BIRDS OF THE ANAMBA ISLANDS, 29 
The comparison of the above specimen with examples of this and 
allied forms has led incidentally to an examination of Hirundo 
rustica rustica, Hirundo rustica transitiva, Hirundo savigni, Hirundo 
gutturalis, Hirundo tytleri, and Hirundo erythrogastris, with par- 
ticular reference to their relationships with each other. After careful 
study of the specimens in the United States National Museum and of 
the literature on the subject, I am led to consider them all geo- 
graphical races of one species, and thus to agree completely with the 
view expressed by Dr. R. B. Sharpe and more recently by Dr. E. 
Hartert.? This is also the same opinion as that held by Mr. Henry 
Seebohm,’ except that he unites Hirundo tytlert with Hirundo ery- 
throgastris. 
That Hirundo rustica rustica, with its usually unbroken dark 
jugular band, intergrades with the broken-banded HMirundo rustica 
gutturalis, both geographically and individually, there seems to be 
not the slightest reason to doubt, for there are altogether too many 
intermediate specimens. Furthermore, some of the darker exam- 
ples of Hirundo rustica guttwralis are exceedingly close to the lighter 
specimens of Hirundo rustica erythrogastris, and are difficult to dis- 
tinguish without actual comparison; in fact the two forms overlap 
individually in all characters. Similarly, the dark extreme of 
Mirundo rustica erythrogastris overreaches individually the light ex- 
treme of Hirundo rustica tytleri, and thus connects these two forms. 
After careful examination and comparison of a large series of 
Hirundo rustica erythrogastris from various parts of its range, in- 
cluding a considerable series from western Alaska, I am entirely 
unable to see any even average differences which entitle the Alaska 
bird to subspecific separation as Hirundo erythrogastra palmeri;* since 
all the supposed distinctions of both size and color seem to be merely 
individual variations. 
Reverting again to Hirundo rustica tytleri, it is evident that inter- 
mediates between this and Hirwndo rustica gutturalis would be practi- 
cally indistinguishable from Hirundo rustica erythrogastris; and that 
such intergradation actually takes place in northeastern Siberia 
where the breeding range of Hirundo rustica tytleri approaches that 
of Hirundo rustica gutiuralis is evident from the fact that birds from 
Lake Baikal are practically like specimens of Hirundo rustica ery- 
throgastris,> although for geographical reasons referable of course to 
Hirundo rustica gutturalis; and from the various winter specimens 
from Burma and Cochin China that so closely resemble Hiruwndo 
rustica erythrogastris that Doctor Sharpe and others have identified 
them as such. 
1 Cat. Birds Brit. Mus., vol. 10, 1885, pp. 126-140. 
2 Vogel palaiarctischen Fauna, vol. 1, 1910, pp. 800-804. 
3 Hist. Brit. Birds, vol. 2, 1884, pp. 171-172. 
* Grinnell, Condor, vol. 4, May 15, 1902, p. 71 (Amaknak Island, Unalaska Harbor, Alaska). 
5 See Sharpe, Cat. Birds Brit. Mus., vol. 10, 1885, p. 127. 
