Nebraska Ornithologists' Union
Date of this Version
6-1989
Citation
Mollhoff, "Young Purple Finch; Some Questions," from Nebraska Bird Review (June 1989) 57(2).
Abstract
A recent note in the Review (Green, 1988) reported on an immature Purple Finch (Carpodacus purpureus) and gave the impression that the bird was hatched in eastern Nebraska. Before a claim is made that would imply a first state breeding record, and it becomes an unquestioned part of the state's literature, I believe the evidence should be closely examined and be as irrefutable as possible. The report cites evidence used to support the claim of recent, nearby fledgling, but, in my opinion, the cited evidence refutes rather than supports that claim. Since the species has never been reported to be a part of the state's breeding avifauna, I believe a response is in order.
My concerns with the report fall into several areas: 1) the age criteria listed in the note are not diagnostic for aging this species; 2) accepted age criteria which are diagnostic were not used, nor even mentioned; 3) the likelihood of finding a just-fledged bird on this date, at this location, is not discussed or even mentioned. I will address these points in turn.
The report cites three points in identifying the bird as recently fledged: 1) an orange gape, 2) "juvenile" plumage, 3) incomplete feather tract.
1) Orange gape: the only reference to gape in the age key used in the Banding Manual (USF&WS, 1980) is the statement "DO NOT age by gape" (their emphasis). Although many passerines may be reliably aged by the presence of a swollen, brightly colored gape, it is NOT a reliable age indicator for this species.
2) juvenal plumage: The diagnostic criteria cited in the Banding Manual to identify juvenile plumage are: "throat finely and heavily streaked and undertail coverts streaked; crissum fluffy and loosely textured". Bent (1968) describes the abdomen as "dull white, streaked with paler olive-brown"; while Roberts' (1955) description of -the abdomen states that the "markings are diffuse, faint yellowish be low". The photo in the Audubon Master guide (1983) labeled "immature" (which appears to be of a juvenal-plumaged individual) illustrates the difference between juvenal and the first pre-basic (first winter) plumage very clearly. The original photo (NOU Records Committee file #517-1), which is labeled "juvenile plumage", shows only the belly and cheek and thus does not show the diagnostic marks as stated in the Banding Manual. It does, however, show an abdomen with sharply defined markings on a clear white background, thus indicating that the bird is not in juvenal plumage. The photo labeled gape does give a good view of the throat. It does not show a throat "finely and heavily streaked" however; it shows, instead, a throat with a clear, unmarked white throat patch, another characteristic mark of an older bird.
Comments
Copyright 1989, Nebraska Ornithologists' Union. Used by permission.