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Counting birds

19 June 2011

By studying populations of Razorbills, Guillemots and Fulmars on St Kilda we can monitor how they are performing across time.  There are 25 plots on different cliff faces around the island.  It takes about ten hours to visit all the plots and I walk the same route five times over a three week period. 

For each plot there is a photograph of the cliff face with the plot boundary marked in pen (Photo 1).  When I arrive at the count point the first thing I do is match the plot boundary photograph to what I see in front of me.  I start counting once I have familiarised myself with the area and am confident I can work my way around the plot while looking through a scope or binos.   

Counting birds - (approximate) Boundary of Fulmar plotPhoto 1: View from count point looking across to a Fulmar plot

One, two, three, four……Surely counting birds can’t be that hard?  Well, the birds do their best to make things tricky!   The guillemots bunch together on ledges and it can be difficult to work out exactly how many individuals there are (Photo 2 & 3).  The razorbills are more anti-social and place themselves in to cracks so I have to look very carefully as sometimes only a tail or wing can be seen.

Counting birds - Guillemot PlotPhoto 2: Part of a Guillemot plot

Population counts - Guillemot plotPhoto 3: Just a few Guillemots on a small ledge

The information we collect contributes to a national data set that is used to monitor the status of seabirds on a much larger scale.  It will be interesting to see whether the populations on St Kilda have declined, increased or remained stable and how our colonies compare to others in the UK.

Gina, Seabird and Marine Ranger

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