466 
SLEEP OF BIRDS. 
penny sterling- for every sixty larks. The quantity may seem pro- 
digious, hut the fields appear to be covered with them from Michael- 
mas to Martinmas. 
These birds are seen in Eg-ypt, about Cairo, in like number, the be- 
g-inning of September, and continue for some days ; they are supposed 
to come from Barbary, and are called in Egypt Asfour Dsjebali, or 
Mountain Birds. 
Whether any portion of the northern breed of these birds visit us in 
winter is not certain, but it is obvious that at particular times they are 
infinitely more abundant in the southern provinces than at others ; 
possibly they only quit one part of the kingdom, and assemble in 
another, where the climate is more mild. In the winter of 1803, large 
flocks of these birds were seen in every stubble-field in the south of 
Devon, in number far beyond any thing that has since appeared.* 
SLEEP OF BIRDS. — Like horses and some other quadrupeds, a 
great number of birds sleep standing ; the perchers, (^Insessores^ 
Vigors,) for example, usually sleep standing on one leg upon some 
tree, brush, or other elevation, with the head turned behind, and the 
bill thrust under the feathers on the back, or under the wing. Indeed, 
these appear to be the general habits of the whole race of birds, in 
regard to their mode of resting' and sleep ; for the duck and goose, 
although they do not perch, will frequently sleep standing on one leg' 
upon the ground, with their heads turned round, and the bills under 
the wing. Poultry, although they invariably perch, if a perch can 
be obtained, do not, when sleeping, rest usually on one leg ; but they 
sink down with their bodies upon the perch, having their legs com- 
pressed under them. The sky lark sleeps upon the ground with his 
legs also similarly compressed. It is probable also that all the tribes of 
birds, even the perchers, occasionally sink down with their bodies rest- 
ing on the perch during their soundest sleep. What is very remark- 
able in the structure of their feet and legs is, that the greater the weight 
upon the muscles, the more firmly the claws grasp whatever they lay 
hold of ; hence the cause that birds do not fall down in sleep, although 
most of their senses are dormant. 
The motion of the branches of trees produced by the wind increases, 
doubtless, the disposition for sleep in many birds ; this may be exem- 
plified in the common fowl ; for placing its bill under the wing, even 
in broad day light, and swaying it to and fro in the hand for a very 
short time, will produce sleep. Most of the tribe of birds sleep during 
the night ; but there are many exceptions to this. Owls in particular 
are, during the night, much more active than in the day ; their sight, 
