310 
REPORT OF THE CHIEF OF ENGINEERS. 
fork of a limb, at other times placing it on the broad upper surface—in other words, 
saddling it. The same variation in plan is observable in the nests of our eastern pewee, 
although in both, the latter method seems to be the favorite. . . 
The nest alluded to above, as also a second found July 23, was saddled upon the terminal 
fork of a cottonwood, and was similar to the usual style of the eastei n pewee, except t iat- 
the exterior lacked the customary sprinkling of lichens given it by the latter bird, in¬ 
stead it was dressed with shreds of a white cottony substance and gray n nous >ar *G 
which served admirably to harmonize its tints with those of the light bark ot the tree, 
precisely the same end being thus attained as effected by the other bird, each using 
the material best adapted to itsown case. It would indeed be a “ blind instinct that 
should induce the western pewee to adopt for its nest the cloak of lichens, the invari-. 
able and successful resort of its eastern relative, an instinct that would prove fatal to 
the safety of its home, and only serve to invite the very danger of couspiciiousuess 
which it is its chief object to avoid. The contrast of differing means to the same end 
which is displayed in the architecture of these two flycatchers is one of many equally 
good illustrations which might be cited to prove the presence in birds of a something 
higher than mere hereditary instinct, and shows that only bv granting the existence 
of an amount of reasoning power can we explain the readiness with which a species 
adapts its existence to new conditions, and the fertility of resonrce which prompts the 
choice of means to a necessary end. 
Empidonax Cabot. 
E. trail'd, Aud. Traill’s Flycatcher.; 
Western specimens of this bird have usually been considered to represent a light- 
colored race, and have found mention under name of var. pusillu. I think Mr. Ridg- 
way is correct in the view recently expressed,* and that western and eastern birds do 
not differ sufficiently to warrant their separation. 
Th e pusillus of Swainson was accepted by Professor Baird as applying to the west¬ 
ern bird, but apparently with some doubt, as Swainsou’s description applies almost 
equally well to minimus. I prefer, therefore, to fall back upon the trailii of Audubon, 
including under this name both eastern and western birds. 
The Trails flycatcher is a numerous summer resident of the eastern slope, well up 
into Oregon. It loves to frequent the willow thickets along the streams, even follow¬ 
ing them to a high elevation in the mountains. 
E. obscurus (Sw.). Wright’s Flycatcher. 
Apparently rather uncommon as a summer inhabitant of the mountains, where only it 
is found at this season. It appears in summer never to frequent the same situations as 
the preceding bird, although the two may inhabit the same general locality. Thus, 
the borders of a stream which meanders through an alpine valley, and which is hedged 
by willows, will be found, almost to a certainty, to be inhabited by the little flycatcher, 
while the present species never intrudes on the domain of this bird, but is contented 
with the hillsides above, where it lives under the pines and among the chaparral. 
It would be interesting to study out the probable causes which thus lead two species 
so closely allied as these two flycatchers, with the same general habits and economy, 
with precisely the same method of capturing food, and living w-ithin sight, as it were, 
of each other, to so maintain their own preserves as never to clash with each other. 
A possible explanation suggests itself in varying tastes as to food, since it is probable 
that each locality differs enough in the character of its plants to harbor different kinds 
of insects, and hence to furnish each species with its own particular bill of fare. 
A nest found June 22 contained four fresh eggs. These are yellowish-white, and 
unspotted. The nest was an extremely neat, pretty structure, composed externally of 
strips of white bark, with an internal lining of tine grasses and feathers. It had a 
depth of two inches, and an internal diameter of the same. It was singularly ex¬ 
posed to view, being placed on an open bush on a hillside, where it was overshadowed 
by large pine trees. 
The E. hammondi is said to also occur along the eastern slope, but I did not meet 
with it. 
CAPRIMULGID.E—Goatsuckers. 
Ciiordeiles Swainson. 
C. popetue henryi, Cass. Western Night Hawk. 
An extremely abundant summer visitant through California, Oregon, and into Wash¬ 
ington Territory. 
* Ornithology of the Fortieth Parallel, page 539. 
