THE OREGON 
fields are smaller and are in the vicinity of 
forests so that the larks learn many things 
from the woodiand songsters and blend 
them with their own songs. 
Indeed there are singers in the mountains 
that utter such a variety of musical notes 
and give such a diversity totheir songs 
that they can no longer be charged with 
being monotonous. 
The young larks possess the power of 
mimicry in no smalldegree, as any one will 
discover who k22ps them in a cag2in the 
vicinity of good sinzers of a different spec- 
ies or in a window near a grove. Under 
such circums'aices a variety of songs will 
be learned and repeated by the lark. In 
the same way larks ina state of nature wil] 
catch strophes and various musical notes 
from the woodland songsters and repeat 
them, not as an independent recita! but 
skilfully blended in their own songs, like 
gay threads woven in a plain fabric. When 
free, larks never neglect their own charac- 
teristic songs, but in captivity, ifthey have 
been taken when very young, they will a- 
bandon the distinctive lark song entirely 
and become mere imitators of other singers. 
ANGUS GAINES, 
Vincennes, Indiana. 
SOME OREGON MAMMALS. 
THE BEAVER 
Castor fiber canadensts. 
The day is past when every slough from Fort 
Vancouver to The Dalles contained its colony 
of Beaver, but still there is hardly a mountain 
stream of any size through the western portion 
of Oregon that dors not contain one or more 
pair tnd it will be many years yet before this 
giant rodent need be scratched from the Jist of 
Oregon mammals for these survivors of a once 
numerous rice have learnt new and cunning 
ways that tax the ingenuity of man, 
The appearance of the Beaver is known to 
every school boy and it is needless to describe it 
NATURALIST. 163 
here. Much also has been written about its 
habits and yet but the half has been told, for the 
short descriptions contained in natural histories 
apply to the Beaver of the past, The Beaver 
of to day has changed his habits to suit the times, 
he no longer lives in large colonies; he no long- 
er builds dams or houses, but with his im- 
mediate relations finds a dwel'ing under some 
old snag or more frequently ih the heart of some 
log-jam from which stronghold he ventures forth 
in quest of food only at night time, and were it 
not for the infallable ‘“‘sign” the marks of his 
powerful teeth on the willow branches along the 
streams very likely his presence would pass 
unnoticed. 
The food of the Beaver consists chietly of the 
young shoots of trees and shrubs of which the 
Cottonwood and Willow are the most sought 
afier. The Willow shoots are easy to reach, 
but in order to reach the Cottonwood it was 
often necessary for the animal to fell large trees 
and many writers assert that the animal was 
capable of felling these trees in such a manner 
as to cause them to fallin the water being after- 
wards used in the construction of the dams. 
This statement is undoubtedly erroneous for 
two reasons: namely; First — Beaver fell a tree 
by gnawing round it,— equally on all sides, — 
and in the natural course of events the tree falls 
which ever way it inclines. 
Secondly — Cottonwood is very bouyant and 
would tend to destroy a dam by floating it out. 
The writer’s observations lead to the belief 
that the dams are constructed of small branches 
up to an inch or so in diameter together with 
grass and mud of which the latter is by far the 
largest ingredient used. 
Many theories have been advanced as to how 
the mud was carried to the dam, some stating 
that it was carried in the mouth of the Beaver; 
others that it was carried on the tail, I do not 
intend to deny either of these statements, but 
from personal observations I have formed a 
theory of my own, which is, that the mud i, 
scraped up from the bottom of the pond, on the 
sloping surface of the dam and deposited on the 
top by the animal’s tail which is bent down for 
the purpose. 
