Tim Guilford strives to share the environments of the creatures he studies, he tells Georgina Ferry.

Birds of a feather: The zoologist who beds down with his flockTim Guilford and albatross at Oxford’s Museum of Natural History

By Georgina Ferry

‘My work life and play life are so tightly intertwined that the boundaries are not real,’ says Tim Guilford, Professor of Animal Behaviour at Oxford. His idea of a good time is sleeping overnight on the floor of a pitch-dark cave on the coast of Mallorca, to be wakened by hundreds of screaming birds scrambling over him as they head out to forage at dawn. While he has a passionate enthusiasm for caving, he visits this particular cave in Mallorca annually in his capacity as a research ethologist – to document the foraging strategy, breeding success and migratory behaviour of the critically endangered Balearic shearwater.

Guilford has been in Oxford since he arrived as an undergraduate in 1979. He had just read The Selfish Gene, Richard Dawkins’s classic work on evolution published in 1976. ‘There’s a moment when you realise that ideas are central to everything,’ he says, and he successfully applied to New College to read zoology with Dawkins as his tutor.

He now holds a tutorial fellowship at Merton, where we meet in the hushed and civilised ambience of the SCR dining room. While Guilford loves Oxford – he says his department is ‘like being at a permanent conference, as thrilling as it is tiring’ – cities are not his preferred environment. Being one of the first into an unexplored cave system in Wales triggered a passion for wilderness that he indulges as often as possible. ‘Seeing amazing spectacles that are completely unchanged since they were formed is very moving,’ he says.

Birds of a feather: The zoologist who beds down with his flockGuilford face-to-face with a Manx shearwater off the British west coast

He also has a long-standing interest in flight, which led him to take up paragliding in the 1990s: he currently holds the British tandem paragliding open distance record with his partner Louise Maurice. ‘You might think it looks easy,’ he says, ‘but it’s an intellectual challenge like no other. You take your mind off it for 10 seconds and it’s over – you’re on the ground.’ How birds meet the cognitive challenge not only of staying aloft but of navigating in three-dimensional space over great distances has been one of the key questions of his research career.

‘I think that getting as close as you can to the environment of the animals that you are studying provides you with ideas about how they solve their problems,’ he says. ‘You really see how the world looks from the bird’s perspective. You get a grip on the distances, a sense of dynamism of the air.’ He has had some memorable encounters while in flight: sharing thermals in South Africa with storks, and being buzzed by a curious peregrine five thousand feet above the Welsh borders. As well as caving and flying, he also takes to the water. He vividly recalls paddling his kayak out into St Brides Bay off the island of Skomer in West Wales and being enveloped in fog, as shearwaters flew out of the mist across the front of his boat, ‘completely unfazed’.

For many years Guilford’s research subjects were not wild birds but homing pigeons housed in a loft at the zoology research station in Wytham. The first experiments involved watching them fly off from the release site and waiting with binoculars for them to reach home. But the advent of tracking devices tiny enough to attach to a bird’s leg or back transformed the questions it was possible to ask.

Birds of a feather: The zoologist who beds down with his flock‘We were among the first to do experiments to see how classical manipulations [such as altering the bird’s sun compass] would affect the way birds move through their entire track,’ says Guilford (pictured right paragliding). His former graduate student Dora Biro continues the work with pigeons, now so precise that it can detect which pigeon in a flock decides the route they all take. Meanwhile Guilford has taken the technology into the wild, focusing on seabirds that make long annual migrations. ‘This is the really interesting problem,’ he says. ‘How do global navigators organise, cognitively, the information they need to fly around the globe repeatedly, when they’ve only got a brain the size of a pea?’

The Manx shearwater lends itself beautifully to this kind of research. It travels enormous distances (up to 25,000km or 15,500 miles in a year), but it nests in burrows in a small number of colonies on western coasts of Britain and Ireland, where each pair of long-lived birds returns faithfully year after year to the same burrow. They raise a single chick, returning from foraging trips to feed them at night, before flying across the Atlantic and the equator to winter feeding grounds off the coast of Argentina.

Guilford and his team haul them out of their burrows (risking a sharp bite) and fix miniature data loggers to their legs, to be retrieved and downloaded the following year. The devices log not only where the bird is and when, but whether it is on the water or in flight. ‘Immersion loggers allowed us to recognise that they almost always stop on the way to refuel, way out at sea,’ he says. ‘Nobody had seen that before.’ The new data has helped Birdlife International to put together a robust proposal for a Marine Protected Area in the middle of the Atlantic, which will also benefit other migrants such as kittiwakes and puffins.

Birds of a feather: The zoologist who beds down with his flock

Guilford’s interests now extend from navigation to broader ecological questions about life history and foraging strategies. He and his colleagues have established that in the breeding season shearwaters from all their study colonies, from Lundy in Devon to Rum in the Inner Hebrides, congregate to feed for up to ten days at a time in rich foraging grounds in the Bay of Dundalk, on the north-east coast of Ireland. ‘Shearwaters spend much of the time feeding their young,’ says Guilford, ‘and then go on long journeys and stuff themselves for self-maintenance. What is remarkable is that the two individuals in a pair coordinate this switching. If they both turn up on the same night to feed the chick, one of them will shorten their next journey and the other will lengthen it. But we have no idea how they communicate.’

The tracking devices have enormously increased the researchers’ powers of observation, but they also make it possible to do experiments. ‘If there’s a thread that runs through my research endeavour,’ says Guilford, ‘it’s to try to apply to field situations the control the laboratory allows.’

Birds of a feather: The zoologist who beds down with his flock

For example, shearwaters don’t notice if the researchers switch their chick for a younger one, and still raise them successfully even though it might mean having to do three weeks’ more work. However, the following year they are more likely to skip breeding. ‘Birds take sabbaticals if they are not in condition,’ says Guilford. ‘The slow breeding strategy that is typical of seabirds really is long-term – what happens one year affects what happens the next.’

This kind of information is vital when developing a conservation strategy that is truly evidence-based – which is what brought the team to Mallorca. The Balearic shearwater breeds in caves on the Balearic Islands and then migrates out of the Mediterranean and up the Atlantic coast as far as Brittany. In recent years it has been seen in British waters. It is thought to have a global population of only 25,000, and at the current rate of decline – mostly due to commercial long-line fishing – the species will be extinct in less than 60 years.

As part of a conservation project with colleagues from France and Spain, members of the Oxford team are tracking birds from the caves of Dragonera off Mallorca. They have established that birds that fail to breed spend longer on their migration. But so far none of the tracked birds has visited the UK. ‘We’ve got this population of a critically endangered species in British waters,’ says Guilford, ‘and we have no idea who they are, what age they are, where they come from or where they breed.’

Natural England is helping to fund the project, which otherwise depends on volunteer donors, including Oxford alumni (see here).

Museum portraits by Joby Sessions / Oxford University Images. Other photos courtesy of Tim Guilford.