For birders all over the world
Color Color Color
Home

Goodies

Feature Articles

I.D. Articles

Rarity News

Sketchbooks

Photo Essays

Bird Books

Trip Reports

Pelagic Directory

Mystery Photos

News & Issues

Links

E-mail Us

About Us

Article by Brian J Small

Photographs by Peter Kennerley and John C. Wilson and Skip Russell

This is the first in a series of features, looking at the identification of members of the Locustella group. The first deals with the identification of Middendorff’s Grasshopper Warbler L ochotensis, and includes information on its occurrence in the USA and the poorly known subspecies subcerthiola – which may, due to its more northerly distribution, be the sub-species accounting for the records in Alaska. The second will look at Pallas’s Grasshopper Warbler L certhiola, and will speculate whether it may be possible to ‘split’ it into two species. A third, on Gray’s Grasshopper Warbler L fasciolata, a potential addition to the USA list, is also in the pipeline.

Much of the information comes from research for a forthcoming guide to the Reed and Bush Warblers of the World, to be published by A&C Black, authored by Peter Kennerley and David Pearson, illustrated by Brian J. Small. I would like to thank Peter and Johnny Wilson for allowing use of their knowledge and photographs.


THE IDENTIFICATION OF MIDDENDORFF’S GRASSHOPPER WARBLER


Middendorff’s Grasshopper Warbler Locustella ochotensis is one of only two members of the Locustella group to have been recorded in North America. There are a small number of records from the western Aleutians (Attu, St Lawrence and Nunivak) in spring, though it is most regularly recorded in autumn, when it is considered a casual visitor in the western Aleutians. Its identification has recently been reviewed in a paper by Kennerley and Leader (1993), in which their studies support those of Nazarov and Shibaev (1983) by giving it specific status distinct from Styan’s Grasshopper Warbler L pleskei. In the not so distant past both Middendorff’s and Styan’s have been grouped with Pallas’s Grasshopper Warbler L certhiola to form a super-species, e.g. Vaurie (1959), but morphological, behavioural and voice studies suggest that they are best treated as separate species.

Distribution and Taxonomy
Middendorff’s Grasshopper Warbler is a fairly common summer migrant to the maritime regions of northeast Asia, with the breeding range largely confined to areas surrounding the Sea of Okhotsk, northern and eastern Hokkaido, Japan, north through the Kuril Islands, Sakhalin, to Kamchatka and the Kommander Islands. The wintering range extends from the Phillippines south to Borneo, with a small number of extra-limital records from neighbouring countries, Wallacea, Sulawesi, Lesser Sundas and Hong Kong.

On both wintering grounds and during migration its unobtrusive nature must hide its true distribution and status, indeed the precise route of its passage through eastern Asia to the breeding grounds remains far from clear. Studies by La Touche (1912) on the island of Sha Wei Shan, off the coast of China, showed it to be common migrant between May 19th and June 12th, with the passage peaking in the last few days of May and the first week of June. Whether the migration route has remained the same or what the population is now, requires further study. There are unsubstantiated reports from Beidaihe, Hebei province, China, but generally study shows that it is likely that it avoids this region.

Middendorff (1853) described ‘Sylvia ochotensis’ from Udskoe Ostrog, along the lower Uda River in the Gulf of Udskaya, and it is generally thought to be monotypic. However, it appears that a ‘lost’ form referred to very rarely in the literature, Locustella (ochotensis) subcerthiola - the ‘Kamtschatkan Grasshopper-Lark’, described by Swinhoe (1874) from migrants passing through Hakodadi (Hakodate), Hokkaido and from two specimens from Kamchatka, is distinct enough to warrant sub-specific status. The northern limit of nominate ochotensis is not known, but speculatively lies somewhere in the Kuril Islands or extends through the Kurils and into Kamchatka, with subcerthiola confined to the sea of Okhotsk and into Kamchatka. (As an aside, I have a vague recollection that Swinhoe called the group ‘Grasshopper-Larks’ because, like other larks, it needed a stronger scalpel to cut through the tendons in the legs than in other warblers – a result presumably of their ground-dwelling habits).

In 1994 Peter Kennerley found a Locustella species breeding on Talan Island, c.30 km south of Magadan. These birds responded to the tape of Middendorff’s and their own song in response was virtually identical. If these birds prove to be subcerthiola then it would suggest that the characters differ subtly yet distinctly from nominate birds from the southern part of the range. As well as having an identical song to that of ‘typical’ Middendorff’s, they were larger on average, exceeding the largest Pallas’s and overlapping with Styan’s. It is interesting to speculate that birds recorded in the US may be of this, most northern, sub-species, and the three Alaska specimens (one each in the California Academy of Sciences, University of Alaska Museum and the San Bernardino County Museum) might be checked for the characters of subcerthiola. I would certainly be grateful for any information, photographs and measurements, relating to any Aleutian birds in both spring and autumn.

The birds described as subcerthiola have been reported to display characters intermediate between Middendorff’s and Pallas’s, which tends to fit the Talan Island birds. Seemingly without foundation, these have been presumed to be hybrids despite Pallas’s being unknown from the region. Similar birds have been recorded in the wintering areas, and the ‘mix’ of Pallas’s and Middendorff’s characters have lead to calls for the ‘lumping’ of them once again.

On a final note, there is an adult female (specimen number 1914.6.12.29) housed at the BMNH, Tring, UK, collected by Styan in May 1896 at Wei Hai Wu, Shantung province, China, which appears to be a hybrid, showing intermediate characters between Pallas’s and Middendorff’s. Although some believe this to possibly be a subcerthiola, this bird differs from the Talan Island birds subtly but distinctly.

Habitat and Habits
Knowledge of habitat and habits may help in finding a Middendorff’s Grasshopper Warbler, on breeding and wintering grounds, or indeed as a vagrant.

In the breeding areas, Middendorff’s is closely associated with water and damp areas. In Hokkaido it prefers damp grasslands with scattered bushes, often adjacent to marshes or rivers at low elevations. It also breeds commonly in dwarf bamboo on exposed, windswept headlands. In winter, it is again closely associated with freshwater marshes. The presence of bushes is no longer a requirement (especially for a vagrant) and it can be found in rank, long grass, water-filled ditches, wet grasslands and reedy swamps.

An account by J C Wilson of the observation of a Middendorff’s at Gambell, St. Lawrence Island, Alaska on 30th August 1996, gives some idea of the difficulties in trying to see Middendorff’s and indeed any Locustella.

"This bird would run (roadrunner-like), with its head down and tail out, across the open gravel into the grass. It would then apparently run along the vole trails and suddenly appear up to 50 feet from where it was last seen. Occasionally, it would fly short distances, dive into the grass, then appear somewhere totally different from where it went down. Fortunately, with the six of us, we could get it somewhat surrounded and eventually one of us would find its location. I would lie on my belly and point the camera down into one of the excavation holes and wait for it to appear out on the gravel, which it would do quite suddenly."

This photo of a Middendorff's Grasshopper Warbler was taken by Skip Russell was taken on Attu at "South Beach" on June 10, 2000.
Article and more photographs continue on Page 2