Tuesday, January 07, 2003

More Comments on Bird Feeding: Good, Bad, or Neutral?

As I mentioned earlier, an article published in the Wall Street Journal at the end of December generated much criticism. Most recently, Scott Shalaway joined the chorus in this excellent article published in his The Wild Side column in the Sunday Gazette-Mail.

While I generally agree with most of what Shalaway had to say, I am prompted to make two points:

(1) While the U.S. Fish and Wildlife Service is generally supportive of backyard bird feeding, it has on at least one occasion discouraged people from feeding waterfowl. Several years ago they published a leaflet that I believe is entitled "DON'T feed waterfowl" (not currently available online). If I recall correctly, the major points are that (a) wild waterfowl can get along just fine without supplemental food from humans; (b) it can encourage concentrations of birds in restricted areas, which produces conditions suitable for disease outbreaks; and (c) it can result in the establishment of resident populations of ducks and geese in urban areas, which can result in many types of "nuisance" problems.

(2) By reason of the fact that they can attract large concentrations of birds, backyard feeders can potentially (and often do) become sites of disease outbreaks. A fact sheet issued by the National Wildlife Health Center (see link below) lists four diseases commonly associated with feeders (salmonellosis, trichomoniasis, aspergillosis, and avian pox) and I would add a fifth (mycoplasmal conjunctivitis). The NWHC fact sheet lists 8 steps that can be taken to "prevent or minimize disease outbreaks at feeders," but closes with this cautionary note: "As ideal as bird feeding may seem, it carries some risk for birds that visit the feeders and some responsibility for people who do the feeding."

While it is true that diseases spread wherever birds gather, it is also true that diseases are able to spread faster when large numbers of birds are concentrated in small areas, as in the immediate vicinity of permanent feeding stations. I suspect that, on average, the incidence of these diseases is higher at backyard feeders than at natural food patches. That is not to say, however, that I believe that disease outbreaks at backyard feeders are a significance source of additive mortality in wild bird populations.

In closing, let me draw an analogy between backyard feeders and national wildlife refuges. Each year, tens of thousands of waterfowl die from various disease outbreaks (botulism, cholera, duck plague). In most cases, the magnitude of the mortality is amplified because large numbers of waterfowl are being forced to pack into relatively small (and decreasing) areas of suitable and protected habitats, which increases the likelihood of diseases being spread from sick birds to nearby healty birds. In essence, these refuges have become mega feeders for waterfowl.

While acknowledging that there are certain risks associated with backyard bird feeding, do I also believe that the benefits outweigh the detriments? Yes, undoubtedly.


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