Bird ringing in West Berkshire

Bird ringing in West Berkshire

© Chris Gomersall/2020VISION

Volunteer bird ringer Jan Legg explains how a lifelong love of birds led to learning to survey the local bird population through bird ringing

I have lived around Newbury all my life. One of my earliest memories is of a visit to the western end of Greenham Common to see the “new” runaway being constructed, I think this would have been about 1950.

For most of that decade, living on the south side of Newbury, I wandered the fields, woods and heath remnants up to the perimeter fences of the USAF airbase watching the wildlife.

At school, my birding schoolteacher mentor Lew Lewis encouraged me to count/survey rather than just list species. As consequence I count every individual bird I can identify, usually on regularly walked routes through the areas I visit.

Greenham Common

Greenham Common by James Osmond

In the early 1970s living on the north side of Newbury a regular walk/count was up to Snelsmore Common Country Park, now managed by BBOWT on behalf of West Berkshire Council, and also to nearby Speen Moors.

At the latter with a colleague using our architectural drafting skills, we produced maps which we used to plot the position of each bird encountered and from these developed territories maps for each species.

Each year we would present our Common Bird Census maps to the British Trust for Ornithology (BTO) and at one meeting it was suggested we should enhance our project by bird ringing. With the contact details of Newbury Ringing Group, we quickly made contact and after a while we were invited to train as bird ringers.

Snelsmore Common

Snelsmore Common Country Park. Photo by Wendy Tobitt

To train to ring birds requires good eyesight, dexterity, good identification abilities, knowledge of all the different avian feather tracks and body features, good colour recognition, a retentive memory, and above all persistence. You can also expect very early mornings sometimes before dawn which can be as early as 03:00hrs at least in May.

I trained mostly to use mist nets to capture birds. These use soft netting and are from 3 to 18 metres long and 2.7 metres high. They are stretched between poles and long rides of nets can be erected by joining several together.

The nets are divided horizontally, usually into four, forming pockets. When a bird comes in contact with a net it drops down into one of the pockets. This is where dexterity is particularly important as the ringer must delicately untangle the sometimes wriggling bird to remove it from the net. Nets are checked every 20 to 30 minutes.

Stonechat

Male stonechat. Photo by Derek Moore

Once extracted the birds are placed in draw-stringed cloth bags and taken to the nearby ringing station for processing. Un-ringed birds have an alloy split ring placed around their legs. These are of different diameters depending on the size of the bird. The are many ring sizes using different alloys depending on the habitat of the species.

Waterfowl, wading birds and seabirds have a much harder alloy capable of resisting the salts of seawater for instance. Bigger birds need a stronger alloy to stop them removing the ring. The size of the ring is governed by the diameter and shape of the tarsus (leg component between the knee and the claw).

Rings are split to enable them to be placed on the tarsus and then carefully closed with plies such that they can rotate, move up and down but not go over the knee or impede the claws. Ringing plies are like normal pliers but have half round holes in each half sized to suit each ring diameter. By closing the pliers and thus the ring the split edges of the ring are butted tightly together.

Each ring has a unique number and is addressed BTO Natural History Museum London. At the ringing station the bird is removed from the bag and checked for the presence of a ring. If the bird is already ringed the ring number is written down in the field log otherwise a new ring is fitted, and its number recorded.

Next it is examined to determine its age. Like racehorses birds are considered to be one year older on the first day of the year. A system of numbers is used to record the age. Odd numbers 1,3,5,7 etc are used when the exact year of hatching can be determined. Even numbers 2,4,6 etc when the  year of hatching is less certain. Age 1 applies to chicks ringed at the nest. Before the turn of the year a bird retaining some juvenile feathers is aged 3 and will become age 5 from the beginning of the new year. Where the age is less clear 2 indicates year of hatching not determined and would become a 4 at the turn of the year.

Redstart

An immature redstart. Photo by Jan Legg

Age is determined by looking at the moult status of the feathers for most species. Most small birds in the British Isles are passerines and have juvenile plumage when they fledge from the nest and lose most juvenile feathers August-September when they have a partial moult, though there are exceptions for some species. Most passerines have their first full moult the year following hatching after breeding and don’t drop their main flight and tail feathers until then.

Non-passerines are mostly bigger, longer lived birds such as crows, gulls, herons, waders and birds of prey, and their moult strategy is more complex varying from family to family. Many species can be sexed on plumage differences, some on size (males usually bigger or sometime smaller than females) and brightness of plumage. Others are identical and can only be sexed in the breeding season when females have large brood patches. To do this quickly all the information for regularly encountered species must be memorised, it would take too long to keep looking it up.

Once the bird is aged and where possible sexed, basic biometrics are taken such as wing length in millimetres (distance between the “shoulder” of the wing and the longest wing feather) and weight to the near 0.1 of a gram. Sometimes the species needs to be verified by checking the wing formula. This is the relationship length-wise of the ten main flight (primary) feathers to one another. For instance, chiffchaff wing shape is different to the visually similar willow warbler and thus the main flight feather relationship with each other is different.

Chiffchaff

Chiffchaff. Photo by Jon Hawkins/Surrey Hills Photography

Once identified and biometrics taken, the bird is released back into the wild usually after about a minute or so sometimes a bit longer if the species is not regularly encountered and when we do have to look it up in specialist ringers reference books. All the forgoing is recorded in the field log, also the ringer's initials, time and site location and any other information thought relevant.

The data gathered is entered via a computer portal onto the BTO’s database. The data is analysed by professionals and contributes to our knowledge of the changes of population abundance and wellbeing of all our species, also their movements both internally and externally of the British Isles. Where migrants winter is, for instance, becoming critical.

Recently it has been discovered that migrant species that breed here go to the same area each year to winter in the Mediterranean and Africa, also they have regular stop-over areas on the way. Many of these once remote wild places need protection from the ever increasing human population if our summer and winter migrants are to sustain.

Since its inception in 1967 the Newbury Ringing Group has ringed well over 250,000 birds of 114 species around the  Newbury area. Including other local ringers' data some have been recovered as far away as: Republic of Congo (spotted flycatcher), Ghana (reed warbler), Benin (stone-curlew), Senegal (blackcap, chiffchaff), Mali (sedge warbler), Lebanon (lesser whitethroat), Russia (starling), Morocco (sand martin), Finland (brambling and peregrine). All the above travelled well over 2000km, and the spotted flycatcher 5910km.

I enjoy ringing our local species, seeing the fluctuation in populations over the 48 years of my ringing career. It is also nice to ring something different occasionally and the photographs show some of the interesting species ringed at Greenham Common since 2010.

Volunteer bird ringer Jan Legg