Little Shearwater Review, 2000.

Status Prior to Review

Little Shearwater Puffinus assimilis was first recorded in Ireland on 6th May 1853, when one came aboard a ship off the Bull Rock, Cork (Ussher & Warren 1900). The specimen is on display in the National Museum, Dublin. The next record was not until over a hundred years later, when, on 22nd October 1964, two were identified passing Malin Head, Co. Donegal (IBR 12: 8-9, British Birds 58: 189-190).

A rapid succession of records followed, with a total of three individuals in 1965, seven in 1966, five in 1967 and eight again in 1968. None was recorded between 1969 and 1972, but in 1973 there were six. By the end of 1978, a grand total of 37 Little Shearwaters and a further 17 unidentified "small shearwaters" were on record. The latter were believed to be baroli Little Shearwaters (the race that breeds on Madeira and the Canary Islands) but the possibility of other "small" shearwaters, such as boydi Little (of the Cape Verde Islands) and even Audubon's Shearwater P. lherminieri could not be excluded.

Then, almost as suddenly as the run of records in the mid-1960s began, records practically dried up in the 1980s and only five occurred in the 1990s. Between 1973 and 1997, 20 claims of Little Shearwater (involving 24 individuals) and two claims of single "small shearwaters" were deemed unacceptable by the Irish Records Panel and its successor, the Irish Rare Birds Committee.

Background to the Review

The sudden change in status from the late 1970s onwards coincided with very significant developments in seawatching practices in Ireland. A new generation of seawatchers became active during the late 1970s and 1980s, as the full potential of seawatch sites such as Ramore Head and Portrush in Co. Antrim and the Bridges of Ross in Co. Clare emerged. Improved optical equipment, particularly telescopes, enabled observers to discern considerably more detail and reduce reliance on jizz and general impressions when identifying distant seabirds.

New insights into the status of several pelagic species off Irish coasts were gained during this period. Leach's Storm-petrel Oceanodroma leucorhoa and Sabine's Gull Larus sabini, for example, were found to be considerably more numerous off northern and western coasts than had been previously believed. The growing competence of observers, backed by increased knowledge of identification criteria, also played a key role in these developments.

This was perhaps most apparent in the case of Long-tailed Skua Stercorarius longicaudus: previously of almost "mythical" status, the species was found to be a regular passage migrant, as observers rose to the challenge of identifying Stercorarius skuas in their difficult juvenile and non-breeding plumages. By the late 1980s and 1990s, observer competence and the quality of optical equipment had risen to such an extent that Wilson's Storm-petrels Oceanites oceanicus were being detected from land with some regularity.

Yet, for most of this period, Little Shearwater was being claimed much less frequently than it had been during much of the 1960s and 1970s. A total of 30 Little and "small" Shearwaters were claimed during the six years 1973-1978 (of which 14 (45%) were considered acceptable), compared to just six during the following twelve years (of which two (33%) were considered acceptable). This abrupt decrease reflects, in our opinion, the greater caution being exercised by observers from the late 1970s onwards, rather than a genuine decrease.

Observation of Manx Shearwaters P. puffinus and Balearic Shearwaters P. mauretanicus revealed that the identification pitfalls provided by both were quite considerable. At the same time, observations of undoubted Little Shearwaters off the Canary Islands and Madeira underlined the need to improve upon the "established" set of criteria that had been relied upon in identifying vagrants in Irish waters (details of many of which had been published).

Moreover, against this background, the basis for upholding the borderline category of "small shearwaters" appeared increasingly questionable. The ongoing paucity of satisfactorily documented sightings of Little Shearwater during the 1980s and 1990s gave rise to growing concern that the record books were not accurately reflecting the species' true status off Irish coasts. As a consequence, beginning in 1990 (Mullarney 1990) the IRBC undertook a review of all accepted records of Little Shearwaters and "small shearwaters", the results of which are published below.

Results of the Review

The following records remain acceptable:

• 1853 Cork One, taken alive, off the Bull Rock, 6th May, specimen preserved in National Museum, Dublin (Ussher & Warren 1900; Kennedy et al. 1953).
• 1978 Cork Up to two, Cape Clear Island: one, 24th September; two, 25th to 26th September (Irish Birds 1: 416). Sightings on subsequent dates in September were considered unacceptable after review (see below).
• 1991 Clare One, Bridges of Ross, 30th September (Irish Birds 5: 82).
• 1992 Cork One, Cape Clear Island, 14th August (Irish Birds 5: 82).
• 1993 Cork One, Cape Clear Island, 26th August (Irish Birds 5: 212).
• 1995 Clare One, Bridges of Ross, 25th August (Irish Birds 5: 450).
• 1996 Clare One, Bridges of Ross, 16th August (Irish Birds 6: 66).

The following records are no longer considered to be adequately documented:

• 1964 Donegal Two, Malin Head, 22nd October (Irish Bird Report 12: 8-9; Brit. Birds 58: 189-190).
• 1965 Kerry Two, Brandon Point, 28th August (Irish Bird Report 13: 13).
• 1965 Mayo One, Annagh Head, 18th September (Irish Bird Report 13: 13).
• 1966 Cork One, Cape Clear Island, 27th August (Irish Bird Report 14: 13-15).
• 1966 Cork Two, Cape Clear Island, 29th August (Irish Bird Report 14: 13-15).
• 1966 Kerry Three, Brandon Point, 2nd September (Irish Bird Report 14: 13-15).
• 1966 Kerry One, Brandon Point, 4th September (Irish Bird Report 14: 13-15).
• 1967 Cork One, Cape Clear Island, 2nd June (Irish Bird Report 15: 17-18).
• 1967 Cork One, Old Head of Kinsale, 7th August (Irish Bird Report 15: 17-18).
• 1967 Kerry Three, Brandon Point, 3rd October (Irish Bird Report 15: 17-18).
• 1968 Cork One, Cape Clear Island, 18th April (Irish Bird Report 16: 16).
• 1968 Cork Two, Cape Clear Island, 19th August (Irish Bird Report 16: 16).
• 1968 Cork Two, Cape Clear Island, 9th September (Irish Bird Report 16: 16).
• 1968 Cork Two, Cape Clear Island, 3rd October (Irish Bird Report 16: 16).
• 1968 Kerry One, Brandon Point, 21st September (Irish Bird Report 16: 16).
• 1973 Cork One, Cape Clear Island, 6th June (Irish Bird Report 21: 8).
• 1973 Cork One, Cape Clear Island, 10th August (Irish Bird Report 21: 8).
• 1973 Cork One, Cape Clear Island, 10th August (Irish Bird Report 21: 8).
• 1973 Cork One, Cape Clear Island, 21st August (Irish Bird Report 21: 8).
• 1973 Cork One, Cape Clear Island, 6th September (Irish Bird Report 21: 8).
• 1973 Cork One, Cape Clear Island, 20th September (Irish Bird Report 21: 8).
• 1975 Cork One, Cape Clear Island, 9th September (Irish Bird Report 23: 7).
• 1978 Cork Two, Cape Clear Island, 27th and 28th September (Irish Birds 1: 416). Sightings on 24th to 26th September at this locality remain acceptable after review (see above).
• 1978 Kerry Two, Brandon Point, 30th September (Irish Birds 1: 416).

Unidentified "small shearwaters" Puffinus sp. None of the records listed as follows proved acceptable as Little Shearwater. As the IRBC does not, as a rule, publish records of "probables", the category of "small shearwater" is now regarded as obsolete.

• 1963 Cork Two, Cape Clear Island, 22nd August (Cape Clear Bird Observatory Report 8: 9-10).
• 1963 Donegal One, Malin Head, 17th September (Irish Bird Report 12: 8-9).
• 1964 Cork One, Cape Clear Island, 9th August (Cape Clear Bird Observatory Report 8: 9-10).
• 1964 Donegal One, Malin Head, 24th September (Irish Bird Report 12: 8-9).
• 1965 Cork One, Cape Clear Island, 4th September (Cape Clear Bird Observatory Report 8: 9-10).
• 1965 Cork Two, Cape Clear Island, 5th September (Cape Clear Bird Observatory Report 8: 9-10; 9:10).
• 1966 Cork One, Cape Clear Island, 5th September (Cape Clear Bird Observatory Report 8: 9-10).
• 1966 Cork One, Cape Clear Island, 21st September (Irish Bird Report 14: 13-15).
• 1967 Cork One, Cape Clear Island, 13th September (Irish Bird Report 15: 17-18).
• 1967 Cork One, Cape Clear Island, 15th September (Irish Bird Report 15: 17-18).
• 1967 Cork Two, Cape Clear Island, 8th October (Irish Bird Report 15: 17-18).
• 1968 Cork One, Cape Clear Island, 2nd July (Irish Bird Report 16: 16).
• 1971 Cork One, Cape Clear Island, 27th August (Irish Bird Report 19: 25).
• 1976 Cork One, Old Head of Kinsale, 29th September (Irish Birds 1: 72).
• 1981 Cork One, Cape Clear Island, 20th July (Irish Birds 2: 202).
• 1985 Cork One, Cape Clear Island, 23rd June (Irish Birds 3: 294).

The following record was withdrawn by the observer prior to the review:

• 1985 Clare One, Bridges of Ross, 31st August (Irish Birds 3: 294).

Discussion

With only eight out of a total of 42 Little Shearwaters (and none of the 19 "small shearwaters") remaining acceptable after review, the status of the species in Irish waters has been very significantly altered. Compared with other much sought-after pelagic seabirds, it is now on an equal rarity ranking with Black-browed Albatross Diomedea melanophris and is considerably rarer than Fea's/Madeiran Soft-plumaged Petrels Pterodroma feae/madeira and Wilson's Storm-petrel. The primary reasons for the changes in the IRBC's approach to the assessment of Little Shearwater claims have been outlined above, but, in view of the radical results of this review, a more detailed explanation of why so many records are now considered unacceptable seems appropriate.

The great majority of birds were identified on a combination of just two or three basic features: the observers' impression of the bird being much smaller than Manx Shearwater (although in many cases Manx Shearwaters were not directly alongside for comparison); slower progress than accompanying Manx Shearwaters and, often, what was usually described as a distinctive "fluttery" flight (sometimes compared to that of an auk Alcidae). In the 1960s and 1970s Little Shearwater identification was largely based on an unquestioning confidence in these jizz features.

The much greater reliance on jizz in seabird identification during this period is easily accounted for by the fact that most observers were, as a rule, identifying distant birds through hand-held binoculars (as opposed to the mounted, higher-powered telescopes now in use). For a time, the species was being recorded so frequently at Cape Clear Island that those visiting the island for a week or two of autumn seawatching might reasonably have expected to encounter the species, and, indeed, such expectations may well have played an "encouraging" part in some of the claims.

In most instances, few or no differences in plumage and structure to Manx were noted. Mention of Little Shearwater's more extensively white "face", blunter wing-tip and more extensively white underwing (compared with Manx) or, especially, its distinctly two-toned upperwing pattern (observations of Porter in Curtis et al. 1985; McGeehan & Mullarney 1995; Mullarney et al. 1999) was quite exceptional.

Furthermore, the claims of Little Shearwater identified on the basis of jizz features very frequently failed to reveal an appreciation of the potential pitfalls provided by Manx Shearwater and, perhaps rather surprisingly from a latter day viewpoint, Balearic Shearwater. There was rarely any reference to the fact that individual Manx in the midst of a typically fast-moving stream of birds are occasionally liable to fly differently, in a manner strikingly similar to that described in so many accounts of Little Shearwater i.e. with more frequent flapping and less shearing, and making slower progress along a lower flight track.

Curiously, several accounts included comparisons with "runt" Manx Shearwaters, dwarf individuals whose existence was for long assumed but never confirmed (Perrins et al. 1965; Bourne 1966) - perhaps a revealing example of our capacity to "see" what we expect to see. In a number of cases, where there was some description of differences in plumage characters and proportions from Manx, the evidence actually suggested Balearic Shearwater much more than it did Little.

Conclusions

While few would argue with the value of jizz-related characters when it comes to identifying distant seabirds, over-reliance on jizz, without the back-up of at least some "solid", more reliably determined evidence can result in serious errors. In this respect there appears to have been little effort to establish more conclusive means of identifying the species during much of the 1960's and 1970's; with regard to identification criteria, the greatest uncertainty then seems to have been the means of distinguishing Audubon's Shearwater from Little.

Observation of white undertail coverts was regarded as sufficient evidence to eliminate Audubon's Shearwater, while failure to detect this feature resulted in acceptance as "small shearwaters". The failure to "test" the validity of the criteria being employed to identify Little Shearwaters was not just confined to Ireland; throughout the whole of the eastern Atlantic, it seems, there was an unquestioning acceptance that identifying Little Shearwater was, for a large part, a matter of determining their small size and "fluttery" flight-action.

This is, of course, not the first time that spurious identification criteria have become established in the absence of anything better. When this happens, it can take a long time to unravel the problem; an accumulating body of records appears to reinforce the validity of the criteria and generates a resistance amongst all concerned to critically reconsider the matter.

In the case of Little Shearwater, it must be said, any attempt at the latter process would hardly have been possible without the advantage of more modern, high-performance telescopes. There is still an urgent need to carry out more research into the most practical and reliable means of identifying Little Shearwaters under normal seawatching conditions.

By applying more rigorous standards than in the past, we are likely to gain a truer picture of the status of Little Shearwater, a species which, amongst the seabirds known to occur in Irish waters, must rate as one of the most challenging from an identification perspective.

Acknowledgements

The IRBC is very grateful to John Burton, Hannu Jännes, Kyran Kane, Frank King, Colm Moore and Pat Smiddy for providing assistance and information during the reviews of the Little Shearwater records. We thank Dr Jim O' Connor and Paddy O'Sullivan of the National Museum (Natural History) Dublin for providing access to the Bull Rock specimen of Little Shearwater and allowing publication of a photograph of it in this Report.

References

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