Phenophase · migration October 2026
Counting the Vaux's swifts into the chimney on Fourth Street
One thousand one hundred and eighty Vaux's swifts entered an old brick chimney in downtown Corvallis between 19:06 and 19:38 on 3 October, a rate of 78 birds a minute at the peak, in the middle of the autumn migration for this species.
| Date | Place | Fourth Street, Corvallis, Oregon | Weather | 15°C · clear, sunset 18:48 · Wind NW 2 m/s |
|---|
Vaux's swifts migrate through this valley in September and October and roost communally in chimneys on the way. The one on Fourth Street takes a few thousand birds on a good night, and it has done so for as long as anyone here can remember.
The count
I sat on the kerb opposite at 18:50 and counted every bird that went down the flue, in five-minute blocks, with a hand counter.
- 19:06 to 19:10 — 96 birds. The first birds dropped in while the sky was still bright.
- 19:11 to 19:15 — 214.
- 19:16 to 19:20 — 268, the peak; then a sharp-shinned hawk crossed at rooftop height and the flock broke up for about ninety seconds.
- 19:21 to 19:25 — 201.
- 19:26 to 19:30 — 236.
- 19:31 to 19:38 — 165, thin and scattered, the last bird at 19:38.
Total 1,180 in 32 minutes, a peak rate of 78 birds a minute. The flock was late: on 26 September the entry started at 18:44, which is what an earlier sunset does to a bird that times its roost by the light.
Why a chimney
A chimney is a hollow tree as far as a swift is concerned: a vertical shaft with a rough inner wall to cling to and a warm, still column of air inside. Swifts cannot perch — their feet are built for clinging, not gripping — so they must roost on a vertical surface, and the inside of an unlined brick flue is close to ideal.
Eleven starlings tried the same chimney about twenty minutes before the swifts arrived and were displaced without much argument. The swifts do not evict them; they simply fill the space.
What to check next time
- Count again on 10 October to see whether the flock is still in the thousands or has dropped to hundreds.
- Note the entry time against sunset: my records show entry starting within twenty minutes of sunset on every clear evening so far.
- Look for droppings on the pavement under the chimney, which is how the building's owner knows how many birds have been using it.
Observed
| Scientific name | Vernacular | Count | Note |
|---|---|---|---|
| Chaetura vauxi | Vaux's swift | 1180 | 1,180 counted into the chimney in 32 minutes, tallied in five-minute blocks |
| Accipiter striatus | sharp-shinned hawk | 1 | one pass at 19:20 that scattered the flock for about ninety seconds |
| Falco peregrinus | peregrine falcon | 0 | recorded only: one seen here on 28 September, not tonight |
| Sturnus vulgaris | European starling | 11 | eleven that tried to use the same chimney and were displaced by the swifts |
Reflection
I count swifts four or five evenings each autumn and I have never once been bored. It is a public spectacle that nobody has to organise, in the middle of a town, and the number is the only thing anyone can disagree about.
Kit carried
- hand tally counter
- stopwatch
- binoculars 8x42
- digital thermometer
- Rite in the Rain notebook
- 2H pencil
- folding stool