When it comes to ringing birds, there are 23 different types of rings that we use, varying in size, shape and the type of metal used. These range from the largest, size M fitted on a mute swan or an eagle, right the way down to AA, the smallest ring for the smallest birds. Essentially the higher up the alphabet you go the larger the ring size. Rings for small species are usually made out of a soft-metal alloy, with incoloy (a nickel-chromium alloy that is resistant to electrolyte corrosion) also used in the same sized rings but for long-lived species or those that live in environments where excessive abrasion or exposure to saline or alkaline water would shorten the rings life. Larger rings tend to be made of stainless steel. The shape of the ring is also important, with most either a C or a V shape, enabling the ringer, using specially designed pliers to fit the ring around the birds legs so that it is close enough so as to not slip over the ‘ankle’, and move freely up and down the leg, but not so tight as to constrict the leg. There are some more unusual shaped rings, namely those specifically designed for guillemots and razorbills. These seabirds site with the back edge of the leg resting on the rocks, so specially designed rings with flattened edges are fitted.
Most of the time, during the course of our general ringing we use sizes AA to C, with most of the small passerines that we ring taking an A. We do often catch things like greenfinch or house sparrow, who’s slightly thicker legs take a B ring despite appearing the same size as something like a chaffinch or robin. Sometimes we catch a blackbird or woodpecker which will take a C ring, and sometimes we catch some of the smallest birds in Britain which will need a AA.
|A very small selection of rings including the smallest AA (red arrow)
and the largest M (yellow arrow).
Also shows the pliers we use to fit small rings.
With the breeding season essentially over, many of our migrant birds are starting to move, feeding up, preparing for their journeys south. Many of the young of our resident birds are also starting to disperse, moving into new habitats to feed, fuelling up for winter. Both were in evidence at the reed bed this morning, and it was the ‘little guys’ who stole the show.
Of the 41 birds caught today, 15 took a AA ring, with the most numerous being the chiffchaff, a small warbler, with an average wing of 59 mm and weight of approximately 8g (BTO Birdfacts) – that’s equivalent to the weight of a 50 pence piece! Most of today’s chiffchaffs were youngsters, with just one adult bird caught. All were either completing their moult or fattening up ready for the trip south for the winter.
|Chiffchaff – One of the best ‘little guys’|
Other small species caught today included the charismatic wren and the beautiful treecreeper. More often seen scurrying up the truck of a tree, like a little mouse, the treecreepers patterned brown back blends in perfectly with the bark whilst its stiff, pointed tail helps it to creep up the tallest of trees. Not surprising it was caught in the net nearest the wood!
|A beautiful treecreeper|