SEA-BIRD NUMBERS AND MAN 79 



another with three or four, and the last with one occupied burrow. 

 Gurnet Rock, the type-locahty of the species, could not be visited. 

 They conclude that there may be fewer than a hundred adult cahows 

 surviving, and that there are not likely to be more. Much of the old 

 nesting-grounds have been destroyed, and rats have established them- 

 selves on some of the islets, where no burrowing tubenoses consequently 

 now nest. Louis S. Mowbray (son of L. L. Mowbray) is now experi- 

 menting with artificial burrows on some of the remoter, rat-free rocks 

 to encourage breeding. Human exploitation seems to have made the 

 first inroads on the cahow population, but its subsequent recovery 

 has certainly been inhibited by other factors. Murphy and Mowbray 

 conclude that "if a suitable alteration of present circumstances may 

 eventually enable the cahows to spread to neighbouring islands well 

 covered with soil, the future of a beautiful and historic sea-bird will 

 be assured." 



!|e « * 



The history of the gannet in the North Atlantic shows well the 

 transition from Man the predator to Man the husbandman and Man 

 the protector. In the eighteen-thirties there were probably a third 

 of a million individual adult gannets breeding yearly in the North 

 Atlantic. By the end of the century the number was down to not 

 much more than a hundred thousand. A diagram of the change in 

 population is shown as Fig. 14, p. 80; it is based on the work of 

 Fisher and Vevers (1943-44). The history can usefully start 

 with the visit of J. J. L. Audubon to the Bird Rocks in the Gulf of St. 

 Lawrence in 1833. He made no actual estimate of the number of 

 occupied nests on this island (it was then much bigger than it is today, 

 after erosion), but it has been possible to calculate from the size of 

 the area occupied, and from the known density (one nest to just over 

 a square metre) of this and other 'flat-top' gannet-colonies like Eldey 

 and Grassholm, that Audubon saw a colony which probably then 

 harboured between a hundred and a hundred and twenty-five thousand 

 nests, or about two-thirds of all the gannets then living. 



Audubon learned from his pilot, Godwin, that the Labrador 

 fishermen annually visited the Bird Rocks to get flesh to bait their 

 cod-fish hooks. Godwin himself had visited the rocks, with the fisher- 

 men, for ten years in succession, for this purpose ; and on one occasion 

 "six men had destroyed five hundred and forty gannets in about an 

 hour, after which the party rested a while, and until most of the living 

 birds had left their immediate neighbourhood, for all around them, 



