Saturday, 18 June 2011

Bird Ringing During May and Early June 2011

The poor weather conditions in May, particularly on days when I was off, made mist netting very difficult, and even when I was able to net the number of birds caught was low. However I still managed to get in a few sessions and ended up catching 64 birds of 16 species. The usual species such as Blackbird, Blue Tit and Great Tit were present in the totals but so were a few migratory species including Common Whitethroat, Garden Warbler and Blackcaps. Several retraps were also captured, the most interesting being a female Garden Warbler, who had returned to the same site 363 days after the original capture, and a Eurasian Jay, again at the same site 3 years 121 days after original capture.

Three new Common Nightingales were the icing on the cake so to speak, with two females and a male captured, but unfortunately the old bird I was hoping to catch, evaded my attempts. 

Common Nightingale May 2011

I also found an active nest with three eggs in, but when I returned two weeks later it had been predated. Interestingly, a pile of Muntjac dung was present right next to the nest, I know that Roe Deer will readily feed on the contents of the bird nests that they find, but I haven't heard the same of Muntjac, but guess that it is very likely.

Predated Common Nightingale Nest

All of the Common Nightingales I capture are marked with individually identifiable colour ring combinations, with the aim of identifying individuals without the need to always capture them. This year I was unable to get complete combinations, nonetheless I did continue with the colour ringing, so keep your eyes peeled for my birds when watching Common Nightingales. 

Common Nightingale wearing BTO Metal Ring and Colour Rings

Common Nightingales are relatively straight forward to age. Adult birds carry out a complete post breeding moult, whereas juveniles carry out a partial post juvenile moult. This means that  juvenile birds returning for their first summer, should have retained juvenile feathers. These show as feathers with obvious pale tips to the primary coverts and some of the greater coverts. In the image below, the pale tips are clearly visible on the primary coverts and also on the first six greater coverts, thereafter they are adult feathers. In addition note the more pointed shape of the primary coverts.

Wing of First Summer Common Nightingale

In contrast to the image above, the image below shows the wing of an adult bird. Note the uniform colouration of the primaries and greater coverts with no pale tips present. In addition note the rounded tip and broadness of the primary coverts.

Wing of Adult Common Nightingale

Other ringing activities included a brood of three Common Kestrels whose parents had taken up residence in one on my barn owl boxes. These three chicks were very relaxed about the whole ringing thing and seemed quite undaunted by the episode. The female bird sat on a post with a vole in her beak, she waited for me to put the chicks back in the box before flying in the feed them, presumably I have ringed chicks of hers before.

Three relaxed Common Kestrel Chicks

The European Nightjar is another species that I don't get to ring very often, in fact the last one I captured was in June 2002. So this individual was a real treat, but I had to work my way through Baker (1993), in order to age it correctly. Baker states that 'juvenile birds undergo a complete moult in their winter quarters, the primaries moult descendantly and the secondaries have at least two moult centres, usually retaining one or two juvenile secondaries'. Apparently adult birds can show two generations of feathers within the secondaries, but the pattening on these feathers is very similar. Sexing is by way of the presence of white patches on the primaries and on the tail feathers.

European Nightjar 

In the first instance it can be seen that this bird is clearly a male, with obvious white patches in the primaries and tail feathers. I aged this bird as a first year for three reasons. 

Wing of European Nightjar

Firstly there appears to be a retained juvenile greater covert, which can be seen in the image below. This covert stands out since it is mainly brown with a pale white tip and is located towards the right hand end of the greater coverts.

Close up of Wing of European Nightjar

In addition there is an obvious break in the secondaries, where a juvenile feather is present. This feather can be seen in the image above, being slightly longer and showing a pale off white tip to the inner web (partly obscured).

Tail of European Nightjar

And thirdly the amount of white on the outer tail feathers is limited mainly to the tip and does not extend up the feather, this patch is much more extensive on adults birds.

1 comment:

  1. Hi Martin, we met at Leckford on Sunday. Thanks for the insight to bird ringing. We chatted about cameras too, here is the link to the book on flash. I haven't seen it myself but the reviews seem good? Dave


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