Windy, and particularly windy weather with
heavy showers, they dislike; and on such days withdraw, and are
scarce ever seen.
There is a circumstance respecting the colour of swifts, which
seems not to be unworthy our attention. When they arrive in the
spring they are all over of a glossy, dark soot-colour, except their
chins, which are white; but, by being all day long in the sun and
air, they become quite weather-beaten and bleached before they
depart, and yet they return glossy again in the spring. Now, if they
pursue the sun into lower latitudes, as some suppose, in order to
enjoy a perpetual summer, why do they not return bleached ? Do
they not rather perhaps retire to rest for a season, and at that
juncture moult and change their feathers, since all other birds are
known to moult soon after the season of breeding?
Swifts are very anomalous in many particulars, dissenting from all
their congeners not only in the number of their young, but in
breeding but once in a summer; whereas all the other British
hirundines breed invariably twice.
Pages:
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292