Relative Methods of Population Measurement and the Derivation of Absolute Estimates

Relative sampling methods usually requiring comparatively simple equipment are described. These often concentrate the animals and provide impressive collections. Factors affecting the size of relative samples are reviewed to show that biological interpretation can be difficult. A wide variety of methods for aquatic and terrestrial sampling are reviewed, including pitfall, interception, light, sticky, and flight traps, electric fishing, drift samplers, and gill nets. The use of baited traps, including vertebrate hosts, is discussed. Removal trapping to estimate population density is described, and R software code listed.

Population density, geographical distribution and habitat of Talaud bear cuscus (Ailurops melanotis Thomas, 1898)

Repi T, Masy’ud B, Mustari AH, Prasetyo LB. 2020. Population density, geographical distribution and habitat of Talaud bear cuscus (Ailurops melanotis Thomas, 1898). Biodiversitas 21: 5621-5631. The Talaud bear cuscus (Ailurops melanotis) has been reported from Sangihe (the largest island in the Sangihe Island group) and Salibabu (within the Talaud Islands). As an endemic species of Indonesia, this species is rare and there is no certainty regarding its precise geographic distribution or population size. This research aimed to estimate population density and provide the first preliminary data on its geographical distribution, as well as general description of its habitat. Our research shows that A. melanotis occurs on three islands: Salibabu Island, Nusa Island, and Bukide Island, and probably also exists in the Sahandaruman mountain on Sangihe Island. Our population surveys estimate, population density on each island as: Salibabu: 3.69 ± 2.54 ind/km2, with an estimated total population of 28.95 individuals, Nusa Island: was 12.31 ± 2.58 ind/km2, with an estimated population of 19.08 individuals, and Bukide Island: 7.17 ± 1.79/km2, with an estimated population of 10.40 individuals. Information regarding population is a key guiding factor in conservation efforts, where population size is related to extinction risk (threat status) and its geographical distribution, this can help to determine conservation priorities for species or habitats.

Estimating leopard (Panthera pardus) densities when populations comprise polymorphic phenotypes: an application of spatial mark-resight models

Melanism is a form of pigmentation polymorphism where individuals have darker coloration than what is considered the “wild” phenotype. In the case of leopards, Panthera pardus, melanism occurs at higher frequencies amongst populations in tropical and subtropical moist forests of south and southeast Asia, presenting a unique challenge in estimating and monitoring these populations. Unlike the wild phenotype that are readily recognizable by their rosette patterns, melanism results in individuals being unidentifiable or ‘unmarked’ through photographic captures obtained using white flash cameras. Spatial mark-resight (SMR) models that require only a subset of the population to be ‘marked’ offer the opportunity to estimate population density. In this study, we present an application of SMR models to estimate leopard densities using camera trap survey data from three sampling sessions at Manas National Park (MNP), India. By using an SMR model that allowed us to include captures of unidentified sightings of marked individuals, we were also able to incorporate captures where identity was either not confirmed or only known from a single flank. Following 18,674 trap-days of sampling across three sessions, we obtained 728 leopard photo-captures, of which 22.6% (165) were melanistic. We estimated leopard densities of 4.33, 2.61and 3.37 individuals/100km2 across the three sessions. To our best knowledge, these represent the first known estimates of leopard densities from such populations. Finally, we highlight that SMR models present an opportunity to revisit past camera trap survey data for leopards and other species that exhibit phenotypic polymorphism towards generating valuable information on populations.

Estimation of Kapapa Bajing Population (Callosciurus notatus Boddaert, 1785) Family Sciuridae in Nagari Koto Dalam, Padang Sago, Sumatera Barat

Estimation of the plantain squirrel (Callosciurus notatus Boddaert, 1785) population was conducted from Februari to May 2016. This study aimed to estimate population density in the traditional coconut plantation, Nagari Koto Dalam, Padang Pariaman. The population density was estimated using line transect survey method. Population density of the squirrels in Nagari Koto Dalam was 5.5 ind/ha. This study shows that population density of the squirrel comparable to previous studies in West Sumatra.