
Noy. 1886.] 

_ AND OOLOGIST. 167 

The petrels are all more or less nocturnal in 
their habits, and all lay white eggs. The Ful- 
mar deposits its egg openly, on ledges on the 
cliffs, but the other members of the group lay in 
crevices in the rocks, under stones, or form bur- 
rows to the depth of two or three feet. All the 
rest of the Laridée lay richly coloured eggs. 
It will be seen from the above that the decolori- 
sation takes place in three ways. In some— 
Swallows, Wrens, Tits, &c.—the ground tint dis- 
appears first, leaving the egg more or less thickly 
marked with small light coloured spots; in others 
—Starlings, Little Auks, &c-—the markings 
vanish first; while in a third class—Puftin, Hen- 
harrier, &c.—both ground tint and spots appear 
in a rudimentary degree. 
In this paper reference has only been made to 
the eggs of British birds, not only because the 
fauna ofthese isles forma very complete and typ- 
ical group, but because the views adduced are 
based solely on the study of thousands of speci- 
mens British eggs in my own and other collec- 
tions, and upon observations made on the moors, 
in the woods, and by the seaside. 
Evidence has been brought forward to show 
that the pigmentary coat on birds’ eggs came into 
existence at a very early period of their life—his- 
tory, and existed in the eggs of the progenitors of 
all the extant species. It has‘also been shown 
that the range of colours on birds’ eggs is very 
limited, but follows the usual course of pigmentary 
changes; that the pigment is unstable and varia- 
ble, making the process of change and decolorisa- 
tion a simple one; and that its primary use is for 
protection from the solar rays, but that it after- 
wards became modified for concealment. 
Lastly, it has been shown that eggs acquire a 
highly developed pigmentary layer, or lose their 
pigment entirely, according to whether they are 
exposed to the full glare of the sun or laid in 
situations inaccessible to its rays, and that the in- 
termediate degrees of coloration are in direct ratio 
to the amount of light to which the eggs are 
exposed. 
The two causes which determine the colouration 
of eggs—protection from the sun’s rays and con- 
cealment from observation—act conjointly ; they 
are not antagonistic like natural selection and 
sexual selection. The limited range of colours 
shows that natural selection alone operates. Dar- 
win states that, in regard to structures acquired 
through ordinary or natural selection, there is a 
limit to the amount of advantageous modification 
in relation to special ends; but in regard to struc- 
tures acquired through sexual selectior there is 
no definite limit; so that, as long as the proper 
variations arise, the work of sexual selection will 
goon. That the causes are different from those 
which produce the colours of the birds them- 
selves, is shown by the fact that eggs from tropi- 
cal regions do not surpass in brilliancy of tint 
those of more temperate climes. 
od 
Nestand Eggs ofthe Short-eared Owl. 
BY G. F. BRENNINGER, BEATTIE, KANSAS. 
During the spring of 1884 it was my good for- 
tune to find the Short-eared Owl (Asio acetpitri- 
nus) breeding. Like most of the owls, they are 
residents, but are found most plentifully during 
the colder months. In the middle of April nest- 
ing is first begun. Their nest is a mere depres- 
sion in a bunch of old grass. The owls inhabit 
the vast uninhabited prairies along sloughs, where 
the banks shelter them from the cold winds of 
winter and the burning rays of the sun in sum- 
mer. A great number of their nests are burnt 
every spring by the prairie fires, and after the 
first set has been destroyed a second set are laid. 
This I think was the case with my sets. 
My first set was taken on May Ist, and con- 
tained seven eggs of the pure white surface and 
spherical form so common with owls. The sec- 
ond set, of six eggs, was taken May 4th, and in- 
cubation was slight in both. 
The ears or tufts of this species are only seen 
when the birds are looking at any object, as at 
other times they are hidden. For the past two 
seasons I have been requested to try and obtain 
some sets of their eggs, by some of our most ad- 
vanced odlogists, and many weary searches and 
tramping over prairies have only proved to be 
repeated failures, and I have not found nor seen 
any of their nests since. 
The food of this species consists chiefly of mice, 
insects, and ground squirrels. Seldom, ifever, do 
they deprive the farmer of his chickens, and only 
in one instance have I known them to catch 
pigeons. This was while they were sitting on 
the outside of their coops during a severe snow 
storm, and the owls were probably driven to do 
this by hunger. The farmer is ignorant of this 
fact, however, and shoots them whenever oppor- 
tunity occurs. 1 have personally known boys to 
place an open steel trap upon a high pole. This 
seldom fails to catch an owl, as they perch on the 
pole at night. In the warmer part of the year 
these owls are rarely seen, and perhaps they seek 
remote places, in the shade of dark gullies, where 
they can live in peaceful solitude. 
