Weather and Birds

Note: [I posted this on the message board of cincinnatibirds.com some time ago and now, with the arctic blast we are currently getting, I thought it apropos to include it here on my blog. There is also an interesting discussion on the Ohio-birds listserve about the cold and bird movements at http://birding.aba.org/maillist/OH].

To borrow the term from "Birding" magazine, this may fall under the category of "Building Birding Skills". 

I just finished reading a fascinating article on weather systems and their associated implications on bird migration and vagrancy in the December 2003 issue of "Birding" magazine (Vol. 35, no. 6 - snowy owl on cover). The article, written by Paul Lehman entitled "A Weather Primer for Birders" was very thourough in its explanation and was complimented nicely by several weather maps drawn by Virginia Maynard. In a nutshell, most fallouts of birds occur in what is called the warm sector ahead of a cold front and south of the warm front. 
Although I have always been interested in the effects of weather on birds, this article sparked my interest further, and I decided to search online for historical weather maps. I think I struck gold! I found the following site extremely useful with free historical weather maps from 1871-present: 

http://docs.lib.noaa.gov/rescue/dwm/data_rescue_daily_weather_maps.html 

Recalling some high counts of birds from personal observations, I decided to check my computerized records for dates of these high counts, then check the above website for the weather patterns on that date. 

Indeed, a high count of 22 Tennessee Warblers (including one single species flock of 15) at the Cincinnati Nature Center on September 23, 2000 occurred in the warm sector just ahead of a cold front and south of a warm front. The low pressure system on that date was centered over Lake Michigan. 

In another example, a high count of 19 Black-throated Green Warblers at the Cincinnati Nature Center on April 27, 1989 was associated with a low pressure system just south of Indianapolis with an occluded front just to our south! 

With these historical weather maps available, we can look at any of our records and study the weather patterns so that we can be able to predict when and where in our area the next fallout of migrants and/or vagrants may occur. 

Just for curiosity, I looked at maps for dates of a couple of vagrants we have had in our area: the Swallow-tailed Kite in Lawrenceburg,IN on August 18, 1997 and the Groove-billed Ani in Owensville, OH on October 21, 1981. The kite was associated with a high pressure located over western Lake Superior and an occluded front over the KY/TN state line, with the low centered over western Kentucky. The ani was associated with an occluded front bordering the south shore of Lake Erie. 

Basically, whenever you see a weather system approaching with a low pressure system and cold front to our west and a warm front to our north, it is prime time to get out and look for birds because you may be rewarded with a fallout of migrants and possibly a vagrant.