The Audubon Society released a report today that has gotten some press attention: the severe decline in many bird species over the past 40 years.

The Greater Scaup can be seen in SF Bay Area waters, but in the US it has declined by 75% since 1967. Other species have declined as much, or more: the Northern Pintail, a beautiful water fowl, by 77%; the Northern Bobwhite by 82%.

What most of the articles don’t mention is that the findings have come through citizen science. Every Christmas Audubon holds a Christmas Bird count. As the Christians replaced pagan mid-winter celebrations with their birth of the Child days, so Audubon related conservationists in the early 1900s replaced the traditional Christmas “Side Hunt” [the side with the most feathers wins] with a bird count. The Christmas Bird Count has become a big deal in the US and elsewhere with some 50,000 participants.

The numbers of birds in each species, at particular sites, on the same day are submitted to a central database and published. It is from these data as well as more from the Breeding Bird Survey –another volunteer effort– that the report is compiled.

For a list of the top twenty declines see here.

Much of the decline is due to development and change of habitat and radical industrial agricultural policies. There are of course climactic changes taking place further affecting birds, as well as bird-watchers, which will be dealt with in a forthcoming report from Audubon. ScienceBlogs, meanwhile, has a report of bird survival projected in several mathematical models.