Here’s a clever use of old tourists’ photos to measure bird populations

23 Mar 20169 Shares

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Science isn’t all lab coats, petri dishes and bunsen burners. Sometimes, it’s as simple as looking through holiday photos, of birds, in Sweden.

Bird watching is the quintessential niche interest, however, that ‘niche’ should never be considered to be too small – it’s pretty much a mainstream, enthusiastically-supported hobby. Millions of people around the world have actively documented bird sightings for their entire lives.

Helpful apps are doing the rounds with detailed descriptions of different bird species, so enthusiasts can keep track of exactly what it is they are looking at. But, beyond personal enjoyment, there’s never an answer as to why they look at birds – until now, perhaps.

For scientists in Sweden twigged onto an exceptionally clever, simple idea: In areas where tourists regularly view birds, why not trawl through their photos over the years to measure populations?

This is a tourist group looking at the common guillemot colony in island of Stora Karlsö in 1975, via Lars-Erik Norbäck

This is a tourist group looking at the common guillemot colony in island of Stora Karlsö in 1975, via Lars-Erik Norbäck

Let’s not wait

Looking at Stora Karlsö, a picturesque island off Sweden that has been a nature preserve for 135 years, Jonas Hentati-Sundberg and Olof Olsson got to work.

With guillemots the bird of choice, the duo spent years tracking back through photos to spot general trends in population growth, with their findings of peaks and dips in numbers correlating to complementary events in the area throughout the past century.

The photos were retrieved from archives, museums and tourists in general, showing that current population growth among guillemots on the island is at an “unprecedented” 5pc – this is while global populations are falling.

Breeding Common guillemots in the island of Stora Karlsö in 1960, via Gösta Håkansson (Gotland museum collection)

Breeding Common guillemots in the island of Stora Karlsö in 1960, via Gösta Håkansson (Gotland museum collection)

The researchers also observed a dip in seabird numbers between the 1960s and 1970s, a time when environmental contaminants such as DDT (dichloro-diphenyl-trichloroethane) and PCB (polychlorinated biphenyls) are known to have been extremely high in the Baltic Sea.

“It’s reasonable to expect that contaminants had a role in the decline,” said Hentati-Sundberg, whose paper is in Cell Symposia. “It has not been known previously that seabird populations were affected by the contaminants.”

If the world ends

Tracking birds can be a good guide to general environmental issues too, warning us of future problems. Reasons for the current growth, though, are only educated guesses at this stage, with the likes of a ban on drift-net fishing for salmon, or a reduction in environmental contaminants likely, but not certain, to have caused the resurgence.

“Seabirds are both integral to the marine ecosystem and, at the same time, easily observed and charismatic, and, therefore, a kind of terrestrial messenger of sub-surface dynamics,” Hentati-Sundberg said.

“It will be very interesting to see how long the increase can go on.”

Incubating common guillemots in island of Stora Karlsö, via Aron Hejdström.

Incubating common guillemots in island of Stora Karlsö, via Aron Hejdström.

Main guillemot image via Shutterstock

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Gordon Hunt is a journalist at Siliconrepublic.com

editorial@siliconrepublic.com