TERN that frown upside down!

18 06 2012

                Before our time on Sable comes to an end I would like to introduce you fellow readers to two additional species that breed here on the island: the Common tern, and the Arctic tern! I am quite proud to say that these feisty little guys are the focus of my study.  These migratory seabirds breed in colonies that vary in size; from fewer than ten pairs to thousands of pairs in a relatively small area. The main component of my project involved capturing terns while they were incubating their eggs, which meant a long wait after we arrived. The terns were definitely worth the wait!

During the two weeks prior to catching terns, I would make a random count of the number of eggs in the first twenty nests I came across in the colony every two-three days.  I quickly learned that the terns are very territorial and protective of their nests. I strongly recommend a jacket with a hood; mine is now completely painted with presents from the defensive birds! One of my favourite things about walking through the tern colony is being able to see the different nests and eggs. Some terns take the time to make beautiful little nests lined with soft vegetation; others are more impatient and pretty much sit in the sand and call the indent their nest.  Eggs also vary in size and colour patterns.

Terns build small nests out of all sorts of vegetation. This nest was made out of still growing sandwort on the east spit of Sable.

In order to catch the terns, we used cages with trap doors and hoop nets that could be triggered from afar. We were really happy to find that it did not take long for the terns to return (they are very dedicated to their future chicks!!) which meant that we were very efficient. Radio tags that will allow us to monitor their movements were attached to thirty-five birds at the two largest colonies on the island. The crew quickly learned to never look up while walking through the tern colony to retrieve the captured birds.

Box traps are set over top of tern nests to catch them. When they walk in, they step on a plate that triggers a door to close behind them.

Jess holds a Common Tern just before releasing it after it’s been measured, weighed and tagged.

We also completed an island-wide census of the breeding terns by visiting the colonies that had been located by past researchers (look for the results in a future blog post). Unfortunately most of the smaller colonies were no longer present on the island. However, while traveling to the eastern tip of the island one day, Zoe and Rob were fortunate enough to come across a group of endangered Roseate terns!! Five were seen together on the beach at a Common and Arctic Tern loafing area near the East Light colony.  Everyone was extremely excited due to continuing decline of the species. I am happy to say that precautions were taken so that they remained undisturbed and photographs were taken from a large distance.

Roseate terns are an endangered species in Canada and the USA. Sable Island is home to a small breeding population of this species. About 5 pairs of Roseates are known to nest among the large Common Tern colony near East Light on Sable. These ones were seen loafing on the beach about 200 meters from the colony.

I think I speak for the entire crew when I say that our experience here on Sable has been one that we will never forget. From dealing with charismatic birds to spending time with some really great people, it has been quite the month! Even though we will be leaving soon, we hope to return sometime in the future to continue our research and gain even more experience! So make sure you all tern-your frowns upside down because there will be more Sable posts to come!


Jess Stephens

Carefully walking among tern nests to catch terns in traps, terns take direct aim at intruders.




4 responses

19 06 2012
Michelle Stephens

Great job Jess!! Your birds are very interesting, you’re so smart :)!! I like your pictures 🙂 !! ❤

19 06 2012
Jim Wolford

Thanks for your reports, everyone! I have three queries/comments: first the photo caption for Jess holding a tern should read “common tern”, since the identification is obvious; second, in the paragraph below that, find the word “due” and add “to”; and, lastly, you mentioned an island-wide census but not a word about the results — can you give at least total numbers of each species, or at least rations of common to arctics plus the number of roseates seen. Thanks for whatever you can provide. ( from Jim Wolford of Wolfville, jimwolford@eastlink.ca . )

19 06 2012
Rob Ronconi

Thanks Jim! Nice to know that people are interested in the details. The total tally on the terns is not quite done yet (still crunching some numbers) but I can say we found 2 small colonies on the east spit in addition to the large colonies at East Light and Main Station. Recent census work in 2006 found 13 colonies and in 2009 there were 11 colonies in total (many of them small). So it seems there have been some recent changes, though fewer colonies may not mean fewer terns since they could have moved in to the large colonies. When we get the numbers together we’ll be sure to post a blog entry and spread the word.
Rob Ronconi, still on Sable Island and waiting for the fog to clear

20 05 2013
Seasons of Colour on Sable | Sable Island Gulls

[…] seasons.  We’ve been there in May and June for the spring nesting season of gulls and terns, in August to work with Ipswich sparrows before their fall migrations, and in January to download […]

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