Black-fronted terns, Potemkin villages and Catherine the Great

As an evolutionary biologist I am interested in the history of life and how it got to this wild, crazy biodiverse natural world. I am also interested in history in the more usual sense, how we got to this wild, crazy and diverse human world. Sometimes these interests intersect.

Another interest of mine is in board games. We are in a golden age of board games at the moment with lots (and lots) of interesting, quirky, challenging games. This is largely due to the crowdfunding site: Kickstarter. There are board games about all sorts of topics. One of the more interesting that I came across this year was Potemkin Empire.

Who or what is a Potemkin? Well, Potemkin was first a lover and then an advisor for Catherine the Great of Russia, back in the 18th Century. By all accounts Potemkin was a wily chap who managed to keep his position through a very turbulent period.

One story attached to him is that Catherine the Great wished to take a slow trip of six months down the Dneiper River to show off her newly conquered lands around the Crimea to ambassadors. She wanted to impress them and get them on side for the next war against the Turks.

Potemkin was concerned that the various dirt-poor villages and slums visible from the river would not send the right message about the glorious power of Imperial Russia. He therefore had a team go to these villages before the imperial flotilla came past and put up facades and shells of substantial buildings. From the river it looked like one glamorous town after the other. Catherine the Great was happy, the ambassadors were impressed.

The Waimakariri River, nicely braided. Image from Adrian Paterson.

Now there is some debate whether the Potemkin villages were as extensive as the mythology suggests, but what is not in doubt is that anytime this approach is used, it is called a Potemkin village.

How does this intersect with biology? Let me introduce you to the black-fronted tern (Chlidonias albostriatus). This tern species lives and breeds on the braided rivers of New Zealand. Braided rivers are an everchanging habitat where water channels flow through a much wider stony riverbed. The species is declining due to changes in braided rivers with introduced plants, changes in water flow, and predation from introduced mammals and native gulls.

With the dynamic nature of braided rivers, the terns are often unable to nest in the same area from year to year. From a conservation point of view, this makes it challenging to protect the species. We can’t put a lot of effort into placing traps for mammals or clearing weedy vegetation in an area when there is no gaurantee that the birds will use that area.

Courtney Hamblin, a masters student from Lincoln University, with her supervisors, Adrian Paterson and James Ross, and Richard Maloney from the Department of Conservation, were interested in how best to support the black-fronted tern. And that is where Potemkin villages come in.

When a tern is looking for a place to live, it flies up and down the river trying to identify the right spot. We are not entirely sure what makes for prime tern real estate. The size of the substrate rocks, distance to vegetation, perhaps access to the main channel of the river may all play a role. What if we could make a part of the river more attractive and more likely for the terns to stop, investigate and nest?

The speakers were housed in a cage. There are also seven decoys in this picture…. Image from Courtney Hamblin.

Courtney reasoned that if terns saw other terns and heard them calling that this might be a good stimulus for making a decision. If other terns had chosen a site then it must be good. Birds of a feather flock together and all that. The terns just needed a reason to stop and consider the area.

A tern decoy. Image from Courtney Hamblin.

Courtney did not have any tame terns on hand so she created tern decoys to place on the ‘colony’ area. She also set up speakers that occasionally broadcast tern calls. Basically, she set up a Potemkin village. Or maybe a Poternkin village?

In a paper in the Wildlife Society Bulletin, Courtney explains what she found after trialling sites in ten different braided rivers. She compared tern behaviour and interest in areas with the Poternkin village and without. This made for lots of long observation periods over the entire breeding season (as well as dashes to retrieve gear with sudden flooding events).

Speakers were used for playing tern calls. Image from Courtney Hamblin.

Courtney found that interaction (visits, calls, circling an area) were much higher near the villages compared to empty stretched of river. She also found that birds chose sites to nest within 300 m of the villages in the majority of the rivers.

The Potemkin village approach looks promising from a wildlife management perspective. If we can drag breeding pairs to certain parts of rivers then we can increase their breeding success. We can put in trapping systems to minimise predators, take out weedy plants to keep the flow and dynamics of the braided rivers as natural as possible, make sure there are no gull colonies too close.

There is still a lot to learn about what makes the sites attractive to terns. We are not sure that the audio made a huge difference, for example. There are likely to be other things that we can add to make the terns more likely to stop and select these sites. But it is a start and the Poternkin village can be added to the toolbox of conservation measures for the black-fronted tern.

Maybe that would make for an interesting board game theme….

One downside of using decoys…. Image from Courtney Hamblin.

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