Wilson’s Phalarope Phalaropus tricolor – a new species for avifauna of Serbia

Wilson's Phalarope Phalaropus tricolor is a swimming sandpiper species of the New World. It is the largest and most terrestrial of the three phalarope species (Hayman et al. 1986), which are broadly known for their reversed sex-role mating system (Colwell & Jehl 2020). Wilson's Phalarope distribution range is entirely continental. It typically breeds in open habitats adjacent to inland wetlands on prairies and agricultural lands in western parts of the United States and southwestern and central Canada (Hayman et al. 1986, Colwell & Jehl 2020). On migration, this species occurs on a wide variety of freshwater lakes, ponds and small pools showing a preference for alkaline waters. Wilson's Phalarope winters in the October–April period across altiplano from Bolivia to Argentina and returns to the breeding grounds in late April and early May (Hayman et al. 1986, Colwell & Jehl 2020). The species is a rare, but regular vagrant in Western Palearctic with most observations reported from British Isles (Alström & Colston 1991). Here, we report on the first observation of Wilson's Phalarope in the territory of Serbia. In the early morning of 22 September 2019, whilst birdwatching on the northern shore of alkaline lake Rusanda close to the village of Melenci (Banat District, Northern Serbia), the first author spotted one individual of Wilson's Phalarope approximately 20 m from the lakeshore (coordinates 45.525952 N, 20.302900 E), foraging together with 12 Dunlins Calidris alpina and three Little Ringed Plovers Charadrius dubius. At first glance, the observer had an impression that it was Marsh Sandpiper Tringa stagnatilis – a regular, but scarce autumn migrant through northern Serbia. Yet, the general structure of the observed bird was pretty different. The observed specimen was notably smaller, short-legged with a thinner and finer bill than Marsh Sandpiper. Besides, the feeding habit significantly differed from that of Marsh Sandpiper. During a short period of observation, the bird was actively feeding in shallow water (1–3 cm deep), making jerky, vigorous darting left-right movements with its head and bill. After five minutes of observation, all the birds flew together to the opposite side of the lake. Before flying off, the observed bird was photographed (Figure 1). Later in the same day, photographs of an unusual bird were displayed by few Internet birding groups, where numerous birdwatchers identified it as Wilson’s Phalarope. Indeed, the additional analysis of photographs by both authors reaffirmed the identification. The observed and photographed specimen was distinguished from similar Grey Phalarope Phalaropus fulicarius and Red-necked Phalarope Phalaropus lobatus by its greyer (paler) plumage, distinctly longer bill, lack of bold black eye-patch and bright yellow colour of legs. Other somewhat similar wader species like Lesser Yellowlegs Tringa flavipes are characterized by their significantly different proportions, behaviour and not so pure whitish colour below. The next day, Vukas Vučković re-found the bird and took several photos of it in flight. The white rump patch, plain dark grey wings and lack of promAcrocephalus 41 (184/185): 31–32, 2020 10.2478/acro-2020-0003