Issue link: https://read.dmtmag.com/i/75042
"As ambush hunters, tigers would find it hard to The study is the first of its kind to systematically investigate the Sumatran tiger's use of different land-cover types for habitat. capture their prey without adequate understory cover," said Sunarto, who now is a tiger expert for WWF- Indonesia. "The lack of cover also leaves tigers vulner- able to persecution by humans, who generally perceive them as dangerous." Addressing these issues can be challenging, because the tiger's rarity and elusive nature makes it a difficult animal to study. Sightings are infrequent, with tiger densities that are quite low—less than one per 100 square kilometers. Researchers in this study used signs of tigers, such as scat and tracks, as well as actual sightings to determine the presence of the wary animal. landscape is natural forest or plantation. Thus, with adjustments in management practices at existing plan- tations to include more understory and riparian forest corridors, tigers could use a mosaic of forest patches across fragmented landscapes. For example, timber or pulp-and-paper plantations could be improved as tiger habitat by reducing the level of human activities and improving the vegetation that benefit tiger prey as well as provide cover for tigers to hunt. Plantations with adequate understory growth should be able to facilitate the movement of tigers among patches of forest, and prey animals are available in most areas, including plantations, where signs of wild boar commonly are found. Animal Sign and Habitat Conditions Across major land-cover types—a patchwork of protected areas, towns and other human settlements, planta- tions, mining areas, and secondary forests in central Sumatra—the researchers conducted systematic sur- veys in 47 grid cells, each 17 by 17 kilometers (11 by 11 miles). Each cell approximates the home-range size of tigers in low-density areas. Within every cell, researchers surveyed 40 plots selected at random, recording habitat variables and tiger sightings or signs of tigers (e.g., scat, scrapings, paw prints, etc.) in 100-meter segments total- ing 1,857 kilometers (1,154 miles) surveyed. Each one-kilometer transect was divided into 10 100-meter segments, where sign surveys and envi- ronmental variables were noted and measured in every segment. The goals were to investigate factors affecting tiger probability of occupancy or habitat use; construct a predictive, spatially explicit species-occurrence model for the forest and plantation landscape in central Sumatra; describe habitat characteristics; and evalu- ate the use and selection by tigers between and within different land-cover types. Researchers used ArcGIS 9.3.1 software to extract 17- by 17-kilometer grid-level landscape variables. The team recorded the weather and GPS coordinates for the start and end of each one-kilometer transect. At every 100-meter segment, researchers measured altitude using the barometric altimeter available in Garmin GPS units. The workers also tallied the scores for overall vegetation cover, canopy cover, subcanopy cover, understory cover and slope. Environmental variables at the landscape level Protected areas, forest plantation areas and forest cover are shown on a geography location map. 16 GEO W ORLD / JU L Y 2O12 were extracted from GIS layers available from WWF- Indonesia. These include land cover; roads updated with original data from the Indonesian national survey and mapping coordinating agency; and boundaries of conservation areas, forestry concessions and agricul- tural concessions. Researchers also obtained public-domain GIS lay- ers such as Bioclim interpolated precipitation version Wildlife Conservation WORLD WILDLIFE FUND