Dreijährige ornithologische Studien in Nordkorea. I. Allgemeiner Teil und Non-Passeriformes

Seasonality of the Arctic WarblerPhylloscopus borealisin Northern Korea, with Refutation of Previous Assumptions of Korean Breeding

“…The date of 11 August is similar in timing to autumn return to Pyongyang and southern Korea (see below), so is not even weakly suggestive of breeding. Fiebig (1995) Austin (1948) concluded (despite great scepticism of others' suppositions of Korean breeding for many species) that Arctic Warbler was "perhaps a not uncommon summer resident in the highlands", even though he traced no specimens from within 9 June -9 August (a gap strikingly similar to summer absence in [2000][2001][2002][2003]. He was presumably swayed by past descriptions as rare in summer (Taczanowski 1888: 463), common and breeding (from Won Hong Koo) and "a summer resident in the forest of the mountains.…”

“…Its weak little song may be heard all through the summer months" (Cumming 1933: 35). This more fairly describes Pale-legged Leaf Warbler's song than Arctic's; Austin (1948), who traced only six Korean records of the former (none in the breeding season), only grudgingly admitted the possibility of its breeding in Korea; yet it is an abundant breeder in Myohyang (Fiebig 1995; own data) and summers, presumably breeds, widely elsewhere (Tomek 2002). Cumming, collecting no specimens, quite possibly confused the two: Arctic Warbler is the only Phylloscopus for which he wrote an account, despite his article "covering the most common [birds] in Korea".…”

“…described the Arctic Warbler Phylloscopus borealis in northern Korean as a "passage migrant and probably rare breeding species", arriving after the first third of April. Some other sources consider it a Korean breeder (Baker 1997, Won Pyong-Oh 2000, implied breeder (Lee et al 2000), probable breeder (Austin 1948, Gore & Won Pyong-Oh 1971, Watson et al 1986, Won Pyong-Oh 1996, Tomek 2002, presumed breeder (Fiebig 1995), or possible breeder (Vaurie 1959, Dementiev & Gladkov 1968, Glutz von Blotzheim et al 1991, Cramp 1992, Park Jin-Young 2002. However, Wolters (1980), Cheng (1987), Sibley & Monroe (1990, 1993, Chrabrij et al 1991, Lowther (2001 and Stepanyan (2003) excluded Korea from the breeding range, while Mauersberger (1981) Standard reviews list Arctic Warbler Phylloscopus borealis as a probable breeder in northern Korea, as well as passage migrant; the most recent states that spring passage begins c. 10 April and finishes within May.…”