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.

New BTO project initiated - Gull Positioning System (GPS)

This summer, 50 Lesser Black-backed Gulls breeding on Skokholm Island, Pembrokeshire and Walney Island, Cumbria have been kitted out with state-of-the-art GPS tags by scientists from the BTO as part of a project funded by the Department of Energy and Climate Change, studying how these birds might use areas of the marine environment earmarked for the development of offshore wind turbines, as well as areas where wind farms already exist.

The Lesser Black-backed Gull was classed as “Amber” in the most recent Birds of Conservation Concern and is declining at a number of breeding colonies where it is protected, included Skokholm and Walney. These tags gather high quality information that is already providing valuable insights into the habitats these birds use, which could be used to improve their conservation and management.

Lesser Black-backed Gulls breeding on Skokholm Island, photograph by Richard Brown

The birds were tagged in May, at which time they were incubating eggs and we are now receiving regular updates on where they have been, the altitude they are flying at and how long they spend in certain areas. Initially almost all birds from Skokholm went inland every day to feed, visiting reservoirs and agricultural areas throughout Pembrokeshire and Carmarthenshire, as well as towns like Milford Haven and Pembroke. However, once their chicks started hatching towards the end of May, birds began to fly out to sea, suggesting these gulls were seeking high quality fresh fish for their youngsters. Recently, one female travelled as far as the Isles of Scilly before returning to her nest site, while another bird visited Great Saltee Island off the coast of Ireland.

A Lesser Black-backed Gull breeding on Skokholm makes a day trip to Ireland

Lesser Black-backed Gulls tagged on Walney Island have spent time in Barrow and other local urban areas, where gulls are not always popular. However, many birds have flown straight over these locations on their way to parts of the Lake District, while others have journeyed far out into the Irish Sea. Birds that do visit towns have tended to favour destinations like Blackpool, while others have made day trips as far afield as Warrington.

You can see where our birds have been going for yourselves if you keep an eye on these pages hosted by researchers at the University of Amsterdam, who made our gulls’ tags:

http://www.uva-bits.nl/project/seabirds-windfarm-interactions-skokholm/

http://www.uva-bits.nl/project/seabird-windfarm-interactions-walney-2/

This project would not have been possible without the help of Skokholm Wardens Richard Brown and Giselle Eagle, and Matt Lipton, Warden at South Walney.

For more information on this BTO project and to watch our gulls on the BBC One Show click here

Adios Caledonia

Roy Dennis' team have colour ringed more than 1500 young Ospreys since 1966 and in 2007 they started using GPS tracking devices to 'fill in' the gaps left by colour-ringing alone. These satellite devices enable live monitoring of individuals and have revealed entire migration routes, identified stop-over sites and disclosed previously unknown hazards for different species. At Loch Garten 12 Ospreys chicks have been fitted with satellite tags and their movements are followed by many online fans and reserve staff. The 12 birds have been named and their return to their birth place as breeding adults is much awaited.

Sadly, the fifth day of the new year brought bad news to Roy Dennis, Loch Garten and all the Osprey fans, as Caledonia, a female bird ringed and satellite-tagged in 2012, had been found dead in Spain. We now know that Juan Antonio Martínez Martín, a member of SEO/Birdlife, found Caledonia dead in the garden of a convent in Seville, where it had hit some cables and killed itself during thick morning fog.

All photos thanks to Jesús Fernández

 At Loch Garten, the return of Caledonia was expected with excitement as this should be only three months away. She seemed to be a 'very safe' Osprey, having spent several days in the Guadalquivir River area where she eventually died, and had travelled the same route that saw her sad end before. The Guadalquivir River basin in south west Spain is used as wintering grounds or stop-over by many species including Ospreys.

San Clemente convent, by the Guadalquivir River, where caledonia was found.

The RSPB Community is devastated with the loss of Caledonia, they have posted photographs of her and told their own personal memories here.

This little story highlights the hazards that large birds face, in particular the iconic Osprey. They tend to attract the love and attention of the public, even reserves and conservation measures are established across countries for their benefit. However, in their lifetime, they not only need to overcome the natural elements, they also have to overcome the barriers that we put for them, for their home ranges expand beyond the reserves.

In the UK and Ireland 189 Ospreys were ringed in 2012, and in that year we received 134 reports of BTO-ringed Ospreys found in other countries. To find out more about ringing totals in the UK and Ireland, visit the Online Ringing reports.

Finding locations of Ospreys ringed in the UK and Ireland (purple)
and ringing location of birds later found in the UK and Ireland (yellow).

Thank you to Juan Antonio Martínez Martín for finding and reporting the bird, to Jesús Pinilla and Arantza Leal from SEO/Birdlife for providing further finding details, to Roy Dennis for ringing the bird and to Jesús Fernández for the photos.