they were followed by such a number of sooty petrels as we had never seen equalled. There was a stream of from fifty to eighty yards in depth and of three hundred yards, or more, in breadth; the birds were not scattered, but flying as compactly as a free movement of their wings seemed to allow; and during a full hour and a half this stream of petrels continued to pass without interruption at a rate little inferior to the swiftness of a pigeon. On the lowest computation I think the number could not have been less than a hundred millions."
He explained how he arrived at this estimate, the reliableness of which is beyond dispute, though it may seem incredible to those who have not been in southern seas during the season when the sooty petrels "most do congregate." Taking the stream of birds to have been fifty yards deep by three hundred in width, and calculating that it moved at the rate of thirty miles[1] an hour, and allowing nine cubic yards for each bird, the number would amount to 151,500,000. The burrows required to lodge this number would be 75,750,000, and allowing a square yard to each burrow they would cover something more than 18½ geographical square miles.
The mutton-bird, it will therefore be allowed, is the most prolific of all avian colonists. It has also played some part in the history of human colonisation. When, in 1790, Governor Phillip sent to Norfolk Island a company of convicts and marines, and the Sirius, the only means of carrying supplies, was wrecked, the population, 506 in all, was reduced to dire distress from want of food. Starvation stared them in the face, when it was discovered that Mount Pitt was honeycombed with mutton-bird burrows. They were slain in thousands. "The slaughter and mighty havoc is beyond descrip-
- ↑ Flinders is calculating in nautical miles of 2026⅔ yards each.
