Image from the Biodiversity Heritage Library.
Contributed by Museum of Vertebrate Zoology, University of California, Berkeley.
| www.biodiversitylibrary.org
Transcription
R.E.Johnson
1967
Black-headed Grosbeak
131
April 28 Tilden Regional Park, Alameda Co., California
Cold, scattered clouds. 8:20 AM. Fight in limbs of oak
tree (3 birds: 2 Ø + 1 ♀). One male leaves. Other male
displays - tail tilted downward 30° from horizontal & spread
widely, wings spread away out & quivering. No notes
were observed. ♀ disappeared. Display was performed
on a #1 inch limb of oak & was begun when
♀ was 2 ft. away.