|A skipper on bird dropping|
|Painting by J B Fraser with Greater Adjutants|
Other scavengers have declined sharply too- the most famous being the vultures - once found along the avenues of Delhi and floating in thermals in large numbers, they are almost absent today and the cause is usually attributed to the non-steroidal anti-inflammatory drug Diclofenac. Interestingly these hit the vultures of the genus Gyps the most. There is however a smaller vulture - the Egyptian Vulture (Neophron percnopterus) which has also declined across its range and some Spanish scientists have suggested that they might have been affected by antibiotics - which apparently depress their innate immune system. Now this black-and-white vulture has a bright yellow bare facial skin and it seems that the birds derive the colour from carotenoids derived from a diet of mammal excreta. The usual ideas is that the fitter males have a brighter face and females choose them as their mates and it seems like this might have the cost of exposing their immune systems to the onslaught of bacteria. And having a weak immunity could be bad under those circumstances - so it seems like antibiotics, pain-killers and sanitation are not without ill-effects for some.
As another aside one should note that the ancient Egyptians who revered both the dung beetles and vultures introduced some innovations in sanitation and it is comforting to see that there are scholars looking at these aspects of daily human life.
- Arillo, Antonio & Ortuño, Vicente M. (2008) Did dinosaurs have any relation with dung-beetles? (The origin of coprophagy). Journal of Natural History 42(19): 1405-1408
- Another blog post on an allied theme
- Campos-Arceiz, A., 2009. Shit happens (to be Useful)! Use of elephant dung as habitat by amphibians Biotropica. 41(4):406-407.