbills during the non-breeding season given the vast area of their habitat in the reserve.

    Small changes in vegetation structure mediate great changes in amphibian ensembles in Colombian Pacific rainforest
    pages 749-769
    Angela Cortes, Fernando Castro and J. Nicolás Urbina-Cardona
    Anthropogenic land use and cover change transforms tropical environments into a mosaic of productive systems and rainforests chronosecuences, and are one of the major threats for amphibian species (frogs, toads and salamanders), likely to be affected by the loss of suitable habitats due to changes in vegetation structure and microenvironment. This study was conducted in the tropical rainforest of the Pacific coast of Colombia, which were sampled amphibians in three different types of vegetation (mature forest, secondary forest and mixed culture). In each vegetation type we measured eight environmental and structural variables to determine which was most important for amphibians. We found that although the number of species was similar in the three vegetation types, the composition of the ensembles was different in responses to vegetation structure being the canopy cover the key variable that differentiate between forest amphibian ensembles and mixed culture ensembles. However, for amphibian ensembles have a mature forest composition, the habitat must have a canopy cover over 89%, a density of woody plants exceeding 231 individuals per 500 m2, and a leaf litter depth above 23 cm. In this regard small changes in vegetation structure create great changes in amphibian species inhabiting tropical rainforests. Determining the distribution of amphibians across the mosaic of productive systems and rainforests chronosecuences and their relationship with microhabitat will allow for the creation of robust tools for restoration and management of the amphibians in fragmented tropical landscapes.

    A preliminary study on the impact of changing shifting cultivation practices on dry season forage for Asian elephants in Sri Lanka
    pages 770-780
    Jennifer Pastorini, H. K. Janaka, H. G. Nishantha, Tharaka Prasad, Peter Leimgruber and Prithiviraj Fernando
    Shifting or slash-and-burn cultivation has been a common practice the world over for thousands of years. It is still widespread in the dry lowlands of Sri Lanka, a tropical island in the Indian Ocean. The practice consists of cutting and burning vegetation in a scrub/forest area at the end of the dry season, and cultivating vegetables and cereals with the annual monsoonal rains. The cultivation period is limited to four months of the year. After harvest, farmers return to their villages located away from the shifting agriculture fields. Traditionally, after 2-3 consecutive years of cultivation, a field is left fallow for 4-5 years. The study by Pastorini et al. looked at what happens in shifting agriculture fields in the dry season. They measured the growth of natural vegetation in the fields after cultivation, and tracked two elephants in the area with GPS-satellite collars. They found that large amounts of plants sought after by elephants proliferated in the post-cultivation fields and that elephants extensively foraged in them in the dry season. Although shifting agriculture is often viewed as a wasteful and unsustainable practice, in this instance it was found to be beneficial to elephants and other herbivores. The system represented a ‘co-existence’ model between elephants and people with a ‘time-share’ arrangement of using the same area without conflict. However, they warn that changing cultivation practices with longer cultivation periods and shorter fallow periods are likely to decrease the benefit to elephants and lead to conflict between people and elephants.

    Integrating occupancy modeling and camera-trap data to estimate medium and large mammal detection and richness and examine matrix influences on their occurrence in a Central American biological corridor
    pages 781-795
    Michael V. Cove, R. Manuel Spínola, Victoria L. Jackson, Joel C. Sáenz, and Olivier Chassot
    Many species in the Neotropics are under threat from habitat fragmentation and degradation from deforestation and land cover conversion to large-scale agriculture and pasture lands. Biological corridors provide valuable habitat to connect remnant forest patches and protected areas for wildlife to travel and disperse between populations. To assess the effectiveness of corridors for this purpose it is important to monitor biodiversity across corridors and within forest fragments which they connect. We used camera-traps to survey medium and large mammals in the San Juan – La Selva Biological Corridor in northeastern Costa Rica. From our camera surveys we were able to estimate species richness for the corridor and within forest patches surrounded by four different land-use categories: eco-lodge reserves, tree plantations/general reforestation, cattle ranches, and pineapple/agricultural plantations. We estimated that approximately 2/3 of the mammal community persists in the corridor and was lower than that observed in protected areas in the Neotropics. Forest cover was significantly reduced at pineapple plantations than other land-use matrices; however, pineapple plantations exhibited the highest observed richness. In these sites, relatively high species richness is likely an artifact that reflects medium and large mammal concentrated occurrence in small forest patches. Species richness may not be a good indicator of ecosystem health when surveying in limited forest cover in areas with pineapple production because endangered species such as tapirs and large carnivores do not appear to use those sites. Fragmentation and connectivity need to be addressed with reforestation and limitations on pineapple expansion for the region to function as an effective corridor.

    The thin-spined porcupine, Chaetomys subspinosus (Rodentia: Erethizontidae), within protected areas in the Atlantic Forest, Brazil: local knowledge and threats
    pages 796-810
    Luciana C. Castilho, Romari A. Martinez, Gastón A. F. Giné, Gabriela C. Ribeirod and Alexandre Schiavettie
    The thin-spined porcupine is a threatened mammal from a small region of the Atlantic Forest in the Brazilian coast. Hunting and deforestation are affecting its populations, and therefore an Action Plan was created in 2011 to protect the species. This Plan aims to increase awareness of the animal, to encourage a better quality of life for the poorest rural communities within the animal’s distribution area and to identify the reasons why the species is hunted. This study sought to understand the knowledge of rural residents on the thin-spined porcupine and which are the uses of this animal within protected natural areas. Furthermore, behavior and perceptions of residents regarding biodiversity conservation were also investigated. 125 interviews were made with residents of the Una Wildlife Refuge and the Serra do Conduru State Park. Hunters and people with low level of formal education had greater knowledge about the animal. Negative behaviors such as hunting, use of fire and deforestation are still held by residents within the protected areas. These behaviors represent a threat to the thin-spined porcupine and the protected areas, and there should be more control of these activities. The information provided by this study seeks to improve and direct the actions of the Action Plan for the protection of the thin-spined porcupine.

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