In contrast to the African great apes, orangutans (Pongo spp.) are semisolitary: Individuals are often on their own, but form aggregations more often than expected by chance. These temporary aggregations provide social benefits such as mating opportunities. When fruit availability is high, costs of aggregating should be lower, because competition is less pronounced. Therefore, average party size is expected to be higher when fruit availability is high. This hypothesis would also explain why orangutans in highly fruit‐productive habitats on Sumatra are more gregarious than in the usually less productive habitats of Borneo. Here, we describe the aggregation behavior of orangutans in less productive Sumatran habitats (Sikundur and Batang Toru), and compare results with those of previously surveyed field sites. Orangutans in Sikundur were more likely to form parties when fruit availability was higher, but the size of daily parties was not significantly affected by fruit availability. With regard to between‐site comparisons, average party sizes of females and alone time of parous females in Sikundur and Batang Toru were substantially lower than those for two previously surveyed Sumatran sites, and both fall in the range of values for Bornean sites. Our results indicate that the assessment of orangutans on Sumatra as being more social than those on Borneo needs revision. Instead, between‐site differences in sociality seem to reflect differences in average fruit availability.

Seed of Jatropha curcas (Euphorbiaceae) is currently established as the source for biofuel Therefore, it is important to understand the diversity insects that pollinated J. curcas inflorescence yellow flowers. We also aimed to study the pollination effects on fruit set on J. curcas. Scan sampling method were carried out to explore the insect pollinators diversity from 07.00 up to 17.00 h in every 15 minutes. Visiting frequency of pollinators insects were observed by using focal sampling. Those information together with flowering periods, flower nectar volumes, and environmental factors were used as the basic data to determine the effectiveness of insect pollination both in covered and uncovered of seed set plants. Results showed that nine species of insect pollinators were from three order (Hymenoptera, Lepidotera, and Diptera) pollinated J. curcas. Four species of Hymenoptera i.e. Prenolepis, Apis dorsata, Xylocopa confusa, and Apis cerana showed the highest abundances. The highest abundance and species richness of pollinators occurred at 08.00-10.15 and 15.00-17.15 h. Bees of X. confusa, A. cerana, and A. dorsata of Apidae are effective as insect pollinators in J. curcas plantations, due to high visited frequencies. The insect pollinators also increased fruits and seeds set of J. curcas in the uncovered experiment plants. Thereby, enhancement the three pollinator insects as part of crop management have to be considered by farmers

This study explores two large carnivores, Javan leopard (Panthera pardus melas) and dhole (Cuon alpinus) that are known to have an overlapping diet and are sympatric in the south-western part of West Java. We characterised their spatiotemporal habitat together with four medium-sized prey species. We used photographs collected along 39.420 night-traps from 108 camera-traps installed on the peninsula of Ujung Kulon National Park (UKNP). We are using maximum entropy modelling (MaxEnt) to investigate seasonal environmental factors. Concerning the dominant prey species, our results showed that distances to secondary forest edge were highly significant for both Javan leopard and dhole in wet and dry seasons. Javan leopard is mostly active at dawn and dusk, whereas spatially correlated with Javan mousedeer and red muntjac. Dhole exhibited diurnal activity and were avoiding Javan leopard to a certain extent. Its spatial use is overlapping with red muntjac, wild boar, and banteng. Using Spatially Explici...

Male homosexual preference (MHP) is an evolutionary enigma because it is partially heritable and imposes a fertility cost. In occidental societies, homosexual men are feminized at various levels and they have more older brothers than heterosexual men. To evaluate whether femininity and the fraternal birth order (FBO) effect are universal features of MHP or not, we collected original data from homosexual men, heterosexual men, and heterosexual women from Java (Indonesia). Facial photographs were used to test whether homosexual faces are feminized when compared with heterosexual ones. We found that faces manipulated to resemble the average face of homosexual men are perceived as facially feminized, suggesting that homosexual men are facially feminized compared to heterosexual men, although a higher facial femininity was not captured by morphological analyses. Then, family data were used to detect differences in siblings’ composition between homosexuals and heterosexuals. Homosexual men displayed a higher number of older brothers than heterosexual men, even when sibship size was controlled for, suggesting that the FBO effect exists in Indonesian populations. Independent of sexual orientation, men with older brothers seem more feminized than those without older brothers, consistent with the immune origin of the FBO effect. In conclusion, MHP in Indonesia is partially feminized and they have more older brothers. Such features are also associated with MHP in other cultural contexts, suggesting a cross-cultural effect of men homosexual preference. An evolutionary explanation is available for the feminizing effect, although the FBO effect remains unexplained even if proximal mechanisms start to be identified.