Tundra Peregrine Falcon  I think

December 2010 was a very cold month in the Netherlands – the coldest December in 41 years. Friday 17 December was memorable for its snowfall and, consequently, complete traffic chaos during the evening rush hour. Over the month, I visited my local patch at IJmuiden on 15 days, recording movements of species like Smew Mergellus albellus, Goosander Mergus merganser, Greater Scaup Aythya marila, Eurasian Woodcock Scolopax rusticola, Hen Harrier Circus cyaneus, Rough-legged Buzzard Buteo lagopus, Short-eared Owl Asio flammeus, Eurasian Skylark Alauda arvensis and Fieldfare Turdus pilaris. Studying a group of c 40 Taiga Bean Geese Anser fabalis near Vlijmen in North Brabant on 14 December was exciting too.

In the morning of 24 December, Jan Jacobs discovered a Great Bustard Otis tarda near Groesbeek 
the first unringed (‘wild’) individual in the Netherlands since 1997. However, as the bird had soon disappeared (it was relocated c 120 km to the south-west by Mark Hoekstein the next day!), I had no reason not to visit my local patch. Shortly after my arrival, I noticed a juvenile Peregrine Falcon Falco peregrinus landing on the South Pier. I watched the bird through my telescope from a distance of c 900 m and was immediately struck by its pale appearance. In particular, its head was very pale, with a whitish forehead, central crown and supercilium and just a narrow dark moustache. I tried to obtain some record shots by digiscoping, but the results were very poor due to the distance and my cold fingers. Three minutes later, the bird was up in the air again and during the next eight minutes it chased a European Herring Gull Larus argentatus and a Great Cormorant Phalacrocorax carbo. In flight it looked big and powerful, with rather long wings and tail. No way this was one of the local peregrines!

Tundra Peregrine Falcon F p calidus breeds in arctic Eurasia and winters south into the Middle East, southern Asia and Africa. In recent years there have been several serious claims of this taxon in north-western Europe. Even a few satellite-tagged Peregrine Falcons from the tundra in north-western Russia have turned up here. Surely my bird ticked off all calidus-features I knew of.

Knowledge of the variation within taxa is essential in bird identification. This becomes even more apparent in identifications to subspecies level. For example, Newson et al (2004) published a set of criteria to separate Atlantic P c carbo from Continental Great Cormorant P c sinensis. Since then, not only ring recoveries of Atlantic Great Cormorant in the Netherlands were accepted by the CDNA, but also well-documented field observations (van der Vliet et al 2006). Soon it turned out that
this subspecies was more common than previously thought and it was no longer considered a rarity (Ovaa et al 2009). Over the years, I have spent quite some time looking at cormorants. Besides typical carbo and sinensis, I have also found individuals showing intermediate characters, which I could not identify with much confidence. It is these birds that create the real identification challenges.

Other subspecies that I find particularly interesting and have identified (or tried to do so) in the Netherlands include Richardson’s Cackling Goose Branta hutchinsii hutchinsii, Greenland White-fronted Goose Anser albifrons flavirostris, Icelandic Godwit Limosa limosa islandica, Baltic Gull Larus fuscus fuscus, White-headed Long-tailed Tit Aegithalos caudatus caudatus, Siberian Lesser Whitethroat Sylvia althaea blythi (confirmed by DNA), Desert Lesser Whitethroat S a halimodendri (confirmed by DNA), Red-spotted Bluethroat Luscinia svecica svecica and Eastern Black Redstart Phoenicurus ochruros phoenicuroides.

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Published 12 August 2018