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. :-)

Here is some of the Birds of North America species account for Common
Nighthawk relevant to fall migration:

*Timing And Routes Of Migration: Fall*

*U.S. and Canada*. Because fall transients commonly travel in flocks, they
are more easily detected than spring transients. Rare fall migrant in
extreme se. Alaska (Armstrong 1995). Mean fall departure from Okanagan, BC,
18 Sep (range 29 Aug–30 Sep, n = 16; Cannings et al. 1987). In Oregon, fall
migration begins late July, peaks early September, with stragglers through
early October (Gilligan et al. 1994). In California, transients noted most
frequently after mid-August, but rare after mid-September, with stragglers
recorded as late as mid-October (Small 1994). Transients recorded in
Arizona deserts mid-August (Bryant and Bryant 1945). Southerly flights
observed 23 Jul in Saskatoon, Saskatchewan (SK) (Wedgwood 1973). Transients
noted in S. Dakota primarily mid-August with latest records during first
week October (S. Dakota Ornithol. Union 1991). In Missouri, fall migration
peaks late August or early September with stragglers late September to mid-
or late Octber (Robbins and Easterla 1992). Transients peak in
Massachusetts late August to early September with stragglers through late
October; most observed in Connecticut River Valley with counts decreasing
toward coast (Veit and Petersen 1993). Transients recorded in Cape May, NJ,
from first week August through third week October with peak during first
half September; transients virtually absent from barrier islands off coast
(Sibley 1993). In Florida, fall migration detected from mid-July through
October, with stragglers recorded through late November (Stevenson and
Anderson 1994).
...

*South America.* Information sketchy for this area. Species rarely observed
at any season west of Andes or in ne. South America from Trinidad and
Tobago (ffrench 1991), Guyana, Surinam, and French Guiana through ne.
Brazil (R. Ridgely pers. comm.), although single specimens have been
collected from Curaçao (22 Oct 1955) and Bonaire (2 Oct 1982) in the
Netherlands Antilles off the ]northern coast of n. South America.
Southbound transient “nighthawks” (which may include Antillean Nighthawk)
are irregular in Netherlands Antilles (Voous 1983). Available records
indicate that transients pass through Colombia (late Aug–late Nov; Hilty
and Brown 1986) and Venezuela (Meyer de Schauensee and Phelps 1978) and
then east of Andes through w. Amazonia to reach their primary “wintering”
grounds, probably reversing this path during their northward flight.
Transients observed at Manaus, n.-central Brazil, 5 Oct–8 Dec (Stotz et al.
1992); Fuerte Olimpo, Paraguay, by 27 Oct (Hayes et al. 1990); and in Rio
Grande do Sul, se. Brazil, by Oct (Tampson 1987).
...

*Migratory Behavior: Fall Departures*

In U.S., more likely to form large flocks during fall migration than during
spring. In Ontario, groups of up to 550 individuals (Ewins 1993), with 706
individuals flying over Toronto in 45 min on 31 Aug 1944 (Parker 1983). Up
to 1,000 individuals observed in Manitoba and in Vancouver, BC (de Graff
1978), Michigan (Brewer et al. 1991), Wisconsin (Tessen 1987), Texas (Gross
1940), Arizona (Bryant and Bryant 1945), and New York (Bull 1985); 16,496
individuals observed in Minnesota on 16 Aug 1986 (Tessen 1987).

Local flocks gather with traveling migrants, forming large horizontal
rectangle of birds, 8–10 birds wide and 15–20 birds long; migratory flight
rapid, unison wingbeats, with no apparent leader (Rust 1947). Engage in
group flight several days before migration: close formation, 2.4–3.1 m
apart horizontally and vertically (Rust 1947). During migration may fly
close to the ground, apparently foraging on insects (Gross 1940), but
probably feed on insects at higher altitudes as well.


Good birding,
Paul Hurtado
Columbus, OH

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