64 NATURAL HISTORY OF SELBORNE. 
Since the ring-ousels of your vast mountains do certainly not for- 
sake them against winter, our suspicions that those which visit this 
neighbourhood about Michaelmas are not English birds, but driven 
from the more northern parts of Europe by the frosts, are still more 
reasonable ; and it will be worth your pains to endeavour to trace 
from whence they come, and to inquire why they make so very 
short a stay. 
In your account of your error with regard to the two species of 
herons, you incidentally gave me great entertainment in your 
description of the heronry at Cressi Hall; which is a curiosity I 
never could manage to see. Fourscore nests of such a bird on one 
tree isa rarity which I would ride half as many miles to havea sight 
of. Pray be sure to tell me in your next whose seat Cressi Hall is, 
and near what town it lies.* I have often thought that those vast 
extents of fens have never been sufficiently explored. If half a 
dozen gentlemen, furnished with a good strength of water-spaniels, 
were to beat them over a week, they would certainly find more 
species. 
There is no bird, I: believe, whose manners I have studied more 
than that of the caprimulgus (the goat-sucker), as it is a wonderful 
and curious creature ; but I have always found that though some- 
times it may chatter as it flies, as I know it does, yet in general it 
utters its jarring note sitting on a bough ; and I have for many an 
half-hour watched it as it sat with its under mandible quivering, and 
particularly this summer. It perches usually ona bare twig, with its 
head lower than its tail, in an attitude well expressed by your 
draughtsman in the folio “ British Zoology.” This bird is most 
punctual in beginning its song exactly at the close of day; so 
exactly that I have known it strike up more than once or twice just 
at the report of the Portsmouth evening gun, which we can hear 
when the weather is still. It appears to me past all doubt that its 
notes are formed by organic impulse, by the powers of the parts of 
its windpipe, formed for sound, just ascats purr. You will credit me, 
I hope, when I assure you that, as my neighbours were assembled 
in an hermitage on the side of a steep hill where we drink tea, one 
of these churn-owls came and settled on the cross of that little straw 
edifice and began to chatter, and continued his note for many 
minutes ; and we were all struck with wonder to find that the organs 
of that little animal, when put in motion, gave a sensible vibration 
to the whole building! This bird also sometimes makes a small 
* Cressi Hall is near Spalding, in Lincolnshire. 
