Let me try this again, I am not sure it went through . . . Best, AF On Thu, Mar 7, 2013 at 12:38 PM, Andrew Farnsworth <[email protected]> wrote:
> Hi John and all, > Thank you for bringing these points to the group, much appreciated. > > First, yes, there is an error (now corrected) - astronomical twilight > should reference the sun's position 18 degrees below the horizon. Apologies > for my poor editing skills! For reference, civil twilight is the sun's > position 6 degrees below horizon, nautical twilight 12 degrees, > astronomical twilight 18 degrees. > > Second, regarding the choice of astronomical twilight as opposed to the > more typical civil twilight that many use for recording flight calls, we > were/are concerned about this issue. We spent a long time thinking about > it (again) after you raised the point, and it is complicated in many ways > (that's a topic for outside the NFC list serve presumably). In the end, we > decided that it is *preferred* to enter NFC Count Protocol data in the > period between astronomical twilights but it is *OK* to enter NFC Count > Protocol beginning from civil dusk and concluding with civil dawn. However, > *please follow *all the instructions outlined in the protocol (for > example, make sure to report *all* other non-NFC-singing/calling birds as > local that you detect, whether by ear or by automated detection)! Not that > any of you wouldn't do that . . . Furthermore, we strongly recommend that > you enter hourly or sub-hourly counts and that any counts entered between > civil and astronomical twilight be entered separately. We amended the > current protocol to reflect these changes and requests: > http://ebird.org/content/ebird/about/nfc-count-protocol. > > As with the previous posting of the protocol, please contact me with > questions (and/or the list if NFC relevant). The original logic behind > astronomical twilight was to separate as truly nocturnal any flight calls > that were reported, basically eliminating the potential confusion > associated with other crepuscular activity, increasing numbers of local > species calling, and so on. As I said above, it's likely a topic for > non-NFC list discussion as it departs into another realm of discussions, > although I am happy to continue the discussion here, or privately, or > offline to be summarized for the list later! > > Hopefully this provides more clarity on some of the issues. And again, > thank you (all) for raising this issue/set of issues! If we've not yet made > it clear, we are eager for all in the NFC community to be involved and for > those not in the community to join! > > Good nocturnal birding! > Andrew (on behalf of teams BirdCast and 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/ --
