Seabirds evoke the spirit of the earth’s wildest places. They spend large portions of their lives at sea, often far from land, and nest on beautiful and remote islands that humans rarely visit. Thanks to the development of increasingly sophisticated and miniaturized devices that can track their every movement and behavior, it is now possible to observe the mysterious lives of these remarkable creatures as never before. Far From Land takes you on a breathtaking journey around the globe to reveal where these birds actually go when they roam the sea, the tactics they employ to traverse vast tracts of ocean, the strategies they use to evade threats, and more.
What inspired you to write this book?
I like nothing more than being at a seabird colony under a sky full of whirring wings, hearing the raucous clamour of thousands of birds while the pungent smell of guano (the polite term!) oozes into my nostrils. For sure, research at such colonies, coupled with observations of seabirds from ships, has taught us much about seabirds’ lives. But the truth is that, once the birds dipped over the horizon, our knowledge of where they were and what they were doing also dipped, even plunged. This began to change around 1990 when results from the first satellite-tracking of Wandering Albatrosses was published. Then, in the last 15-20 years, knowledge of what seabirds are doing at sea has expanded amazingly thanks to solid-state electronic devices. The transformation of our knowledge of their habits has arguably been more profound than for any other group of birds. It is now possible to document where a seabird is when far from land, whether it is flying or sitting on the water. If it is on the sea, it is possible to register whether it is on the surface or underwater, and not just underwater but at what depth at what moment. It is possible to record when it opens its mouth – I should say beak – to take in food, and how big that food item is. A seabird one thousand kilometres from land can be monitored almost as intensively as a patient in hospital. My hope is to bring this astounding knowledge revolution to many, many readers who, like me, enjoy the salty tang of sea air.
Can you give us some stand-out findings that have emerged?
- i) Murphy’s petrels, mid-sized oceanic birds nesting on South Pacific atolls, go for 20-day journeys covering up to 15,000 km, before returning to the colony to relieve the mate sitting on the egg at home.
- ii) Male Brunnich’s Guillemots (Thick-billed Murres) may swim southward from Greenland for 3,000 km accompanied by their chick at the end of the breeding season.
- iii) Arctic Terns, migrating south from Alaska, enjoy feeding stopovers off Oregon and Ecuador before crossing the Andes and Patagonia to reach the South Atlantic for the (northern) winter.
- iv) Atlantic Puffins nesting in the UK use many different parts of the North Atlantic in winter, but each individual tends to have its own consistently-used ‘patch’ that is repeatedly visited year after year.
- v) Wandering Albatrosses nesting on the Kerguelen Islands in the Southern Ocean adopt different strategies when not breeding. Some linger in that region, while others repeatedly circumnavigate the globe at high latitudes. Once a bird has adopted one habit, it sticks with it for the rest of its long life, perhaps 30 or more years.
- vi) Penguins, leaping out of the water onto sea ice, start their ascent at a greater depth, and accelerate to a faster exit speed, the higher the ice ‘cliff’ they need to clear.
I realise the book is not really about the electronic devices that have yielded so much information, but can you give us a sketch of some of the devices researchers deploy?
Yes, positional information comes from three main categories. There are devices which transmit the bird’s position to satellites overhead, devices that use the global GPS array, and light-sensitive devices called geolocators that detect the time of local sunrise and sunset. This geolocator data can be translated into a somewhat imprecise estimate of the bird’s position, an estimate that is good enough for plotting migration routes but inadequate for plotting, say, 5-hour feeding journeys from the colony.
Loggers attached to a bird’s leg can register every few seconds whether the leg is immersed in salt water and the bird swimming, or dry and the bird flying. Coupled with information about the bird’s location this can tell us when the bird is feeding, which normally means getting the feet wet!
Depth recorders combined with accelerometers which register a bird’s acceleration along three mutually perpendicular axes can yield a detailed picture of a bird’s underwater track. For example there may be spells of steady movement interspersed with abrupt wiggles which are likely moments when prey is captured, at a known depth.
What biological messages have emerged from the studies you describe in the book?
Two messages instantly spring to mind. The first is that seabird movements across the high sea are not random wanderings. For example the routes seabirds take on long-distance migrations often take advantage of prevailing winds, and indeed mirror the routes taken by sailing ships in days of yore. And, on those journeys, there may be mid-ocean ‘pit-stops’ that are used by most individuals. The existence of such mid-ocean refuelling stations was not anticipated 20 years ago. On a smaller spatial scale, birds leaving colonies to feed frequently head directly to areas where water mixing probably enhances local marine productivity and the availability of food. The birds clearly ‘know’ the whereabouts of rich pickings.
A second finding is that individual birds often have consistent habits that may differ from those of their fellows. I mentioned earlier the consistent habits of Kerguelen Wandering Albatrosses and wintering Atlantic Puffins. This pattern tells us that there may be several ways of making a living on the high seas, ways that are pretty much equally successful.
What are the remaining unknowns? What further advances do you anticipate in the next decade?
Devices are becoming ever-smaller. Even so, there remains limited information about the smallest seabirds, for example storm petrels weighing under 100 g, for which a 5 g device would be too great a burden. I am sure smaller devices will be developed that allow more tracking of these waifs but perhaps it will transpire that their habits are not fundamentally different to those of their larger cousins.
It is also likely that greater use will be made of base stations planted at colonies that can ‘interrogate’ devices attached to the colony’s seabirds. This will eliminate the need to re-catch a bird to download the information on a device; convenient for bird and researcher alike. But the old-fashioned dinosaur in me might yearn for the old days when seabird research involved clambering over slimy boulders rather than peering at a computer screen.
Michael Brooke is the Strickland Curator of Ornithology at the University Museum of Zoology, Cambridge. He is the author of Albatrosses and Petrels across the World and the coeditor of The Cambridge Encyclopedia of Ornithology, and has written widely on science and travel for outlets such as the Daily Telegraph and the Guardian.