RE: [nfc-l] Moonwatch question
Hi everyone, I've been lurking and enjoying reading the posts so far ... much as I'm intrigued by all the possibilities for nocturnal observations, for the fall I'm primarily preoccupied with being up at dawn to do migration monitoring via mist-netting (at McGill Bird Observatory in Montreal, Quebec). As an aside, we happen to have an Environment Canada radar station within 1 km of our site, but as was noted the other day, the images released to the public aren't useful for tracking migration - if anybody does find a way around that, we'd be most interested. Regarding the direction of flight paths, I have a couple of comments. A couple of years ago I had an opportunity to take a portable radar unit into the foothills of northeastern British Columbia (approx 1800 - 2000 m / 5500 - 6000 ft elevation). I operated it for a few hours after dusk in three different locations to get an idea of how migrants were moving (both direction and height). While topography would certainly be expected to have an effect in a landscape with stark ridges and valleys, I was still surprised at just how varied the movements were ... even in early September, there were nearly as many heading straight north as south (let alone most other directions). The other note is that analysis of banding data suggests that for a lot of species, the notion of "traditional" north-south migration may not be all that accurate. In fact, the Canadian Atlas of Bird Banding (http://www.cws-scf.ec.gc.ca/publications/BBA-AOB/v1ed2/index_e.cfm) shows quite a strong northwest-southeast axis of movement for many species across much of the continent (and skewing toward northeast-southwest in the far east). This is shown particularly well by Common Redpoll (http://www.cws-scf.ec.gc.ca/publications/BBA-AOB/v1ed2/ShowBird.cfm?lang=e; aou=5280), though admittedly it isn't a typical migrant. Still, the pattern isn't all that different for others I randomly picked to look at, such as Yellow-rumped Warbler (http://www.cws-scf.ec.gc.ca/publications/BBA-AOB/v1ed2/ShowBird.cfm?lang=e; aou=6550) and Swainson's Thrush (http://www.cws-scf.ec.gc.ca/publications/BBA-AOB/v1ed2/ShowBird.cfm?lang=e; aou=7580). For many other species there aren't enough recoveries mapped to describe any clear pattern, but it still looks like truly north-south movements are far from typical. How this translates on a local level I'm not sure - I expect we have much yet to learn (a common sentiment it seems). But I wouldn't be surprised if in some cases different species (or even different populations of the same species) moving through the same area might be heading in somewhat different directions. Happy observing, Marcel Gahbauer Executive Director The Migration Research Foundation Montreal QC www.migrationresearch.org mar...@migrationresearch.org -- 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 --
Re: [nfc-l] Moonwatch question
Mike et al, to your point.. >It makes sense, but I saw more birds at 60x than at 20x. Also again, > more birds with a polarizing filter on the end, this was also easier > on the eyes. So where does that leave us? Well definetly we need much > more thought of optics used and how to assign some type of detection > probability. I have only limited experience with moonwatching, but can make some comments as an astronomer. Consider a full moon. It shows a contrast to the adjacent background. For all purposes of Moonwatch the surrounding sky is informationless and "black", so an optimum field of view would be such that the moon fills the whole field of view. The moon itself is not really that bright. It is actually quite close to the brightness of green grass in daylight. To alleviate the "large contrast problem", you could be better off if your vision was **not** dark adapted. I would actually observe the moon in conditions were the back yard lights and city light ;-) are on and not switched off. Quite different from standard astro observing in that sense. Because the moon is a celestial body it moves its diameter in 2 minutes with the rest of the sky. This creates a problem as one should really be tracking the moon with a proper setup mount. If a tracking mount is not available then one could obtain a 1 minute nonstop stare if the magnification were such that it covered 2/3 of the diameter of the moon. Then a few seconds for repositioning etc. I would guess that having the telescope still for 1 minute would be better than manually trying to follow it all the time. Regards Harry J Lehto -- 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 --
Re: [nfc-l] Moonwatch question
Good point Erik, usually all the migrating birds I am seeing in PA are going in generally the same direction, but often high birds will be going one direction and low birds another ( like upper se, lower sw), but some of the watching I have done along the gulf coast and atlanic birds were flying in every direction, likely resulting from a lot of confused birds circling or heading back inland when they hit the coast. Birds hitting these barriers will often fly back a few miles inland if they are not ready to cross, or head againt the wind if they are course correcting. Good discussion! Best, Mike Lanzone Sent from my iPhone On Sep 4, 2009, at 7:31 AM, Erik Johnson wrote: David et al., All the birds are flying the same direction while other critters have random flight paths. Is this really a safe assumption? Last night I did some moon watching and the majority (just barely) of birds were headed westish. But others were flying south, some northeast, etc. I was fairly confident these were birds and not bats, but Mike made a good point about optics (I was using 10x binocs) and wasn't videoing so I have no way to prove to myself (or you guys) what I was seeing. In any case, I checked out the radar and there was decent volume, but the radial velocity had a trend of movement to the SW, but with a lot of scatter. Again, were these birds? I think so. Perhaps variation in the direction of movements is more apparent where I am along the gulf coast where topography and bird ecology (water-crossing avoidance vs not; trans-gulf vs circum-gulf; etc) significantly alter the behavior of individual birds. I can imagine that farther north birds are pretty much bombing south (although no doubt topography and ecology are important there, too). I have had similar experience listening to call notes - where you can pick out birds going in all directions. So I think this phenomenon is real, at least here. Happy listening, Erik Johnson S Lafayette, LA (~40mi N of the Gulf of Mexico) ejoh...@lsu.edu On Fri, Sep 4, 2009 at 5:30 AM, David Mozurkewich wrote: On Fri, 2009-09-04 at 02:53 -0600, Ted Floyd wrote: I should think that, given distant and fleeting views of such animals, there's the potential to over-count birds by accidentally counting bats and moths. Any pearls of wisdom on this one? Ted, All the birds are flying the same direction while other critters have random flight paths. This eliminates most false alarms and is good enough except when the birds are a minority of your detections. -- David Mozurkewich Seabrook, MD USA -- 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 -- -- 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 -- -- 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 --
Re: [nfc-l] Moonwatch question
there are already too many Davids on this list... ;) if you check out that moonwatching vid I posted, you'll see that indeed the bad was moving in the right "general" direction, and the only way I told it from a bird was based on the cadence of the flight, plus when I viewed it on the big screen you could make out the forward appearance of the wing, etc. What David is talking about, though, can be seen in this really cool paper by Sid Gauthreaux and John Livingston (http://tinyurl.com/m7q2t5), where bats especially show more erratic flight on thermal imagery. But, when moonwatching, given prevailing winds, bats which are not actively feeding could (and probably do) move in the same direction as birds, and insects definitely will move with the prevailing winds. Most of the separation, then, falls on the observer, and as Mike pointed out, magnification may be the key. good moon watching David David A. La Puma, Ph.D. Dept. of Ecology, Evolution, & Natural Resources Online Teaching Portfolio: http://www.woodcreeper.com/teaching Lockwood lab: http://rci.rutgers.edu/~jlockwoo Websites: http://www.woodcreeper.com http://badbirdz2.wordpress.com Photos: http://www.flickr.com/photos/woodcreeper On Fri, Sep 4, 2009 at 7:31 AM, Erik Johnson wrote: > David et al., > > All the birds are flying the same direction while other critters have > random flight paths. > > Is this really a safe assumption? Last night I did some moon watching > and the majority (just barely) of birds were headed westish. But > others were flying south, some northeast, etc. I was fairly confident > these were birds and not bats, but Mike made a good point about optics > (I was using 10x binocs) and wasn't videoing so I have no way to prove > to myself (or you guys) what I was seeing. In any case, I checked out > the radar and there was decent volume, but the radial velocity had a > trend of movement to the SW, but with a lot of scatter. Again, were > these birds? I think so. Perhaps variation in the direction of > movements is more apparent where I am along the gulf coast where > topography and bird ecology (water-crossing avoidance vs not; > trans-gulf vs circum-gulf; etc) significantly alter the behavior of > individual birds. I can imagine that farther north birds are pretty > much bombing south (although no doubt topography and ecology are > important there, too). I have had similar experience listening to > call notes - where you can pick out birds going in all directions. So > I think this phenomenon is real, at least here. > > Happy listening, > Erik Johnson > S Lafayette, LA (~40mi N of the Gulf of Mexico) > ejoh...@lsu.edu > > > > > > On Fri, Sep 4, 2009 at 5:30 AM, David > > Mozurkewich wrote: > >> On Fri, 2009-09-04 at 02:53 -0600, Ted Floyd wrote: > >> > >>> I should think that, given distant and fleeting views of such animals, > >>> there's the potential to over-count birds by accidentally counting bats > >>> and moths. Any pearls of wisdom on this one? > >> > >> Ted, > >> > >> All the birds are flying the same direction while other critters have > >> random flight paths. This eliminates most false alarms and is good > >> enough except when the birds are a minority of your detections. > >> -- > >> David Mozurkewich > >> Seabrook, MD USA > >> > >> > >> -- > >> 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 > >> -- > >> > > > > -- > 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 > -- > -- 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 --
Re: [nfc-l] Moonwatch question
Here are some digiscoped clips I took in Sept 07 http://www.youtube.com/watch?v=OOVXdVooAeQ=1 http://www.youtube.com/watch?v=rQOGPtAfmr0=1 http://www.youtube.com/watch?v=uASqg7OHBSw=1 http://www.youtube.com/watch?v=gz6qyvsBnrI=1 I'm pretty sure in the first clip, the first two objects are birds (the close one even looks like a duck/loon-type) and the third, beginning at the upper left quadrat of the moon and moving down and right, appears to be a bat based on flight style. I've viewed these on a projected screen which makes it easier to interpret (maybe). In the other three clips I'm pretty confident the objects are birds. These were taken through a Leica Televid APO 77mm scope, with a Nikon Coolpix 4500 camera. Good Moon Watching! David David A. La Puma, Ph.D. Dept. of Ecology, Evolution, & Natural Resources Online Teaching Portfolio: http://www.woodcreeper.com/teaching Lockwood lab: http://rci.rutgers.edu/~jlockwoo Websites: http://www.woodcreeper.com http://badbirdz2.wordpress.com Photos: http://www.flickr.com/photos/woodcreeper On Fri, Sep 4, 2009 at 6:30 AM, David Mozurkewich wrote: > On Fri, 2009-09-04 at 02:53 -0600, Ted Floyd wrote: > > > I should think that, given distant and fleeting views of such animals, > > there's the potential to over-count birds by accidentally counting bats > > and moths. Any pearls of wisdom on this one? > > Ted, > > All the birds are flying the same direction while other critters have > random flight paths. This eliminates most false alarms and is good > enough except when the birds are a minority of your detections. > -- > David Mozurkewich > Seabrook, MD USA > > > -- > 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 > -- > -- 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 --
Re: [nfc-l] Moonwatch question
On Fri, 2009-09-04 at 02:53 -0600, Ted Floyd wrote: > I should think that, given distant and fleeting views of such animals, > there's the potential to over-count birds by accidentally counting bats > and moths. Any pearls of wisdom on this one? Ted, All the birds are flying the same direction while other critters have random flight paths. This eliminates most false alarms and is good enough except when the birds are a minority of your detections. -- David Mozurkewich Seabrook, MD USA -- 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 --
[nfc-l] Moonwatch question
Hi, Mike et al. Well, I gave it a whirl last night, Thursday, Sept. 3rd, around 9pm Mountain Daylight Time. (Location: Lafayette, eastern Boulder County, Colorado.) In less than 2 seconds, a passerine flew across the disk of the moon; sweet. But then I had an unexpected complication. The next object to transit the moon was a bat. Then another bat (or the same one). Then a large moth. I should think that, given distant and fleeting views of such animals, there's the potential to over-count birds by accidentally counting bats and moths. Any pearls of wisdom on this one? Thanks, Ted --- Ted Floyd Editor, Birding --- Please support the American Birding Association: Click on http://www.goodsearch.com/?charityid=884482 to search the internet. Check out the American Birding Association on FaceBook: http://www.facebook.com/group.php?gid=22934255714 Check out the American Birding Association on Twitter: http://twitter.com/abaoutreach Please visit the website of the American Birding Association: http://www.aba.org -- 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 --
