Tropical Animals

Muhammad Akbar Saputra

Habitat degradation in former production forests necessitates systematic rehabilitation to restore ecological functions and biodiversity. Monitoring avian communities serves as a vital bioindicator for evaluating the success of such restoration efforts. This study aimed to evaluate bird species diversity and community structure within the forest rehabilitation zone of Resort PTN Tapos, Mount Gede Pangrango National Park. Surveys were conducted in July 2023 using point count and MacKinnon list methods across observation points in the Cinakimun forest block. The study documented a relatively diverse bird community consisting of endemic and protected species, indicating that the rehabilitation area provides important habitat resources for avifauna. Ecological analyses demonstrated moderate species diversity, high distribution evenness, and low species dominance, reflecting a relatively stable bird community structure within the rehabilitated forest ecosystem. Vertical stratification observations further revealed that most bird activities were concentrated in the middle canopy layer, highlighting the ecological importance of vegetation structure in supporting bird habitat utilization. The findings indicate that the rehabilitation zone effectively supports a stable and diverse avian community, validating the success of current ecosystem recovery strategies in restoring vital wildlife habitats.

Tropical Animals

Muhammad Khoirudin, Noril Milantara, Gusmardi Indra

Rapid forest degradation and land-use change in West Sumatra threaten the persistence of sun bear (Helarctos malayanus) populations by altering habitat availability and increasing human–wildlife conflict. This study aimed to predict habitat suitability and identify key environmental drivers influencing the distribution of sun bears using the Maximum Entropy (MaxEnt) model. A final dataset of 167 verified occurrence records—obtained after filtering and spatially thinning an initial pool of 466 field-compiled presence points to mitigate sampling bias—was analyzed alongside multiple environmental variables. The model demonstrated high predictive performance (AUC = 0.922 ± 0.004), indicating strong reliability in estimating habitat suitability. Quantitatively, less suitable habitats covered 46.23% (314,471.97 ha), suitable habitats 32.85% (223,493.41 ha), and highly suitable habitats 20.92% (142,305.43 ha). Results revealed that suitable habitats are spatially heterogeneous, with high-suitability zones primarily concentrated in protected and conservation forests, contributing 55% and 44% of suitable habitats, respectively, while production forests accounted for only 1%. Elevation (31.1%), land use (21.4%), precipitation (15.5%), and distance from roads (11.7%) were identified as the most influential variables. Sun bears showed a preference for elevations of 1,500–2,000 m, primary and secondary forests, rainfall of 240–260 mm/month, and areas located 4–5 km away from roads and settlements. These findings provide critical spatial insights for conservation planning, emphasizing the importance of protecting forested landscapes and managing anthropogenic disturbances to ensure the long-term survival of sun bear populations in West Sumatra.

Tropical Animals

Ahmad Riski, Fauzan Fauzan, Zulmardi Zulmardi

Tropical reptile diversity is increasingly threatened by habitat degradation and anthropogenic disturbance, while baseline ecological data in many protected forests of West Sumatra remain limited. This study aimed to document reptile diversity and habitat distribution in the Nagari Simancuang Protected Forest, West Sumatra, Indonesia. Reptile surveys were conducted from September to October 2023 using the Visual Encounter Survey (VES) method combined with line transect sampling in terrestrial and aquatic habitats during daytime and nighttime observations. A total of 56 individuals representing 13 species from 7 families were recorded, with Colubridae as the dominant family. The overall Shannon-Wiener Diversity Index (H') indicated moderate diversity (H' = 2.44), while terrestrial habitats showed higher diversity values than aquatic habitats. The Evenness Index (E = 1.0) suggested relatively even distribution among recorded species. Differences in species composition between habitat types were reflected by a low Sorensen Similarity Index (IS = 14%), indicating variation in habitat use and microhabitat characteristics among reptile species. The presence of endemic species such as Trimeresurus parias sumatranus highlights the ecological importance of the Nagari Simancuang Protected Forest for reptile conservation in West Sumatra. These findings provide baseline information that may support future ecological monitoring and conservation management within the protected forest area.

Tropical Animals

Jihan Lutfi, Ibnu Maryanto, Galih Kholifatun Nisa

Geographic isolation across the Sunda Shelf islands has historically resulted in subspecific classifications in several murid rodents, yet the morphological distinctiveness of insular populations remains inadequately evaluated using quantitative approaches. Clarifying intraspecific variation in Rattus tiomanicus is necessary to determine whether western Indonesian island populations represent discrete evolutionary units or a morphologically continuous taxon across the region. This study analyzed cranial and external morphometric variation in 168 adult specimens collected from 17 islands, incorporating 21 cranial and 4 external body variables. Descriptive statistics, one-way ANOVA (α = 0.05), and Principal Component Analysis (PCA) were employed to assess inter-island differentiation and sexual dimorphism. Greatest Skull Length (GLS) exhibited the largest absolute values, ranging from 33.66 ± 1.75 mm in Sumatra to 44.15 mm in Nusa Kambangan males, with comparable ranges in females (34.56 ± 1.65 mm to 44.39 mm). Despite differences in mean values, extensive overlap occurred among populations for all variables. PCA of cranial measurements showed that PC1 accounted for 76% of total variance, whereas PC2 explained 5.9%, indicating that overall size constituted the primary axis of variation. External body PCA revealed similar overlapping distributions. ANOVA results demonstrated no statistically significant geographic differentiation or sexual dimorphism (p > 0.05). These findings demonstrate that western Indonesian populations of Rattus tiomanicus form a morphometrically cohesive unit without clear morphological discontinuities across the sampled islands. Consequently, these continuous size gradients do not provide diagnostic support for traditional subspecific boundaries, highlighting the critical need for future molecular phylogeographic studies to evaluate potential cryptic genetic differentiation.

Tropical Animals

Yazee Shyne C. Tulbo, Nethan A. Ramos, Alleyah Nicolette I. Lina, Clinton D. Sequihod

The butterfly species found in Sitio Inadan, San Miguel, Surigao del Sur, Philippines were surveyed and documented using transect walks, visual observation, and hand net collection. Four transects were established in selected habitat areas, each measuring approximately 3.05 mi. Sampling was conducted from 7:00 AM to 5:00 PM over six consecutive weekends, with one primary observer recording all sightings and captures. A total of 16 species belonging to four families and 14 genera were identified. The family Nymphalidae comprised about 56% of the recorded species, followed by Pieridae, Papilionidae, and Lycaenidae. Abundance categories were based on encounter frequency, where species observed once or twice were classified as Very Rare, and those seen more often were categorized as Common or Very Common. Conservation status was verified using the International Union for Conservation of Nature (IUCN) Red List to distinguish global status from local rarity. Although most species are listed as Least Concern, limited sampling suggests possible undersampling of the area.

Tropical Animals