birds was met with
is about 160 miles due west of Brest, and this is the least distance the
birds must have been carried. It is interesting to note that the
position of the ship is nearly in the line from the English and French
coasts to the Azores, where, after great storms, so many bird stragglers
arrive annually. These birds were probably blown out to sea during their
spring migration along the south coast of England to Wales and Ireland.
During the autumnal migration, however, great flocks of
birds--especially starlings, thrushes, and fieldfares--have been
observed every year flying out to sea from the west coast of Ireland,
almost the whole of which must perish. At the Nash Lighthouse, in the
Bristol Channel on the coast of Glamorganshire, an enormous number of
small birds were observed on 3d September, including nightjars,
buntings, white-throats, willow-wrens, cuckoos, house-sparrows, robins,
wheatears, and blackbirds. These had probably crossed from
Somersetshire, and had they been caught by a storm the larger portion of
them must have been blown out to sea.[172]

These facts enable us to account sufficiently well for the birds of
oceanic islands, the number and variety of which are seen to be
proportionate to their facilities for reaching the island and
maintaining themselves in it. Thus, though more birds yearly reach
Bermuda than the Azores, the number of residents in the latter islands
is much larger, due to the greater extent of the islands, their number,
and their more varied surface. In the Galapagos the land-birds are still
more numerous, due in part to their larger area and greater proximity to
the continent, but chiefly to the absence of storms, so that the birds
which originally reached the islands have remained long isolated and
have developed into many closely allied species adapted to the special
conditions. All the species of the Galapagos but one are peculiar to the
islands, while the Azores possess only one peculiar species, and Bermuda
none--a fact which is clearly due to the continual immigration of fresh
individuals keeping up the purity of the breed by intercrossing. In the
Sandwich Islands, which are extremely isolated, being more than 2000
miles from any continent or large island, we have a condition of things
similar to what prevails in the Galapagos, the land-birds, eighteen in
number, being all peculiar, and belonging, except one, to peculiar
genera. These birds have probably all descen