An unexpected but timely recovery

Gary Clewely (BTO) writes:

Nightingales are one of the best-known species in the UK for their impressive vocalisations, yet will be increasingly unfamiliar to many of us due to a marked range contraction and population decline in recent decades.

The motivation behind the BTO Nightingale tracking study is to identify key migratory routes and wintering areas to inform conservation. Fieldwork during the 2016 Spring was particularly exciting, because in addition to retrieving geolocators from previous years, this was the first time GPS loggers weighing less than 1 g were fitted to Nightingales in the UK, which if recovered the following year would give us unparalleled data on their migration.

Nightingale. Photo taken by John Spaull

During a mist-netting session at Alton Water (blue pin on map), in Suffolk (managed by Anglian Water, one of the tracking study partners) where we were catching males for tagging, one of the birds caught was already carrying a BTO metal ring – NA82699. This was initially not too unusual, especially as ringing was taking place on the site. The bird was swiftly processed and fitted with a GPS tag before being released safely back into its territory. Later, it came to light that NA82699 had in fact been ringed in January 2016 during an expedition to the Kartong Bird Observatory in The Gambia (orange pin on map). This is the first case of a Nightingale ringed in sub-Saharan Africa being found in the UK but remarkably, it is not the first exchange of Nightingales between East Anglia and the Kartong survey area. In 2011 and 2012, Nightingales ringed in East Anglia were recorded in Kartong, including a bird originally from a site near Ipswich, just 10 km from Alton Water.

Of course, recoveries in and from Africa are hugely dependent on effort and are biased depending on where ringing activities take place. Nonetheless, it is extremely encouraging that the ongoing monitoring at places such as the Kartong Bird Observatory is valuable and well placed to help inform us about migrant bird populations.

Olly Fox, who was on the January trip to The Gambia, reports that the Kartong ringing survey has a relatively high retrap rate for Nightingales with four birds encountered in multiple winters (in addition to the three exchanges between Kartong and the UK) from only 17 birds ringed between 2011‒15. Olly goes on to tell me that wintering Nightingales in the coastal part of The Gambia are generally found in patches of dense vegetation but can also occupy secondary habitat, such as disused farmland. For males at least, these territories are defended throughout the winter months. However, increasingly these habitats are under pressure from development of agriculture and clearance of woodland and scrub to satisfy a rise in demand for firewood and charcoal. These are perfect examples of land-use changes occurring across the range of many migrant species that are important to identify and understand when considering their conservation.

Nightingale singing. Photo taken by Amy Lewis

Far from jumping the gun on the tracking study results, recoveries such as this complement tracking well, providing useful context and help to focus winter ringing efforts and inform local conservation, in this case by the Gambian Department of Parks and Wildlife Management and other NGOs. We will still need the detailed tracking information to understand the precise routes taken and the timing of their movements. The combination of continued tracking work and further ringing in The Gambia will help us understand how typical the apparent connectivity of Nightingales between East Anglia and coastal Gambia is.

Out of Africa... and into Norfolk, for a 13 gram bird

Oliver Fox writes:

Monitoring of wintering passerines is one of the main objectives of the Kartong Bird Observatory (KBO), a project run by volunteer ringers in the south of The Gambia, West Africa. Situated on the Atlantic coast close to the Senegalese border, the Kartong wetlands were formed relatively recently as a result of wet-season flooding of disused sand mines and form part of the Allahein to Kartong coast IBA.


Palearctic passerines being processed at Kartong Bird Observatory taken by Colin cross



The wetland reedbeds and surrounding scrub provides an excellent wintering site for many Palearctic passerines, and mist-net surveys have highlighted the importance of the site for Western Olivaceous Warblers, Common Whitethroats, Subalpine Warblers and Common Nightingales in particular. In dry years the area provides refuge for Sahel-dependent species, such as Western Orphean Warblers and Woodchat Shrikes, when conditions further north become unfavourable. Located on a promontory extending into the Atlantic, the site is also well placed to observe passage migration of Blackcaps and Garden Warblers moving south in October and November and Willow Warblers moving north in early Spring.

Wintering Reed Warblers are regularly encountered at Kartong, both in the Typhus reedbeds and the dry coastal and Acacia scrub that surrounds the wetlands. A proportion of those ringed at Kartong seem to be faithful to the wintering site, with five birds recaptured the winter after ringing and one bird returning to Kartong in two successive winters.

Reed Warbler about to be released at Kartong taken by Oliver Fox

News from the BTO has been received that a Reed Warbler ringed on 18/01/14 at Kartong was recaught at Hilgay Wetland Creation, Norfolk on 11/08/2015 BTO's Graham Austin, only 29 km from BTO HQ. There were several BTO staff members on the expedition in 2014, so it seems fitting that the bird was caught in Norfolk a few months later.

This is the sixth Reed Warbler ringed at KBO to be recaptured back in Europe during the summer months, with three having been previously recaptured in Spain, one on Guernsey and one in Surrey. Similarly, the ringing teams at Kartong have recaptured two Spanish and one British & Irish-ringed bird in the last few years, showing the migration pattern of Reed Warblers from Western Europe to the coast of West Africa.

Details of this latest recovery can be found on the Recoveries and Controls page of the KBO website.

Ringed birds in the Gambia part 3!

The increasing work done in Africa to find out about our declining migrants is picking up pace, with the BTO Cuckoos still going strong and the Out of Africa project. As mentioned in a post previously, a team of volunteer ringers have just returned from their third trip to Kartong Bird Observatory, The Gambia, in an attempt to gain more knowledge on our European passerines and gain more information on African birds.

I was part of the team, my second trip, and we managed to catch 1200 birds of 121 species during the 10 day ringing session. Good numbers of herons, raptors, terns, shrikes and African passerines were caught including 70 Long-tailed Nightjar and 50 Jacana. Most importantly 250 Western Palaearctic passerines were caught including Whitethroat, Chiffchaff, Melodious Warbler, Subalpine Warbler, Reed and Sedge warbler and a Nightingale (but without a data logger!). We also saw an Osprey with a satelite tag but were unable to read the colour ring.

Some birds were doing some very interesting moult while in Africa - one 1st winter Chiffchaff was actively finishing off a complete primary moult. As we know neither adults or first year birds are supposed to moult in their wintering quarters.

The team also proved some direct migration thanks to birds that were already ringed by other ringing schemes. The first was from a Sandwich Tern with a BTO ring that had been ringed on Coquet Island, Northumberland this year. We also caught a Sandwich Tern from Helgoland, Germany and a Sedge Warbler wearing a French ring. The next trip in January will focus on terns, waders and Acrocephalus warblers in the reed beds.

For more information on Kartong Bird Observatory see www.kartongbirdobservatory.org.

This was an amazing experience and if you wish to be considered for future trips (probably 2013) please contact Jez Blackburn (jezblackburn@sky.com) for more details and an application form. Note - you need to be a ringer and have good knowledge of moult!

Top picture- Squacco heron. Middle picture - Woodchat Shrike. Above - The team

New Bird Observatory in the Gambia

Volunteer ringers from the UK have just returned from their first trip to the Kartong Bird Observatory, to help understand bird demography in the Gambia. During the 11 day trip more than 800 birds were processed and measurements taken. The majority of the birds ringed were African but there were some Palearctic migrants which were just arriving including Blackcap, Garden Warbler, Olivaceous Warbler, Yellow Wagtail, Sedge and Reed Warbler.


During the nights it was very dark, due to the new moon and provided great lamping conditions for Long-tailed Nightjar, Painted Snipe, Senegal Thick-knee and Spur-winged Plover. Local bird guides and birders will be able to take part in reporting leg flagged Spur-winged Plovers throughout Gambia and the movements of the whoosh netted Hooded Vultures will be very interesting (below).



Ringing demonstrations were run mid week to introduce the local school children to bird conservation and it was received very well with many fascinated faces. Some notable birds were Yellow-crowned Gonolek (pictured), Levaillant’s Cuckoo and Blue-breasted Kingfisher (1 of the 6 species of kingfishers caught).


Future annual expeditions will provide more valuable data, with the next trip being March 2011. Maybe more new birds will be added to the Gambian list like Cassin's Honeyguide as on this occasion.