The above male Common Fruit Bat (Cynopterus brachyotis) was photographed at 2240 hours on 30th July 2014. He was one among the small colony that arrived in the porch at around 1800h to roost, continuing to remain roosting until well past midnight.
The two spotlights were then on and this apparently encouraged the colony to remain until then. Usually, in the absence of the lights the colony dispersed by around 2000 hours LINK.
Note the dark orange-red collar characteristic of the male. The female’s collar is yellow-orange LINK.
The presence of the penis, fully erect in the image at the top and with only the tip visible in the image above, confirms its maleness. Note that in the above image, the prominent right nipple of this male is fully visible. This is normal as all male primates have nipples. When the penis is not visible, the male can be recognised by the pair of prominent testicles (below.
Note that some male species of fruit bats have enlarged nipples that when squeezed produce small amounts of milk LINK. However, there are no reports of males nursing young. This milk producing ability can be due to the food they eat, like leaves of certain plants that contain estrogen-like compounds that can stimulate milk production. Leaves contaminated with pesticides can similarly have the same effect as certain breakdown products of these chemicals mimic the effect of estrogen.
The video clip above shows the male grooming his penis.