Tapping nature’s barometer

A cuckoo about to be released wearing a BTO satellite tag''Phil Atkinson/BTO
A cuckoo about to be released wearing a BTO satellite tag''Phil Atkinson/BTO
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The British Trust for Ornithology began 80 years ago this July with a letter to The Times and is now internationally respected for its expertise.

From its headquarters in a listed former nunnery in Thetford, it’s professional scientists work with data gathered with the help of more than 40,000 volunteers and, like the birds they study, look well beyond our own shores.

Reed warbler being ringed by BTO volunteers''Lee Barber/BTO

Reed warbler being ringed by BTO volunteers''Lee Barber/BTO

But this is no purely academic study of bird behaviour, the data it has gathered since its inception has helped influence the policies of, not just our own government, but of governments worldwide and given early warning of environmental impacts ranging from pesticides to over fishing.

Chief executive Dr Andy Clements explained; “One of the first studies the BTO did was a survey of rooks to understand the balance between how they were beneficial to crops, by eating pests, and how damaging they were to the crop.”

At the time people assumed that if they were on the field they were eating the crop, not the pests. Today, BTO data shows EU financed schemes paying farmers to help birds do work, and do help us and our environment.

Andy said: “There’s this term ‘ecosystem services’ — what nature provides us for free, clean water, clean air, looking after carbon in the environment. Birds are a barometer of the ecosystem and have a strong link to what nature is providing for us.”

Big read feature on work of the BTO''Pictured: Director Andy Clements

Big read feature on work of the BTO''Pictured: Director Andy Clements

Often, the data the BTO’s ornithologists examine to see such links was not gathered for that purpose.

“One of the values of long term data is that it provides answers to questions you never thought you needed to ask when you collected it,” he said.

Looking for evidence of climate change? BTO data gathered long before many of today’s climatologists were born has pointers.

“The breeding birds survey has been running since 1994 and its predecessor was the common bird census. Our experts merged the data from those two sources and got a 50-year data set,” Andy said. “It has shown birds are nesting earlier.”

We also know many migrant birds are arriving earlier because of data gathered through the Birdtrack scheme, which allows birdwatchers to enter their watching records online, contributing to a national picture.

“We can compare that with data from the 1960s and you can see the change in arrivals,” Andy said. “Some birds’ arrival dates have changed by 15 to 20 days but some haven’t, like cuckoo and turtle dove, whose arrivals have only advanced a day or so.”

Many species that have not adapted are declining.

Some methods for obtaining this information have not changed since the founding ornithologists wrote to The Times.

The volunteers are still the trust’s great strength. Andy said the founders realised early on how important ordinary birdwatchers would be and today there are many ways you can volunteer, ranging from recording the birds in your garden for an hour each week to becoming a trained bird ringer or one of the dedicated 3,000 who are tasked with going to a specific map square for a set task at a certain time. Visit www.bto.org for details.

Andy stressed: “Our volunteers are skilled volunteers. They’re collecting data within a scheme that’s designed by professionals. We also have 150 regional representatives, super volunteers, who each look after their constituency and they know a lot of these people personally.”

Today 80 per cent of volunteers’ records are filed online and the BTO’s software helps validate information logged.

“If I were putting in a snow bunting in Norfolk in June it would ask me ‘are you sure’ because it’s out of season,” he said.

But while things like 103 years of bird ringing has told us much about where birds go, and is still vital, it cannot show us their routes and relies on rings being seen by someone prepared to report them.

But the use of technology goes well beyond that, with high tech kit often used, from remote cameras to satellite tags.

The cuckoo tagging project which began in 2011 has not only shown scientists things we did not know about these endangered birds but allowed everyone to follow them online. Sadly, cuckoo Clement, named after Andy, was first to meet a sticky end.

Andy explained: “In 100 years of ringing we only had one record of a cuckoo outside Europe, and that was in 1928.”

Satellite tagging has shown where they winter in equatorial Africa and how they get there. Latest data shows cuckoo Chris, tagged in Santon Downham in June 2011, was the first back to Europe this year having crossed 582 miles of sea from Algeria to north-west Italy in about 48 hours.

There are surprisingly common migrants whose winter homes we do not know. For example, this year the trust will put geolocators on house martins. They are too small for satellite tags but the tiny geolocators record time, date and light, so when birds return next year the scientists can calculate where they have been by day length.

On top of that there are apps for bird ringers and for Birdtrack users and the trust uses social media to keep in touch — including Twitter, naturally.

The trust is playing a more active part in training volunteers who want to do more and has just formed its first Youth Council to encourage young people.

It is helping other countries set up data collection for bird atlases and has just entered a cooperation agreement with American counterpart, The Cornell Lab of Ornithology.

“The aim is to allow any organisation to put its bird data in a common place so we can analyse movement on an international scale.” Andy said. “Birds know no boundaries. We think of these birds as ‘ours’ but we need to be international in understanding what happens to them. One of the tagged cuckoos spent only six weeks in this country.”

Britain is ideally placed for such international efforts, not just because of the BTO’s expertise.

“We’re an island on the edge of a continent so we attract birds from many different places,” Andy said. “We’re in the middle of a flyway between the northern hemisphere and Africa. Many birds come here from further north in winter and many come through here to go further north in spring.

“The UK is a hub for birds.”