Matt-- That's a good question I haven't thought about. I don't think cold weather prompts unusual local arrivals of northern birds any more than hot weather does the same for southern birds. They are adapted to the weather extremes in their ranges. For example, we are probably not seeing this invasion of snowy owls because it is too cold up north. The important factor is food. I don't think anyone can predict large incursions of birds based on weather alone, unless the weather affects food sources. Back in the late 19th century, Ohio and neighboring states experienced a winter invasion of thick-billed murres, which was thought to have been caused by a failure in an important food source for this species: I wrote an article for the Cardinal about this species, not seen here for many many years, in the Winter 2003-4 Ohio Cardinal. It seems similar factors may have been involved in the unprecedented (for humans at least) incursion of razorbills last winter, which appeared in large numbers as far south as Miami (see the new issue of North American Birds)! Many birders are aware of the extreme variations in the numbers of winter finches each winter, which seem to be influenced by varying seed crops in the northern forests. These seem to be the best factors we humans can use to predict occurrences so far ahead for birds of the north. Extralimital occurrences happen for reasons we cannot always predict. We had a royal tern here near Columbus three years ago, but no one had any idea ahead of time that violent storms along the Gulf would sling one up this way in 2011. So my answer would be we can't tell, and isn't that part of the intriguing mystery? Shivering, Bill Bill … Can you also pontificate on what types of birds might be coming down with the arctic weather we should be on the look out for? Thanks! Matt ______________________________________________________________________ Ohio-birds mailing list, a service of the Ohio Ornithological Society. Please consider joining our Society, at www.ohiobirds.org/site/membership.php. Our thanks to Miami University for hosting this mailing list. You can join or leave the list, or change your options, at: listserv.muohio.edu/scripts/wa.exe?LIST=OHIO-BIRDS Send questions or comments about the list to: [log in to unmask]