Terns and Gulls

Since his early days as a ringer, Ken has been studying Gulls and Terns in Donegal, beginning in 1984.  Over this period he has ringed over 10,000 birds, with a focus on Sandwich Terns, with 8377 ringed since 1986 (to 2015).  Other important species were Black-headed Gull, Common Gull and Common Tern
Much of the early study work was carried out on the islands of Mulroy Bay, Donegal but the invasive American Mink became a huge problem and devastated the colonies.  The Mink not only ate as they went, but also killed every sitting bird they found (left uneaten) and cashed hundreds of eggs in burrows.  The Mink are still prevalent in the area and it is no longer studied.  Since then Inch Islet, at Inch Island Wild Fowl Reserve, has become the sole focus for study.  The islet has breeding populations of Common & Sandwich Terns and also Black-headed Gulls - Common Gulls are thus no longer ringed.   
As you can see from the totals below the Sandwich Terns have remained fairly constant, with the one blip in 2011, when high water flooded the whole islet.  This year was also quite poor, with the bad weather in early summer, killing many chicks and lots of eggs were abandoned.  The Common Terns are much more susceptible to changes in water levels, because they nest just above the water mark.  Black-headed Gulls breed in big numbers on the island but there is limited focus on this species.   
  
Tern Species - Chicks Ringed
Gull Species - Chicks Ringed
Arctic
Common
Sandwich
Black-headed
Common
Great Black-backed
Herring 
1984
100
98
160
1985
31
50
145
1986
203
5
71
1987
10
14
133
16
136
3
1988
26
415
138
1989
342
131
1990
267
22
1991
144
1992
238
1993
294
1994
320
1995
197
1996
329
1997
131
1998
45
155
15
1999
86
324
95
3
2000
19
365
3
2001
24
335
49
2002
26
267
5
2003
23
272
5
2004
453
2
3
2005
317
2006
322
2007
343
2008
319
2009
11
291
10
2010
12
387
9
2011
94
2012
6
410
7
2
2013
251
26
2014
22
270
5
2015
2016
2017
31
32

189
357
139
22
161

Total
10
508
8873
573
816
5
3


Since the start of the project there have been 113 recoveries (more than 5km away) of the birds ringed.  The Sandwich Terns, as expected, have weighed in with the majority, with 94 recoveries.  The birds that are recovered experience a wide range of fates.  For the lucky birds, they have had their rings read in the field, have been re-caught by ringers or caught unintentionally and released.  Some are not so lucky with many being trapped and eaten, kept in cages, kept by children as pets, trapped for their rings to make jewellery, caught by dogs or simply found sick/dead. 

The Sandwich Terns have been recovered in an impressive 23 countries (24 if we grant the Basque independence) although surprisingly none yet in Northern Ireland.  I suspect some of the ringed birds I see in the Bann Estuary originate from Inch.  Generally the main concentrations in West Africa are found near the main cities e.g. Dakar and this is down to the population size, increasing the chances of the birds being found/caught.  Thumbs up to the people who found the birds in the Namib desert! 
The biggest distance travelled was for a Sandwich Tern that reached Sardinia Bay, Port Elizabeth, Cape Province, South Africa at a straight line distance of 10,399 km.  The bird was approaching 5 years old when it died, so it may have flown to South Africa and back to Ireland three/four times.   
 In terms of longevity there have been a few birds that have passed the 15 years old mark but the oldest two birds were both recovered in Spain at the ages of 20 years, 10 months and 5 days and 20 years, 4 months and 13 days.  The majority of the birds recovered in the Europe are generally at least 3 years old, whereas many of the birds in West Africa are recovered in their first winter or second year.
Sandwich Tern Recoveries
Ireland
8
Guinea Bissau
2
Scotland
3
Guinea 
1
Wales
1
Sierra Leone
7
England
5
Liberia
2
France
2
Ivory Coast
3
Belgium
1
Ghana
8
Netherlands
1
Gabon
1
Germany
1
Congo
6
Denmark
2
Angola
2
Spain
3
Namibia
2
Morocco
1
South Africa
8
Senegal
24
Total
94
Sandwich Tern Recoveries - Europe & North Africa
Sandwich Tern Recoveries - West Africa
Sandwich Tern Recoveries - Southern Africa
With much fewer birds ringed, there are less recoveries for the other species.  The Common Terns have managed a couple of recoveries in Ghana.  In terms of longevity, the oldest Common Tern to date stands at 11 years, 3 months and 1 day.  The oldest Black-headed Gull recorded = 12 years, 8 months and 6 days  and Common Gull = 21 years, 6 months and 3 days. 
Commn Tern Recoveries
B-headed Gull Recoveries
Common Gull Recoveries
Ireland
3
N Ireland
5
N Ireland
1
England
1
Ireland
7
Ireland
9
Ghana
2
Scotland
1
Scotland
1
England
1
Total
6
Total
11
Total
14


Recoveries of Black-headed & Common Gull and Common Tern - North of Ireland

Recoveries of Black-headed & Common Gull and Common Tern - UK & Ireland

Common Tern Recoveries - Ghana

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