As I have had daily business to transact in the city for the past few weeks, I have had the opportunity to observe the process of decomposition of the carcass a road-killed deer that appeared alongside the rural road I use to get from our home in the country to the heart of Portland and its surrounding sprawl. Black-tailed Deer, Odocoileus hemionus, are plentiful in northwest Oregon and as might be expected, are not uncommonly seen in a post mortem state near roads. As the city of Portland occupies most of the county of Multnomah, the few outlying rural roads within that county are not particularly well tended by the road crew charged with cleaning up (or at least moving off into the brush) the remains of insufficiently nimble ungulates. Thus the particular deer I have been passing daily has been allowed to undergo a natural process of, shall we say, carbon exchange.
What has been most perplexing to me, however, is why at this point much of anything remains at all of the carcass. On a few trips I have noted the expected scavengers startling and rising from the remains, including on one occasion a Bald Eagle, Haliaeetus leucocephalus. I readily assume that the local coyotes have been paying nightly visits as well. Yet what I have not seen, not even once, are vultures.
The Turkey Vulture, Cathartes aura, is a common bird in the area. I see them circling high above Scappoose and the outlying areas every day now and have for roughly the past month when the first one was spotted this spring. By rights they should have picked the carcass more or less clean by this time; which makes me wonder if perhaps their populations are not quite as healthy in the local area as might be assumed.
The IUCN Red List citation for the Turkey Vulture indicates that they are a species of Least Concern with a “large global population estimated to be 4,500,000 individuals.” While I have no reason to doubt this, I do wonder if such a reportedly healthy global population necessarily indicates a locally healthy one. As vultures are carrion feeders, they tend to concentrate toxins and other harmful substances of the animals they consume. One only need contemplate the frightening 40% annual declines noted in the White-rumped Vultures, Gyps bengalensis, in India likely brought about by the use of diclofenac in local cattle.
Of course, one deer does not make a herd. However not two hundred meters down the road is another deer carcass that appeared only a few days after the first. It doesn’t even show any signs of scavenger activity, avian, mammal, or otherwise. The answer to this mystery, of course, lies beyond the scope of these idle observations, yet contemplate them we should for the simple reason that they could very well be a piece of a much larger puzzle that has yet to be assembled.
Peace and good bird watching.
