Hi All, Jim Danzenbaker from Battle Ground, Clark County, (southwestern) Washington State, USA here.
First, I want to thank all the folks who have been posting to this listserve - such a wealth of information on Night Flights in one place is exciting and its great to hear about night flights in different parts of the country and the world. I feel that any question about night flights, if not answered immediately, is certainly open for discussion among those more knowledgeable than me. Visiting birder Ann Nightingale from Victoria, BC, Canada and I had about 875 SWAINSON'S THRUSHes flying over my yard in Battle Ground, Clark County from about 5:15am through 5:50am on September 1st. This number was determined based on 100 calls per minute times 35 minutes divided by 4 (total number of calls heard from one individual bird flying over earlier in the night - from extreme northern end of hearing to extreme southern end of hearing). My questions are: 1.) Has anyone determined if nocturnal migrants call at the same rate throughout their entire night flight or do they call more (or less) when descending? 2.) Should it be assumed that when birds are descending at the end of their night flight, they are continuing in their migratory direction at the same rate as the previous hours of their flight or is their rate of descent significantly reducing their forward progress? I ask because of my calculation of the number of birds on September 1st. A bird flying over in the middle of the night that has four audible "chips" could have five audible chips when descending by actually "chipping" at the same rate? Does anybody know? Thanks. -- Jim Danzenbaker Sales Manager for the Americas Kowa Optimed Inc. perched in Battle Ground, WA, USA 360-723-0345 jdanzenba...@gmail.com -- NFC-L List Info: http://www.NortheastBirding.com/NFC_WELCOME http://www.NortheastBirding.com/NFC_RULES http://www.mail-archive.com/nfc-l@cornell.edu/maillist.html --
