Re: [nfc-l] Austin, Tx - Hourly count - Through May 7, 2012

[Jeffrey Buler]

Here's a link to NOAA's solar calculator. There is a nice convenient Excel spreadsheet you can download that calculates sunrise and sunset for any location. http://www.esrl.noaa.gov/gmd/grad/solcalc/calcdetails.html I've found that flight calls seem to steadily increase throughout the night and peak just before sunrise. Thanks for sharing your data! Cheers, Jeff Jeffrey Buler, Ph.D. Assistant Professor of Wildlife Ecology Department of Entomology & Wildlife Ecology University of Delaware 246 Townsend Hall Newark, DE, USA 19716 Office: 302-831-1306 Mobile: 302-723-0156 Fax: 302-831-8889 http://ag.udel.edu/enwc/faculty/Buler.htm Center for Managed Ecosystems On 5/10/2012 4:15 PM, Mike Farmer 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: Welcome and Basics Rules and Information Subscribe, Configuration and Leave Archives: The Mail Archive Surfbirds BirdingOnThe.Net Please submit your observations to eBird! --