Nesting season 2001
Broad Street, Guildford, UK.
Page eight.
21st May 2001. It is warm and sunny today. The new hatchlings are four days old (if they hatched on Thursday) or three days old (if they hatched on Friday). There seems to be little difference that we can see between the 5 older birds and the 4 younger birds.
Nest box 1 with chicks.
West
East
We can see that the nest cup is offset towards the SW corner of the box. The house wall is opposite the entrance hole, on the South side of the box.
Our chicks have not yet developed spine ridge feathers. This will happen in two days time. Jumping ahead a bit, we see
Spine ridge feathers 23rd May
But for now, the chicks' backs are new and bare.
Chicks close up 21st May
23rd May 2001. Today was a lovely warm and sunny spring day, with temperatures about 20 Celsius in the afternoon, and 14 Celsius at midnight. After dark, our female bird has to stand away from the chicks to prevent them from overheating. The thermometer in the floor of the box says 18 Celsius under the warm chicks. It is usually only 2.5 degrees hotter under a roosting adult.
Cooling off.
These cooling off periods last for a considerable time, up to 15 minutes, while the bird stands motionless. Sometimes she stands on their backs with one foot, and sometimes straddles the nest cup, as here
Astride the hot chicks.
At about 11:30 pm there seems to be a disturbance. The female lunges at the SE corner of the box, for no apparent reason
Fright in the night.
And our bird shows us eleven tail feathers
Feather count.
Later on, she pays attention to a tail feather
Tail feather preen.
Earlier, we have had a good couple of views of the family gathering.
Birdiferous - -
The family together.
Feeding proceeds all the while. Here is a caterpillar arriving, with nine mouths just visible
Food arriving.
Later on, we get a good impression of the nine gaping beaks. Proto-beaks.
In box 2, the female is still sitting on her six eggs, counted during a brief intermission. We are puzzled, because the egg count there has gone from six to seven to six to seven to six....we are not sure what the problem is. Perhaps the bird has poor calcium reserves and has laid fragile shells. We expect these to hatch on Thursday the 24th May, or perhaps a day later.
In box 1, the four-day-old chicks intermittently spend time jockeying for position. Their activity could be termed "synchronised gaping". They have also become mobile, stretching their necks out of the rim of the nest cup and even clambering out for a while. All this vigorous exercise must aid in their muscle development. It was a surprise to us that after only 19 days after hatching, they have strong enough wing muscles to fly, considering that most of those 19 days are spent within the confines of a nest cup.
From the colour pictures above, we see that the youngsters' mouth rims are bright yellow, and the insides of their throats are orange. If I were a caterpillar, I would develop a phobia about the colour yellow.
The female spends a great deal of time rooting around in the bottom of the nest cup, forcing further exercise on the hatchlings. This vigorous activity can be seen from outside the house; the nestbox wobbles on its suspension (which has a wire safety-hanging as well as a screw fixing).
At night, the female gets scarcely any sleep. She is having to move on and off the chicks to regulate their temperature. They provide a continuously mobile mattress for her; an electrified water bed comes to mind, with a wave machine. From their point of view, they are not sleeping either, as each has a mobile mum and eight wriggly siblings to contend with. It makes a whole new meaning to the concept of "feather-bedding".
24th May 2001. As it has been up to 26 Celsius on the Box 1 thermometer during the afternoon, the birds have not been having to keep the chicks warm. The mother only got a few hours of sleep last night. The chicks in Box 2 have hatched, and there are five bald youngsters and one egg. We make no predictions as to whether the other egg will hatch.
Pink youngsters - Box 2 on Thursday 24/5
And a mouth amongst the backs
When the birds come in to feed the chicks, they make a curious noise which is a cross between a squawk and a cluck, to attract their attention. This noise is not made if they come in without food. We are interested in the very high pitched sounds which the youngsters make, and sometimes we see beak movement in the adults with no accompanying sound. We have a plan to use an ultrasonic microphone and some digital frequency translation software to down-shift any ultrasonic noises, while preserving the correct time clock. This will now have to be a project for next year.
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There are many pictures of the kind of activity now proceeding, on the pages from earlier years. Please see the links on the page "Old birdsite" below.
Old birdsite http://www.ee.surrey.ac.uk/Personal/D.Jefferies/bird/birdsite.html
Lifeforms pictures http://www.eryptick.net/lifeforms.htm
Email dj@eryptick.net
diary continues......