UN 
es) 
Mar., 1920 THE NESTING HABITS OF THE ALASKA WREN 
varying from eight to one hundred feet. The spot chosen may be a crevice be- 
tween shattered blocks of rock, or in a small blowhole in the ancient lava flow, 
or, more frequently, underneath banks of moss where rain and frost have ex- 
eavated cavities of tidy size. In three instances the nesting site had been chos- 
en the year before, the new nest being built upon the remains of the old one. 
In my experience the nest is never hidden far beneath the general surface of 
the cliff. Of twelve nests described in my field notes four were plainly visi- 
ble, while the others were merely concealed by an overhanging fringe of grass 
or moss or by a few small shattered scales of rock. Four other nests were 
placed in cracks at a considerable elevation and in overhanging cliffs that 
effectually prevented a close examination. 
The nest of the Alaska Wren is indeed a work of art, with the materials 
composing it bearing a definite relation to the nature of its surroundings. 
Generally speaking, it is a globular, more or less bulky affair with, the en- 
trance at one side. When situated in a lava bubble or in cavities where the 
adjacent rock is relatively dry, it usually consists of an external sheath of 
moss, thick or thin, according to the size of the space to be filled. Where the 
soil inclines to be soggy the roof alone is built of moss (at least in three in- 
stances) to absorb the moisture and prevent its precipitation upon the sitting 
female. Farther down, at the sides of the nest,.it rests upon a meshwork of 
erass and roots that not only drains away the water from above, but permits 
of rapid drying. To determine the correctness of this theory a nest of this type 
was brought in from the field, and was left overnight under the slow drip from 
a water tap. The next morning the mossy roof was soaked and the grassy base. 
adrip, but not a drop of water had made its way into the interior. While a 
_ nest of this construction operates satisfactorily during periods of intermittent 
rain it is altogether likely that the lining itself must eventually absorb moisture 
in excessively damp situations; whereupon it may be abandonéd until a later 
time when the soil is free from ice and the temperature is higher. 
The lining of the nest forms a heavy feltwork of which delicate roots and 
a fine filamentous lichen form the chief constituents. With these are usually 
associated the feathers of the least auklet (and other birds to a less degree). 
fox hairs, and in Jate years, the hair of the reindeer. The long white heirs, 
found in the nest described by J. A. Allen’, and believed to be those of the polar 
bear, were probably from the bleached-out winter coat of the blue fox that is 
shed in the spring. Those examinéd microscopically this year were all from 
this source; and besides, no polar bear has been known to have touched the 
shores of the Pribilofs, at least in recent years. 
With the aid of a field glass one can usually determine more or less ac- 
curately the various stages of the nest-building process. Where the female is 
bringing in bits of moss or grass stems the external sheath is obviously under- 
going construction, while feathers and fluffy bill-loads of lichen indicate the 
finishing touches. This period of restless activity on the part of the female 
finally comes to a close, and the quiet egg-laying season is ushered in. Never 
vet have I seen either the female or the male about the nest durine the week 
when the eggs are being laid, and in most eases they are seemingly absent alto- 
gether, probably at some distant point along the coast. 
In the majority of the nests examined this year the number of eggs laid 
"Nest and Eggs of the Alaskan Wren, Bull. Nutt. Orn. Club, II, 1877. p. 82. 
