Gull ringing on the Breakwaters of Portland Harbour, Dorset

A project organised by The Radipole Ringing Group and heavily supported by the AERG on the North Eastern and Outer Breakwaters in Portland Harbour targeting the Great black-backed Gulls (GBBGU) and Herring Gulls (HERGU) and with kind permission of the Portland Harbour Authority.

The scheme is registered with the British Trust for Ornithology (BTO) and was begun in 2011. 

A challenging environment

The project, begun by Terry Coombs and Steve Hales, is now run by Guy Hayden and Doug Rudge. In more recent years we have carried out Nest and Egg surveys before the ringing season. This year we found 317 nests, 622 eggs and 114 pulli, we were late with the second survey as weather got in the way and hence a significant number of pulli instead of eggs! At this stage the pulli are too small to ring. Incubation is around 27 days and then it is between 49 to 56 days from hatching to fledging. We gathered some interesting egg weight data. (For the analysis you will have to see our end of year report.) The breeding productivity is reported to be around 1. 

Eggs being weighed

A hatching!

Pulli too young to ring

In the ringing season, from late May to early July, we fit both BTO and Darvics to pulli  of the GBBGU and HERGU. This years totals were 91 GBBGU, 28 HERGU, 2 Oystercatchers, 36 retraps or sightings of this years pulli, and 5 Sightings of adult GBBGU returned to the Breakwaters. The pulli are very difficult to find once they have left the nest. 

Big challenge: identify the species- L HERGU, R GBBGU

L HERGU, R GBBGU

2 Oystercatcher pulli also ringed this year

Our Darvics are white with red letters and a code similar to P:45Z for the Great black-backed gulls and black with white numbers similar to 687 for the Herring gulls.

Putting a Darvic on a GBBGU

Our email for sightings is  seawaterbirds@gmail.com

We always aim to include a variety of experience in the teams to promote education and learning.

In the last 5 years we lost two complete years' activities to COVID and Highly Pathogenic Avian Influenza (HPAI) and one year was ended early with potential HPAI signs in the colonies.

It is now common for us to find some  previously rung Great black-backed gulls on the Breakwaters. The oldest one seen is 11 years old but they are known to achieve 26 years old. The project has now rung over 600  Great black-backed gulls and nearly 500 Herring Gulls. 

We have a spread of sightings from Lubeck in Germany,  Bay of Txingudi in France and  A Coruña in Spain and this year we have had our first sightings from Ireland and we know of one gull that has managed a trip of over 132 miles within in two days.

P:18C ringed 27/11/19

Transport to & from the Breakwaters is by the Pilot boat

The Team (well, one variation of it!)

Guy Hayden

Sand martins on the 4th of July

 A team of six did our second mist netting session in front of the sand martin bank on Friday and followed that with some sand martin nestling ringing to complete our mornings ringing.  It meant an early start, with the nets up at 5 am.  We walk the nets, already set, into place in front of the bank, and as we move in birds leaving their nest holes are caught whilst we are on the move.  We were more efficient in getting the nets out this time compared to last, but as always we learnt new lessons for next time.

The team of six looking cheerful despite the early start!

The catch was very good. We limit ourselves to an hour to minimise the disturbance to the colony.  We are planning to continue this at approximately two week intervals, with this being the second catch.  We caught 83 birds.  One of these was a sedge warbler, only the second one for the year so far.  Of the remaining 82 only 6 were birds that hatched this year.  I have read reports from other colonies of first year birds roosting in the colony, but this does not seem to happen much here.  There are reports from local birders of sand martins roosting in reed beds near the tramway line so this may well include our first year birds.  All six were already ringed. 

 

First year bird showing characteristic paler fringes fringes to feathers.

28 of the 76 adult birds caught were retraps, 27 of them were birds we had ringed previously this year.  The 28th was our third French ringed bird.  

French ringed sand martins.  Just as attractive as all the others.

 We will post details of these three encounters when we have the details for this third bird.  This left 48 new adult birds, so adding 49 to the total of breeding adults encountered this season.

The nets just before we finished.

Having packed up from our mist netting session we turned out attention to nestlings.  It is very busy at the moment behind the bank with many pairs bringing up their second broods with the earlier second broods really coming to the ringing stage over the next week or so.  We dealt with 8 broods of youngsters ringing a further 34 chicks.  

Overall an extremely productive morning!

Mist netting & Sand Martin Cliff

This post will cover another 3 sessions.....

On Sunday 22/6/25 a team of 4 put up 4 nets in the reed bed in front of the Discovery Hut. We caught 23 birds, including a Reed Warbler originally ringed as an adult on 9/5/19, making it at least 6 years old. The typical life expectancy is 2 years, but it still has a long way to go to reach the oldest known bird of 12 years, 11 months & 21 days. 

The Team

	Ringed	Re-trapped
Blackcap	1
Cetti’s Warbler		1 (9/1/25)
Chiffchaff	3
Reed Warbler	15	1 (9/5/19)
Robin	1
Sand Martin	1
	21	2

Once the mist nets went quiet, we moved on to ring 5 broods of youngsters in the Sand Martin cliff, where Doug had already spent the morning surveying the nests with an endoscope. 

Endoscoping the young Sand Martins

On Sunday 29/6/25, another session took place at the back of the Sand Martin cliff. It was a busy session with 13 nest boxes being checked, and 11 broods ringed, the remaining 2 broods being too small to ring. We then checked out the condition of the Abberton duck trap which had been removed from the scrape behind the Discovery Hut whilst it was dredged. The trap requires some attention, but hopefully it will be back in operation soon.

Assessing the 'flat-packed' Abberton duck trap....modifications are needed as the water is now deeper.

Today, a team of 5 set 5 nets mainly around the feeder area, but with one in the reed bed to the rear of the Discovery Hut. It was an excellent session with 39 birds of 13 species being caught, mostly youngsters. We caught 5 Sand Martins, including an un-ringned juvenile....I wonder how it escaped our attentions in the cliff!

A  young Song Thrush....we caught 3

The wing of a young Song Thrush

Comparison of Reed Warbler wings: pristine juvenile top, worn adult below

1st Sedge Warbler of the year...a juvenile as shown by the spotty 'necklace'

Pristine wing of the juvenile Sedge Warbler

Juvenile Greenfinch

Wing of the Greenfinch. The thickness of the yellow on the primaries indicates that it's a male.

	Ringed	Re-trapped
Blackbird	1
Blackcap	4
Blue Tit	1
Cettis’ Warbler	1
Chiffchaff	3
Great Tit	1
Greenfinch	1
Reed Warbler	10	2 (17/6/25 x 2)
Robin	1
Sand Martin	4	1 (19/6/25)
Sedge Warbler	1
Song Thrush	3
Wren	3	1
	34	4

Countryfile, Reed Warblers & adult Sand Martins

We've been busy! This post will cover 3 sessions......

Firstly, on Wednesday 4th June a Sand Martin monitoring & pulli ringing session was carried out at the Sand Martin cliff. This would normally have taken place on the Thursday, but was brought forward to fit in with the Countryfile filming schedule. The episode features several activities at the Wetlands, including the Group's work at the cliff. Countryfile visited the Wetlands back in 2013 and featured Matt Baker discussing the construction of the cliff with Doug. Matt & Doug re-convened to cover the current Sand Martin activity, including a demonstration of monitoring by means of an endoscope, and the ringing of 4 broods of young. 

The presenters & crew were all very friendly & it seemed to go quite well....we'll find out how it actually went when they air the episode on Sunday 22nd June!

The Mallard family was the centre of attention as it lashed down!

Doug & Matt chatting behind the cliff

Robin & Miriam (the ringing Team) with Sammi Kinghorn. 

On Tuesday 17th June we had the first mist netting session on the Wetlands since 12th Jan. We planned to put up 6 nets in the vicinity of the Discovery Hut. However, having put up 4, a surprisingly large number of birds blundered into the nets & we didn't get around to putting up the last 2. 

We set up base on the picnic bench below the Discovery Hut, & were joined by Mariana, a researcher from the Zoological Society of London. Mariana is part of the 'VB-RADAR' project (Vector-Borne Real-time Arbovirus Detection & Response), which aims to improve understanding of diseases of wild birds which are spread by mosquitoes & which may in rare cases transmit to humans. In particular, Mariana was sampling for Usutu virus & West Nile virus. There are particular species being targeted, including Blackbirds which are susceptible to Usutu virus with a resultant decline in infected populations. A later post will go into more details of the project, but it's great that the Group is getting involved in such important research. 

Ringing & sampling base

Mariana taking samples from a Reed Warbler

Our nets were set up behind the Discovery hut, with 3 around the reed bed. We were amazed at the number of adult Reed Warblers we caught from such a small area, with only 6 of the 25 being this year's birds, and they were all caught quite late in the session. Of the adults, 2 were re-traps, with one having been ringed as a a young bird on 31/7/2018, making her almost 7 years old! Not bad when the average age is 2 years. 

We did have plenty of other juvenile birds that will have bred nearby, with Chiffchaff, Cetti's Warbler, Dunnock, Blackbird and a large family of recently fledged Blue Tits. 

Young Reed Warbler (Age code 3J)

Young Dunnock (Age code 3J)

We also caught a Sand Martin....just the one. 

	Ringed	Re-trapped
House Sparrow	2
Reed Warbler	23	2 (3/7/18, 19/5/22)
Blue Tit	12
Chiffchaff	2
Dunnock	1
Sand Martin	1
Cetti’s Warbler	1	1 (9/1/25)
Blackbird	1
	43	3

We wondered if we'd see the Sand Martin again at our next session planned for 2 days later, when we were going to attempt to catch adults at the front of the Sand Martin Cliff. After taking down the nets, we spent quite a long time making plans & preparing for the attempt, something we'd never tried before. 

On Thursday 19th June we re-convened at the Discovery Hut at 5am. We put up two 30m nets on the grass near to the Sand Martin cliff, and walked them in open. As we walked in front of holes, the birds started to fly out straight into the nets. Ensuring that the net was kept tight & the birds held well above the water, we used umbrella bases to hold the poles upright on the concrete path that runs in front of the cliff.  

The nets being erected in front of the cliff.

Sand Martins being extracted after the initial catch.

Sand Martin adult (Age Code 4)

Sand Martin juvenile (Age code 3J)

Comparison of heads, Juv at top.

We were surprised by how few ringed juveniles we caught considering how many pulli (nestlings) had been ringed in the cliff....230 to be precise.  All the youngsters were caught quite late in the session, and of the 5 young birds we did catch, 3 were ringed during the filming of the Countryfile episode! The others were ringed on 25/5 & 29/5. 

We also caught 2 ringed adults, and were very excited to find that they were both controls ie not ringed at the Wetlands, & in fact both had been ringed in France! The details of when & where they were ringed will be posted when we know. 

Unsurprisingly considering that both females & males incubate,  most of the adults had brood patches, although the female brood patches are more comprehensive.

Female Sand Martin brood patch

We did continue to catch a few birds in the net after the initial catch. The net was only left up for an hour so as not to prevent free access to the cliff for too long. The net was far enough from the wall that birds could continue to access the holes even with it open by going over the top, & they even used the net as a perch!

Birds perching on the net strings! A few occasionally toppled in & were quickly extracted. 

It had been a very successful 1st attempt to catch the adults!

Sand Martins	Ringed	Re-trapped	Control	Total
Adults (4)	50		2	52
Juveniles (3J)	9	5		14
Totals	59	5	2	66

The happy Team!