GOING DOWN TO KENT later today after another long gap. It's a fine day here in London but a band of rain is forecast to cross the whole of England tonight. I'm hoping this won't discourage the two nestbox owls from showing themselves around or after dawn tomorrow. As readers of this diary will know, I'm hoping to get some photos to put up this time as well as recordings.
I have a real problem when down there. Several attempts to load stuff on to the website have been frustrated for one or another reason. After getting software and font problems sorted out, we now get FTP errors when trying to upload. This means that at the moment I can only add to the site from my own computer here in London.
It's crunch time for the nestbox design concept. At 10-15 days tawny chicks become very active, and we'll find out whether the five-inch drop from the entrance to the floor is enough to stop them falling out. I'm expecting it to be safe enough, but I could be wrong. They don't try to fall out of course! All the nestbox needs to do is to minimise the chances of them walking out backwards when they poo, which they do many times a day. Most times they're going to back against one of the walls, which is fine. The five-inch rise to the entrance has got to stop them on those occasions when they back towards the door. It should do, but I'm a little anxious because the litter on the floor reduces that drop just a bit. The mother, by the way, tends to leave them for much of time after the oldest chick has reached 10-15 days, so they're unsupervised. By this time she's done nearly 40 days on the nest, so one can hardly blame her for wanting a break!
BACK IN LONDON with a good haul of material after four (cold!) nights out under the owls. So much that it's going to take until tomorrow to get the first pics and sound tracks into a state to put up here.
Basically all seems to be well. We've had our first sight of the nestbox chicks. There is no sign that the pine nest chicks have hatched, but the mother is on duty.
Today is a special day because it's the third anniversary of the day we found Owly -- 5th May 2003.
Back to the night of 30 April/1 May . . .
Night of 30 April to 1 May -- Nestbox owls
CAMPING UNDER THE NESTBOX. Well, that forecast rain certainly came! Hardly had I set up in the tent at about quarter to ten than it began. Light at first, it slowly increased in intensity through the night. And the amazing thing is that the male hunted through the whole downpour, coming in with something he'd caught three times during the night. At least, I assume he wouldn't have turned up if he hadn't found something. The intervals between his visits -- from one to two hours -- certainly matched a more normal night's hunting pattern.
Just after 4.30 am I turned on the camcorder and quickly found I was being watched (first pic below). This is probably the male as he flew off when I adjusted the camcorder a minute or so later. I'd brought the camera out to take pics after dawn, but it has nightshot settings and I thought I'd give them a try. I didn't discover until the next night that there's a more powerful setting (Super Nightshot) that can illuminate the owls with infrared light from 50 feet away. The pic below was taken on the weaker setting.
4.30 am: Stared at by an owl . . . !
The owl's right eye is partly hidden by the side of the entrance door. The eyes clearly have a layer in the retina that reflects at these wavelengths. One is tempted to speculate that this may be an aid to detecting warm prey in the dark, but research has shown that owls have no ability to see infrared light.
(Pic not clickable -- shown here at actual size)
6.05 am: A cold wet dawn
The nestbox in the early dawn light after a long wet night. It's 6.05 am, and the male has left for the last time to roost elsewhere. The rain didn't stop him hunting throughout the night.
Postscript July 2007 -- Can owls see in infrared light??
Karla Kinstler and Alice the Great Horned Owl seem to have the definitive answer here, in an August 2006 page of Alice's blog. Karla did some fairly convincing tests with light ranging from red, which Alice could see, to infrared, which she couldn't. When you think about it, it's not so odd as many retinas reflect infrared, including I believe our own, and we can't see at those wavelengths.
Night of 1 to 2 May -- Nestbox owls
A DRY NIGHT. This time I found the Super Nightshot setting on the Sony camcorder, and two results are shown below. Both owls are very well aware that I'm down there in that tent! But each reacts differently. With the camcorder I was able to discover that Mrs Owl occasionally has a good look (left), especially just after she's flown in, after which she settles down to fuss the chicks or have a rest. In contrast her mate is very suspicious. In the right-hand pic he's just arrived on the ledge, where he takes a good hard look at me. Unfortunately the tent flaps were open, my face was lit by the camcorder display, and seconds later he was off. This was the last time I saw him this or the next night.
Left: the mother owl examines me and the tent, but soon after her attention has turned to other things. Right: the only pic so far of the dad. As soon as he landed he stared into the tent, saw me, and seconds later was in the air again. The mother's head and tail can be seen in the box. Their eyes reflect the infrared light with amazing intensity -- so brightly that they look like blazing coals. Their pupils seem to be completely dilated. A further note: he's just flown in but doesn't seem to have brought anything -- there's nothing in his beak.
Mrs Owl's reaction to this behaviour was, later on that night after he hadn't come in for some time, to fly off to the end of the wood next to the fields and call for him, at times with an urgent-sounding rapid series of kewicks. Still later, when she had returned to the nestbox, he did come into the wood and they met up just behind the tent -- but he didn't come to the nestbox itself. That was the last time I heard him during this visit.
Fortunately none of this appeared to put Mrs Owl out much and the next morning she was quite active round the nestbox. The next page has some pics showing her comings and goings.
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