26 Vol. Xe 
PROBLEM: DO BIRDS MATE FOR LIFE?” 
By J. EUGENE LAW 
WITH ONE PHOTO BY L. E. WYMAN 
TiE excellent article entitled ‘‘ Evidence that many birds remain mated for 
life’’, by F. C. Willard (Conpor, xx, 1918, p. 167), is pregnant with prob- 
lems for the bird ecologist. Another angle of view may further emphasize 
the value of intensive study, such as Mr. Willard’s article indicates, and the ne- 
cessity of carefully recording in the minutest detail every incident in a bird’s 
life history. 
Fig. 10. NEST oF CALIFORNIA BLACK-HEADED GROSBEAK CON- 
STRUCTED MAINLY OF WILD OATS. THE EGGS SHOWN ARE 
BORROWED, AS THE TWO EGGS ORIGINALLY FOUND HAD BEEN 
DESTROYED WHEN THE NEST WAS NEXT VISITED. THE STRIPS 
AT TOP AND RIGHT ARE EACII ELEVEN INCHES LONG. 
Photo by L. EH. Wyman. 
The precariousness of life among birds leads one, even though paired birds 
normally remained so, to doubt so uniform an escape from fatality as would 
follow, did the numerous incidents noted cover pairs mated throughout the 
period of Mr. Willard’s observations. If lost mates were replaced, no doubt the 
surviving mate drew the new one to the old home of the survivor’. Male hum- 
mingbirds are notoriously indifferent to any family relations, further than the 
actual act of fertilization. The Anna Hummingbird is pugnaciously solitary 
1The writer has had two pairs of Anthony Towhees about his acre-plot home for 
five years. These birds seemed beyond question to be paired throughout the year and 
consequently for life. At least twice during that time one of these four individuals was 
killed in a mouse trap, soon to be replaced by a new mate, 
