On reviewing the three lists I find the Turtle Dove (T. communis) appears in all three, and as I have observed it on a previous occasion, it seems to be quite a common visitor, and one feels inclined to wonder if it is gifted with insufficient powers of flight to cope with the great strain put on the species at this period of the year.
The same remark certainly cannot apply to the Hirundinidæ, yet they appear on my list and Dr. Hurlestone Jones's, and I can remember in 1893 catching three Swallows (H. rustica) in April when serving as a middy in H.M.S. 'Calypso.' Unfortunately I did not keep a note-book in those days, but we were somewhere between the Land's End and the south of the Irish coast. By the way, the Wheatear appears on all three of our lists.
Why do birds settle on ships—that is the question? One reason undoubtedly is the attraction of lights at night, especially the powerful white light which all steam vessels carry. For example:—One night, when off the Australian coast, a Red-tailed Tropic bird (Phaëthon rubricauda, Bodd) flew up against the mast this light was on, and, having stunned itself, fell on to the deck, where I picked it up, and skinned it. Its two long tail feathers were fortunately undamaged.
During autumn a vessel steering north in the Red Sea, where most of the birds on my list were observed, would meet, and attract, birds flying in a southerly direction. Several birds I have mentioned arrived and perched during the night.
But what about the daytime? In some cases, notably that of the Turtle-Doves, land was in sight all day, yet they did not leave us. The Red Sea is no great distance across at its widest part, and is well provided with littoral islands, offering many resting-places where the birds would be free from molestation. The only really weary wayfarer was the Quail, which appeared completely fatigued, and only rose at the last moment to avert capture.
In the Suez Canal, for example, the Willow Wren must have visited us out of pure curiosity, as it left a green and favourable-looking locality to perch on board.
The silence of birds on board I have already touched on, also the question of hunger.
