Thursday, 21 June 2012

Post-juvenile Starlings

One thing I enjoy most about ringing independently in the garden is that I'm able to examine different birds at different time of the season.

The Starlings are flocking to my sultanas this week and have been bringing their youngsters along too, some of which are undertaking their post juvenile moult and I've noticed that they do some slightly different things which readers of the blog might find of interest.

Starlings are a species which undertake a complete post-juvenile moult, replacing body and flight feathers before the Autumn. In the image below you can see that the bird has started to moult its primaries along with the corresponding primary covert, contrasting with what we usually encounter with say, a Blue Tit, which undertakes a partial post-juvenile moult and retains the primary coverts and alula.


A good number of birds have started to moult their tail feather too, you can see this in the image below with new feathers appearing in the centre as the bird moults outwards.



Other individuals are showing more obvious signs of their moult, with new feathers appearing in patches upon the breast as in this image, something can we usually see in the field without having the bird in the hand.


The thing which strikes me is that there seems to be no hard and fast rules in terms of the moult sequence, of the birds I have ringed today, some are undergoing wing and tail moult with no body moult at all, whilst some are just starting with odd breast feathers and haven't started wing moult yet, yet others are kicking off by replacing body contour feathers on their back and central tail feathers!

It is known that Starlings on rare occasions show signs of eccentric primary moult as well as retaining alula and / or secondary feathers every now and again and I will certainly keeping an eye out for this in the future.

Ian

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