BTO Cymru

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Friday 26 July 2019

Club Sandwich

Henry Cook, Marc Hughes and Robin Sandham have over the past autumns been busy reading colour rings on Terns on the North Wales coast. Together with Sandwich terns from the colony at Cemlyn which has had a proportion of their birds colour ringed and with some of the Little terns from Gronant, add to our understanding and knowledge of how these enigmatic sea birds use the Irish sea.

STOP PRESS  Danish ringed Sandwich tern found 25/09/19 

Follow their ring reading this year on Twitter using @BTO_Cymru, 

Following a successful colour-ring reading effort of Sandwich Terns Sterna sandvicenis at Rhos Point (Caernarfonshire) in 2017, visits were increased from late July to early September 2018 resulting in the most revealing year yet. The majority of birds (80%) were reported at Rhos Point with three other sites providing the rest. However, coverage and ease of viewing has a large bearing on this result. During this period, it is thought the North Wales coast of Liverpool Bay sees 1500-3000 birds roosting daily. A total of 123 sightings of 86 individuals were read across the sites in 2018 (41 and 32 respectively in 2017). The highest daily total was of 15 individuals read on 20/08/18.

The closest colony and only breeding site in Wales is at Cemlyn on Anglesey (52km away), however, ringing has only just started there this year. Colonies at Lady's Island Lake, Wexford, Ireland and Hodbarrow, Cumbria were the origin for two thirds of all resightings. Later in August, a higher proportion of birds from the east coasts of Scotland and England appeared including a couple of Dutch-ringed birds. This indicates a post-breeding movement of some North Sea birds presumably heading northwards and around the top of Scotland in to the Irish Sea to feed up before continuing their journey.

  A selection of phone-scoped images at Rhos Point which often aid in clinching the ring combinations (RS). 

There were inevitably some notable resightings elsewhere on the bird's migration. Most notably Red KND was sighted at Rhos Point on 24/07/18 and seen at Strand, Western Cape, South Africa on 21/10/18. Assuming it took an inshore route to the wintering grounds, this is a journey of nearly 14000km in that time. A number of other Sandwich Terns seen at Rhos Point have been resighted in the cape region of South Africa.  The oldest bird resighted was 4807 days old (13 years, 1 month), Red ECL from Inner Farne, Northumberland and seen subsequently most years in Scottish colonies. This individual has also been resighted in Namibia in 2012.

The totals included birds from the following ringing locations (direct distance in brackets to Rhos Point):
·         48 from Lady’s Island Lake, Wexford, Ireland (218km),
·         25 from Hodbarrow, Cumbria (102km) 
·         8 from Ynyslas, Ceredigion (89km)  
·         8 from Ythan Estuary, Scotland (459km)
·         5 from Coquet Island, Northumberland (266km)
·         5 from Inner Farne, Northumberland (290km)
·         2 from Forvie NNR, Scotland (460km)
·         2 from Scolt Head, Norfolk (299km)
·         2 from Netherlands (550km*)

N.B. the totals for birds on the sites-ringed chart is lower than for the sites-seen chart as feedback wasn't received for all individuals.

Red KND - photographed at Rhos Point on 24/07/2018 and resighted nearly 14000km away in Strand, Western Cape, South Africa on 21/10/2018, inshore route below. 

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