The Last-Surviving Moroccan Dorcas Gazelle (Gazella dorcas massaesyla) Viability Analysis [M’Sabih Talaa Reserve, Morocco]

The single remnant Moroccan dorcas gazelle (Gazella dorcas massaesyla) has been isolated for more than five decades in the M’Sabih Talaa reserve, an arid area of west-central Morocco. This population has been subject to different disturbances, especially poaching and depredation by feral dogs. A five-season line transect survey revealed that the population size has been halved in less than 15 years with a lower apparent fecundity rate. In the present work, we carried out a population viability analysis simulating different scenarios using VORTEX software based on available demographic and life-history data from captive populations,. A sensitivity analysis revealed that inbreeding depression and possible catastrophic events could have a considerable impact on the population’s prospects. Scenarios of splitting population into two subpopulations with different management measures reducing/deleting mortality sources, is proposed. Such scenarios resulted in reducing the consequences of catastrophic events would significantly mitigate the harmful effects of both inbreeding and environmental stochasticity. These results may be of a general interest to conservationists dealing with this unique and imperiled population.

Variance Propagation for Density Surface Models

Spatially explicit estimates of population density, together with appropriate estimates of uncertainty, are required in many management contexts. Density surface models (DSMs) are a two-stage approach for estimating spatially varying density from distance sampling data. First, detection probabilities—perhaps depending on covariates—are estimated based on details of individual encounters; next, local densities are estimated using a GAM, by fitting local encounter rates to location and/or spatially varying covariates while allowing for the estimated detectabilities. One criticism of DSMs has been that uncertainty from the two stages is not usually propagated correctly into the final variance estimates. We show how to reformulate a DSM so that the uncertainty in detection probability from the distance sampling stage (regardless of its complexity) is captured as an extra random effect in the GAM stage. In effect, we refit an approximation to the detection function model at the same time as fitting the spatial model. This allows straightforward computation of the overall variance via exactly the same software already needed to fit the GAM. A further extension allows for spatial variation in group size, which can be an important covariate for detectability as well as directly affecting abundance. We illustrate these models using point transect survey data of Island Scrub-Jays on Santa Cruz Island, CA, and harbour porpoise from the SCANS-II line transect survey of European waters. Supplementary materials accompanying this paper appear on-line.

KARAKTERISTIK DAN KERAPATAN SARANG ORANGUTAN (Pongo pygmaeus wurmbii) DI DUA TIPE HABITAT YANG BERBEDA DI STASIUN PENELITIAN CABANG PANTI TAMAN NASIONAL GUNUNG PALUNG KABUPATEN KAYONG UTARA

Cabang Panti Research Station has diverse habitat, therefore the researchers are interested to conducting a research on the characteristic and densities of Orangutan nests (Pongo pygmaeus wurmbii) in two on different habitat namely in alluvial bench forests and peat swamp forests. The purpose of this study want to see a comparison of the characteristic and density as an Orangutan nest (Pongo pygmaeus wurmbii) in two different habitat types. The method used in this research was Line transect survey. The nests were searched by walking through the midline while observing and recording the discovered nests in the line transect. Based on the result of the Independent Sample Test, it showed that there was no difference of tree trunk diameter, but there was a difference of height of the nest tree and the nest itself. The nest position was almost similar which was position 3 (tip top) in the amount of 83% in alluvial bench habitat while it was position 1 (among the main branching) in the amount of 42% and 3 (the canopy of the tree in form of fork) in the amount of 42%. The class of the nest which mostly found in both habitat was nest class D in the amount of 50% in the alluvial bench habitat and 83% in the peat swamp forest. The type of tree which was mostly used by the Orangutan to create their nest in both habitat was Shorea spp. The densities of the nest of Orangutan was 30 nest/km² in the alluvial bench habitat and 60 nest/km² in the peat swamp habitat. Keyword: Cabang Panti, Nest Characteristics, Nest Densities, Orangutan

PROFIL KERAGAMAN VEGETASI EKOSISTEM MANGROVE DI DESA TAMUKU KABUPATEN LUWU UTARA

This study aims to describe the profile of vegetation diversity in the mangrove ecosystem in Tamuku Village, Bone-Bone-Bone District, North Luwu Regency. This research is a qualitative research using survey methods. The data collection technique uses the Quadrant Line Transect Survey technique. The data analysis technique uses the thinking flow which is divided into three stages, namely describing phenomena, classifying them, and seeing how the concepts that emerge are related to each other. The results of this study are the profile of mangrove vegetation in Tamuku Village, which is still found 16 varieties of true mangrove vegetation and 7 varieties of mangrove vegetation joined in the coastal area of Tamuku Village, Bone-Bone District, North Luwu Regency, South Sulawesi. The condition of mangrove vegetation in Tamuku Village is currently very worrying due to human activities that cause damage such as the project of normalization of flow, opening of new farms, disposal of garbage, water pollution due to chemicals, and exploitation of mangrove forests for living needs. The impact is ecosystem damage and reduced vegetation area as a place to grow and develop mangroves.

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.

Density, habitat use, and activity patterns of a vulnerable population of the Solitary Tinamou (Tinamus solitarius) in a Brazilian Atlantic Forest fragment

We present the first estimates of density of the Solitary Tinamou (Tinamus solitarius (Vieillot, 1819)) in the Reserva Natural Vale (RNV), one of the two largest remnants of the Atlantic Rainforest in the state of Espírito Santo, Brazil. We also modeled the spatial distribution and habitat use of the species using occupancy and detectability modeling. We used a line-transect survey to estimate density and abundance and camera traps to estimate habitat use and activity pattern. We conducted the survey within a 13 month period (April 2013 to May 2014). Estimated density was 9 ± 2 individuals/km2 and estimated population size for the entire RNV was 2115 ± 470 individuals. Occupancy was best described by distance to forest edge, distance between trees, poaching intensity, and understory cover. Detectability was affected by distance between trees and poaching intensity. We conclude that in the RNV, the Near Threatened T. solitarius is a diurnal species preferring intact closed-canopy forest but tending to avoid areas near to forest edges or areas under comparatively high intensity of poaching. These results reinforce the importance of RNV as a resource source for T. solitarius reproduction at Brazilian Atlantic forest remnants.

Techniques for Estimating the Size of Low-Density Gopher Tortoise Populations

Gopher tortoises (Gopherus polyphemus) are candidates for range-wide listing as threatened under the U.S. Endangered Species Act. Reliable population estimates are important to inform policy and management for recovery of the species. Line transect distance sampling has been adopted as the preferred method to estimate population size. However, when tortoise density is low, it can be challenging to obtain enough tortoise observations to reliably estimate the probability of detection, a vital component of the method. We suggest a modification to the method based on counting usable tortoise burrows (more abundant than tortoises) and separately accounting for the proportion of burrows occupied by tortoises. The increased sample size of burrows can outweigh the additional uncertainty induced by the need to account for the proportion of burrows occupied. We demonstrate the method using surveys conducted within a 13,118-ha portion of the Gopher Tortoise Habitat Management Unit at Fort Gordon Army Installation, Georgia. We used a systematic random design to obtain more precise estimates, using a newly developed systematic variance estimator. Individual transects had a spatially efficient design (pseudocircuits), which greatly improved sampling efficiency on this large site. Estimated burrow density was 0.091 ± 0.011 burrows/ha (CV = 12.6%, 95% CI = 0.071–0.116), with 25% of burrows occupied by a tortoise (CV = 14.4%), yielding a tortoise density of 0.023 ± 0.004 tortoise/ha (CV = 19.0%, 95% CI = 0.016–0.033) and a population estimate of 297 tortoises (95% CI = 210–433). These techniques are applicable to other studies and species. Surveying burrows or nests, rather than animals, can produce more reliable estimates when it leads to a significantly larger sample of detections and when the occupancy status can reliably be ascertained. Systematic line transect survey designs give better precision and are practical to implement and analyze.