Monday, 12 March 2012

A Double Surprise in the Garden on a Sunday Afternoon

My final ringing session of last weekend was a couple of hours on Sunday afternoon. It was a glorious sunny day, which wasn't ideal, since it made my nets stand out like a sore thumb! Despite this obvious disadvantage there were still a few birds who thought that flying at the net at full speed would see them through, thankfully they were wrong!

The session included the usual Blue and Great Tits, Dunnocks, Long-tailed Tits and a couple of Goldfinch's, both females, but the surprise was a pair of Reed Buntings. In ten years of ringing in my garden I have only caught two previously, but this year I have been putting out millet in the hope of attracting more....these were the first two to have found it.

Male Reed Bunting

Now, I have not ringed many Reed Buntings in the last few years, and those that I have, have been autumn juveniles, and so there is every chance I will age these wrong, but here goes anyway. My trusty Svensson warns that the abrasion of tail feathers should not be used past February, unless you have a thorough experience of the species. However, since adults undergo a complete post breeding moult and juveniles a partial post juvenile moult, I hoped that there would be some visible features to assist me. Firstly I examined the greater coverts for a moult limit, but there was nothing visible on either bird.

Primaries of Male Reed Bunting

The primaries on the male bird (above) were fairly broad, dark and showed very little wear, whereas the primaries of the female (below) were more pointed, fairly pale in colouration and abraded and chipped at the tip.

Wing of Female Reed Bunting

The tail feathers of the male were interesting, with what appeared to be two generations of feathers present. The majority of the tail feathers were mainly pointed, and dark brown in colouration and heavily abraded, with the exception of the third feather from the birds right (upper half of tail in image below) which was an adult type feather. In addition, the brown pattern on the outer tail feathers is pale brown in colour. 

Tail of Male Reed Bunting

Whereas the tail feathers of the female bird were darker, broader and more rounded, with the pattern on the outer tail feathers blackish in colouration, appearing to be adult type, yet they were more abraded than the juvenile feathers in the male bird above.

Tail of Female Reed Bunting

In the autumn eye colour is a useful feature, with adult birds having a brownish iris, whereas as juveniles a dark grey iris. Whilst this feature is typically an autumn feature, a dull iris in the spring is still indicative of a juvenile bird.

Male Reed Bunting

Both the male and female bird had a brownish iris, so this feature was not really usable.

Female reed Bunting

So having gone through all the features I concluded that the male bird was a first year, since the majority of its tail feathers are juvenile type, with the exception of a single adult type feather, where it must have lost one. However, the female bird was a bit more tricky. Its tail feathers appeared to be all adult type, whereas the primaries seem to be juvenile since they are pointed and  heavily abraded......and therefore I also think this bird is a first winter bird but I was unsure so left it unaged.

A Nice Pair

All in all a challenging and very rewarding end to a great weekends bird ringing.

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