Custom demised: St. Francis’s day swallow hibernation

 “But if hirundines (swallow family) hide in rocks and caverns, how do they, while torpid, avoid being eaten by weasels and other vermin?”  

Gilbert White in his  1776 Naturalist’s Journal

Such was the puzzle until recent times about how the swallow bird and its relatives survived the winter unscathed. The country folk even had a date in the calendar for it – St Francis’ Day, the 4^th.

On this date it was widely believed that they would survive the winter at the bottom of a lake or pond deep in the mud remaining asleep or else torpid in some hole in the bank of such a river or even trees. It would appear that this belief even marked itself on the landscape with Swalcliffe the a cliff where swallows nested, being an example.  The greater founders of modern science – Linneaus, Buffon and Baron Cuvier – accepted without question Cuvier in his 1819 Le regne animal recorded:

“It appears certain that swallows become torpid during winter, and even that they pass his season at the bottom of the water in the marshes.”

Richard Carew in his Survey of Cornwall recorded:

“In the west parts of Cornwall during the winter season, swallows are found sitting in old deep tin works and the holes in seacliffs; but touching their lurking place, Olaus Magnus makes a stranger report; for he saith that that in the north parts of the world, as summer weareath out, they clasp mouth to mouth, wing to wing, and leg to leg, and so after a sweet singing, fall down into a certain great lakes or pools amongst the canes from whence.”

Olaus Magnus theory was repeated by Carl Linnaeus in his Systema naturae (1758); and even Samuel Johnson stated that swallows@

‘certainly sleep all the winter …in the bed of a river’.

Again Gilbert White in his 1789 The Natural History and Antiquities of Selborne failed to believe that a British bird would leave Britain so hibernation was the obvious choice.

This view began to become questioned as an empirical view of science developed. Even so late into the 19^th century it was an unquestioned view provided by local evidence such as in the third volume of Kingston’s Magazine for Boys, where an anonymous communication called M. K., stated that:

“A friend of his father once found a bird-ball upon the banks of the Ribble, which sprang into life upon being placed near the fire.”

An another account is given in the following 1883 letter.

“The wife of our village blacksmith was the daughter of a respectable farmer, renting under the Harcourts at Newnham, and incapable of falsehood. She told me this: ‘When I was a young girl, we had lots of swifts nesting under the eaves. Father thought they brought in a deal of dirt and vermin, so when the birds were gone in the autumn he had all the holes plastered up. The spring of next year was very early, fine and warm; and sister and I were disturbed by a strange scrabbling noise. Told father. He said, Rats, and had the skirting board knocked away, and out came what we all thought was a great bat. Father took it up, and it was a swift, and we took out about forty of them, and as the poor birds were mere skin and bone we tried to feed them. No use; so the poor things were tossed out of the window and flew away.”

Another account stating that:

“In the early part of the year 1843 I was residing at Great Glenham, in Suffolk. One morning about the beginning of March, I was told that a swallow had been seen coming out of a pond near our house. I expressed my disbelief in the correctness of this information, but was assured that there could be no mistake. Some days afterwards our gardener came to me in triumph, and told me that he had brought the swallow, which had been found dead near the pond where it had before been seen.”

However whilst misinformation was still being spread, evidence for the counter view was being gathered.  As the 19^th century progressed, colonialism had allowed British naturalists to explore globally and hence encountered swallows in places such as India in the British winter.  Even so works such as Maurice Burton’s Animal Legends from 1955 recorded a discovery by a Professor Jagger of a swallow hibernating in a rockface but these may have been misidentifications, often storm petrels or sick birds. Now the 4^th is a date for the birds to start migrating!