Sunday, 15 June 2014

Quantity and Quality whilst Bird Ringing

I managed two ringing sessions this weekend, the first was yesterday (14th June) afternoon in my garden and the second was this morning at Botley Wood. The sessions were entirely different with one being made up of a large quantity of a Blue and Great Tits whereas the other was made up of predominantly quality birds, such as Whitethroats, Blackcaps and Garden Warblers.

Garden Ringing - 14th June
Over the last couple of weeks I have seen increasing numbers of birds returning to the garden feeders, but I just hadn’t had the time to put a net up. The most numerous species are Blue and Great Tits, and so not everyones cup of tea, but I don’t mind ringing them. If I want to put a net up in the garden to try for other species, then the tits are just a by-product. But its not all bad as it is possible to build up some good longevity data through retrapping the same birds. In fact only this week I heard back from BTO HQ, that a Blue Tit that I had ringed on 31st December 2008 was killed by a neighbours cat on 9th May 2014, 5 years and 129 days since ringing. This is not a record by any means, that stands at 9 years, 9 months and 2 days, but it is a good age for a species that on average survives for just 3 years (according to BTO facts). Interestingly this bird had not been re-trapped since its original ringing date, but was evidently still in the area.

This session was made up of 39 birds of which 18 were Blue Tits and 14 were Great Tits, all of the tits were new birds, and all except one were juveniles. The remainder of the birds were made up of two Dunnocks, two Greenfinch’s and single House Sparrow and Nuthatch. The only re-trap was one of the Dunnocks, which was originally ringed on 28th October 2011. My first juvenile Greenfinch of the year was trapped, and whilst this bird was clearly a juvenile, its tail was broader and not as pointed as other juvenile feathers I have seen in the past.

Juvenile Greenfinch - note streaking on breast
Juvenile Greenfinch Wing - note the brown fringed greater coverts and
pointed primary converts
Juvenile Greenfinch Tail - this tail is broader and not as pointed as many
juvenile greenfinch tails that I have seen. It will obviously wear over time
but it is always worth looking at a combination of features when ageing birds.

Botley Wood Ringing - 15th June
This session required a 5am start which was not idea since I had stayed up late to watch the England vs Italy match. Given the result I wished I hadn’t but we make these mistakes in life, when it comes to watching England playing football I never seem to learn! It was a steady morning that resulted in 30 birds from only four nets. Unlike my garden, only two tits were caught, one blue and one great. The most numerous species was Common Whitethroat, with nine birds ringed, followed by Chiffchaff, with eight birds ringed.

Juvenile Chiffchaff - the plumage is very fresh and fluffy; a yellow gape
is still obvious

Two of the whitethroats were retraps, one from 2nd June 2012 and one from 1st May 2013, four were adults and five were juveniles. This was great training for Chris who was able to compare the differences between adult and juvenile whitethroats in prep for the autumn at Titchfield Haven. 

Adult Whitethroat - note pale iris
Juvenile Whitethroat - note dark iris - when ringing whitethroats in the
autumn always check the eye as the colour of the iris will give you a clear
clue to the birds age

Similarly the Chiffchaff numbers were made up of adults and juveniles, and so it was possible to compare the different ages. The other species ringed were four each of Blackcap and Garden Warbler and three robins. Surprisingly, we did not catch any juvenile Garden Warblers or Blackcaps, I would have certainly expected some to be on the wing: the robins were all juveniles. 

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