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Post by kentyeti on May 13, 2017 19:16:15 GMT
Long time, no update! It's been flat out Shortie observations. I watched the Sheppey roost until it went down to one owl. Including watching one actually leave and head off to start its North Sea crossing. And I dovetailed that field observation work in with what so far are two trips to Langholm Moor this year. Back last Sunday after an exhausting trip to the moor, but I did find 5 or 6 Shortie breeding territories. Not sure about the number of voles, but at least three territories could have had females on a nest. Fingers crossed for them! Spending tonight indexing a lot of Shortie photos that go back to March. Here's one from 30 March on the Isle of Sheppey. This Shortie could well have left for its North Sea crossing not long after I took this photo. It wan't the one I certainly saw go, but it's down as a probable for one that did go that day. Cheers, Bryan
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Post by accipiter on May 13, 2017 19:37:12 GMT
Nice photo well done Bryan, Alan was beginning to think you may have been abducted by a strange creature in the night. Alan
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Post by kentyeti on May 14, 2017 10:40:20 GMT
Not yet Alan!
And now a question, for you and indeed anyone who can answer.
Using my thermal imager throughout the winter months and into the spring, it is clear that Short-eared Owls are well insulated, as you would expect a ground roosting bird to be.
As expected a lot of my watching on my recent Langholm trip was at night, and I noticed the Shorties giving a much stronger heat signature. Most noticed on their breasts.
All I can think of, is that their feathers are wearing in advance of the post breeding annual moult, (to be expected of course), and as a result are not retaining as much heat as normal.
Has anyone come across this with other birds that have a complete annual feather moult please?
Cheers,
Bryan
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Post by accipiter on May 14, 2017 22:50:16 GMT
Hi Bryan, like you I cannot think of a real definitive answer but I do know a little about a birds moult and feather function in general, and so what follows is some “general information” that you may be able to gleam some ideas from starting with the number of feather on an individual species in relation to its size. And so what follows may also be of interest to other members too, anyhow here goes. Birds such as swallows have 1,500 feathers whilst a large bird such as the swan has over 25, 000 in which the density follicles varies, which only help make the whole criteria, moulting, and associated functions a complex process and a whole science in its own right in which more study is still needed. This is also the main reason why I only concern myself with bird behaviour and only a very few species at that, e.g. Sparrowhawk, kestrel, buzzard, little owl, carrion crow, rook, jay, magpie, raven, plus the fact I find these species social behaviour during the breeding season extremely interesting and takes precedence over any other type of study. Nevertheless I have included a list of just a few examples and sequence of the moult for you. And so in general a bird’s moult takes place in two ways e.g. complete and partial in which only some feathers are replaced. Just to add to the complexity long distance migrants differ however it can also apply to resident species too. There is also a pre breeding moult in some species but really the complexity goes on and on, far too much for my little grey cells to understand even if I had the interest. Anyhow here is another example concerning the moult. Suspended moult, moult after autumn migration, moult before autumn migration, and moult during the breeding cycle. Palmer 1972, Payne 1972, Stresemann and Stresemann 1966. Funnily enough the willow warbler (on another thread) has two complete moults per year one in the breeding season and one in the winter, whilst the chiffchaff has only the one complete moult after breeding which is thought to be connected with the distance of migration between the two. That is not to mention the timing of the moult in other species of juvenile birds which is only partial; the complete moult taking part in their second year and the final condition of the feathers is thought to be connected with the particular diet and stress it is exposed to. However here are my thoughts and some information concerning your particular question. Short eared owl
Primary moult descending from p1 duration 58 -89 days, tail feathers dropped more or less when p6 –p8 is dropped, the tail normally drops two feathers at a time from the middle outwards. There is also a difference in the time span depending on the sex of the bird.
However warmth is primarily provided by the down feathers but once the birds are on their breeding grounds abrasion of the down / body feathers may well be a contributing factor allowing more heat to escape at the same time as the outside temperature rises. Of course as more and more time passes the condition, quality, usefulness, of the feathers is becoming progressively worse by which time the breeding season is over they really do need replacing.
Best regards Alan
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Post by kentyeti on May 15, 2017 21:17:35 GMT
Thanks Alan. I will mention it in the relevant part of the book. It's a benefit of using the Thermal Imager I did not envisage!
Of interest is that the secondary wing feathers moult from the centre, not from one end as the primaries do. I have got some photos, not from close, but one of them may have to do as by the time of the moult they are usually going back to being fully nocturnal. So catching one mid moult in daylight has not proved easy.
Thanks again,
Bryan
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Post by accipiter on May 15, 2017 22:17:49 GMT
No problem Bryan, but it was just a theory based on the abrasion that would have taken place, causing air that is normally trapped inside the layers to escape as the barbule locking mechanism gradually loses its efficiency; this heat signature would then show up as bright red on your sensitive equipment, which seems to be as good an explanation as any. Although having said that and giving the matter more thought there are other possible causes that could exacerbate the problem such as excessive allopreening that takes place during the breeding season, I am not aware how much this takes place in short eared owls but it is very frequent occupation in little owls as I have often observed. There are also nutritional and viral infections that effect the efficiency of feathers but unlikely I should have thought, also contamination through contact with oil and other substances which in turn can cause the barbules to fail to lock or even a problem with the preen gland causing a condition called wet feather more common in ducks causing their waterproofing function to fail. There is even the possibility your bird may have experienced an encounter of food piracy in which the other bird concerned turns completely upside down and presents its talons in an effort to steal its food. But really as I remarked earlier the study of feathers, moulting, and their associated functions are a complex process and a whole science in its own right, not to mention some kind of trauma such as I just mentioned taking place. The only other reason I can think of for this is the brood patch where feathers in the region shed automatically in preparation for incubation but start to grow back after the hatch, birds such as ducks and geese pluck them out in order to line their nests. Anyhow this would imply there is nest in the region say no more but this link may interest you Bryan. www.featheredphotography.com/blog/2012/12/20/brood-patch-in-a-female-short-eared-owl/And yes some species even have a different moulting pattern and they may also drop more than one feather in the same wing and not in the other or more than two at once in the tail. And in the case of some non-breeding birds moulting earlier then breeding ones, all terribly complex. Anyhow changing the subject somewhat I forgot to mention Jumbo the jackdaw that I also had as a young boy, I named it Jumbo on account that it was the smallest jackdaw I had ever seen then or since, happy days. Indeed those were the days when one could safely walk on the cracks in the pavement without the fear of being arrested! But interesting to note all those members of the crow family mentioned in my previous post (except for a raven that I never kept) had their own tin food plates that they would throw up in the air whenever they wanted food, clever I should say so. But for some reason Jumbo never returned one morning to perform the spinning plate trick, mind you by that time society had changed somewhat, and so it was probably arrested for behaving in a disorderly manner. Alan
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Post by kentyeti on Jun 14, 2017 18:29:56 GMT
Back from an exhausting but very, very rewarding 3 week trip to Langholm for the Short-eared Owl breeding season, and they are breeding this year as there are voles around. Will add more here and a photo or two when I catch up with typing my field notes. 76 A4 pages to do!
Went to one nest a couple of times, and as always up there, despite open access and Shorties not being Schedule one birds, I only went when they were being checked for being right to ring. So as to minimise disturbance.
The young in the nest were a bit slow developing as there were 3 or 4 other Shortie nests, at least one Merlin nest, and four Hen Harrier nests in that particular valley area. So voles were in demand.
On both visits I noticed the young had a grey/ blue tinge to their pupils. Both on a sunny day and on part cloudy day, so I presume it was not just the pupils reflecting the sky.
Does anyone know if some owls/birds don't have jet black pupils to start with, but that they move to that colour as the young get older?
Cheers,
Bryan
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Post by kentyeti on Jun 14, 2017 19:47:53 GMT
I'll have to check I-Player, but the young Long-eared Owls on Springwatch tonight seemed to show the same grey/blue tinge in their pupils. Either that, or there was something in my Highland Spring water that wasn't put there by me!
Cheers,
Bryan
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Post by rowanberry on Jun 14, 2017 20:47:18 GMT
It sounds like you had a rewarding trip, Brian... I look forward to seeing the photos.
I don't envy you having to type 76 pages of notes! That's going to take a while.
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Post by accipiter on Jun 14, 2017 22:32:24 GMT
Hi Bryan, as far as I am aware a birds pupil remains what could be described as basically black, although the iris colour changes with age as in Sparrowhawks to name just one species, also the age when the eyes first open in owls varies with the species normally eight to ten days in little owls for instance which is an owl species I know the most about and twelve days in barn owls I believe. Nevertheless I think the colour you describe is basically an illusion if you will the shadowy colour depending on how the light falls on to the back of young birds eyes / retina which is not fully developed, also (showing myopia) anyhow, this may help to explain things a little better even though this link refers to human eyesight the function / purpose of the “pupil” remains basically the same. en.wikipedia.org/wiki/Pupil
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Post by kentyeti on Jun 15, 2017 20:00:27 GMT
Hi Bryan, as far as I am aware a birds pupil remains what could be described as basically black, although the iris colour changes with age as in Sparrowhawks to name just one species, also the age when the eyes first open in owls varies with the species normally eight to ten days in little owls for instance which is an owl species I know the most about and twelve days in barn owls I believe. Nevertheless I think the colour you describe is basically an illusion if you will the shadowy colour depending on how the light falls on to the back of young birds eyes / retina which is not fully developed, also (showing myopia) anyhow, this may help to explain things a little better even though this link refers to human eyesight the function / purpose of the “pupil” remains basically the same. en.wikipedia.org/wiki/PupilThanks Alan. Reading that and the link, leads me to think the best way to describe the grey/blue tine in the pupils is because the inside of the eye, including the retina, is not yet fully developed allowing some light to be reflected back out, rather than almost all absorbed within the eye. Still bashing away on my keyboard. 55 pages of A4 handwritten notes now typed, 20 more to do. Saw and heard some incredible things. A Shortie doing its own version of the male Hen Harrier sky dance! And listened to a pair of Shorties giving absolute hell to a fox. They shouted and dived at it for nearly 20 minutes until it was 800 m from their nest. A super night for my thermal imager so I saw it all as well. And it looked like the owls did hit the fox with a wing from time to time. And then, sadly, the fox came back and predated their nest 4 nights later. A whole range of calls from the owls. 2 "attack" calls, and 3 "distraction" calls. But to no avail. From the circuit the fox was following I suspect it was the same one that was felt to have wiped out one of the Hen Harrier nests. Sad that the gamekeepers were pulled off the moor last spring (2016), and the foxes are getting back now. In all the nights I've spent up on the moor in the previous three breeding seasons I'd never heard any sign of one getting near an Owl nest. This trip it was four times at two different locations I heard the Owls trying to force a fox away. More positive was watching two juvenile Shorties make their first flights, the night after I could see they were very close to that. So I spent the next 14 days, or should I say nights or parts of nights, watching their progress with developing their flying skills. All with thermal imager because, as I have found a number of times before, they start flying at night. And indeed they also learn to hunt at night. No surprise, they will be nocturnal most of their lives. Thankfully some do get active in daylight, especially in spells of bad weather in the breeding season, so I did get a few photos. One below. Cheers, Bryan
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Post by accipiter on Jun 15, 2017 21:46:27 GMT
I was hoping my explanation helped, the probable is my notes / information is badly in need of filing into some sort of order as there are open folders lying all over the place at present, anyhow very sad news about your predated nest Bryan you probably experienced that heart sinking moment we all know oh so well. Something along the same lines happened to one of my little owl pairs recently, not sure what but I suspect stoats were to blame as I saw one hanging around this one box in question.
This particular box is the very last of my tree mounted ones but I plan to remedy the problem by pole mounting it for next year, anyhow climbing ladders is not such a good idea if you take my meaning. I also noticed a kestrel had taken over the same box since but alas this too has not returned yet, but I plan to do another long stint tomorrow just to make sure but somehow I do not hold out much hope. Anyhow I should have a better idea on that score once the breeding season is over when I plan to check the boxes out again for cleaning / maintenance.
As for my writing not done any for some time as field work has somehow taken over (not enough hours in the day or night,) not sure how you manage to get enough sleep either but I am beginning to struggle, much the same as a pale faced zombie shift worker I suspect, probably an age thing! Correction I know it’s an age thing.
Anyhow I plan to add an update on this year sometime at end the breeding season all being well that’s if I manage not to fall over again in the dark, oh yes thinking about adding this year’s report to my bird box thread as it seems to make sense.
Alan
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Post by kentyeti on Jul 24, 2017 9:48:28 GMT
Been in Scotland for 9 out of the last 15 weeks, and most of that has been at night which is when the Shorties are active, as expected. I would never have made a shift worker, I just don't get decent sleep in the daytime! A very good breding season on Langholm Moor and I am told elsewhere up North. Found 12 territories on my 7 mile observation stretch, that is the same as the mega year of 2014. Coming to an end now, the juveniles are at the initial dispersal stage, and likely some will be leaving on longer distance flights around now. As I've always seen on the moors, the young start flying at night and learn to hunt at night. When I left they were getting active around 22.30 and were mostly back down before 04.00. Just enough time to catch the prey they need, as it is a very good vole/shrew/mouse year. Very interesting to hear that three were seen at Elmley on Sheppey in Kent on Saturday. Maybe some bred locally, rare these days, but not impoossibe. Or some of the many in the north of Britain that have bred are now heading south. Have to wait and see if we are going to get a mega winter in the South. Be back soon with some photos, but thought I'd give a brief update after a long break away. Regards to all here. Bryan
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Post by rowanberry on Jul 25, 2017 9:33:27 GMT
Good to hear from you again, Brian - it sounds as though you've had a productive time up in Scotland, and I look forward to your photos... they are always superb!
I know what you mean about trying to sleep during the day- I struggle with that as well.
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Post by kentyeti on Jul 29, 2017 10:00:08 GMT
Just posted this on WAB Castaways, but I think it may be of interest here too. It is one photo of a whole series I was taking directly into the light over several days, only so I could try and work out what was happening. They are all poor quality, but they help me put the story together after the event. Including the timing of events to the nearest second. I hope to be sorting all the other photos from that trip soon and will pull out a half decent one to post here! ".....A really rubbish photo, I was looking straight into the light. But a very interesting adult to watch for a few days during my last Langholm trip.The only area where there was daylight activity, with what looked like two adults and three independent juveniles still with their adults.This adult was catching food morning and late afternoon, and it look me several days of watching to work out he was caching it, and not feeding the juveniles or a nest. I am not sure the juveniles were taking any of it, as I saw them hunting at night, and indeed I was a few metres from one when it made a kill in the early hours. I think a high prey level had got the adult into a sort of killing obsession, where it hadn't worked out that its juveniles no longer needed to be fed. I have seen that before to some extent, but not as much as this time. But as the juveniles weren't begging for food anymore, the adult just cached it. I watched the juveniles fly up at dusk from near where the cache was, and go off hunting, so they looked like they were already following Shortie form in going for live prey, rather than carrion from the cache. I found it was a cache only at dusk on my last evening there. I changed viewing positions on a very dull dusk and got a very good Thermal Image viewing of the adult landing with prey. I could see his top half all of the few seconds he was on the ground, and there were certainly no other owls, adult or juvenile, where he left the prey. I'll post this on WABI as I think it will interest Alan, (Accipter) at least....." Cheers Bryan Benn
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