LETTER XXXIII.

TO THE HONOURABLE DAINES BARRINGTON.

HEARD many birds of several species sing last year after Midsummer; enough to prove that the summer solstice is not the period that puts a stop to the music of the woods. The yellowhammer, no doubt, persists with more steadiness than any other; but the woodlark, the wren, the redbreast, the swallow, the white-throat, the goldfinch, the common linnet, are all undoubted instances of the truth of what I ad

vance.

If this severe season does not interrupt the regularity of the summer migrations, the black cap will be here in two or three days. I wish it was in my power to procure you one of those songsters; but I am no birdcatcher; and so little used to birds in a cage, that I fear if I had one it would soon die for want of skill in feeding.

Was your reed-sparrow, which you kept in a cage, the thick-billed reed-sparrow of the " Zoology," p. 30; or was it the less reed-sparrow of Ray, the sedge-bird of Mr. Pennant's "Zoology," p. 16?

As to the matter of long-billed birds growing fatter

in moderate frosts, I have no doubt within myself what should be the reason. The thriving at those times appears to me to arise altogether from the gentle check which the cold throws upon insensible perspiration. The case is just the same with blackbirds, &c.; and farmers and warreners observe, the first, that their hogs fatten more kindly at such times, and the latter, that their rabbits are never in such good case as in a gentle frost. But when frosts are severe, and of long continuance, the case is soon altered; for then a want of food soon overbalances the repletion occasioned by a checked perspiration. I have observed, moreover, that some human constitutions are more inclined to plumpness in winter than in summer.

When birds come to suffer by severe frost, I find that the first that fail and die are the redwing, fieldfares, and then the song-thrushes.

You wonder, with good reason, that the hedgesparrows, &c. can be induced at all to sit on the egg of the cuckoo without being scandalized at the vastly disproportioned size of the supposititious egg; but the brute creation, I suppose, have very little idea of size, colour, or number. For the common hen, as I know, when the fury of incubation is on her, will sit on a single shapeless stone instead of a nest full of eggs that have been withdrawn: and, moreover, a hen-turkey, in the same circumstances, would sit on in the empty nest till she perished with hunger.

I think the matter might easily be determined whether a cuckoo lays one or two eggs, or more, in a ,by opening a female during the laying-time.*

season,

See note to Letter xxx. p. 128.

If more than one was come down out of the ovary,' and advanced to a good size, doubtless then she would that spring lay more than one. I will endeavour to get a hen, and examine her.

Your supposition that there may be some natural obstruction in singing birds while they are mute, and that when this is removed the song recommences, is new and bold: I wish you could discover some good grounds for this suspicion.

I was glad you were pleased with my specimen of the caprimulgus, or fern-owl; you were, I find, acquainted with the bird before.

When we meet, I shall be glad to have some conversation with you concerning the proposal you make of my drawing up an account of the animals in this neighbourhood. Your partiality towards my small abilities persuades you, I fear, that I am able to do more than is in my power: for it is no small undertaking for a man unsupported and alone to begin a natural history from his own autopsia !

*Professor Owen is not aware that more than one ovum is ever contained in the oviduct at one time in any bird. In a female cuckoo, which he dissected at the breeding season, he found one egg in the uterus with the shell partially formed, the rest of the oviduct was disposed in close transverse folds not exceeding two lines in diameter. The ovary, besides a cluster of small ova, contained one ovum about half an inch in diameter, and no doubt ready to pass into the oviduct when disburthened of the egg which it was then perfecting. The ovum next in size was about three lines in diameter, but whether its further development would have been progressive or retrograde in the ovary he could but conjecture. As only the empty and collapsed calyx existed in the ovary, the egg in the oviduct must have been the first which the cuckoo had laid that year, continues the Professor, and the appearances generally bespoke a bird that produced more than one egg in the season, but whether more than two he was unable to determine.-ED.

Though there is endless room for observation in the field of nature, which is boundless, yet investigation (where a man endeavours to be sure of his facts) can make but slow progress; and all that one could collect in many years would go into a very narrow compass.

Some extracts from your ingenious "Investigations of the difference between the present temperature of the air in Italy," &c. have fallen in my way; and gave me great satisfaction; they have removed the objections that always arose in my mind whenever I came to the passages which you quote. Surely the judicious Virgil, when writing a didactic poem for the region of Italy, could never think of describing freezing rivers, unless such severity of weather pretty frequently occurred!

Two swallows have appeared amidst snows and frost.

SELBORNE, April 12, 1770.

JAST month we had such a series of cold turbulent weather, such a constant succession of frost, and snow, and hail, and

tempest, that the regular migration or appearance of the summer birds was much interrupted. Some, as the black-cap and white-throat, did not show themselves (at least were not heard) till weeks after their usual time; and some, as the grasshopper-lark and largest willow-wren, have not been heard yet. As to the fly-catcher, I have not seen it; it is indeed one of the latest, but should appear about this time: and yet, amidst all this meteorous strife and war of the elements, two swallows discovered themselves as long ago as the 11th of April, in frost and snow; but they withdrew quickly, and were not visible again for many days. House-martins, which are always more backward than swallows, were not observed till May came in.

Among the monogamous birds several are to be found single after pairing-time, and of each sex: but whether this state of celibacy is matter of choice or necessity, is not so easily discoverable. When the