The amazing Purple Sandpiper!

Purple sandpiper (Calidris maritima), Scarborough on 20 Dec 2015
Purple sandpiper (Calidris maritima), Scarborough on 20 Dec 2015

A small flock of Purple Sandpipers overwinter in Scarborough, North Yorkshire, every year. It is very easy to see these beautiful birds roosting just above the water on the artificial concrete sea defences on the East Pier of Scarborough Harbour. They fly off to feed on nearby locations were they feed on a variety of marine invertebrates. The nice thing about Purple Sandpipers is that there are very confiding; meaning that they don’t much mind people looking at them! Numbers seen in Scarborough harbour vary, but as many as 77 birds were seen on 24th Dec 2015 (1).

Purple sandpipers (Calidris maritima) 20 Dec 2015
Purple sandpipers (Calidris maritima) 20 Dec 2015

Apparently, there are long and short-billed populations of Purple Sandpipers. There are long-billed birds which come over from Canada or east Greenland, and are found predominately in the north and west of the British Isles (3). The short-billed population found along the east coast of Britain (Scotland and England) – so presumably the birds we see in Scarborough – is said to originate from Norway. These birds have both shorter bills and shorter wings than their Canadian cousins, and comprise about a quarter of the British population (4); said to number about 21,000 birds (3). It seems that some of the birds seen on the eastern coasts of Britain return to breed in the beautiful mountain plateau, known as Hardangervidda, in central southern Norway (3). It would be nice to go there to see these birds in their attractive breeding plumage. A tiny number of birds have bred in Scotland (4) but this does not occur every year according to the BTO (6) and the location is a closely guarded secret to protect them.

Purple sandpiper (Calidris maritima) 23 Dec 2015
Purple sandpiper (Calidris maritima) 23 Dec 2015

Purple Sandpipers overwintering in northern Scotland and southwest Ireland were fitted with tiny (1.4g) geolocators, which established that they were breeding in northern Canada (Baffin Island and Devon Island) (4). Incredible as it may seem, this study showed that the birds flew from Baffin Island to Scotland and Ireland in about 2.5 days, travelling about 1,400 km per day. To achieve that they would have had to average over 36 mph, day and night! It is also not clear why some long-billed Purple Sandpipers from Canada fly all the way to Scotland and Ireland, when others from the same breeding location only fly as far as south-west Greenland and Iceland (4). Some, like those breeding in Iceland, are said to be completely resident (3).

Purple sandpiper (Calidris maritima) 20 Dec 2015
Purple sandpiper (Calidris maritima) 20 Dec 2015

So amazingly, the Purple Sandpipers we see around the British Isles are a mixed bunch, though you would have to be a pretty skilled birder to differentiate them, and I have not seen a handbook which attempts to describe the short- and long-billed forms, so the difference must be very subtle. The bills vary in length by about 4 mm between the short- and long-billed populations (3), although the average lengths differ according to region (Iceland, Canada, Norway, Russia and so on). Still, it’s nice that these different populations have chosen to come to the British Isles to spend their winters!

Purple sandpiper (Calidris maritima) 23 Dec 2015
Purple sandpiper (Calidris maritima) 23 Dec 2015

 

Female Purple Sandpipers are larger than the males, although I have not found it easy to separate them in a flock!

Purple sandpiper (Calidris maritima) flock
Purple sandpiper (Calidris maritima) flock
  1. http://www.scarboroughbirding.co.uk/
  2. http://jncc.defra.gov.uk/pdf/UKSPA/UKSPA-A6-66.pdf
  3. Wernham, Chris. “{The Migration Atlas: Movements of the Birds of Britain and Ireland}.” (2002).
  4. http://www.birdwatchireland.ie/LinkClick.aspx?fileticket=LFPY0CTxO1E%3D&tabid=1486
  5. https://britishbirds.co.uk/wp-content/uploads/article_files/V76/V76_N12/V76_N12_P563_565_A146.pdf
  6. http://www.bto.org/about-birds/bird-of-month/purple-sandpiper

One thought on “The amazing Purple Sandpiper!

  1. Pingback: The amazing Purple Sandpiper! | Ray Cannon's nature notes

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