Every spring and autumn, therefore a vast multitude of birds, belonging to more than a hundred distinct species, migrate northward or southward in Eastern America. A large proportion of these pass along the Atlantic coast, and it has been observed that many of them fly some distance out to sea, passing straight across bays from headland to headland by the shortest route.
Now as the time of these migrations is the season of storms, especially the autumnal one, which nearly coincides with the hurricanes of the West Indies and the northerly gales of the coast of America, the migrating birds are very liable to be carried out to sea. Sometimes they may, as Mr. Jones suggests, be carried up by local whirlwinds to a great height, where meeting with a westerly or north-westerly gale, they are rapidly driven sea-ward. The great majority no doubt perish, but some reach the Bermudas
and form one of its most striking autumnal features. In October, Mr. Jones tells us, the sportsman enjoys more shooting than at any other time. The violent revolving gales, which occur almost weekly, bring numbers of birds of many species from the American continent, the different members of the duck tribe forming no inconsiderable portion of the whole; while the Canada goose, and even the ponderous American swan, have been seen amidst the migratory host. With these come also such delicate birds as the American robin (Turdus migratorius), the yellow-rumped warbler (Dendrœca coronata), the pine warbler (Dendrœca pinus), the wood wagtail (Siurus novæboracensis), the summer red bird (Pyranga æstiva), the snow-bunting (Plectrophanes nivalis), the red-poll (Ægiothus linarius), the king bird (Tyrannus carolinensis), and many others. It is no doubt in consequence of this repeated immigration that none of the Bermuda birds have acquired any special peculiarity constituting even a distinct variety; for the few species that are resident and breed in the islands are continually crossed by individual immigrants of the same species from the mainland.
Four European birds also have occurred in Bermuda;—the wheatear (Saxicola œnanthe), which visits Iceland and Lapland and sometimes the northern United States; the skylark (Alauda arvensis), but this was probably an imported bird or an escape from some ship; the land-rail (Crex pratensis), which also wanders to Greenland and the United States; and the common snipe (Scolopax gallinago), which occurs not unfrequently in Greenland but has not yet been noticed in North America. It is however so like the American snipe (S. wilsoni), that a straggler might easily be overlooked.
Two small bats of N. American species also occasionally reach the island, while two others from the West Indies have more rarely occurred, and these are the only wild mammalia except rats and mice.
Insects of Bermuda.—Insects appear to be very scarce; but it is evident from the lists given by Mr. Jones, and more recently by Professor Heilprin, that only the more conspicuous species have been yet collected. These
comprise nineteen beetles, eleven bees and wasps, twenty-six butterflies and moths, nine flies, and the same number of Hemiptera, Orthoptera, and Neuroptera respectively. All appear to be common North American or West Indian species; but until some competent entomological collector visits the islands it is impossible to say whether there are or are not any peculiar species.[[109]]
Land Mollusca.—The land-shells of the Bermudas are somewhat more interesting, as they appear to be the only group of animals except reptiles in which there are any peculiar species. The following list was kindly furnished me by Mr. Thomas Bland of New York, who has made a special study of the terrestrial molluscs of the West Indian Islands, from which those of the Bermudas have undoubtedly been derived. The nomenclature has been corrected in accordance with the list given in Professor Heilprin's work on the islands. The species which are peculiar to the islands are indicated by italics.
| List of the Land-Shells of Bermuda. | ||
| 1. | Succinea fulgens. (Lea.) | Also in Cuba. |
| 2. | ,, Bermudensis. (Pfeiffer.) | ,, Barbadoes (?) |
| 3. | ,, margarita. (Pfr.) | ,, Haiti. |
| 4. | Pœcilozonites Bermudensis. (Pfr.) | A peculiar form, which, according to Mr. Binney, "cannot be placed in any recognised genus." A larger sub-fossil variety also occurs, named H. Nelsoni, by Mr. Bland, and which appears sufficiently distinct to be classed as another species. |
| 5. | ,, circumfirmatas (Redfield.) | |
| 6. | ,, discrepans. (Pfr.) | |
| 7. | ,, Reinianus. (Pfr.) | |
| 8. | Patula (Thysanophora) hypolepta (Shuttleworth.) | |
| 9. | ,, vortex. (Pfr.) | Southern Florida and West Indies. |
| 10. | Helix microdonta. (Desh.) | Bahama Islands, Florida, Texas. |
| 11. | ,, appressa. (Say.) | Virginia and adjacent states; perhaps introduced into Bermuda. |
| 12. | ,, pulchella. (Müll.) | Europe; very close to H. minuta (Say) of the United States. Introduced into Bermuda (?) |
| 13. | ,, ventricosa. (Drap.) | Azores, Canary Islands, and South Europe. |
| 14. | Bulimulus nitidulus. (Pfr.) | Cuba, Haiti, &c. |
| 15. | Stenogyra octona. (Ch.) | West Indies and South America. |
| 16. | Stenogyra decollata (Linn.) | A South European species. Introduced. |
| 17. | Cœcilianella acicula. (Müll.) | Florida, New Jersey, and Europe. |
| 18. | Pupa pellucida. (Pfr.) | West Indies, and Yucatan. |
| 19. | ,, Barbadensis. (Pfr.) | Barbadoes (?) |
| 20. | ,, Jamaicensis. (C. B. Ad.) | Jamaica. |
| 21. | Helicina convexa. (Pfr.) | Barbuda.[[110]] |
Mr. Bland indicates only four species as certainly peculiar to Bermuda, and another sub-fossil species; while one or two of the remainder are indicated as doubtfully identical with those of other countries. We have thus about one-fifth of the land-shells peculiar, while almost all the other productions of the islands are identical with those of the adjacent continent and islands. This corresponds, however, with what occurs generally in islands at some distance from continents. In the Azores only one land-bird is peculiar out of eighteen resident species; the beetles show about one-eighth of the probably non-introduced species as peculiar; the plants about one-twentieth; while the land-shells have about half the species peculiar. This difference is well explained by the much greater difficulty of transmission over wide seas, in the case of land-shells, than of any other terrestrial organisms. It thus happens that when a species has once been conveyed it may remain isolated for unknown ages, and has time to become modified by local conditions unchecked by the introduction of other individuals of the original type.