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The ability for climbing crabs of East African mangrove swamps, Sesarma leptosoma, to recognize predators visually is examined by experimentation with three dummy objects made to look like the predators. The results show that the crabs hesitated in their movements when confronted with the dummies which had the open claws of the predator. From this it can be concluded that the crabs are able to visually detect shapes and sizes and the presence of danger.

Objectives Infanticide by males is assumed to promote permanent male-female associations, although its importance for social monogamy is still debated. We examined the consequences of male membership change in the largest socially monogamous primate, the siamang ( Symphalangus syndactylus), a species that also forms polyandrous groups and where males may provide offspring care. We examine (a) the potential risk of infanticide by documenting changes in female-offspring relationships following male change, expecting abrupt weaning; and (b) the potential importance of male care and polyandry for offspring survival. Methods We witnessed four male changes at Way Canguk Field Station (Indonesia) in groups where the youngest offspring was estimated to be about 2 years of age. We quantified aspects of mother-offspring relationships (interindividual distance, body contact, and nipple contact) and estimated the proportion of time being carried during travel (August 2007-April 2009). Results In the two groups into which new males immigrated, offspring were weaned abruptly, suggesting infanticide by males as a potential risk. Even though no attacks on infants by males were witnessed, both infants disappeared shortly after the male change. Another infant disappeared after its main carrier (a male) emigrated. Conversely, in a group where the resident subordinate male replaced the dominant male, the offspring experienced no change in care and survived the transition. Conclusions These findings suggest that male immigration in hylobatids increases mortality risk for infants, emphasize the importance of offspring care, and cast doubts on prior classifications of 2-year-old siamangs as independently traveling individuals. [ABSTRACT FROM AUTHOR]

Intense intolerance among males is considered to be an important mechanism maintaining the uni-male organization traditionally attributed to socially monogamous gibbons. Long-term field work, however, has revealed the existence of stable, socially polyandrous groups in at least two populations, raising questions about the mechanism that allows two adult males to co-reside in the same group. I collected 21 months of behavioral data on 7 two-male groups of wild siamangs ( Symphalangus syndactylus) in southern Sumatra (Indonesia) to test the hypothesis that dominance relationships regulate the interactions of adult male siamangs and ultimately facilitate multi-male social groups. A dominant male could clearly be identified in each dyad, based on a consistent direction of agonistic interactions, displacements and the maintenance of an advantageous position in the canopy. Males identified as dominant enjoyed greater social access to the resident female and monopolized copulations. These results suggest that gibbons possess the psycho-social flexibility to regulate intra-sexual aggression and live in multi-male social units under certain social conditions. I discuss the effects that relatedness between males and female choice have in determining this grouping pattern, and the role of male intolerance in the maintenance of primate mating systems. Am. J. Primatol. 78:288-297, 2016. © 2015 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

The article describes a sighting of a wild marbled cat, Pardofelis marmorata, in the Bukit Barisan Selatan National Park (TNBBS) in southern Sumatra, Indonesia on September 30, 2008. The animal was observed near the Way Canguk Research Station, a lowland primary forest with relatively low levels of encroachment and poaching. It was seen lying on the ground under a fruiting tree, which may indicate that the cat was waiting for animals attracted to the ripe fruits.

I report the first documented case of a wild siamang killed by a clouded leopard. The event, involving a juvenile male (weighing 3.7 kg), occurred at dawn, near a known sleeping tree in a lowland tropical forest in southern Sumatra (Indonesia). Examination of the siamang's body revealed that the first 2 cervical vertebrae were crushed and the face was partially eaten. This attack highlights the potential importance of predation as an evolutionary pressure for hylobatids, and poses some questions about the antipredator adaptations of this population of siamang., (Copyright © 2011 S. Karger AG, Basel.)