Jessie and Mike, I will answer both of your posts in more detail later when I have time, but to my knowledge there has only been one person to collect definitive data on call rates of birds during nocturnal migration (from know individuals). It was on was on Swainson's Thrushes where he had a transmitter attached to it during nocturnal migration transmitting back to a vehicle to be recorded via radio. I saw a partial manuscript on this several years ago, I hope it gets published, its an invaluable study. Here is a short excerpt from Cochran's study- http://www.inhs.illinois.edu/inhsreports/sep-oct97/migrants.html
One of the published papers out there dealing with this is the Farnsworth et.al. paper- "A comparison of nocturnal call counts of migrating birds and reflectivity measurements on Doppler radar" Mike Michael Lanzone [email protected] On Fri, May 11, 2012 at 11:14 AM, Mike Farmer <[email protected]> wrote: > Thanks everyone....I wish there was a central place for all your > knowledge for us newbies to peruse. It would make getting started > easier....but maybe less fun in the floundering? > > I’ve had this discussion with a bunch of people just starting to record or > who have given up after attempting to record. It seems to be a naturally > progression that newby’s like myself take. First, we are amazed at how > well the detectors will find such small packets of energy above the > background noise. Then we go into near depression because a beautiful OVEN > bird zeep is some how missed. Then horror that my big night of 500 calls > could have been 750 if I would just wade through 20,000 false positives > instead of 3,000. > > The OLDBIRD detectors and Raven Pro detector....to name the only two I > have used....are amazing detectors. State of the art for what they do. > But the background noise is varying so rapidly and randomly that some calls > are missed and false detection are many. > > It is at this point that the newby must decide. What am I trying to > do? For me, I finally realized that I want as unbiased a sample of the > birds calling over my house as I can get and I want a sufficient sample. > A good number, that is. I’m not so concerned that I get every call that > my mic hears as long as I don’t miss OVEN birds at a higher rate than CCSP, > for instance. But I also don’t want just 10% of the calls because > although that may be good enough for the many CCSP, it may not be enough > OVEN birds calls to analysize. > > Notice that I said that I want an unbiased sample of the birds > calling.....not that I am getting an unbiased sample of the birds flying > over my house. Sure, I would want that but apparently you professionals > haven’t even determined what the call rate of each species is. So we > newbies have to realize that we are in no way counting how many birds fly > over our house. Right? Do I have that right? > > But when I read your professional papers and talk to the gurus like BIll > Evans, I see that we can talk about changes in the proportion of the calls > of each species. At least until you professionals give us more ways to > crunch the statistics. > > Sorry for the mini-rant. I think newbies should be less frustrated by > missed calls than we just naturally seem to be. The pursuit of perfection > should not be the enemy of the good. > > -Mike Farmer > -Oldbird and Raven Pro detectors are great....newbies, use them! > > *From:* Lewis Grove <[email protected]> > *Sent:* Friday, May 11, 2012 8:26 AM > *To:* Andrew Albright <[email protected]> > *Cc:* Mike Farmer <[email protected]> ; NFC-L <[email protected]> > *Subject:* Re: [nfc-l] Austin, Tx - Hourly count - Through May 7, 2012 > > Hi Andrew and all, > > Automated detection of calls is a tricky business, though it is relatively > easy to figure out the proportion of calls that you are actually pulling > out - just count calls manually, screen by screen and then see how many > your detectors find. We looked at 90 different random 15-minute segments > from three different recording sites, using multiple observers to find the > total number of calls present. > > Basically, depending on the software package and the parameter > combinations you use (SNR and occupancy are the big ones other than having > your time and frequency bounds correct), you can get wildly different > proportions, ranging from near zero to near 100% of calls. I can't > remember the exact numbers but I believe Tseep-x finds something just shy > of 50% of the warbler/sparrow calls present in a file. Other factors come > in to play here too - background noise (insects) particularly. > > Hopefully all of this data (there's a lot) will someday see the light of > day in a journal - it's overdue. > > Lewis > > > On Fri, May 11, 2012 at 8:19 AM, Andrew Albright < > [email protected]> wrote: > >> Mike - I enjoy reading your reports, so keep 'em coming! >> >> I'm no expert, but I think when I asked the question before it seems >> that the general idea is that nfc are easier to detect in the first >> couple of hours and then around dawn as birds will be flying at lower >> elevations (and they can get so high that you can't detect nfc). But >> I don't know how much data supports this hypothesis and it's quite >> possible that it's from East Cost migration which could be >> significantly different from that seen in Texas. >> >> I have one question - have you ever gone through an hour or a night of >> your data to see/hear how well the automatic detection works? >> Also, what % of nfc can you not assign to a certain species? >> >> Sincerely, >> Andrew >> >> On Thu, May 10, 2012 at 4:15 PM, Mike Farmer <[email protected]> wrote: >> > Since March 1, our Austin city station has recorded 4250 night calls. >> The >> > quieter station 10 miles to the west had 6372. See the attached graph >> > showing the number of calls per hour of the night. This is for the >> quiet >> > station. >> > >> > This chart seems rather too convenient. I am suspicious of it. What is >> > known about this kind of timing? The curve matches the inverse of the >> > relative quiet of a typical night. Life is just quieter in the middle >> of >> > the night. So can’t a lot of this be a detector and noise effect? >> Or do >> > the birds actually fly and call more in the middle of the night? >> > >> > Also this data doesn’t adjust for daylight savings shift in the third >> week >> > of March or the fact that dusk shifts to later times as spring >> progresses. >> > What we really want to plot is the hour after dusk not the actual >> time. But >> > has anyone here figured out a formula for the number of minutes each >> night >> > that dusk shifts? You can google this and get a bunch of graphs but >> there >> > must be a formula ..... probably involving a bunch of cosines and other >> > witchcraft? >> > >> > -Mike Farmer >> > >> > >> > equipment >> > >> > Mic – Oldbird 21c >> > >> > Software – Oldbird tseep, thrush, GlassOFire, Raven Pro, Excel >> > >> > -- >> > NFC-L List Info: >> > Welcome and Basics >> > Rules and Information >> > Subscribe, Configuration and Leave >> > Archives: >> > The Mail Archive >> > Surfbirds >> > BirdingOnThe.Net >> > Please submit your observations to eBird! >> > -- >> >> -- >> >> 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/[email protected]/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/ >> >> -- >> >> > > > -- > Lewis Grove > PhD Student, Wildlife Ecology > President, Graduate Student Association > SUNY *E*nvironmental *S*cience and *F*orestry > (814) 880 - 5667 > > > -- > *NFC-L List Info:* > Welcome and Basics <http://www.northeastbirding.com/NFC_WELCOME> > Rules and Information <http://www.northeastbirding.com/NFC_RULES> > Subscribe, Configuration and > Leave<http://www.northeastbirding.com/NFC-L_SubscribeConfigurationLeave.htm> > *Archives:* > The Mail Archive<http://www.mail-archive.com/[email protected]/maillist.html> > Surfbirds <http://www.surfbirds.com/birdingmail/Group/NFC-L> > BirdingOnThe.Net <http://birdingonthe.net/mailinglists/NFCL.html> > *Please submit your observations to eBird<http://ebird.org/content/ebird/> > !* > -- > -- 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/[email protected]/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/ --
