More importantly is why are there no green mammals?
(and no, algae or moss rubbed into the fur does not count)
The first mammal I will note is Felis domesticus. What? You've never seen a green housecat? Well, neither had anyone else until a green housecat appeared in Denmark. This very odd cat was reported in the newspapers, along with a photo. It may have been a mutation, or it may have been caused by environmental factors. I was recently informed that the cat has since lost its bright green color, fading as it grew older. But, to continue...Bat Conservation International puts out an annual calendar with great photos. Their 1998 calendar includes a photo of the African yellow-winged bat (Lavia frons), which has brownish-yellow wings, feet, ears, and nose. It's fur, however, is a distinct green in the photographs. I previously mentioned on this page that I was unsure whether the photograph was accurate. I was recently told (thanks to Terri McElhinny) that "'Walker's Mammals of the World' notes that while the back of Lavia is grey, their rumps are brown or olive green." Terri stated that three specimens in the Michigan State University collection have distinctly green rumps.
Meanwhile, Kingdon (1997, The Kingdon Field Guide to African Mammals. San Diego, CA: Academic Press) also gives the following:
Olive Colubus (Procolobus verus) - "greenish olive upperside, graduating to brown on the back."
Tantalus Monkey (Cercopithecus (aethiops) tantalus) - "grizzled, gold to greenish back and crown."
Putty-nosed Monkey (Cercopithecus (nictitans) nictitans) - "dark, grizzled olive fur."
House Bats (genus Scotophilus) - "Colouring varies from greenish olive and yellow to dark brown and off-white."