Monday, 13 August 2018

Rare Warbler at the Res

We ring approximately 500 Reed Warblers every year. On each of these birds we measure the notch on the second primary and then close the wing to see where it lines up. On Reed Warblers it lies between the last two primaries and the secondaries. We do this because there is a very similar and rare bird, the Marsh Warbler which by contrast has a shorter notch which aligns with the mid-primaries. On Thursday 9 August Mick, Adam and I were working our way through a selection of small birds on the CES, when Adam found a warbler with a notch of 9mm (a bit too short for a RW), but which crucially fell between primary 6 and 7.

Reed and Marsh Warblers

The bird on the left is a Reed Warbler, on the right is the Marsh. As the Collins Guide puts it 'immature Marsh and Reed Warblers are extremely similar'. Something of an understatement. We also confirmed it with the length of the inner claw in relation to the adjacent toe, and the supercilium. This is only the fourth Marsh Warbler to be ringed by the SRG and I think it is true to say that without measuring the notch, we really wouldn't have picked this fabulous bird from its congeners. 

Marsh Warbler

These birds definitely fall into the category of Little Brown Jobs (LBJs), but for ringers that is part of the challenge and we will certainly be measuring our notches for many seasons to come.

Peter N