Lesser Short-toed Lark Review, 2000.

Background and Results

Of all the species added to the Irish List in the last fifty years, none has given rise to more controversy, both nationally and internationally, than Lesser Short-toed Lark Calandrella rufescens. The species was recorded on four occasions between January 1956 and March 1958 as follows:

1956

1. 30, Derrymore Island, Tralee Bay, Co. Kerry, 4th January (Irish Bird Report 4: 15; British Birds 53: 241-243; Sharrock & Grant 1982).
2. Five, Great Saltee Island, Co. Wexford, 30th March, four on 31st (Irish Bird Report 4: 24; British Birds 53: 241-243; Sharrock & Grant 1982).
3. Two, near Belmullet, Co. Mayo, 21st May (Irish Bird Report 4: 15; British Birds 53: 241-243; Sharrock & Grant 1982).

1958

1. Five, Great Saltee Island, 22nd March, one on 23rd, two on 24th and four on 25th (Irish Bird Report 6: 30; British Birds 53: 241-243; Sharrock & Grant 1982).

At a time when there was little indication of vagrancy potential to the north of the species' breeding range, the Irish records (in particular the first, involving a flock of 30 birds on the west coast in mid-winter) could hardly have been more unexpected. Spectacular and unprecedented occurrences were, however, a frequent feature of this exciting post-war period in Irish and British field ornithology and a lack of precedent was not, in itself, a serious obstacle to the acceptance of the records.

Kenneth Williamson, commenting on the records, thought they were probably the result of "classic irruptive behaviour", like that formerly displayed by Pallas's Sandgrouse Syrrhaptes paradoxus before its range contracted (in litt. to Frank King). Indeed, many species rated as extremely rare vagrants in northern Europe at that time were subsequently discovered to be of more or less regular occurrence, e.g. a wide variety of Nearctic waders and landbirds.

In the case of Lesser Short-toed Lark, however, a pattern into which the records might fall failed to emerge. On the contrary, the uniqueness of the occurrences grew with time; the species has not been recorded in Ireland since and it remains an exceptional vagrant elsewhere in northern Europe, with records of single individuals in Germany (26th May 1879), Finland (18th November 1962 and 16th January - 1st February 1975), Sweden (27th-28th April 1986 and 10th-11th May 1991), Norway (7th-23rd November 1987), and Britain (2nd May 1992), (British Birds 80: 13; 84: 9; 85: 10; Dickie & Vinicombe 1995; H. Jännes pers. comm.).

As a new generation of more widely travelled observers gained first-hand experience of Lesser Short-toed Lark within its normal range and as the understanding of its identification improved, anomalies in the published accounts of the Irish records became more obvious. Indeed, the records, and the apparent weakness of the documentation, even attracted attention from further afield (Eigenhuus 1992; Smiddy 1993).

With reviews of previously accepted records being undertaken on numerous occasions by the IRBC from 1984 onwards, e.g. of Greenish Phylloscopus trochiloides and Arctic Warblers P. borealis, Semipalmated Calidris pusilla and Western Sandpipers C. mauri and Short-billed Dowitcher Limnodromus griseus (Irish Birds 2: 536-545; 3: 491-494, 649-652), the spotlight on the remarkable series of Lesser Short-toed Lark records inevitably intensified.

After overcoming some difficulties in tracking down all of the available original documentation, the IRBC commenced reviewing the records in 1999. The Committee concluded that none of the records met the standard required for acceptance. As a result, the species has been removed from the Irish List. The main reasons for this decision are outlined below.

Discussion

Had the 1956-1958 records been simply measured against the standards nowadays required for acceptance, it would have been a relatively straightforward matter to conclude that the lack of certain diagnostic details renders them unacceptable. Much of the criticism of the Lesser Short-toed Lark records in the past has indeed been based on such a "purist" approach. However, when reviewing older records such as these, the IRBC does attempt to take the circumstances that pertained at the time into consideration.

The subsequent discovery of diagnostic features not alluded to in the documentation does not automatically render old records, and the genuine efforts of the observers involved, as unacceptable or substandard. Like many other species, Lesser Short-toed Larks can be reliably identified on various combinations of features without all of the currently known diagnostic characters being noted.

Such an approach does meet its limits, however, when the evidence is plainly inconsistent with the species being claimed. Occasionally, such shortcomings can be attributed to inaccurate observation or an inadequate understanding of bird topography on the part of observers, but others cannot be readily accounted for in this way. In the case of the Lesser Short-toed Lark records, it was above all the presence of serious inconsistencies in the detail (rather than the lack of certain detail) that determined the Committee's decision: a range of the characters noted were clearly at variance with the appearance and vocalizations displayed and uttered by the species in the field.

Size & Structure: In all four observations the birds were judged to be very small, but in only one case (Great Saltee, 1956) was a comparison made to another species seen directly alongside: "about the size of a Meadow Pipit which was feeding with them, though a little dumpier." It is widely recognised nowadays that judging the size of birds in the field, even when familiar species of known size are nearby, is not necessarily as straightforward an exercise as it was long assumed to be (Grant 1983; British Birds 77: 323-326). It would be unsafe, therefore, to regard the perceived small size of these birds as a key identification factor, especially when in three of the four instances there was no opportunity to gauge their size against other species.

The detailed account of the 1958 Great Saltee birds describes the bill as "noticeably small and neat and relatively fine". Lesser Short-toed Lark has a particularly short and stubby bill, marginally heavier in some eastern populations (Cramp 1988) but it could never be described as "relatively fine".

Plumage and markings: According to the detailed description of the 1956 Great Saltee birds, some showed "a thin pale trailing edge to the secondaries" in flight, while the description of the 1958 birds, also on Saltee, includes a reference to their "similarity to a small Skylark [Alauda arvensis], with its white outer tail feathers and pale edgings to wings". It is not unknown for Lesser Short-toed Lark to appear to have a thin white trailing edge to the secondaries (Dickie & Vinicombe 1995) but it is not usual in the species. However, combined with the call descriptions (see below), the presence of this feature acquires a greater significance.

The 1956 Tralee Bay and Great Saltee birds were described as having a "buff" breast colour, overlain with streaks. Lesser Short-toed Lark may have a light buff wash at the sides of the breast but the centre is usually, though not invariably, off-white.

Voice: In one crucial respect, the evidence supporting these records strongly suggests the identifications were erroneous: the various transcriptions of the calls completely fail to evoke any association with the particularly distinctive sounds uttered by Lesser Short-toed Larks. The voice of the Tralee Bay birds was described as "reminiscent of the call of a Skylark, but weaker and more metallic - though not as metallic as that of the Short-toed Lark [Calandrella brachydactyla]. A second note was not unlike the "rick-kick-kick" of a Turnstone Arenaria interpres, but sharper; this was sometimes delivered as a single call and at other times repeated fairly rapidly (possibly by more than one bird)." The account of the 1956 Great Saltee birds describes the call-note as "a Skylark-like ripple but not quite so loud [underlined by observer] and sometimes rather more metallic. Another note was heard once or twice - a clicking conversational note with a "sik" sound intermingled." The call of the birds on Great Saltee in 1958 was described similarly, "a note lower, weaker and more melodious than that of Skylark". The Mayo birds were silent apart from when "one bird flew up once or twice to a height of nine or ten feet and sang a brief snatch of song - a rather jangling mixture of clicking and sweetly musical notes".

In written form, the various calls of Lesser Short-toed Lark and Skylark may appear to resemble one another a good deal more than the actual sounds do, so additional qualifying remarks, usually in the form of comparisons with other familiar species are of crucial importance. Lesser Short-toed Lark has a particularly distinctive voice, the commonest call being a dry "drrrrd" which has a gravelly, almost Sand Martin Riparia riparia-like quality and clearly differs from the usual calls of Skylark (Alström et al. 1992; Jonsson 1992). The descriptions of the Irish Lesser Short-toed Larks' calls are somewhat ambiguous with regard to their "metallic" quality, but the basic impression they impart is that their quality lay between that of Skylark's and Short-toed Lark's calls, apparently closer to the former.

Concluding Remarks

It appears that the distinctiveness of Lesser Short-toed Lark's call-notes was not widely appreciated prior to the series of records in Ireland or, for that matter, for some years afterwards. The very brief voice description in the early editions of Peterson et al. (1954), while not actually inapt, could almost equally well apply to Skylark. Indeed, the voice transcriptions of the 1956 Great Saltee birds were to later feature prominently in essential reference books of the period such as The Popular Handbook of Rarer British Birds (Hollom 1960), a clear indication of how poorly known the species' vocalizations were at the time.

This review has served as a reminder to us of how much has changed in bird identification over the past forty years. Only a small fraction of the wealth of information and images which now exists, and which we take so much for granted, was available then. Frequently, observers had to work out the identity of unfamiliar and less distinctive species with just a minimum of reference material, especially when, as in this case, the species was not among those treated in detail in the essential reference, The Handbook of British Birds (Witherby et al. 1938).

The basic lack of familiarity with Lesser Short-toed Lark at this time is illustrated by the fact that the Tralee Bay birds were not identified until almost three months after the sighting, when the second flock was discovered on Great Saltee. Further evidence of this unfamiliarity is provided by the case of two larks photographed at Cley, Norfolk, on 16th September 1954, which were first identified as Short-toed, later as Lesser Short-toed and finally as Skylarks (British Birds 48: 36-38; pl.6, Williamson 1961).

While every effort was made to confirm that identification of the Irish birds was correct, serious anomalies in the evidence would have been difficult to detect, considering the inadequacies of the reference material available at the time. The fact that we can now re-examine the evidence relating to the series of Lesser Short-toed Lark records and determine (as we believe) that the identifications were incorrect, is testimony not only to the clarity of the original accounts, but also to the foresight of Major RF Ruttledge and others who appreciated at that time the importance of retaining documentary evidence on rarities for posterity.

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 Lesser Short-toed Lark records.

References

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