Monday, 2 February 2015

A morning's bird ringing

I'm sure that anyone reading this will probably be quite familiar with bird ringing, but a little bit of background for anyone interested.....

Bird ringing as we know it now has been around for over 100 years, in the UK the scheme is overseen and managed by the British Trust for Ornithology (BTO). It was originally developed out of our desire to understand bird migration. Old theories of Swallows hibernating at the bottom of ponds over winter and of Barnacle Geese developing from barnacles sound ridiculous to us now, but for a long time it wasn't understood where birds went at particular times of year, or why. Ringing birds, which involves putting a small uniquely numbered metal ring on a bird's leg, enables the bird to be identified if recaught or found again in the future. The information obtained gives us a much better understanding not only of migration patterns, but also of longevity and survival rates, as well as monitoring of population increases and decreases over time. 

A selection of my ringing paraphernalia - rings of different sizes, wing rules, scales, ringing pliers, and identification and ringing guides.

A still cool day on Sunday provided the ideal conditions for bird ringing, this was at a site close to Knutsford which has produced a large amount of data for the BTO over several years. Using a mist net a steady 44 birds of various species were caught and ringed and their details collected. As well as information such as species, date and location, the birds were also sexed and aged as far as possible (sometimes easier said than done!) and also wing measurements as well as weights taken, and also noting particular feather details (as an example looking for old (unmoulted) greater coverts which can indicate age). Wing measurements can sometimes help to differentiate between the sexes depending on the species, as well give an indication between 'locals' and 'visitors' (as an example Blackbirds visiting us from colder eastern climates for the winter will often have longer wings than those who reside in the UK all year). Weight can give a good indication as to the general condition of a bird and also whether it is building up its weight for example in preparation for migration. Looking at particular feather shapes and colours can indicate (to a greater or lesser extent depending upon the species) a bird's age and sex.

Mistle Thrush (first year bird)
The session last Sunday involved a nice mix of birds - Coal, Blue and Great Tits, a Robin, and also finches such as Greenfinch, Bullfinch and Goldfinch. A Mistle Thrush and Lesser Redpoll were also amongst the birds ringed, and for anyone interested I've included some of the details of what was looked at when noting the details of these birds.  

The plumage of male and female Mistle Thrushes are the same, and the wing length is also very similar so we cannot be sure whether this bird is a male or female (in the breeding season birds are checked for brood patches which generally only develop in females). From looking at the tail feathers, the ends of which are quite pointed and chipped, what we can tell is that this is a bird that hatched last year and has not yet moulted and replaced his/her tail. An older bird (hatched before last year) would have broader, more rounded ends to the their tail feathers.  

Lesser Redpoll (first year bird)

With Lesser Redpolls, adult males will develop a reddish feathers extending down their neck and chest in addition to the red patch on their head. The bird pictured did not have this additional red in the plumage and again from looking at the tail we could tell that the bird which hatched last year. From knowing this was a first year bird, it was too soon to be certain of the sex of the bird - it could be that the additional red just hadn't developed yet so again the age was recorded and biometric details taken. Fortunately for most of the other birds ringed that morning telling males from females was far more straightforward!


Reporting a ringed bird

Vital information is obtained from 'recoveries'  which are reports of dead or alive ringed birds. Some of these reports will come from licenced bird ringers themselves but many reports come in from sightings and findings by members of the public. These can be reported through the Euring website, noting details such as the bird species, location seen/found, circumstances (e.g. alive or dead and if the latter, the cause if known) and also details of the metal and/or coloured leg ring(s) (or other markers such as wing tags).

Black-headed Gull '2F69'
The gull pictured, as well as the typical metal BTO ring also has a 'darvic' - a numbered plastic ring which enables the bird to be identified from sightings alone (these additional identifiers are used for specific recognised and approved research projects, and sightings can be reported through the same Euring website). When reported this information allows researchers to start piecing together a picture of the birds' lives, on an individual as well as population level with information on the locations they are visiting, their longevity and survival outcomes. The Black-headed gull above I saw at Redesmere and reported - in return I was given information about when and where the gull had been ringed - also at Redesmere, almost two years previously, and also the details (dates and locations) of other sightings of the same gull in the interim. In this case the sightings had all been at Redesmere in autumn and winter months. Other Black-headed Gulls I have previously reported at Redesmere have also been sighted in spring and summer months in Norway (2F95), Sweden (2F88) and the Netherlands (2F91), another was originally ringed in Lithuania (2C49). I find it fascinating to think that when I visit Redesmere in the summer and it seems strangely quiet of gulls, that these birds which feature so prominently during wintertime could be busy raising their chicks in any of a number of places on the continent, and will hopefully return to us again for our milder winter. 


  1. How lovely to get so close and the images are gorgeous Jan! I love the mistle thrush... Beautiful!! :) x

    1. Thanks very much Kez - yes it was a really good morning, and wonderful to see a Mistle Thrush so close! :)