Hi all, Just a few comments to catch up on all of these threads. And a big welcome back to all of those checking this list regularly!
On Wed, Mar 17, 2010 at 7:57 PM, Andrew Albright <[email protected]> wrote: > Is this too early for a big NF in the mid-atlantic region? Broadly, no, I don't think so - this week should see some nice movements given the return flow that's been building since the nastiness of last weekend moved past. However, if you're hoping for a flight with the magnitude and diversity of some spectacular fall movements, probably not. Such large calling events appear to be generally rarer in spring than in fall; they can occur, especially in places like coastal Florida and Texas certainly in May; and it's quite possible that larger calling events occur with some greater regularity even this early in the season - honestly, not enough data to say, because most nocturnal acoustic monitoring programs start after the first Song Sparrows and American Tree Sparrows and such (and waterfowl) begin moving north! > > Are these the main factors? > 1) Date during migration season (higher numbers during peak) > 2) What has happened during previous nights - i.e. if the wind was > blowing strongly in the wrong direction or > 3) Wind speed and direction > > It should have been backed up recently with all the rain and northern > winds. Wind is out of the WSW tonight. But, is it still to early for > a big spring NFC? To follow up on these questions and on what David and Brian were discussing and additionally to frame in terms of vocal behavior. . . I agree, winds are of great interest (and annoyance sometimes)! In the modeling for BIRDCAST about 10 years ago (and in Sid Gauthreaux's and Ken Able's modeling 30 years prior to that), we found that wind speed, direction, its decomposition into vectors at the surface were useful, without question, in predicting radar reflectivity in simple (!) regression models for the mid-Atlantic and Northeastern US. Not surprisingly, the position of pressure centers, presence and distribution of rain, temperature and relative humidity measurements (all surface level) were correlated in various ways and related to our success in forecasting migration on WSR-88D (there are some good papers by Able, Richardson, Erni et al. and others I can dig up if people are interested). We also used wind speeds aloft at 900/925 mb, which were particularly valuable when thinking about the more regional extent of favorable conditions for migration - for example, considering the wind speed, direction, vectors at that level allowed us to consider how birds might favorably exploit the lowest 500-700 m above the ground if they were moving on that night and over what geographic distribution that movement might occur, rather than the more local forecasting of winds, temperature, humidity, etc. BUT, these factors in total were not always important in forecasting a large calling event - this was decidedly more complex, requiring consideration of cloud ceiling, cloud cover, and then some factors that we could not/did not consider like artificial lighting and ambient noise conditions. Generally, and the extent of the modeling of this is still in it infancy in my estimation, increasing cloud cover and decreasing cloud ceiling were decent predictors of higher calling events, especially in the presence of seasonally appropriate winds and proximity to boundaries between air masses, even if you controlled for varying bird densities as depicted on WSR-88D. However, we never had quite enough analysis to have much power with these models - so I still think of these as trends that need more robust analysis! I'm blathering on and on here - the point is, there is SO much cool analysis to be done. . . Great thread Andrew/Andy/David/Brian. Best, Andrew (F) -- NFC-L List Info: http://www.NortheastBirding.com/NFC_WELCOME http://www.NortheastBirding.com/NFC_RULES ARCHIVES: 1) http://www.mail-archive.com/[email protected]/maillist.html 2) http://birdingonthe.net/mailinglists/NFCL.html 3) http://www.surfbirds.com/birdingmail/Group/NFC-L Please submit your observations to eBird: http://ebird.org/content/ebird/ --
