Fitting the metal ring
Each bird is identified to species and its age determined. The larger (four-year) gulls have distinctive plumage in their first and second winters, but development of the adult plumage from the third winter onwards
varies in pace, probably depending on the condition of the bird and food availability.
Black-headed Gulls can attain adult plumage in their second winter, although some retain some black in the outer primary coverts allowing them to be accurately aged in the hand as second winter birds.
The correct size of uniquely numbered metal ring is fitted, using special pliers, with care being taken to ensure the ends of the ring are butted without leaving a gap.
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Measuring the head and bill
There is some sexual size dimorphism in large gulls, males being larger, and the measurement of head size
from the tip of the bill to the back of the head can allow us to assign a sex to birds at the extremes of the range.
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Measuring the wing
Wing length is another good indication of overall body size and is a relatively quick and reproducible measurement to take.
The standard technique is "maximum chord" which involves both straightening and flattening the wing against a metal ruler.
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Colour ringing
The colour rings are fitted to the opposite leg to the metal ring. Our rings are currently orange with a combination of four black letters or numbers, the last of which is a "T".
They are supplied pre-rolled so need to be carefully opened, slid over the birds leg, overlapped and glued.
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Re-sighting
Our hope is that the colour-ringed birds are then re-sighted, allowing us to build up an understanding of the movements and life-histories of individual birds.
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