MiNOT on Colorado Birds. 227 



song and the Redstart's as alike : but the first always has a falling, and 

 the second a rising inflection. 



16. Dendroeca striata, Baud. Black-polled Warbler. — Local 

 summer residents about Seven Lakes. Recoi-ded by Mr. Henshaw from 

 Denver in May. 



17. Dendroeca auduboni, Baird. Western Yellow-rump. — A 

 summer resident, u'regularly distributed, but preferring high willow swamps 

 and spruce timber. Yet June 1, at Boulder, I found some, singly or in 

 pairs, several miles out from the hills, — perhaps migrating however, 

 though so often gregarious. Habits like those of the Eastern Yellow- 

 rump ; same chip, and chnp (sometimes repeated rapidly) ; song similar, 

 a weak little warble, but often pretty. June 24, at Seven Lakes, I found 

 four eggs, almost ready to be hatched. These are curiously like a com- 

 mon type of the Yellow Warbler's, being greenish- white, marked, chiefly 

 about the crown, with olive-brown and neutral tint, and averaging about 

 .70 X .55 of an inch (but I have no instrument here for precise measure- 

 ment). The nest, composed of shreds and feathers, with a few twigs 

 without and hairs within, was built in a dead, bare spruce, about twenty 

 feet from the ground, compressed between the trunk and a piece of bark 

 that was attached beneath and upheld above, where a bough ran through a 

 knot-hole, — so compressed that the hollow measures 2^ x 1|, and 1^ 

 inches deep. Such a position for the nest is probably not unusual, for I 

 more than once saw tlie birds about dead timber, though, on the other 

 hand, an old nest that I attributed to this species was in a live spruce, 

 — against the trunk, in a crotch at some height. 



18. Siurus auricapillus, Sioain. Orange-crowned " Thrush." — 

 Boulder and Nederland in May : identified by notes only. Recorded from 

 Denver. 



19. Siurus naevius, Coues. Water " Thrush." — Present at Boul- 

 der, Nederland, etc., in the latter part of May. Probably a summer resi- 

 dent. 



20. Geothlypis macgillivrayi, Baird. Western Mourning 

 Warbler. — At Boulder, abundant along creeks, in the latter part of 

 May. At Manitou, as summer residents, less numerous. Their ordinary 

 song-notes, chee-cJiee-cJiee-chee, I could not positively discriminate froui 

 those of Wilson's Black-cap, when the two sang on either side of me in 

 a thicket. To these chee' -che-chu, or a few terminal notes, may be added. 

 Sometimes, however, in May, this little Warbler has a fit of ecstasy, and, 

 with a short, nervous flight, bursts into sweet song, though not so liquid as 

 his Eastern cousin's. He is not at all shy. An old nest that I attributed 

 to this species was built of shreds, lined with hairs, and situated in a 

 thorn-bush, a foot from the ground. June 21,1 took a nest near Manitou, 

 remarkable for being five feet from the ground, and three feet from a 

 travelled road. It was in a scrub-oak, rather bulkily built of shreds and 

 stalks, with a thick lining of hairs, in a hollow about two inches across 



