GENERAL NOTES 
167 
GENERAL NOTES 
BATS ON MIGRATION 
It may interest students of bat migration to know that the British Museum 
has received from Mr. P. E. Cheesman two specimens of the silver-haired bat 
(Lasionycteris noctivagans) and one of the red bat (Lasiurus borealis), which 
were obtained out of a flock of about a hundred which caught up with and settled 
on Mr. Cheesman’s ship some twenty miles off the coast of North Carolina on 
the 3rd of September, 1920. The special interest of the record is that these two 
species were migrating in a considerable flock some way out to sea and in company 
with one another. — Oldfield Thomas, London, England. 
THE NEST OP THE WASHINGTON WEASEL (mUSTELA WASHINGTON! ) 
On July 17, 1920, while setting a biological survey line of traps in the flats of 
the Nooksack River, at Excelsior, Whatcom County, Washington, in a thicket 
almost purely of salmonberry bushes, I was casually observing the mountain 
beaver burrows occurring in this locality. One burrow looked especially fresh 
but unusually small. Stooping, I was surprised to see, deep down in the burrow, 
the head of some small creature like a weasel. It drew back almost at once, so 
a wooden and a steel rat trap, both baited with the skinned body of a small mam- 
mal, were put down. 
By evening a large female weasel, apparently the mother of those captured 
later, was taken in the steel trap. Next morning both traps were found un- 
touched. By evening two nearly fullgrown weasels were taken at the same time, 
one in each trap. Both were males. Next morning another young male was 
taken in the steel trap. 
It appeared that here might be a nest, for there were some indistinct though 
clearly worn trails leading through the salmonberry bushes to the hole, with 
here and there a bird feather scattered about. The hole itself, 2.5 inches in 
diameter, was driven between the roots of the salmonberry bushes and kept 
open by them. The animals had gnawed the bark from those roots adjacent to 
the hole to make the entrance larger. That large bluebottle flies were passing 
in and out this burrow not only suggested the presence of a nest but that the den 
might be occupied by a carnivore. 
After posing and photographing the adult female, we dug into the burrow to 
search and found that it almost immediately entered a mountain beaver den. 
There, in an enlargement of one of the twisting burrows, we found a nest, about 
as big as a dinner plate, made of moss, and resembling a grouse nest. Under this 
present nest between it and the entrance were the remains of what seemed to be 
a very old nest, which would suggest that this den had been used in former years 
and had possibly functioned also as a winter nest. 
The main den seemed to be inhabited by the mountain beaver as well, as fresh 
earth was thrown out of a burrow within a few feet of the weasel nest. 
The exact dimensions of this nest are as follows: Diameter from surface of the 
ground to bottom of the nest, 18 inches; distance from top of ground to top of 
nest cell, 5 inches; diameter of nest cell, 13 inches by 14 inches; diameter of actual 
nest, 9 inches by 9 inches; dished portion of the nest, 2 inches deep; distance dug 
