Paul and anyone else interested--
        Some speculations about your nighthawk questions. Nighthawks are
diurnal migrants, and while we may see as many as a dozen together in
the spring, this time of the year you can seem them in much larger
numbers, when migration is more leisurely, and there are more
inexperienced birds in the flocks.
        There are published fall records of 3000+ and ~2500 over Columbus. The
most I've ever seen was 600+; most of the time I see straggling birds,
not often in tight flocks, but continually moving in small numbers. The
flock of 600 were all moving north--the 'wrong' way--just before dark.
        Nighthawks aren't communal in most ways, but like a lot of other
species when they find others of their kind moving in migration,
survival is served by keeping in sight with one another, and they may
roost communally after dark in trees. Nighthawks don't have much use for
trees during the breeding season, but they seem to like their cover in
unfamiliar surroundings by night.
        My half-baked explanation for the wrong-way movement is that here on
the north side of Columbus, birds moving south as it's getting dark
eventually see the bright and relatively treeless city center, and
U-turn toward the parks, etc., north of downtown for safe roosts. I
wonder if others have noticed this on the north side of big cities.
         Nighthawks adapt to urban settings; they will nest atop buildings, but
given the choice, I imagine the migrating birds that choose dense trees
for roosting are more likely to survive, so they may often have to
backtrack at dusk to areas more suitable for roosting. Clusters of large
trees are denser along the rivers, too.
Bill Whan
Columbus

On 8/21/2012 11:42 AM, Paul Hurtado wrote:
> Yesterday I was out driving around a sleeping baby before the two of us
> took a walk around the OSU wetlands, and I noticed a good number of Common
> Nighthawks (some in small flocks; maybe family groups??) over the
> neighborhoods between the Scioto and Olentangy rivers, and over the OSU
> Wetlands. I saw a total of 22 over about a 2 hour period and all were
> flying north:
>
> 6:30-7:15pm: 1 singelton and one group of 3 seen while driving around.
>
> 7:15-7:35pm: 10 over the OSU Wetlands in 2 groups; the first group of 6
> flew over around 7:15 and then a second group of 4 flew over 5 minutes
> later, also heading north up the river valley.
>
> 7:45-8:25pm: 7 over the OSU Wetland in 2 groups; 1 high over the river
> around 8:10pm and a second group of 6 at 8:25pm high over the wetlands.
>
> When I returned home (north of Kenny Rd. and Ackerman) at 8:30pm another
> singleton was seen flying north over our neighborhood.
>
> The fact that all 22 of these birds were very deliberately heading north
> was a bit unexpected.  Perhaps there's a staging ground somewhere up north?
> Maybe near one of the reservoirs north of Columbus (Delaware or Alum
> Creek)? In any case, it looks like they're starting to aggregate in
> preparation for their long trip to some (relatively unknown) wintering
> location in or beyond the Amazon basin.  If we can figure out where Black
> Swifts spend the winter, it'll only be a matter of time before someone
> straps geolocators on a few CONIs too. :-)
...
>
> Good birding,
> Paul Hurtado
> Columbus, OH
>
>

______________________________________________________________________

Ohio-birds mailing list, a service of the Ohio Ornithological Society.
Our thanks to Miami University for hosting this mailing list.
Additional discussions can be found in our forums, at www.ohiobirds.org/forum/.

You can join or leave the list, or change your options, at:
http://listserv.muohio.edu/scripts/wa.exe?LIST=OHIO-BIRDS
Send questions or comments about the list to: [log in to unmask]