A Second Revision of the Seaside Sparrows

Ludlow Griscom
Journal: 
Ornithological Ephemera
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Volume: 
19

Abstract

  1. All Seaside Sparrows are proved to be resident or at least partially resident in their respective ranges, even the northern maritima wintering as far north as Massachusetts. They are casual away from saltwater.
  2. The amount of individual variation in most subspecies is simply extraordinary, and its degree depends entirely on how many specimens have been collected, and how large the series amassed for study.
  3. The view is urged that long overland flights are most improbable, and that even coastal migrations of any distance are most unlikely in any of the southern resident subspecies.
  4. The practice of recording aberrant and non-typical specimens as vagrants of other subspecies, on the ground that they are “nearer” the other subspecies, is to be deplored as biologically unsound. It is suggested that in so variable a group all such records be expunged, until validated by the recovery of banded individuals.
  5. The subspecies fisheri proves to be the most variable of all Seaside Sparrows. The original diagnosis was based on the dark phase; a light phase is common, and intermediate birds exist. It ranges from northeastern Texas to Pensacola, Florida.
  6. The subspecies howelli is regarded as the light phase of fisheri and is reduced to synonymy.
  7. The subspecies pelonota is regarded as a barely recognizable minor population in northeast Florida.
  8. The subspecies macgillivraii does not require a new diagnosis, but waynei Oberholser is invalid, being nothing but the light phase. This race breeds commonly in southeastern North Carolina8. The conclusions of Tomkins are accepted.
  9. The northern subspecies maritima requires a new diagnosis, as it has previously been compared only with the dark phase of macgillivraii. About 97% of the individuals cannot be distinguished from the intermediate phase of macgillivraii; 3% resembled the greener light phase. It has no characters of its own, and is consequently the poorest race in the usual systematic sense. It should, however, be recognized on the following counts: (1) the black phase is absent; (2) the “intermediate” phase of macgillivraii is the least common, and the light phase is common, instead of very rare. Moreover maritima has an isolated breeding range south to Cape Charles, Virginia; no Seaside Sparrow breeds from Back Bay to southern North Carolina. Final proof of the migration of maritima south into the range of macgillivraii will depend upon banding. No reliable systematic criterion can be found.
  10. The characters of all the remaining Seaside Sparrows can be expressed in terms of the dominance or predominance of one phase or the other of the ancestral sparrow. The most extreme variations are local populations on the periphery of the range, e.g. nigrescens, mirabilis, and sennetti.
  11. The maintenance of nigrescens as a distinct species can be defended, as it possesses certain “absolute” characters; reasons are given for reducing mirabilis to a subspecies of maritima.
  12. Reasons are given for the possible or probable existence of a dark phase of peninsulae and sennetti, and a light phase of juncicola. Nothing is to be gained by the further shooting of odd-looking birds in winter. Proof will depend upon a competent search for and the collecting of breeding birds, before they become too worn.
  13. A gap in our knowledge of Seaside Sparrows exists on the Gulf coast of western Florida.
  14. Finally, resident ornithologists are urged to copy the field studies of Tomkins in South Carolina and Georgia. To what degree do other southern subspecies migrate? Over a period of years is there any fluctuation in numbers or local occurrence of one phase or the other?
Year: 
1944
Pages: 
313-328
Total votes: 0