Wednesday, March 03, 2010

USFWS Revises Migratory Bird List and Adds Pacific Species

This week the US Fish and Wildlife Service published its first revision of the List of Migratory Birds that are protected under the Migratory Bird Treaty Act (MBTA) since 1985. The MBTA protects birds that occur in the United States and its territories, especially bird species that are not covered by the Endangered Species Act. It bans the "taking" of wild birds – which includes killing, capturing, injuring, or possessing bird parts or nests – without a federal permit. While enforcement is uneven, it provides a tool for addressing some of the most egregious bird killings.

Since this was the first revision in 25 years, there were a lot of changes to make. The USFWS added 186 species to the list and subtracted 11, so that the list now includes 1007 bird species. The final rule published in the Federal Register contains the complete list of changes (pdf).

Some changes are very basic. The USFWS relies on lists published by the American Ornithologists Union's checklist of North American birds and Monroe and Sibley's checklist of world birds. The AOU has made numerous changes to bird taxonomy and nomenclature since 1985; these changes needed to be reflected in the federal list. The common or scientific names of 114 species were changed to conform with current practices, while 38 species were added to the list due to taxonomic splits. Meanwhile, one taxon, Black-backed Wagtail, was removed because it is now considered a subspecies of White Wagtail. It also corrects some misspellings.

Past versions of the List of Migratory Birds excluded species viewed as accidental or casual within the United States. The USFWS has since changed its views regarding such rare birds and now views protection of these species to be consistent with the MBTA's purposes. The current revision thus adds 94 species whose normal range occurs outside of the United States but that have accepted records within the country. This group includes such species as Common Chaffinch, Red-footed Falcon, and Western Reef-Heron. Ten species were removed due to lack of evidence that they occurred naturally within the United States.

Muscovy Duck, native to South and Central America, was added to the list because its range has been expanding northward. A small wild population now occurs naturally in Texas. However, most of the Muscovy Duck populations in the United States are the result of human introductions and in some cases they are bred for food production. A separate rule (pdf) addresses some of the issues regarding this species.

The headline change, announced in its own press release, is that the new List of Migratory Birds includes more birds from Pacific islands. The new list adds 24 Hawaiian endemics, such birds as Akikiki, 'I'iwi, and Hawaii Creeper. It also adds 28 species that occur on other US territories, such as American Samoa and the Northern Mariana Islands. The latter group includes such species as Mariana Crow and Micronesian Kingfisher. I am not sure why the Hawaiian species were not covered by previous versions of the list, but at least the omission has been rectified.

One addition that the USFWS chose not to make is Cackling Goose. In 2004, the AOU split the 11 subspecies of Canada Goose into two groups; 7 remained as Canada Goose while four became Cackling Goose. The USFWS regards the genetic basis for the split to be inconclusive since some analyses of nuclear DNA show evidence of hybridization. It requests further evidence before making any change to these 11 subspecies. In the case of Canada and Cackling Goose, changing the list would require changing hunting regulations and educating the public about identifying the new species, so the agency wishes to proceed more cautiously.