Sunday 25 February 2024

Shelduck Migration Project

At the cannon netting session on 19th February the group took part in a shelduck research project which aims to identify the risks to migrating individuals from collisions with offshore wind farms.  The research is being carried out by Ross Green from the BTO.

Shelduck don't perform the classical spring and autumn migrations between breeding and non-breeding sites like most migrant birds. Instead they migrate in summer – from mid-June to early August – to large estuaries to moult before moving on to wintering sites, which may or may not be near their breeding areas. All the known offshore migration routes pass through areas  that may have offshore wind farms in future. The likelihood of interaction is therefore high, but it is unclear if the interactions will have any effect at the population scale, or an impact on migratory routes in the long term.

GPS data shows that these ducks mostly fly at night, and at heights above sea level that put them at risk of collision with turbine blades. 

Isotopes in the feathers of shelduck may be site specific and so it is hoped that each moult site will have a unique chemical signature. Analysis of feather samples could help to identify the movements of shelduck. 

Our group collected small fragments of secondary feathers at our cannon session and these will help the project by showing where our birds go.


Snipping a section of feather for analysis. 

GPS data has been unable to establish where birds go after they've moulted, so this feather analysis will help to fill that knowledge gap. This method is also considerably cheaper than GPS tracking. 


Robin Pearson

Saturday 10 February 2024

Cannon netting 11/2/24 ....or not!

The catch area at Seaton Marshes had been baited with grain since the last cannon netting session, and decent numbers of ducks and waders, including Shelduck & Black-tailed Godwit, had been seen feeding in the area. The cannon net was set up yesterday, and a team of 12 keen ringers attended for the catch this morning. At one stage there were about 30 Shelduck on the scrape, but they refused to feed on the grain and then flew off. At about 945am the decision was made to give up & disassemble the net. 

The catch area during the week (photo: Adrian Bayley)


The net set & ready (photo: Adrian Bayley)
                                                                   

The disappointed Team 
                                       


Wednesday 7 February 2024

Cannon netting 13/01/2024

The group undertook its first cannon netting session of the year at Seaton Marshes. The catch area had been baited for several days. The net was set on the afternoon before the catch day by a few members of the group


Setting the net and the cannon

Weather conditions on catch day were ideal - cold with light winds – as about 15 members of the group waited for the bang of the cannon to send them scurrying down to the net. 27 birds were caught, which was about 2/3 of the birds in the target area. The catch comprised 22 shelduck, 3 teal, one wigeon and one moorhen. 16 of the shelduck were re-traps.


The catch safely bagged and ready for processing

All new shelduck were fitted with a metal BTO ring together with a yellow colour ring with large black lettering which can be read in the field using binoculars or a telescope. 


Fitting a plastic colour ring

Next we determine the sex of the bird and its age. The most obvious difference in the sexes is that males (usually) have a noticeable knob on the bright red bill. The female’s bill is duller.



Female (1st bird shown) and male shelduck for comparison

The principle ageing character is the obvious white tips to the secondaries in immature birds, which give the wing a distinctive white trailing edge in flight. In adults the secondaries are either all black or have only narrow white tips.


Adult birds. Although the 1st bird shown has narrow white tips to the secondaries they are not the broad white tips that would be seen in a 1st winter/spring bird.


Then it’s time to get some biometric measurements: the length of the wing chord (from the bend in the wing to the tip of the longest primary feather); head + bill length; tarsus length (from the notch in the ‘elbow’ to the bend of the foot) and the bird’s weight.


Tarsus measurement is taken from the notch behind the elbow to the bend of the middle toe

Taking measurements and giving them to one of the most important members of the team – the scribe

The team busily at work. 

And away! Birds are released at the water’s edge where they can choose to fly or swim away


Gathering in the net at the end of the session

The three oldest re-trap shelduck were all at least 10 years old and had been re-caught or re-sighted at Seaton Marshes on multiple occasions as detailed in the table below. They were each given the age code 6 at ringing and because age code 6 means ‘hatched before previous calendar year’ they were at least 2 calendar years old when ringed.  



The typical life span of a shelduck is 10 years and the oldest shelduck recorded (maximum age from ringing) was 19 years 7 months (BTO data) so our old birds have not done too badly!




Robin Pearson

Tuesday 17 October 2023

Mist netting 17/10/2023

Four members of the Group were joined by Fiona, a Countryside Assistant with Wild East Devon, for a session in the 'Willows'.  This area, which is quite close to the Discovery Hut, hasn't been ringed for quite some time. Severn nets were set, including one across the small brook which runs along the edge of the area, and a ringing base was set up in the pond-dipping shelter. 

Ringing underway in the pond-dipping shelter. 

It was rather windier than ideal, although better than had been forecast, and quite slow going with just a few birds each round. A Long-tailed Tit already wearing a ring turned out to have been originally ringed as a newly hatched bird on  9/8/21,  by one of the Group present at this session, and to have been subsequently re-trapped on 18/11/21 & 19/1/22. The typical lifespan of a Long-tailed Tit is 2 years, so it's already doing fairly well, although it has a long way to go before reaching the maximum known age of 8 years & 11 months. 

Long-tailed Tit first ringed 9/8/21

The undoubted stars of the show were two Grey Wagtails, caught in the net over the brook. The Group has only previously caught nine Grey Wagtails, the last one having been ringed in November 2019. Both birds were hatched this year. The birds were aged using the difference in colour between the Median Coverts, which had been moulted during the Post-juvenile Moult & were dark black, and the duller brown Greater Coverts, which were grown in the nest. 

The first Grey Wagtail.

Feature used to age the Grey Wagtail as having been hatched this year (age code 3)

Second Grey Wagtail

Underside of Grey Wagtail 


Ringed

Re-trapped

Blackbird

1


Chiffchaff

3


Dunnock

2


Great Tit

1


Grey Wagtail

2


Long-tailed Tit

4

1

Robin

1


Wren

3



17

1


Friday 22 September 2023

A successful wader catch 13/9/23

It was in the pre-covid era that the last wader catch on the Axe took place, so there was much trepidation and excitement between ringers as we set up on Colyford Marsh. Teal, Curlew and Little Egret were all noted in this period, and their flight patterns influenced our placement of nets. 


Wader footprints on the mud at Colyford – a promising start. (Photo: T. M. Mylett)


Mist-netting for waders requires a different approach to our monthly passerine sessions; whilst the former group is best targeted from the early morning, it tends to be more successful to catch waders as they come into roost. We set up 5 60ft nets (and herded cattle) across the tussocky terrain from 4:30-6pm, while Adrian kindly marked a clear pathway for us to use once darkness set in. Without the white bamboo canes to follow, there may have been a few too many You’ve Been Framed moments. 



Setting up nets. (Photo: Robin Pearson)


Watching the nets was at first frustrating, as a small troupe of Ringed Plover gallingly fed underneath the nearest shelves. After some time, however, our first bird was caught – a magnificent Curlew – and from there, the evening really took off. 




Robin and Mark measure the wing of a Curlew. (Photo: Mark Wills)



Per BTO guidance for Curlew and Dunlin, and for the sake of parity, we measured tarsus and bill length of all birds caught. This proved a good opportunity to refine our skills in these areas, generally not used for the smaller birds we catch during our monthly crop field sessions. In Curlew, these measurements can prove useful to identifying the sex; females are, on average, altogether larger. In Dunlin, the same measurements can prove indicative of different subspecies. 


A total of 5 Dunlin were also ringed. Because these were caught within the same net round, we were able to compare them during processing, which proved a valuable lesson in identification and ageing. Much conversation was had regarding the slight differences in plumage, and the guidance given by Jeff Baker and Laurent Demongin’s texts. The latter had a point of particularly pertinent advice preceding all discussion of the species – ageing may prove ‘very difficult’. Indeed. 




A Dunlin in the hand (Photo: Mark Wills)


In simplified summary, Dunlin can be aged based on the overall colour of their feathers. More warm, golden-brown birds are younger, and those with greyer hues are older. The below picture shows all 5, which comprised of 4 immature birds and 1 adult (at the left of the circle).


Comparing Dunlin. (Photo: Mark Wills)


Other appearances were made by a Common Snipe, 5 of (presumably) the 6 cheeky Ringed Plover mentioned earlier, and 2 Common Sandpiper. The Ringed Plover were another treat, as they are the first the AERG has ever ringed.



Common Snipe (Photo: Sue Murphy)


A Ringed Plover in the hand. This bird hatched this year – According to Baker and Svensson, in adults, the beak would also be bright orange contrasting to a well-marked black tip, and the legs would be of a similar orange, unlike the yellowish tarsi this bird has. (Photo: Sue Murphy)



Alan processes a Common Sandpiper, Demongin to hand. (Photo: Mark Wills)



Common Sandpiper (Photo: Robin Pearson)

The session proved to be the largest catch for the site, with 14 birds of 5 species caught. It was a great turn out with 10 ringers from Devon and beyond attending. All birds were newly ringed, and there were no retraps (bar 1 Dunlin, who seemingly enjoyed being processed so much the first time they hopped back into the net around 10pm). 


Species

Total ringed

Common Sandpiper

2

Common Snipe

1

Curlew

1

Dunlin

5

Ringed Plover

5


14



Dismantling the nets in the deep jurassic dark proved a final challenge, but, as always, many hands made light work. The marsh is a mucky site to navigate and most of us had a liberal splash of Colyford mud on our gear and hands by the end of the evening. Final comments between the group included a humorous quip from Allan regarding how our own earthy covering could rival Gweneth Paltrow’s own ‘Goop’ range. We’ll leave the marketing of that idea to him… 


-T. M. Mylett


And in other news.....

On 3/9/23, the Group set up a display stand at the annual Seaton Wetlands Wildlife Day. The event was rather quiet, possibly due to the fact that it was a gorgeous day & everyone was on the beach, and the holiday-makers were on their way home as the school term was about to start. 



A couple of days prior to the wader session, on 11/9/23,  4 members attended Colyford Common for the more usual passerine ringing session. 35 birds were caught and processed, which included 4 re-traps. 


Ringed

Re-trapped

Blackbird


1

Blackcap

6


Blue Tit

7

1

Cetti’s Warbler

1


Chiffchaff

5


Dunnock

3


Goldfinch

1


Great Tit

2


Greenfinch

1


Reed Warbler

1


Robin

2

2

Whitethroat

1


Wren

1



31

4