Good morning, I am curious to know if recording stations in the Northeast have experienced, numerically – with respect to quantity of night flight calls, a reduced number of migrants this spring as compared to past years. My perception is that there was a noticeable lack of birds moving throughout certain regions of the Northeast this spring. Conversely, did recording stations elsewhere (perhaps in the mid-west) record higher numbers of migrants this spring?
On the ground, for example, I don't ever remember a year when I only heard or saw 2-3 Blackpoll Warblers. Period. Usually, I would hear or see several Blackpoll Warblers on any given day over the course of a few days during the peak movement for this species. Of course, maybe a mass die-off of Blackpoll Warblers and other migrants went unnoticed this past fall or this spring, similar to the infamous mass die-off from 2-3 October 2011 at the Laurel Mountain wind facility in West Virginia. See: http://www.birdfellow.com/journal/2011/10/29/in_the_news_484_blackpoll_warblers_die_at_wind_farm. Note: it is suggested these birds succumbed to exhaustion from becoming trapped in the sphere of fog-reflected light produced by a lighted substation, which was accidentally left on overnight at the facility, rather than actual deaths caused by direct turbine strikes. I know there was a memorable weather-related fallout on the Gulf Coast of Texas this past 25-27 April 2013. See: http://www.texasbirdimages.com/home/2013-fallout---cameron-county/nueces-co-list---april-25-2013. It makes me wonder if it is at all possible for unfortunately-timed severe weather-related events, during key trans-Gulf crossings, to result in population-wide declines of neotropical migrants. Or, is this just an anomalous year as a result of the negative phase of the North Atlantic Oscillation, producing unfavorable conditions for nocturnal movement of small passerines into the Northeast. In possible scenarios like this, do boreal neotropical migrants favor an alternate springtime route that may carry them North, up the Mississippi Flyway to a point North of the Great Lakes, allowing them to then catch the prevailing West wind in an Easterly direction to their breeding grounds? If such a scenario were to play out, how do first spring individuals learn of these routes? Do they follow the masses? Interestingly, I'm finding that the cuckoos seem most unaffected by minor Northerly airflow at night (such as the night of 2-3 June). I'm sure their body size and wing length have everything to do with the ability to migrate into a headwind as compared to smaller passerines, such as warblers. Last night, in calm to light winds, I recorded 7 different Black-billed Cuckoos and a single Yellow-billed Cuckoo, plus a single Virginia Rail, one Alder Flycatcher, one Swainson's Thrush, and a single Indigo Bunting. Unfortunately, I was not recording sooner this spring in Etna, NY, so don't have a good comparison of this year to last year (for peak migration); however, I did get out as much as possible to a migrant stopover patch on most mornings (see the Hawthorn Orchard: http://www.birds.cornell.edu/cayugabirdclub/hawthorn.htm and check eBird for this site). My perception from daytime observation was a serious lack of neotropical migrants, yet with a reasonable amount of resources (insect larvae) for them to feed upon. This was one of the more memorable springtimes for me, with respect to flowering trees. I don't recall a time in the recent past of a springtime with the same amazingly full quantity of flowers remaining on the trees for as long as they did, yet with so few migrants. Though, perhaps in actuality there may have been fewer food resources (insect larvae) available than in past years, due to the cooler weather this spring (in the Northeast). If weather conditions correlate as closely to food resource availability as is probably the case, perhaps the birds use weather-related cues to avoid migration routes that may lead through regions with a dearth of food resources as compared to routes through other regions with high food resources. Or, perhaps there was a mass die-off in the Gulf this spring or the Atlantic and/or Gulf last fall, or at nighttime lighted facilities on unfortunately fog-enshrouded nights. It all seems so speculative without looking at long-term population trends in different regions. I think it will be interesting to watch for the comparative results from this year's Breeding Bird Surveys to past Surveys and of Surveys to come in future years, as well as the gradual accumulation of records in eBird. Thanks for any thoughts and input on this! Sincerely, Chris T-H -- Christopher T. Tessaglia-Hymes Field Applications Engineer Bioacoustics Research Program, Cornell Lab of Ornithology 159 Sapsucker Woods Road, Ithaca, New York 14850 W: 607-254-2418 M: 607-351-5740 F: 607-254-1132 http://www.birds.cornell.edu/brp -- NFC-L List Info: http://www.NortheastBirding.com/NFC_WELCOME http://www.NortheastBirding.com/NFC_RULES http://www.NortheastBirding.com/NFC-L_SubscribeConfigurationLeave.htm ARCHIVES: 1) http://www.mail-archive.com/nfc-l@cornell.edu/maillist.html 2) http://www.surfbirds.com/birdingmail/Group/NFC-L 3) http://birdingonthe.net/mailinglists/NFCL.html Please submit your observations to eBird: http://ebird.org/content/ebird/ --