. Bulletin. Science; Natural history; Natural history. NATAL PTERYLOSIS OF HUMMINGBIRDS 15. Fig. 1. Typical distribution of neossoptiles in most hummingbirds examined. Each dot represents a single feather. The number of paried neossoptiles varied from 8 to 12. lacking downs. Skutch (1972) also reports that two-week-old nestlings of the Long-billed Starthroat. loiii^'irostris. had "their upper parts, throat, and breast . . covered with short, whitish doun. more abundant than that on any other ; It seems unlikely that this refers to true natal downs: it may wel
. Bulletin. Science; Natural history; Natural history. NATAL PTERYLOSIS OF HUMMINGBIRDS 15. Fig. 1. Typical distribution of neossoptiles in most hummingbirds examined. Each dot represents a single feather. The number of paried neossoptiles varied from 8 to 12. lacking downs. Skutch (1972) also reports that two-week-old nestlings of the Long-billed Starthroat. loiii^'irostris. had "their upper parts, throat, and breast . . covered with short, whitish doun. more abundant than that on any other ; It seems unlikely that this refers to true natal downs: it may well represent an early appearing portion of the first teleoptile plumage. Such down-like coverings have been noted for many swifts (Collins. 1963b, 1965. and unpubl.) and at least one passerine (Collins, unpubl.). but are presently un- known for hummingbirds. In addition to the paired mid-dorsal downs. I observed a single advantitious down, probably representing the coronal tract, on the head of one of two nestlings of the Ruby-topaz Hummingbird. Chrysolanipis Diosqiiitiis. The only other report of capital region downs is that of Haverschmidt ( for the Glittering-throated Emerald. AmuzUia fimbriata. However, if the head were bent back against the interscapular region, the typical posture of nestling hummingbirds, it would ha\e been easy to mistake some of the filamentous mid-dorsal downs as originating on the crown. A further exception to the general pattern of a single mid-dorsal row of neos- soptiles is found in the Rtifous-breastcd Hermit. Cilaucis hirsiita. My data (Table 2) from nine living nestlings examined in the field and three preserved specimens, all from Arima Valley. Trinidad, indicate that this species has an average o'( ^^ neossoptiles per bird (range 25-76) distributed on eight or nine tracts. The t.\ pical number (based on the modal number present on each individual tract) (Fig. 2) for the 12 individuals examined was 50 neossoptiles on eight tracts. Except
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