39 2 
Chapman, A Hybrid Swallow. 
TAuk 
LOct. 
A HYBRID BETWEEN THE CLIFF AND TREE 
SWALLOWS. 
BY FRANK M. CHAPMAN. 
The American Museum of Natural History has recently acquired 
from the collector what seems to be a hybrid between Petrochelidon 
lunifrons and Tachycineta bicolor. The specimen (No. 78,119 
Springfield, Mass., Aug. 20, 1902, Leon C. Holcomb) is apparently 
a bird of the year and, in addition to presenting evidences of 
hybridism, exhibits also albinistic characters, though it is possible 
the latter may be a result of hybridity. Generally speaking this 
specimen resembles bicolor below and lunifrons above, the rusty 
and buff markings of the last named species, however, being, in 
this supposed hybrid, white. A more definite understanding of 
this interesting bird’s color and markings may be gathered from 
the appended comparative tables : 
Form. 
T. bicolor. $ im. 
Hybrid. $ im. 
P. lunifrons. $ im. 
Bill. 
Medium ; width at nos- 
tril 4.5 mm. Nostril el- 
liptical; a well-developed 
operculum. 
Medium ; width at 
nostril 4.5 mm. Nos- 
tril circular; a well- 
developed operculum. 
Rather heavy and broad; 
width at nostril 6.3 m. 
Nostril circular ; no 
operculum. 
Long, 1 18 mm. 
Wing. 
Short, 103 mm. 
Medium, 105 mm. 
Tail. 
Medium, 50 mm.; fork, 
9 mm. deep. 
Short, 40 mm.; fork, 
4 mm. deep. 
Medium, 45 mm.; fork, 
2 mm. deep. 
Feet. 
Slender, tarsus 11 mm.; 
middle-toe, 11 mm.; nail, 
4 mm. 
Medium, tarsus, 11 
mm.; middle-toe, 11 
mm.; nail, 3 mm. 
Rather stout, tarsus, 11 
mm.; middle-toe, n 
mm.; nail, 5 mm. 
