Tag: monitoring

Migration – guaranteed to impress

Posted on by Rebecca Lee

Anyone who doesn’t have at least some degree of admiration for the feat of bird migration either isn’t aware of the challenges involved or must lack any sense of wonder and imagination. It’s World Migratory Birds Day this Saturday 10 October and with excellent timing a new wave of sightings of black-tailed godwits from outside the UK has flooded in to the team at Project Godwit.

Black-tailed godwits which breed in the UK are of the Limosa limosa limosa sub-species and mainly breed in the East Anglian Fens of Cambridgeshire and Norfolk, plus a few sites in the south-east and north-west of England. A small number of the sub-species L. l. islandica also breed in Orkney and Shetland.

While L. l. islandica winters in Iceland, black-tailed godwits of the L. l. limosa race migrate south to Spain, Portugal or West Africa – to countries like Senegal, Mauritania and Guinea, 2800 miles away.

L. L. limosa at the RSPB Ouse Washes (Photo: Jonathan Taylor).

Black-tailed godwits use ‘staging areas’ (stop-over sites) on their migration route to rest and feed, in places such as the crucially important Tagus estuary in Portugal, which connects breeding sites across the northern hemisphere to wintering areas in Africa. It’s not just godwits from the UK that come here – Icelandic black-tailed godwits, plus godwits from the Netherlands (where the majority of the north-west European population breed) also gather here. Around 300,000 waterbirds of a plethora of migratory species including 80,000 black-tailed godwits stop here to regain energy and forage on the rice fields and mudflats of the Tagus estuary.

The Tagus estuary is designated as a Special Protection Area (SPA), a Wetland of International Importance (Ramsar site) and an Important Bird Area (IBA). Despite the vital importance of the area for biodiversity, the Tagus estuary is threatened with the development of an airport for Lisbon. This is another risk this species with its Near Threatened global status can really do without, especially when the UK population is already so small and vulnerable, not to mention the multitude of other reasons this airport should not be built.

Amongst some of the godwit sightings recently to have arrived in the team’s inbox is that of a female godwit reported from the Tagus estuary by Hugo Areal. This female was ringed as a chick at RSPB Nene Washes nature reserve, Cambridgeshire (the stronghold for the UK breeding population) an amazing 19 years ago and was spotted in what would be a part of the airport experiencing the highest levels of noise pollution and disruption if it goes ahead. This godwit has been seen regularly at the Tagus estuary over the years, in autumn and spring.

This female was observed breeding at the Nene Washes again this year. There have also been multiple sightings of this bird on the north Norfolk coast, at reserves like RSPB Titchwell and Norfolk Wildlife Trust’s Cley Marshes in late summer/early autumn, feeding up before migrating south.

Birds ringed by Project Godwit have a lime colour ring on the right leg stamped with the letter ‘E’ and can be reported to the team here.

One muddy godwit – bearing the Project Godwit colour-marking scheme of a lime green ring on the right leg with a black ‘E’ (caked in mud here). (Photo: Hugo Areal)
Project Godwit colour rings when clean (Photo: RSPB).

One-year-old female godwit ‘Sky’ was reported at a national nature reserve near Yves in Western France in September by Jérémy Dupuy. Sky was head-started as a chick at WWT Welney Wetland Centre in June 2019 and released at the Nene Washes. This is the first observation of Sky since her release in well over a year – fingers crossed she will return to the UK next year to breed in the Fens.

Sky as a chick in June 2019 at WWT Welney (Photo: WWT).

Head-started birds have been reported in 10 countries along the species’ migration flyway, including Portugal, Spain, France, Belgium, Austria, Germany, the Netherlands, Morocco, Senegal and Mauritania. Head-started godwits are also breeding in the UK, pairing with ‘wild-reared’ adults as well as with other head-started birds.

To date, head-started godwits have been reported from 10 different countries.

A male black-tailed godwit was spotted in September in the Algarve, Portugal – ringed as a chick at the Nene Washes in 2003. This godwit breeds at the Nene Washes every spring and was seen with its partner and chicks in May this year by a member of the team. Thanks to Dr José Tavares for reporting this sighting to Project Godwit.

Another one-year-old godwit head-started in 2019 has just been reported this week from Senegal, in Djoudj National Park near Debi. Female godwit ‘Rainbow’ was last spotted in Senegal in October 2019, therefore she may have stayed on the wintering grounds this whole time. This behaviour is common for juvenile godwits, whereby they often don’t return to the UK breeding grounds until the age of two years.

Rainbow at WWT Welney in June 2019, before release as a head-started chick (Photo: WWT).

Project Godwit and all our colleagues working to protect godwits are indebted to all who go to the trouble of reporting colour ring sightings. These volunteer recorders are making a significant contribution to conservation science, helping us better understand the movements of these migratory waders all along the migration flyway.

Project Godwit is a five-year partnership project between the RSPB and the Wildfowl & Wetlands Trust with major funding from the EU LIFE Nature Programme, HSBC 150th Anniversary Fund, Natural England, the National Lottery Heritage Fund through the Back from the Brink Programme, Leica and the Montague-Panton Animal Welfare Trust.

What does a godwit scientist do in lockdown?

Posted on by Rebecca Lee

Our latest blog post is by Mo Verhoeven, RSPB Senior Research Assistant for Project Godwit.

On January 14th this year, Jelle Loonstra and I handed in our joint PhD on “The behaviour and ecology of the Black-tailed Godwit”. The next day, I was on an airplane to Chile with the mission of outfitting Hudsonian Godwits with transmitters to record their 14.000+ km migration from Chile to the North American Arctic. I was coming from winter, which was clear from my pale skin and a permanently smoky smell imparted by my woodstove. But suddenly I was in Chile, wearing shorts and freed from my PhD for the first time in months. A good start to 2020!

Mo Verhoeven (taken by Rob Buiter).

A few weeks later (at which point I happened to be in the forests of Maine, wearing smoky snowpants), I received a job offer to work for the RSPB as a Senior Research Assistant on Project Godwit to monitor the godwits nesting at the Nene Washes. I imagined the tumbling Lapwing, the whirring Snipe and the nesting Godwits. It was hard to say no. On March 15th I arrived in the UK. It was sunny, the Washes were partly flooded and the first godwits had returned! The stage was set for a beautiful spring. And a beautiful spring it was, with flowers blooming, nests being built, and chicks to come…but on the 23rd a nation-wide lockdown was announced and all fieldwork was cancelled! What to do?

Project Godwit had already collected data on breeding godwits at the Nene Washes in 2015-2019, which meant I could start analysing some of that. First, I analysed data from the eight geolocators that had been retrieved in previous years. Geolocators are data-loggers that continuously log the ambient light-level. Each geolocator is attached to a ring that is placed on a godwit’s leg. The godwit then carries this geolocator with it throughout the year – on migration to the non-breeding grounds and back to the Washes again in the spring. Researchers then do their best to capture that same bird again; if they’re successful, they remove the logger and use the stored light-level data to establish the moment of sunrise, midday and sunset throughout the year. When you know the length of each day, you can estimate the latitude (north/south), since this varies predictably with date across the world. Estimating longitude (east/west) comes next and this relies on a centuries-old technique. First you log the moment of midday at a specific location, usually Greenwich. From this you can calculate the shift in the time of midday relative to Greenwich, and therefore determine how much the godwit has moved to the west or east relative to Greenwich. This is why seafarers had chronometers and why precise chronometers were worth a lot of money.

Raw light-level data recorded on the geolocator carried by OB-OL(E)

Two of the geolocators I examined had logged especially interesting migrations (during my PhD, I analysed more than 300 migrations by Dutch godwits – these two were immediately distinguishable from the pack!). The first was from ‘Cornelia’, a head-started chick released at the Nene Washes in 2018 (also learn more here). Black-tailed godwit chicks are being head-started to boost the number of godwit chicks that survive to fledging age. Chicks are reared by our project partner the Wildfowl & Wetlands Trust (WWT) at Welney Wetland Centre and released once fledged. The nearly fledged chicks are fitted with a unique combination of colour-rings and some are also fitted with a geolocator. Cornelia was released on June 27th 2018. She left the UK on the evening of August 13th and arrived in Africa on the night of August 15th, having probably flown non-stop.

The other was from a male godwit known as OB-OL(E). In 2018, this male left the UK on June 21st, went to the Balearic coast of mainland Spain, and stayed there for three months. That’s not very uncommon. But on October 2nd, he crossed the Sahara and went to the Inner-Niger Delta in Mali. This is very late in the season for such a flight – in fact, it’s the latest southward Sahara crossing on record for an adult godwit! For context: some godwits start migrating in the opposite direction, from west Africa back north, as early as the second week of September. Why do godwits behave so differently, and how do these individual differences come about? Interesting questions that challenge current knowledge!

Map of the migration route of godwit ‘OB-OL(E)’.

The other analysis I have worked on during lockdown is comparing adult, nest and chick survival rates between an earlier period of research at the Nene Washes, during which the godwit population at the Nene Washes increased (1999-2003) and a more contemporary period (2015-2016) in which the population has declined. This work shows that nest and chick survival, but not adult survival, are low in the contemporary period compared to the early period. The recent decline at the Nene Washes is therefore likely the result of lower reproductive success resulting in fewer birds recruiting at the Nene Washes. This study also indicated that nest survival was lowered because of an increase in nest predation. The reserve managers had already been thinking this was the case, and in 2017 started using special gates and electric fences to keep mammalian predators from depredating godwit nests. My next task will be to evaluate whether and how effective those efforts were. I’ll keep you posted!

 

Project Godwit is a partnership between RSPB and WWT with major funding from the EU LIFE Nature Programme, the HSBC 150th Anniversary Fund, Natural England, the National Lottery Heritage Fund through the Back from the Brink Programme, Leica and the Montague-Panton Animal Welfare Trust.