reliable authorities, because in particular instances they do not accord with their own observations. Neither should differences in habits, in song, etc., be taken as infallible evidence of a difference of species. It is well known that in Massachusetts the Brown Thrush (Harporhynchus rufus) is not uniform in the location of its nest, as about Springfield it almost invariably builds on the ground (in the many scores of nests that I have seen there I have met with but a single exception), while in other localities it as invariably places its nest a little above the ground in bushes. At Evanston, Ill., I once found one in an oak higher than I could reach; the locality, however, was swampy. How universally the Chipping Sparrow (Spizella socialis) breeds in trees, and generally at an elevation of several feet, is well known, but several authentic instances of this bird's nesting on the ground have come to my knowledge, one of which I myself discovered. Variations of this character in other species are of occasional occurrence, examples of which have doubtless been met with by every experienced collector.

The materials which birds select in the construction of their nests are well known to vary in different localities; the greater care exhibited by some species to secure a soft warm lining at the north that are much less precautious in this respect at the south, is already a recorded fact. Aside from this, the abundance of certain available materials occurring at only particular localities gives a marked character to the nests there built, which serves to distinguish them from those from other points. Some of the Thrushes, for instance, make use of a peculiar kind of moss at some localities that elsewhere, from its absence, are compelled to substitute for it fine grass or dry leaves. At Ipswich, on Cape Cod, and perhaps generally in the immediate vicinity of the sea, the Purple Grackles (Quiscalus versicolor) and Red-winged Blackbirds (Agelæus phœniceus), and in fact numerous other species, in building their nests often use little else than dry eel-grass or "sea-wrack," which results in

nest-structures widely different in appearance from those of their relatives residing in the interior. Every egg-collector is aware of the wide variations eggs of the same set may present, not only in the markings and in the tint of the ground color, but in size and form, and especially how wide these differences sometimes are in eggs of different birds of the same species. Also how different the behavior of the bird is when its nest is approached, in some cases the parents appearing almost utterly regardless of their own safety in their anxiety for their eggs or helpless young, while other parents of the same species quietly witness the robbing of their nest at a safe distance, and evince no extraordinary emotion. Those who have witnessed this, and have also watched the behavior of birds when undisturbed in their quiet retreats, will grant, I think, the same diversity of disposition and temperament to obtain among birds that is seen in man himself.

In respect to the songs of birds, who that has attentively listened to the singing of different Robins, Wood Thrushes or Purple Finches, has not detected great differences in the vocal powers of rival songsters of the same species? Different individuals of some species, especially among the Warblers, sing so differently that the expert field ornithologist is often puzzled to recognize them; especially is this so in the Black and White Creeper (Mniotilta varia) and the Black-throated Green Warbler (Dendroca virens). But the strangest example of this sort I have noticed I think was the case of an Oriole (Icterus Baltimore) that I heard at Ipswich last season. So different were its notes from the common notes of the Baltimore that I failed entirely to refer them to that bird till I saw its author. So much, however, did it resemble a part of the song of the Western Meadow Lark (Sturnella magna; S. neglecta Aud.) that it at once not only recalled that bird, but the wild, grassy, gently undulating primitive prairie landscape where I had heard it, and with which the loud, clear, rich, mellow tones of this beau

tiful songster so admirably harmonize. This bird I repeatedly recognized from the peculiarity of its notes during my several days stay at this locality. Aside from such unusual variations as this, which we may consider as accidental, birds of unquestionably the same species, as the Crow, the Blue Jay, the Towhe and others, at remote localites, as New England, Florida, Iowa, etc., often possess either general differences in their notes and song, easily recognizable, or certain notes at one of these localities never heard at the others, or an absence of some that are elsewhere familiar. This is perhaps not a strange fact, since it is now so well known that birds of the same species present certain well marked variations in size according to the latitude and elevation above the sea of the locality at which they were born, and that they vary considerably, though doubtless within a certain range, in many structural points at one and the same locality. In other words, since it is known that all the different individuals of a species are not exactly alike, as though all were cast in the same die, as some naturalists appear to have believed.

Certain irregularities in the breeding range of birds have also come to light. It is perhaps not remarkable that a pair of birds of species that regularly breed in northern New England should now and then pass the summer and rear their young in the southern part, as has been the case in certain known instances in the Snow Bird (Junco hyemalis), the Pine Finch (Chrysomitris pinus), and the White-throated Sparrow (Zonotrichia albicollis); but it is otherwise with the Snow Bunting (Plectrophanes nivalis), which rarely breeds south of Labrador, of which there is a single well authenticated instance of its breeding near Springfield. The casual visits of northern birds in winter, which we may suppose sometimes results from their being driven south by want of food or the severity of the season, are also less remarkable, it appears to me, than the occurrence here of southern species, as of the two Egrets, the Little Blue Heron

(Florida cærulea) the Gallinules and other aquatic species, which never, so far as known (with one exception perhaps), breed so far north. In the latter case they are generally young birds that reach us towards fall in their chance wanderings.

It may here be added that the cause of the migration of our birds still offers an interesting field for investigation. Observers are of late noting that in the case of some northern species that reach us only occasionally in their winter migrations, young birds only are at first seen, but if the migration continues the older birds appear at a later date. But sometimes young birds only are seen. This frequently happens in the case of the Pine Grosbeak (Pinicola eneucleator). The cause of their visits is not always, it is evident, severe weather; the last named species appearing sometimes in November, -weeks before severe cold sets in-while at other times it is not seen at all during some of our severest winters. The probable cause is more frequently, doubtless, a short supply of food, as last winter was remarkable in this state for its mildness and for the great number of northern birds that then visited us. It has repeatedly been observed that on their first arrival these unusual visitors are generally very lean, but that they soon fatten; an argument in favor of the theory that their migration was compelled by a scarcity of food.

Probably fewer birds are actually permanently resident at a given locality than is commonly supposed, for species seen the whole year at the same locality, as the Blue Jay, the Titmouse, the Brown Creeper, and the Hairy and Downy Woodpecker, etc., in Massachusetts, are represented, not by the same, but by different sets of individuals, those seen here in summer being not those seen in winter, the species migrating north and south, en masse, with the change of season. We are generally cognizant of a migration in a given species only when the great "bird wave" sweeps entirely past us either to the north or south. Some species, how

ever, seem actually fixed at all seasons, and are really essentially non-migratory, as the Spruce Partridge, and Quail (Ortyx Virginianus) are in New England. But only a small proportion, doubtless, of the so-called non-migratory birds at any given locality are really so.

In connection with this topic of migration, the fact that some of the young or immature individuals of our marine birds, as the Herring Gull (Larus argentatus) and other species of that family, and several of the Tringa, linger on our coast during summer, while the adult all retire northward, is one of some interest. Mature and strong birds only, in species that breed far to the north, evidently seek very high latitudes. Birds of the first year also appear to roam less widely than the older. In different species of the Gull family it is generally only the mature birds that in winter are seen far out at sea, though in the same latitudes the young may be numerous along the coast. All observant collectors are well aware of the fact that those birds that first reach us in the spring, of whatever species, are generally not only very appreciably larger, but brighter plumaged and in every way evidently more perfect birds than those that arrive later; and that in those species that go entirely to the north of us there is a much larger proportion of paler colored and immature birds, especially among the Sylvicolide, or warblers, towards the close of the migrating season than earlier. Hence the presence here of a few individuals in summer of species that usually go farther north is not always sufficient evidence that the species breeds with us.

In reference to the notes which follow, they may be considered as forming a supplement, as already stated in a foot note, to a "Catalogue of the Birds of Massachusetts" published by me five years since. In the present paper seven species†

*In respect to the proof whereon this proposition rests, see my remarks on this point in the Memoirs of the Boston Society of Natural History, Vol. i, Pt. iv, p. 488 (foot note).

Strix pratincola, Surnia ulula, Turdus nævius, Seiurus Ludovicianus, Centronyx Bairdii, Micropalama himantopus, Pelecanus erythrorhynchus.