Saturday 2 August 2014

Put A Ring On It!

My fascination with bird ringing began back in 2003, when my family and some family friends visited the then recently built Barnes Wildfowl and Wetlands Trust reserve. There we met a man who had collected some birds for ringing. He down a little cloth bag, reached in and pulled out a Blue Tit, which he proceeded to give to my little sister to hold. He showed her how to hold its head gently still between her fingers and cup its body in her hand, and I remember how tiny it was and how amazing it was to see it close up.

Ringing birds is, of course, not really about seeing birds close up but its easy to see why my 13 year old self might have latched onto this! Since then I've learned a lot more about why birds are ringed, and how recoveries can teach us so much about the species; its migration patterns, its lifespan, its population movements, and its presence in new locations. The basic principle, for those who haven't heard of ringing, is that a lightweight metal ring is put around the leg of the bird giving the location it was caught and a unique reference number. That means if the bird is caught again or the ring is found, the number can be used to find out all sorts of information about the bird. In Britain as far as I know its possible to ring any species of bird if you have the right licenses and know the right techniques, but the type of ringing I got the opportunity to see today was mist net ringing. This is when a thin, billowing net stretched between poles is used to catch small birds in flight. Other techniques include ringing chicks in the nest (I've seen a program where this was used for raptors- I can imagine that ringing could be especially important for species of raptor that are still illegally killed in this country) and using a type of throwing net to surround members of a flock of birds, such as geese. I think I've seen this one on a program too, possibly Autumnwatch, where it was used to not-particularly-great effect on a flock of Brent Geese- only about two were captured! In general I don't know much about these techniques.

This morning, I was lucky enough to attend a ringing session at Titchfield Haven, along with my mum and about 10 other visitors. It started at 6am! This meant getting up at 4.30 for me. But it's amazing how getting up horrendously early to do something you love is a million times easier than, say, getting up at that hour for work. When we arrived, we were taken to a secret part of the reserve, behind one of the mysterious 'keep out' signs on one of the boardwalks. Here there was a little hut, with wires running towards it, and a table outside covered in ringing equipment. The wires, we soon discovered, were powering a CD player in the hut, and several speakers around by the nets that were playing various bird songs. There was a Willow Warbler song, which I've heard many times in real life, and a Grasshopper Warbler song, which I've never heard in real life but recognised from descriptions (it sounds just like a very loud grasshopper). Grasshopper Warblers are active at dawn, so the tape had been playing for a while before we arrived to encourage them into the net, and the trained ringers doing the session had already been round the nets once and emptied them.

 There were three or four fully trained ringers, and one trainee ringer (a young woman just like myself- yay! Sometimes I feel like the only young female birdwatcher in the world) doing the session. The trainee ringer started out being the scribe, which is the person who will record details of the birds species, its age, its ring number and its condition. This information, once computerised, will be the information that anyone recapturing the ringed bird will get, so its very important, and it looked a complicated job too as information comes very thick and fast during the actual ringing!

Hanging outside the hut were many cloth drawstring bags, some of which were vibrating slightly. The ringers began removing the birds from the bags, and the first birds that were revealed were the Grasshopper Warblers that the recorded song had attracted. This was the first time I'd ever seen one, and though I was expecting that we would see them and had hoped I would recognise them, being familiar with pictures of them, I was somewhat baffled when the first birds were drawn out of the bags, as birds in the hand look so different. But were were shown their distinguishing feature- the barred feathers under their short tails, which are plain on most birds.

The warblers were held in the way the man at Barnes showed my sister- head supported between two fingers with the body against the palm and the legs pointing outwards for the ring to be attached. The rings were taken from a plastic string, placed in a pair of pliers and gently attached to the bird's leg, loosely enough that it can move freely up and down the leg and will never pinch into it. While in the hand, each bird's wings were measured (while closed, from the first joint to the end) and they were weighed, by placing the bird beak down into one of those little film container pots, for the shortest time possible for the scale to register their weight.

Soon the Grasshopper Warblers were all done, and released straight away in the opposite direction from the nets. The next birds were Reed and Sedge Warblers, which I did recognise, especially the Sedge Warblers with their distinctive pale eyebrows (actually superciliums but that's a mouthful) and their bright ochre streaky plumage. The Sedge Warblers made no noise in the hand, but the Reed Warblers were very noisy, calling indignantly even while inside the weighing device. None of the birds made any noise in the bags. Being in a dark place is generally calming for birds.

Next came some young Whitethroats, which were again hard to identify in the hand. Whitethroat juvenile plumage is pale all over the underside and not just the throat, so it was hard to make the association, even though I've seen young Whitethroats in the wild. The ringers were assigning the birds a number based on their estimated age, and while for some birds it was easy to tell they were juveniles (the Whitethroats, a Dunnock that had the streaky breast and pink beak juveniles have), for others it was harder. The ringers showed us how to guess a bird's age using its feathers- the adults would be expected to have worn edges to their wing and tail feathers (especially as some birds like Reed and Sedge Warblers apparently don't moult until they've migrated back to southern Africa), while the juveniles were more likely to have clean edged feathers. I think they said the code was 1 (for birds still in the nest) up to 8 for aging the birds, with these juveniles being assigned a 3. All aging had to be done very carefully with no assumptions recorded.

There was one young bird that was put in the 2 category, and we were shown why. When the ringer brought it round to us from the nets he said he was going to release it back where it was found instead of at the ringing area because it was so young. It was a Cetti's Warbler, and while it looked fairly well feathered at first, under its wings you could see all the feathers weren't grown yet, which led to a very odd effect- the wing bone actually shows between the feathers! I've seen this before in young birds (not living ones but sadly dead ones that I've had to opportunity to study), and while I didn't get a photo of the Cetti's warbler's underwings (it moved so quickly and my camera is not great for quick moving subjects so I got very few photos throughout the session) I do have this photo of a dead young Great Tit I found in May this year to show you what it was like.

You can see the bone where it joins the body, as well as the 'tubes' the new feathers grow from.

It's so strange to think of young birds going about with their bones showing under their wings! Seeing a Cetti's Warbler up close was wonderful as well, as they are very good at hiding and are hard to see in the field. (Though I did get a very good view last year of one singing right out in the open! I talked about it in my new year's post.) It was a lovely chocolate brown, and had very short, rounded wings that were very different from the other warblers' wings.

An adult Cetti's Warbler in mid-moult, which is why it's so scruffy.

The ringers went around to empty the nets several more times, and in small groups were were able to go and see this happening. Only a trained ringer can extract a bird from a mist net, because they can sometimes be tangled and have to be extracted very carefully. When we first approached the nets there were several more small warblers, and something bigger and much more colourful. It was a Kingfisher! When it had been carefully extracted, the ringer showed us an odd quirk of the Kingfisher- when in the hand, it revolves its head slowly round and round, like a tracking CCTV camera, going almost 360 degrees, or so it looked! Apparently the only other British bird to do this in the hand is the Wryneck, and though I have heard Wrynecks use this odd neck action in the field to scare or confuse predators (which is where the name comes from, and I have heard this is supposed to look like a snake but I don't know for sure), no one seems to have seen Kingfishers doing this in the field. Presumably it does it to look out for danger.

It made no sound in the hand, but kept opening its giant beak all the same.

When the Kingfisher came out of the bag, the ringers had to get a special, extra short ring out to accommodate the Kingfisher's very short legs.

The Kingfisher was a juvenile, which was tentatively sexed as a male due to the only small amount of orange at the base of the bill (females have more). They said it's not possible to tell for sure at this age though. There are no suitable nest sites for Kingfishers at Titchfield Haven so this one must have moved in from elsewhere, and Titchfield Haven is a great place to see Kingfishers outside of the breeding season so I'm sure it's finding the fishing very good!

Only about a third of the lower mandible was orange- sexing clue!

The Kingfisher was definitely the star of the morning! Just look at this wonderful plumage.

Spangled' is the only word to describe those feathers!

The birds were also assigned a number to show how much body fat they were carrying. This was judged by the simple technique of blowing on the birds' breast feathers to part them and show the shape of the chest. The fat showed up as pinky-yellow bumps. We saw an adult Sedge Warbler that had an extremely large amount of fat on its body, so that it was put category 8 meaning the highest amount! When it was released the ringer said it might drop right to the ground because of its weight. This didn't quite happen, but almost! This bird will have to do an incredibly long migration quite soon, so it's building up for that. It's normal for migratory birds to put on an incredible amount of weight, and some (like some waders) even compress their internal organs to make more room for fat stores.

On the other side of this was the other 'big' bird caught (the Kingfisher being the other, though they aren't big at all really), a juvenile Blackbird. It had lots of speckling still, though a full tail. The tail was dark so I guessed it was a male, but the ringers guessed female (though too soon to tell for sure) and said that even female Blackbirds have very dark tails, so I may have been wrongly sexing a few tail feathers in my collection! When the ringers blew on its feathers to judge the weight there was no fat on it at all, just a sharp ridge along the middle of its chest that was the bird's keel bone jutting out under its skin. You couldn't see it at all when the feathers were in their normal positions, and it's so strange to think that feathers cover up these huge differences in the shapes of birds' chests. The young Blackbird pooed while it was in the bag, and the purple colour of the dropping suggested the bird had been living on fruit, so maybe it hasn't got good enough at feeding itself on invertebrates yet? I'm sure there's lots of good weather left this season so it has plenty of time.

One of the things I had hoped would happen during this session was a recapture of a bird from elsewhere or a previous year, and this sadly didn't happen, though a bird ringed a few days ago by the same ringers did show up. However as a feather enthusiast I also wanted to learn more about feathers, and that certainly did happen! In the past I've seen feathers that have dark bars of wear across them, and I'd assumed this was part of the natural wear of the feather. But one of the ringed birds had these dark bars on its tail feathers, and the ringer told us this can be caused by a disruption in feeding while the bird is a baby in the nest, such as if it rains for a couple of days and the parent bird can't feed them constantly like they would on a dry day. It was fascinating! I had a quick look in my collection to see if I had a feather with these bars handy but couldn't find one.

The other fascinating thing I found out was about Chiffchaffs and Willow Warblers, and the one way to confidently tell them apart in the hand. I always used to go by the old 'dark legs=Chiffchaff, pale legs=Willow Warbler' thing but that's not reliable. (To be honest, I still go by it sometimes as it's just easier! Of course if the birds are singing their incredibly different songs then it's ok. ^^) But when they're in the hand, the ringers showed us how to look at the primary feathers to tell the difference. In both birds, after the first feather in the wing, the outer webs of the primaries are emarginated. In Chiffchaffs this continues to the the 6th primary, but in Willow Warblers it only goes up to the 5th primary. It was really good to finally hear a concrete way of telling them apart, but not exactly something you can use in the field! 

There were several Willow Warblers in the session, and all were the loveliest lemon yellow colour in their eyestripe and all over their underparts. The ringers said Willow Warblers were more likely than Chiffchaffs to be bright like this, which confused me as a few years ago in autumn we had a very yellow leaf warbler in the garden for a few weeks that I'd always thought was a Chiffchaff. I'd been going by leg colour which isn't reliable, but thinking about it it might have been a bit late for Willow Warblers at the time, as they leave for their migration earlier. Maybe colouring varies depending on where the 'batch' of Chiffchaffs or Willow Warblers are from. The ones we caught today were probably migrants grounded by the cloudy weather, and they might have all come from the same place.

Look at those lovely bright yellow feathers!

Some of the Willow Warblers had quite dark legs (though always with a pinkish tinge) but they also all had very brightly coloured feet that were this strange pinky-yellow colour! Late in the session a Chiffchaff was caught (one of only a couple in the whole session) and it had brightly coloured feet too, showing just how unreliable the dark legs thing is. But its plumage was totally different from the Willow Warblers', being much paler and with less yellow, though there were lovely big yellow patches on the edges of its wings! We were each given the opportunity to release a couple of birds, and I was given this particular Chiffchaff to release. It was incredible to hold it and feel it take off and fly away. :)

I've been wanting to attend a ringing session for most of my birding life and it was wonderful to finally do so! Thanks to all the ringers ran the session and taught us their knowledge. :) Though I don't think I'm quite ready to train as a ringer just yet (I don't have enough time to dedicate to the training, plus as far as I know there's no one ringing any closer to me than this Titchfield Haven, which is almost an hour away) I'm so happy I got to see it today, not to mention I got to see my first Grasshopper Warblers, and my second ever Garden Warbler!

The final list: multiples of Grasshopper Warbler, Reed Warbler, Sedge Warbler, Cetti's Warbler and Willow Warbler; a few Chiffchaffs, Whitethroats and Garden Warblers; two Wrens; and one each of Robin, Dunnock, Blackbird and Kingfisher. About 100 birds in total were ringed!

For more info on ringing, here's the BTO faqs:

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