SELBORNE, _Feb. 8th_, 1772.
Dear Sir,--When I ride about in the winter, and see such prodigious
flocks of various kinds of birds, I cannot help admiring at these
congregations, and wishing that it was in my power to account for those
appearances almost peculiar to the season. The two great motives which
regulate the proceedings of the brute creation are love and hunger; the
former incites animals to perpetuate their kind; the latter induces them
to preserve individuals: whether either of these should seem to be the
ruling passion in the matter of congregating is to be considered. As to
love, that is out of the question at a time of the year when that soft
passion is not indulged: besides, during the amorous season, such a
jealousy prevails between the male birds that they can hardly bear to be
together in the same hedge or field. Most of the singing and elation of
spirits of that time seem to me to be the effect of rivalry and
emulation: and it is to this spirit of jealousy that I chiefly attribute
the equal dispersion of birds in the spring over the face of the country.
Now as to the business of food: as these animals are actuated by instinct
to hunt for necessary food, they should not, one would suppose, crowd
together in pursuit of sustenance at a time when it is most likely to
fail; yet such associations do take place in hard weather chiefly, and
thicken as the severity increases. As some kind of self-interest and
self-defence is no doubt the motive for the proceeding, may it not arise
from the helplessness of their state in such rigorous seasons; as men
crowd together, when under great calamities, though they know not why.
Perhaps approximation may dispel some degree of cold, and a crowd may
make each individual appear safer from the ravages of birds of prey and
other dangers.
If I admire when I see how much congenerous birds love to congregate, I
am the more struck when I see incongruous ones in such strict amity. If
we do not much wonder to see a flock of rooks usually attended by a train
of daws, yet it is strange that the former should so frequently have a
flight of starlings for their satellites. Is it because rooks have a
more discerning scent than their attendants, and can lead them to spots
more productive of food? Anatomists say that rooks, by reason of two
large nerves which run down between the eyes into the upper mandible,
have a more delicate feeling in their beaks than other round-billed
birds, and can grope for their meat when out of sight. Perhaps, then,
their associates attend them on the motive of interest, as greyhounds
wait on the motions of their finders, and as lions are said to do on the
yelpings of jackals. Lapwings and starlings sometimes associate.