The mild U.S. winter is reflected in the most unusual reports in the 15-year history of the Great Backyard Bird Count, a citizen's science project conducted across North America for four days in February.
"Every bird species has a captivating story to tell, and we're certainly seeing many of them in larger numbers farther north than usual, no doubt because of this winter's record-breaking mild conditions," said John Fitzpatrick, executive director of the Cornell Lab of Ornithology.
Some of the unusual sightings included early migrating sandhill cranes and fish-eating belted kingfishers in northern areas that normally would be frozen over.
This winter was the fourth-warmest winter on record for the 48 contiguous states. It also has been drier than normal in the West and the Southeast, though wetter conditions prevailed in the Central and Southern Plains and some parts of the Ohio Valley.
A few arctic bird species also moved farther south than usual. Snowy owls were reported in record numbers throughout the Great Plains and Pacific Northwest. Experts believe they move south from their usual arctic habitats when prey such as lemmings are scarce.
With the lack of ice, more than 2 million snow geese were recorded at Squaw Creek National Wildlife Refuge in Missouri. High numbers of mallards, ring-necked ducks, hooded mergansers and American coots never left or returned early to waterways that remained unfrozen.
Bird watchers submitted 17.4 million bird observations on 104,000 checklists. The top 10 birds reported on the most checklists in the 2012 count were:
The count is a joint project of the Cornell Lab of Ornithology, at Cornell University, and the National Audubon Society with Canadian partner Bird Studies Canada.