when the whole Grouse population of a district, driven by hunger, rises in huge packs and works its way southward in search of food; this never happens Wholesale
migration. unless a heavy undrifted snowfall has been followed by a hard frost, whereby a whole district is covered with an impenetrable sheet of frozen snow, thus cutting off all access to the heather. Such wholesale migrations often result in a complete loss of the stock, for the birds appear to lose their bearings, and though they may sometimes find a haven on some distant moor, where weather conditions are more propitious, several cases have been recorded of the packs being seen on the low ground 20 or 30 miles from the nearest hill, or even flying out to sea, whence presumably they never return.
In the case of normal annual migrations many opportunities have Powers of
flight of
Grouse. occurred for observing the power of flight of the Grouse. The following passage may be quoted from Macpherson in the Fur and Feather Series:[1]
"When snow and sleet have driven them down from the hills they will then fly long distances. It is not at all unusual for Red Grouse to cross the Solway Firth at a point where the estuary measures two miles in breadth, and I have known them fly longer distances. They often cross the valley of the Tees, flying about a mile from one hillside to another." And he quotes Millais, who says: "I have twice seen Grouse on the wing when they were crossing the 'Bring,' a wide channel which separates the islands of Hoy and Pomona, Orkneys. The fishermen told me this distance . . . was quite four miles across, and the birds must have come at least another mile on the Pomona side from the point where they left the moor."[2] In Millais' "Game Birds" it is stated that Grouse have been observed flying from Thurso to Hoy, a distance of over 11 miles.[3] The following instances are vouched for by the Committee's own correspondents. A gentleman in Banffshire, writing in January 1907, says: "Packs of Grouse are continually flying across the valley during stormy weather, some 5 or 6 miles between moors": while in Cumnock, in Ayrshire, there are "two ranges of hills divided by a valley about 2 miles wide, with a moss lying in between. In the pairing season Grouse often fly at a considerable height over the valley between the hills." Even during a Grouse drive a pack has been observed to leave the hill where it had been flushed, and not to rest until it had reached another moor 6 miles
