Review of Previously Accepted Irish Records of Western Sandpiper, 1994.

Up to 1988 there were two accepted records of Western Sandpiper Calidris mauri for Ireland, both from the early 1960s. These records were reviewed by the IRBC in 1988 (Mullarney 1988). In view of the recent reinstatement of Western Sandpiper to the Irish List (Smiddy and O'Sullivan 1993, Mullarney 1994) it seems appropriate to explain why the two earlier records were deemed unacceptable.

There is no doubt that in the past fifteen to twenty years great progress has been made in refining reliable criteria for distinguishing the small calidrids. Much of the progress can be indirectly linked with the development of far better optical equipment, especially telescopes, leading to better opportunities for field observation. In the case of stints, an awareness of the importance of establishing the age of autumn birds before applying the appropriate identification criteria was a significant development. It also gradually became apparent that certain criteria which had once been considered reliable means of distinguishing species were in fact unreliable. A better understanding of age-related plumage features revealed a host of reliable, albeit often very subtle, differences between the most similar species. It revealed also that some species can be even more similar in appearance than was once thought. In particular, there is evidence that a proportion of Semipalmated Sandpipers Calidris pusilla, especially birds from populations in eastern North America, can be noticeably longer-billed than the usual, and this feature alone can easily lead to them being misidentified as Westerns (Grant and Jonsson 1984, Grant 1986, Kaufman 1990, McGeehan 1991).

Kilcoole, Co. Wicklow, 14 October 1960

The only evidence on file pertaining to this record consists of extracts from the description published in the Irish Bird Report (Ruttledge 1960). While this provides some indication of what the observers saw and heard, it would have been much more satisfactory to reconsider the record on the evidence of the original descriptions and the critical opinion of experts consulted at the time. It was stated in the IBR entry that a fuller description would 'in due course be published elsewhere', but this never happened. Bearing in mind the level of detailed description that would be required for a record to be accepted today, even allowing for a certain amount of expansion around the salient points published in the IBR, the Committee was unanimous in considering the Kilcoole claim to be untenable. It is possible that the bird was a Western Sandpiper, but the available evidence leaves too much room for doubt.

Akeragh Lough, Co. Kerry, 17-23 September 1961

This record was published in the Irish Bird Report (Ruttledge 1964). Fortunately the file in this case is much more complete. Some of the bird's features were indeed suggestive of Western Sandpiper (a bill much longer than a Little Stint's Calidris minutus, long legs which looked very thin, a tendency to 'swim' more than a Little Stint) but other features, the significance of which was perhaps not clearly understood at the time, suggested to the reviewers in 1988 that the bird was possibly a long-billed Semipalmated Sandpiper. The most serious obstacle to identifying this bird with any confidence is the fact that in spite of the level of detail presented in parts of the description it is difficult to decide whether the bird was an adult in winter plumage or a juvenile / first-winter. Convincing identification of a vagrant winter plumaged Western Sandpiper would require extremely critical observation of details such as bill shape, head pattern, breast markings and primary projection, little of which can be extrapolated from the description of the Akeragh Lough bird. The description of the bill as 'noticeably thick, even right at the tip, looked as if it were cut off rather than tapering to a normal point' is one that applies to more Semipalmated Sandpipers than Western Sandpipers, though not all Westerns show the fine bill tip that is considered typical of the species (Mullarney 1994). The description of the upperparts as 'just a dull brown' with 'no warmth whatever and no pale V' could perhaps apply to a juvenile Semipalmated but certainly excludes a juvenile Western or one moulting into first-winter plumage. The description of the voice as short bursts of 'pritt' or 'preet', considered by referees at the time to be indicative of Western, is of doubtful value against present-day requirements; without a good deal more information it would be difficult to interpret the calls as they are described as strongly indicative of either species

In view of the uncertainties outlined here, the Irish Rare Birds Committee recommended that neither of the above records merited continued acceptance and consequently Western Sandpiper was removed from the Irish List in 1988 (Mullarney 1988).

References

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