Image from the Biodiversity Heritage Library.
Contributed by Museum of Vertebrate Zoology, University of California, Berkeley.
| www.biodiversitylibrary.org
Transcription
Holmes R.
1961
Encounters passerines
3.
7 June Barrow, Alaska
The display seen again near Voth's area. The birds
were 1st noticed in a territorial pursuit, where 2 birds
were chasing a third. The indiv then veered off +
The other two kept together + finally landed. The 8
went into the posture described yesterday with
Tail cocked + wings spread at a great then
horizontal L. The 4 then took flight, the 8 following
close behind as they darted forth. The 8
would set his wings at 20 above the horizontal +
glide for a short time. He would fly a glide
just behind (usually slightly below) the 4.
All this activity was accompanied by a quiver-like
trill, similar to the aerial song. The bull was given
in short phrases of 2-10 sec. duration. Whenever
the birds landed, the 8 went into posture. On 2
such cases, he did not have time to raise his wings
(just tail was cocked) before the 4 took flight. He
would fly 30 to 200' land + then take off
The air again after a few seconds. This went on
for up to 2 min. - before they flew out of sight.
The head & is held up at about a 45° L +
not horizontal while in the air.
8 June - Two birds seem displaying aerially.
They came close together + it looked
like a chase would ensue. One
followed the other + they both
landed. One went into the courtship