Urban rivers in Southeast Asian megacities are severely degraded, yet some still support unexpected wildlife persistence. This study examined site-use patterns and environmental thresholds of the Asian small-clawed otter (Aonyx cinereus) in the Ciliwung River, Jakarta, Indonesia, one of the region’s most polluted urban waterways. We conducted systematic sign surveys at 60 sites across three river segments representing an urban pollution gradient from Bogor to Jakarta between May and November 2025. Environmental variables, including water quality and substrate heterogeneity, were measured at each site. Otter signs were detected at 33 of 60 sites (55%). Site use declined slightly along the gradient, from 60.0% in the upstream segment to 50.0% in the urban core, although differences among segments were not statistically significant. Total Dissolved Solids (TDS) emerged as the most important predictor of otter presence, with site use declining markedly beyond approximately 194 ppm. Substrate heterogeneity also showed a strong positive association with site use: sites with mixed substrates had 75.0% site use, compared with 41.7% at predominantly concrete sites. Site use was higher in the wet season (68.0%) than in the dry season (45.7%), suggesting seasonal variation in habitat suitability. These findings indicate that A. cinereus can persist in heavily modified urban river systems, but continued persistence likely depends on maintaining structural habitat complexity and improving water quality. The study provides quantitative benchmarks for urban river restoration and supports the relevance of reconciliation ecology in tropical megacities.

Diet and nutrition are critical factors influencing energetics and health. Laboratory studies show that organisms adjust to changes in nutrient intake through flexible metabolic responses such as fuel switching. While the physiological effects of nutrient balance in humans have been studied, data from closely related species living in nature are lacking. We integrate macronutrient regulation and metabolic flexibility to elucidate how wild orangutans (Pongo pygmaeus wurmbii) are buffered against natural fluctuations in nutritional resources. We found that these orangutans regulate protein and regularly switch between exogenous and endogenous nutritional substrates as preferred food resource availability declines. When total caloric, lipid, and carbohydrate intake declined during episodes of fruit scarcity, orangutans drew on fat and endogenous amino acids for energy. This strategy is beneficial only in the context of alternating periods of fruit scarcity and abundance. We discuss our findings in relation to the current global obesity pandemic, which has arisen with transitions in human diets toward low-cost, energy-dense, protein-dilute foods.

Humans accumulate extensive repertoires of culturally transmitted information, reaching breadths exceeding any individual's innovation capacity (culturally dependent repertoires). It is unclear whether other animals require social learning to acquire adult-like breadths of information in the wild, including by key developmental milestones, or whether animals are capable of constructing their knowledge repertoires primarily through independent exploration. We investigated whether social learning mediates orangutans' diet-repertoire development, by translating an extensive dataset describing wild orangutans' behaviour into an empirically validated agent-based model. In this model, diets reliably developed to adult-like breadths only when simulated immatures benefited from multiple forms of social learning. Moreover, social learning was required for diets to reach adult-like breadths by the age immatures become independent from their mothers. This implies that orangutan diets constitute culturally dependent repertoires, with social learning enhancing the rate and outcomes of diet development past individual potentials. We discuss prospective avenues for researching the building of cultural repertoires in hominids and other species.

In human infants, exploratory object manipulations (henceforth called “EOM”) stimulate cognitive development and affect cognitive performance in later life. Zoo-housed great apes are frequently used to study the evolution of human cognition, however, it is unknown how the zoo environment affects their daily expression of EOM. We investigated how wild and zoo-housed Sumatran orangutans differ in their daily EOM throughout life. We collected ~ 12′000 EOM events by 51 wild and zoo-housed individuals of all ages. Zoo-housed orangutans showed significantly higher EOM rates than wild orangutans. Exploratory actions were more diverse in zoos than in the wild, even with objects available in both settings. Zoo-housed orangutans also showed a larger repertoire of exploratory actions and a higher probability of multi-object exploration, including tool use. There was no difference between settings at which age individuals first showed specific exploratory actions. Our results show that the zoo environment significantly affects EOM in orangutans and that the species’ exploratory potential exceeds its natural expression. This may have important implications for cognitive performance, as zoo-housed individuals are likely to have a broader range of affordances to draw from when confronted with novel problems. These results highlight the potential of captive-wild comparisons to study cognitive development and evolution.

ABSTRACTMarine plastics stranded on the coastlines of remote small islands threaten both the ecological integrity of local ecosystems and communities’ well‐being. However, despite the growing quantities of stranded plastics in these locations, the remote nature of these sites renders monitoring and intervention efforts difficult to undertake. Within this context, we developed a citizen science approach to monitor stranded marine plastics in collaboration with villagers living on a remote small island in Indonesia. This study reports the co‐development and application of an approach that can be used and maintained independently by remote coastal communities. In the monitoring stage, the participants quantified both the weight and composition of stranded marine debris on a beach located in their village for a 4‐week period from late May to mid‐June 2021. The results revealed that the weekly accumulation of stranded marine debris on the beach was 3.97 kg/m2, with 58% categorized as plastics. The stranded plastics sampled in this study were sorted and collected for recycling, estimated to provide a total economic value of 91,700 Indonesian Rupiahs (USD 5.84), or equivalent to 12.77% of the average monthly household income in the area. The citizen science activities indicated that the local villagers were capable of operating the designed monitoring system effectively, with the added benefits of supplementary earnings from recycling. An independently operated monitoring approach combined with collection efforts for recyclable items is important as remote islands have to manage increasing quantities of stranded marine debris despite the lack of an adequate local waste management system.

The adult competences that underlie humanity’s global dominance are massively dependent on learning from one’s culture across many years of childhood[1][1],[2][2]. Recent research has demonstrated cultural learning in a growing diversity of species[3][3],[4][4], but has largely been studied through mere snapshots of animals’ lives and specific behavioural achievements like tool use[5][5],[6][6]. Thus, how different forms of learning interact to shape the full arc of individuals’ behavioural development in the wild remains unknown. Here, we analyse nearly seven thousand records of behavioural indicators of social and asocial learning in wild, immature orangutans, from birth to independence at around eight years. We show that learning is largely triggered by social observation, the effect of which lasts for hours. Social learning events were five times more frequent than asocial learning events. Immatures show substantial differences in their reliance on different forms of social and asocial learning during development. We demonstrate that individuals with the highest rates in both modes of learning developed the broadest diets, and the benefits of social learning were the strongest when asocial learning was low. Extending to over 250 food items in adults, diet breadth represents a comprehensive measure of ecological competence, rather than reflecting mastery of a single behaviour. Our detailed analyses reveal that social and asocial learning synergistically shape great ape ecological competence substantially more than previously recognised. Our study marks a step-change in methodological approaches concerning both the scale of cultural and asocial learning across development and its impacts on broad-scale competences critical for later life. It offers a launching point for both the focused investigation of individual-specific learning trajectories shaping development, and the interaction between social and asocial learning in progressing toward adult-like repertoires in non-human wild animals and humans alike. ### Competing Interest Statement The authors have declared no competing interest. Marie Sklodowska-Curie Actions postdoctoral fellowship, 101150646 Leakey Foundation (Primate Research Fund and project grant) Volkswagen Stiftung (Freigeist fellowship) Stiftung für Mensch und Tier (Freiburg i.Br.) Max Planck Institute of Animal Behavior, https://ror.org/026stee22 University of Zurich, https://ror.org/02crff812 A.H. Schultz Foundation SUAQ Foundation [1]: #ref-1 [2]: #ref-2 [3]: #ref-3 [4]: #ref-4 [5]: #ref-5 [6]: #ref-6

In many group-living species, individuals are required to flexibly modify their communicative behaviour in response to current social challenges. To unravel whether sociality and communication systems co-evolve, research efforts have often targeted the links between social organisation and communicative repertoires. However, it is still unclear which social or interactional factors directly predict communicative complexity. To address this issue, we studied wild and zoo-housed immature orangutans of two species to assess the impact of the socio-ecological setting on the production of non-vocal signal repertoires. Specifically, we compared repertoire size, dyadic repertoire similarity, and number of social goals (i.e. observer’s estimate of the signaller’s intended interaction outcome) for communicative interactions with mothers versus other conspecifics, controlling for critical individual and environmental factors. In this small sample of immature orangutans, wild-captive contrasts were statistically significant only for other-directed repertoires, but not for mother-directed repertoires, and not for the number of social goals that immatures communicated towards. While the repertoires of individuals living in the same research setting were more similar than those living in contrasting settings, this difference was most pronounced for other-directed repertoires of the less socially tolerant orangutan species. These results suggest that the boosted interactional opportunities in captivity rather than mere differences in environmental affordances or communicative needs drive the wild-captive contrast in orangutan communicative repertoires. Overall, this fine-grained analysis of repertoires further underscores that not only a species’ social organisation but also the targeted audience may have a profound impact on communicative behaviour. Significance statement Navigating a dynamic social environment often requires flexible signal use. While it has repeatedly been shown that the social organisation and structure of species predict the complexity of their communication systems, the mechanisms underlying these relationships are largely unknown. Because targeted studies to assess this issue in great apes are difficult, we take an alternative approach here: we compare the same species living in the wild and in artificial habitats in captivity. This contrast allows a direct test of how repertoires respond to the relevant difference in socio-ecological conditions. Our results show that the diversity of interaction partners (i.e. social opportunities), but not the diversity of social goals (i.e. possible interaction outcomes) or the broader physical opportunities (i.e. safe ground use), predict the size and consistency of wild and captive signalling repertoires.

Abstract The community's habit of owning wild animals is still ongoing until now. This has become one of the threats to the existence of wildlife in their natural habitat. Parrots, with their ability to imitate surrounding sounds, have become a popular pet choice. Therefore, the purpose of this study is to determine the influence of knowledge, attitudes, and practices about parrots on the profile of the community. The study differentiates between those who owner bird and those who do not. Data collection was conducted for two months in Ternate and Sofifi, North Maluku. The method used was purposive sampling, interviewing as many as 104 respondents who had been determined. The interview data was processed into multiple linear regression values and canonical correlations. The results of this research identified that the majority of those who owned parrots were aged between 42–57 (36%); female (52%); with high school graduates (46%); and engaged in various professions, such as housewives or entrepreneurs (71%). On the other hand, those who were non-owner parrots were dominated by individuals aged 10–25 (46%); male (65%); with undergraduate degrees (62%); and categorized as students (38%). The results of this study show that knowledge and attitudes have an influence on education, profession, and age of the community on the topic of curly-billed bird maintenance. Abstrak Kebiasaan masyarakat memiliki satwa liar masih berlangsung hingga sekarang. Hal ini menjadi salah satu ancaman terhadap keberadaan satwa liar di habitat aslinya. Burung paruh bengkok memiliki kemampuan meniru suara di sekitarnya, dan menjadi satwa liar yang populer sebagai peliharaan. Oleh karena itu, tujuan penelitian ini adalah untuk mengetahui pengaruh pengetahuan, sikap, dan kesadaran tentang pemeliharaan burung paruh bengkok terhadap profil masyarakat. Studi ini membedakan, antara masyarakat yang memelihara burung dan yang tidak. Pengumpulan data dilakukan selama dua bulan di Kota Ternate dan Sofifi, Maluku Utara. Metode yang digunakan purposive sampling, mewawancarai sebanyak 104 responden yang telah ditentukan. Data wawancara tersebut diolah menggunakan software SPSS 22.0 untuk memperoleh nilai regresi linier berganda dan kolerasi kanonikal. Hasil penelitian, mengidentifikasi bahwa mayoritas dari mereka yang memiliki burung paruh bengkok berusia antara 42–57 (36%); berjenis kelamin perempuan (52%); tingkat pendidikan SMA (46%); dan memiliki profesi lainnya, seperti ibu rumah tangga atau pengusaha (71%). Di sisi lain, masyarakat yang tidak memelihara burung paruh bengkok, didominasi yang berusia 10–25 (46%); berjenis kelamin laki-laki (65%); tingkat pendidikan sarjana (62%); dan lebih ddidominasi oleh pelajar/mahasiswa (38%). Hasil penelitian ini menunjukkan bahwa pengetahuan dan sikap memiliki pengaruh dengan pendidikan, profesi, dan usia masyarakat terhadap topik pemeliharaan burung paruh bengkok.

Male orangutans (Pongo spp.) exhibit bimaturism, an alternative reproductive tactic, with flanged and unflanged males displaying two distinct morphological and behavioral phenotypes. Flanged males are larger than unflanged males and display secondary sexual characteristics which unflanged males lack. The evolutionary explanation for alternative reproductive tactics in orangutans remains unclear because orangutan paternity studies to date have been from sites with ex-captive orangutans, provisioning via feeding stations and veterinary care, or that lack data on the identity of mothers. Here we demonstrate, using the first long-term paternity data from a site free of these limitations, that alternative reproductive tactics in orangutans are condition-dependent, not frequency-dependent. We found higher reproductive success by flanged males than by unflanged males, a pattern consistent with other Bornean orangutan (Pongo pygmaeus) paternity studies. Previous paternity studies disagree on the degree of male reproductive skew, but we found low reproductive skew among flanged males. We compare our findings and previous paternity studies from both Bornean and Sumatran orangutans (Pongo abelii) to understand why these differences exist, examining the possible roles of species differences, ecology, and human intervention. Additionally, we use long-term behavioral data to demonstrate that while flanged males can displace unflanged males in association with females, flanged males are unable to keep other males from associating with a female, and thus they are unable to completely mate guard females. Our results demonstrate that alternative reproductive tactics in Bornean orangutans are condition-dependent, supporting the understanding that the flanged male morph is indicative of good condition. Despite intense male-male competition and direct sexual coercion by males, female mate choice is effective in determining reproductive outcomes in this population of wild orangutans.

Kepulauan Seribu have diverse biodiversity, one of which is macroalgae located in the Tourism Utilization Zone and the residential zone. Environmental factors, such as substrate, water quality and the presence of human activities, are very different on each island. The purpose of this study was to determine the differences in the composition and structure of macroalgae communities on islands in the Tourism Utilization Zone, Semak Daun Island and islands in the Settlement Zone, Pramuka Island. Settlement Zone, Pramuka Island. The method used is a quadrat transect. 16 types of macroalgae were found on Semak Daun Island and 26 types of macroalgae on Pramuka Island. The diversity value on Semak Daun Island is categorized as moderate with a value of 1.84 and on Pramuka Island is categorized as moderate with a value of 2.64. The highest INP value on Semak Daun Island is Sargassum binderi and the highest INP on Pramuka Island is Halimeda macroloba.

Vocal complexity is central to many evolutionary hypotheses about animal communication. Yet, quantifying and comparing complexity remains a challenge, particularly when vocal types are highly graded. Male Bornean orangutans (Pongo pygmaeus wurmbii) produce complex and variable “long call” vocalizations comprising multiple sound types that vary within and among individuals. Previous studies described six distinct call (or pulse) types within these complex vocalizations, but none quantified their discreteness or the ability of human observers to reliably classify them. We studied the long calls of 13 individuals to: (1) evaluate and quantify the reliability of audio-visual classification by three well-trained observers, (2) distinguish among call types using supervised classification and unsupervised clustering, and (3) compare the performance of different feature sets. Using 46 acoustic features, we used machine learning (i.e., support vector machines, affinity propagation, and fuzzy c-means) to identify call types and assess their discreteness. We additionally used Uniform Manifold Approximation and Projection (UMAP) to visualize the separation of pulses using both extracted features and spectrogram representations. Supervised approaches showed low inter-observer reliability and poor classification accuracy, indicating that pulse types were not discrete. We propose an updated pulse classification approach that is highly reproducible across observers and exhibits strong classification accuracy using support vector machines. Although the low number of call types suggests long calls are fairly simple, the continuous gradation of sounds seems to greatly boost the complexity of this system. This work responds to calls for more quantitative research to define call types and quantify gradedness in animal vocal systems and highlights the need for a more comprehensive framework for studying vocal complexity vis-à-vis graded repertoires.

Passive acoustic monitoring is a promising tool for monitoring at-risk populations of vocal species, yet, extracting relevant information from large acoustic datasets can be time-consuming, creating a bottleneck at the point of analysis. To address this, an open-source framework for deep learning in bioacoustics to automatically detect Bornean white-bearded gibbon (Hylobates albibarbis) “great call” vocalizations in a long-term acoustic dataset from a rainforest location in Borneo is adapted. The steps involved in developing this solution are described, including collecting audio recordings, developing training and testing datasets, training neural network models, and evaluating model performance. The best model performed at a satisfactory level (F score = 0.87), identifying 98% of the highest-quality calls from 90 h of manually annotated audio recordings and greatly reduced analysis times when compared to a human observer. No significant difference was found in the temporal distribution of great call detections between the manual annotations and the model's output. Future work should seek to apply this model to long-term acoustic datasets to understand spatiotemporal variations in H. albibarbis' calling activity. Overall, a roadmap is presented for applying deep learning to identify the vocalizations of species of interest, which can be adapted for monitoring other endangered vocalizing species.