Radde's Warbler (LBRC)

Gustav Radde, a Prussian apothecary and keen naturalist found and collected a leaf-warbler he had never seen before near Lake Tarei Nor in eastern Transbaikalia, October 5th, 1856. He named it after himself and later gave it the Latin name Sylvia (Phyllopneuste) schwarzi in honour of his friend the astronomer Schwarz (Neufeldt 1961). Later of course it became Radde’s Warbler, Phylloscopus schwarzi. The occurrence of the first county record of Radde’s Warbler in 1898 is described in brief below. The second record some 90 years later was a happier experience for the bird concerned and is described in more detail towards the bottom of the page.

Caton Haigh shot the first county and British record in October 1898, a female, at North Cotes. An extract from Caton Haigh's description of the discovery of the bird (Bowdler Sharpe 1896) is as follows:

The summer-home of L. schwarzi appeared to be in South-eastern Siberia, and reached about as far west as Tomsk, according to Godlewski, who had mentioned the powerful note of the bird; this was described by Mr. Haigh as disproportionately loud, and it led to the thorough beating-out of the hedge in which the bird was skulking. It would be remembered that easterly winds had prevailed for a considerable time....

The description of "the thorough beating-out of the hedge" evokes the ethic of the day as he sought to collect his next victim. Since then there have been a further 13 county records involving 14 birds (two trapped at Donna Nook 2016) in all to 2021, all of them at coastal sites. They have all turned up in the period October 1st-24th. Six of the 15 were birds trapped including two of the three birds which occurred in 2016. Radde’s Warbler ceased to be a BBRC description species from 2006. White and Kehoe (2020) noted that there have been 444 records, 1958-2018 with an average of 12 records per year, 1990-2018. Along with the six birds ringed in the county, 112 others have been ringed in Britain, 1909-2019, but not unexpectedly perhaps, there have been no recoveries or controls. 

Finder’s report: Radde’s Warbler at Saltfleetby-Theddlethorpe NNR, October 16th, 1988

by F. E. and M. Boddy.

Note: this account is taken from the original BBRC submission and was the second county record, but the first in the modern era. There was a total of 21 Radde's Warblers recorded in 1988. The Rarities Committee noted that the basic biometrics and wing-formulae of this and Dusky Warbler are so similar that ringers handling either species should note bill-depth and bill-width, measured at the proximal edge of the nostril. They advised that estimates in the field are not recommended 'unless you have a nose for measurements'. This was a 'big year' for Radde's but with a remarkably tight pattern of arrivals between October 12th and 24th October, plus a late one in Scilly, October 28th.

Circumstances

The high pressure system had built over northern Europe and there had been slack air or light easterlies over Britain and the North Sea with low cloud and mist above the Lincolnshire coast. This morning saw another large arrival of thrushes, Robins and Goldcrests, though less than on Wednesday October 12th. My wife (FEB) extracted this bird from the mist-net and told me that it was a Phylloscopus-type warbler, but rather heavy looking, bright yellow underneath with orangy undertail coverts. My reaction even before handling the bird was that it was probably a Radde’s Warbler, and that was confirmed by careful examination and critical comparison with Svensson (3rd ed.), Williamson (1962), Madge (1987) and the letter by Round (1988), all of which I had to hand.

Description

Upperparts – brownish-olive; uppertail coverts and rectrices slightly browner; no wing bars.

Underparts – belly bright yellow, chin dusky-white with buffer throat and pale brownish chest band. Undertail coverts rufous-yellow; flanks buffy-brown; underwing coverts light buff, lighter on the carpal joint. Undertail covert colour contrasts strongly with flanks and belly.

Head markings – supercilium long, wide and buff in front of eye, narrower and white-buff behind; darker bands above and below supercilium; mottled cheeks.

General state of plumage – all fresh, including remiges and rectrices, with no active moult. Rectrices sharply pointed suggesting a first-year bird.

Legs and claws – legs stout and of a very pale straw colour behind with a reddish tinge at the front of the legs. Strong claws, straw coloured, pale yellowy underneath.

Bill – stout and broadly based bill with pale tip, darker upper mandible, orange base to lower mandible. Bill width (rear end of nostrils) 4.1 mm; bill depth (at same point) 3.3 mm.

Wing formula – wing length 61 mm; wing point = primaries 4 and 5.

• P1 = 10 mm. > primary coverts.
• P2 = P10/S1.
• P3 = 2 mm.< P4 and P5; P6 = 1 mm. <P4 and P5.
• Emargination not recorded.

Weight – 10.1 g at 10.00h.

References

Bowdler Sharpe, R. (1896) Bulletin of the British Ornithologists' Club 8: vi.

Neufeldt, I. (1961). Studies of less familiar birds 104. Radde's Bush Warbler. British Birds 53: 117-122.

(Account as per new Birds of Lincolnshire (2021), included October 2022)