How to find and count Jack Snipe

 

 

 

I was talking to someone today who asked a simple question-''-what do birds look like using this thermal imager you're always banging on about?''
I realised with a start that indeed I've been mentioning using the thermal imager a lot over the winter period and most people will never have looked through one--so here goes.
We have used the imager a lot at night and the results are remarkable in terms of finding birds like Skylark, Fieldfare and Woodcock. However, we've also been using it during the daytime especially for finding, counting and ringing Jack Snipe, which are one of the most difficult species to census.
The following picture shows a typical patch of prime habitat for Jack Snipe to roost in during the day:

 

Believe it or not there IS  a Jack Snipe roosting on the ground in this picture!! But their plumage brilliantly matches the plants and they sit rock still to avoid detection by predators. If you can spot the bird you must have magnificent eyesight!!

 

Now here is the same patch of land a few minutes later photographed through the thermal imager:-

 

 

 

 

The bright white spot is the Jack Snipe. The smaller head is to the left and the fatter body to the right. The imager picks up the heat radiated from the bird's body --the vegetation is grey/black because it isn't generating heat. Birds stand out  best on cold dull days because as the vegetation heats up with sunlight it starts to glow white and the birds are much more difficult to find.

On suitable days it is possible to scan the area in some detail and count the number of roosting Jack Snipe more easily than any other technique.

 

Just to prove it was a Jack Snipe. a split second later the bird decided to take off:-

 

 

Just to remind you of what a Jack Snipe looks like and why they blend in so well with the vegetation in the top picture. We have photographed this one against an atypical background of dead leaves so you can see it more easily.....:-



 

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Jack Snipe ageing-further thoughts

Our evening time thermal imaging season is at an end and a few days ago we had our last daytime imaging session at our snipe site. There were still 4 Jack Snipe there and one Common Snipe and we ringed two new Jack Snipe.

We are still learning about ageing this very difficult species but having handled almost 80 new and re-trapped birds this winter, we think we are getting better. We have already posted items looking at leg colour, outer tail feathers and so on and the last two birds we ringed showed some pretty convincing features of a second year ( juvenile ) bird and an adult.

(Ignore the chestnut feather) With imagination(!!) you can just make out a very fine line reaching the tips of the feathers--a juvenile feature

 

 

 

 

This adult bird has broader rounder tail feathers with no faint line reaching the tip

This bird is the juvenile with pale fawn fringes to the median coverts

This is an adult wing with broader edged median coverts, more chestnut in the tertial and back areas and broader black centred inner greater coverts, and secondary feathers with very much longer white points

So--it looks like we have  clear cut juvenile and adult birds BUT--there's a couple of anomalies in the 'adult' bird:- first the outer primary wasn't broad-it was pointed; second the leg colour was green like a juvenile and third if you study the outer 3 or 4 greater coverts they are grey and narrower-just as in a juvenile. This time of year also makes deciding more complex! That's because individuals of any age in this species undergo a pre-breeding moult which means this could be a juvenile bird which has progressed further along the pre-breeding moult than the more obvious juvenile. Because of our indecision we decided to bottle out and sit on the fence. If anyone can guide us we would be very grateful

As one season ends another begins

As winter gives way to spring, some activities are ending. During last week we had a couple of imager sessions and while one was quite successful ringing 8 Skylarks, the other was less so with only one Fieldfare. There are still quite a few birds about but migratory restlessness means they are very jumpy--and we are noticing resident birds in pairs which we are avoiding. We have one last session planned for next week and that will be it until autumn.

Our Twitter followers will have seen a note about our item on the Radio 4 Farmers World programmes this week. This was linking our ringing to the numbers of birds being attracted to the farm which is being managed to attract wildlife by using a no plough policy. Check out the podcast on the Sounds App for the programme aired on 14th March.

Feeding stations will be active for quite a while yet--and we used the action at one yesterday to give our trainees experience as well as providing the volunteers who look after the feeder and the site, the experience of seeing and releasing some common birds. The looks on their faces make it all worthwhile:-

 

Having taught for many years I can say for certain that I knew more about my subject after having taught it than I did on leaving university. I'm delighted to see so many of our team of trainees interacting with the public and sharing their knowledge--while learning themselves!

 

We have a continuing training programme over the coming weeks--more about them as they unfold.

Jack's High

I tied to convince myself that the Met Office forecast last night would be accurate but ended up sitting in the car for half an hour watching the rain not stop--back home early without managing a thermal session. The season is coming to an end for us this week because some of the birds are beginning to pair up so we just leave them alone. There are still a few winter visitors still around but essentially we avoid disturbing any birds seen in pairs.

I needed to make up for last night so I visited my superb Jack Snipe site to see if any were still there. It looks like there are still birds lingering and feeding up ready to migrate ( another three retraps from the site)--but there are still new birds  passing through. I saw 13 Jack Snipe of which I caught 4--including one new bird.

As I've tried to point out previously, ageing this species is tricky, but we feel we are coming closer to being more confident-- but you still have to be very wary and look at a variety of clues. This is a known adult and at first sight the outer primary looks rather pointed like a juvenile. On closer inspection you can see that this bird appears to have interrupted its primary moult and you can see the outer three primaries are old, faded and pointed due to wear:-

 

We have recently come across a fairly new paper by some French ornithologists using the pattern on the outer tail feather to age birds, which they reckon is very accurate--but only until November. After that they reckon it is not as reliable. However, used with other clues, we are feeling quite confident. A known adult from today showed the adult appearance of this feather with a broad black section at the tip and a cream blotch on one side with a whiter one on the other:-







This contrasts with the juvenile outer tail feather shown here which has a fine black line at the tip and a continuous white outer margin to the feather--apologies for my useless focus but you can still see the effect:-

 

Finally, I posted a couple of pictures a while ago about the leg colour differences between juveniles and adults--the former looking green, and the latter blue. We've been really checking this out carefully and we would like to revise this. Juveniles have uniform green legs and feet, whereas adult are less uniform with the feet being a different colour to the legs. The leg colour does vary however, from green to blue but the feet of adults develop a sort of straw/pink colour. I've tried to show that in the picture but I'm not sure it's come across too well:-

 

They certainly don't look green anyway!

 

Training hard

Apologies for lack of posts recently but we have been very busy helping folk experience the potential of thermal imaging for a range of uses.
First up was an old friend who is starting a PhD study into the interaction of hedgehogs with nesting tern species. To date they have used a variety of methods--for example illuminating the colony at night to see what's happening--all of which have a potential impact on the behaviour of the animals being watched. I suggested he explore the imager, and took him out for an evening on one of our farms. He was quite excited by the potential of watching activity without disturbance. The ease with which we could see mice in the field I'm pretty sure was the deal breaker! We also caught another 3 Jack Snipe and a couple of Fieldfare. A few years ago having caught these birds in one night I would have been buzzing--but in truth I was a tad disappointed given the number that didn't allow close contact--several Woodcock, Snipe, Fieldfare and Skylark, were all super jumpy.

Next day I travelled to Leicestershire to demonstrate the machine to a couple of ringers. It was a very sunny day and by the time I got there one of the major limitations of the imager was very apparent. When vegetation soaks up the sunlight it heats up very quickly so you end up looking for a little glowing white bird in a big glowing mass of grasses and sedges. We didn't catch but I hope we saw enough for them to pursue their intent to buy an imager.

Next day I was back at our main Jack Snipe site to demonstrate to another ringer from Northampton. Conditions were again far from ideal with bright sunshine--but we arrived earlier in the day than the previous day so the vegetation wasn't too warmed up. Fortunately we caught a couple of Jack Snipe--giving our visitor Peter a new species to begin to get to grips with. I'm pretty sure he will be getting an imager when he can pull together the finance. I called in to the site again today and caught another three Jacks--two new birds and one we caught originally in December 2019, and have re-caught twice now--providing some useful information about how long some of these birds use the site. It was good to give Paul A the chance to ring these new birds given that like many ringers he had only ringed one Jack Snipe previously. We have now ringed just under 50 Jack Snipe at this very small site since November 2019--superb!

Our decision to put on training sessions for our trainees every Wednesday and Saturday ( weather permitting ) is paying off handsomely. Our trainees are responding well with a good turnout to each session; their progress is good and it's giving those of us who are a bit long in the tooth an extra impetus to get out there and help these enthusiastic youngsters--I can call them that cos they're all younger than Pete and me! In addition we've had great support from the trainees for our evening lamping sessions but we were conscious that they needed some time to develop their skills at finding birds with the imagers. This is starting to become evident now and last night Liz and Jen were buzzing after catching their own 5 Skylarks and a Blackbird -- great stuff well done!!

I hope to have some pictures to lighten things up in my next post--but for now I'd like to register my thanks and those of our trainees to Paul T, Kev and Pete who have kept the training programme going all through since October. Thanks team!!