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A new study used tracking data from 52 seabirds over 20 years to help scientists understand how to best protect them.
Slowly, gliding easily along, the Wandering Albatross heads home.
She has spent three days over the ocean, trying to find food. Having travelled up to 1,000 kilometres away from her nest to fill up on squid and small fish she’s now flying back to the roost on South Georgia, an island of polar tundra in the South Atlantic where her mate sits, incubating their egg.
Later in the year, off the coast of the Shetland islands, an Atlantic Puffin flies back to his burrow, sand eels for his newly-hatched chick clutched in his mouth. He, however, hasn’t gone out as far as the Albatross to find this food – traveling only up to around 37 kilometres away from the nest.
While this Wandering Albatross Diomedea exulans and Atlantic Puffin Fratercula artica look and behave very differently, they actually have a lot in common. They both breed in coastal areas. They both spend a significant period of their lives on the open ocean looking for food. And they are both Vulnerable to extinction, just one category short of being Endangered.
This is a common theme for seabirds, the most threatened of all the bird groups. Of the 360 different species, nearly half – 47 percent – are experiencing population declines. Thirty one percent are Globally Threatened with extinction. Yet, because they spend such long stretches at sea, and because different species go to different areas, it’s hard to know exactly what is threatening many species, or how best to protect them.
“Seabirds face many threats,” Maria Dias, Senior Marine Science Officer at BirdLife International said. “They are vulnerable to things like pollution from oil, overfishing, and bycatch [when seabirds are accidentally caught in fishing equipment]. Because they face these threats it’s important to know where they go, as these are the sites we need to make sure are well preserved.”
Now, a new paper has given scientists a lot more information about this. The study tracked 52 species of seabirds between 1998 and 2017 to see how far from their nests they go when feeding during their breeding period. The study looked at what areas the birds visited, whether they spent time in groups or were mostly solitary, and how long they stayed out at sea.
The study was made possible through tracking. Trackers, small devices that relay a bird’s location at any given time, can tell scientists how far out to sea the birds are going, where they are feeding and where they are breeding. It’s only recently, however, that scientists have been able to gather this data, as for a long time, it was impossible to tag smaller birds.
“You can really only put a tag on a bird if the tag is less than three percent of its body weight,” Stephanie Winnard, International Marine Project Manager says. “When you’re tagging a bird, you have to consider how much weight you’re putting on it, and what impact that might have on that bird’s behaviour and wellbeing. In the beginning, there was just no way you could make a tag that was small enough to track tiny birds. Over the years though, as technology improved, tags got smaller and smaller.”
With the advances in technology, the study was able track birds of a variety of sizes, from the tiny European Storm-petrel Hydrobates pelagicus (26 g) to the impressive Wandering Albatross (7 kg). With this ability, scientists were able, for the first time, to compare foraging practices on a wide scale.
“What this study showed is that what we consider the ‘area around their colony’ really depends on the seabird,” Dias said. “For example, a penguin may explore just a few kilometres around the colony – maybe thirty to fifty, while an Albatross can easily travel a few thousand kilometres when searching for food during the breeding season.”
As a result of this study scientists will be much better able to recommend how best to protect different groups of seabirds. For example, the results showed that for families like Cormorants or Auks, which forage within a relatively small radius, Marine Protected Areas, which safeguard specific ocean spaces, would be an excellent tool for protecting their food sources. However, for birds like Albatrosses which occupy a wide area, measures that can be applied at a broader scale — for example, by working with the fishing industry to mitigate bycatch — may be better.