Saturday, 26 April 2014

What a Gropper.

I have to admit to getting caught out yesterday and it was not by the weather. No, it was by an olive grey Grasshopper Warbler that made some very unusual noises to boot. This bird was striking, very very striking and it was clearly a Grasshopper Warbler of sorts but it was not on Fair Isle, North Ronaldsay or the East coast of England, no it was in Wigan.

pale olive-grey looking Grasshopper Warbler ringed 25/04/13
Now if it doesn't seem that pale to you lets have a look at a more typical warm brown Gropper.

Grasshopper Warbler ringed 20/04/14.
The only reference I had with me was Svensson, the ringers bible, and having checked all the specific features I was satisfied that it was a Grasshopper Warbler but given its pale appearance there was clearly a chance it was one of the eastern subspecies. The main contenders are straminea from Eastern Russia, Western Siberia and Central Asia and obscurior from the North Caucasus.

Now where I was caught out is that I now know that it would have been useful to take more measurements than I actually did and especially of the tail. A bit of a cock-up with hindsight but then there is so much overlap between the subspecies they may not have helped anyway. The wing length of 64mm means it wasn't particularly small but it could still be OK for straminea, just. At the time I was more concerned about confirming that it was actually a Grasshopper Warbler as it looked so different. However, I did take a good series of photographs as I thought it may be identifiable as to the subspecies on its appearance alone.

Further enquiries are currently being made to see if it can be attributed to one of the eastern subspecies although we may only be able to say that it showed some characters of an 'Eastern type' Grasshopper Warbler. Unfortunately it didn't drop a feather so taking the DNA route isn't an option. A remarkable bird whichever way you look at it and one that seems likely to spark quite a bit of debate over its appearance and origin although it may well remain a mystery bird. I will keep you posted when I get some feedback from my enquiries.

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