Wednesday, May 28, 2008
De Mortel: on the move
De Mortel juveniles are moving out. 2 Of them have been on the ledge and platform on top of the Toren. Unfortunately we hav eproblemens with getting the feed from teh Tower on to the internet. But we are taping everything 16 hours a day and I'm making clips of this. So we will not have to miss the important moments.
Lambert Cox is making great videos from teh nestbox and ledge at the foot of the Toren. And that gives an even more acurate impression from what's going on. You can watch all video's on the De Mortel 2008 You Tube channel:
http://www.youtube.com/user/demortel2008
Derby Peregrines: 25 days old
In their fourth week of life, the chicks undergo significant changes almost daily. Around day 25, the brown tips to the secondaries become clearly visible, and the number of coloured feathers visible on the breast increases noticeably. Behaviourally, they are rarely resting on their tarsi anymore at this age.
http://derbyperegrines.blogspot.com/
From Hatch to Fledge
Click the pictures to enlargeCondition At Hatching
The peregrine falcon eyases are semialtricial, nidicolous; covered with off-white (prepenne) down. Semi altricial means: Covered with down, incapable of departing from the nest, and fed by the parents. In species like the peregrine falcon we speak of semi-altricial 2, hatch with the eyes closed.
The bill and feet pinkish to pale gray with eyes closed. They weigh about 35–40 g. If eyes open with food-begging first day, they are slitlike. The eyases obtain 2 downy plumages.
Growth and development
At 5 days after hatch, their mass has doubled. The eyas can sit with relative ease, and the open eyes are more round.
At 6–8 days of age the second down (mesoptile or preplumulae) starts to emerge, first on humeral and alar tracts but no down visible on belly at 6 day, although on the legs and belly at 8 days.
Also second down is well out on the wings and looks a bit blueish and sheaths of primaries breaking skin on wings.
By 10 days of age the second down is complete and uniform and outer rectrices are breaking skin. At 10 days, primaries growing at 2–3 mm/d, rectrix sheath not yet split.
At 14 days the second down is dense and long, rectrix sheath about 2 mm and typically ninth primary emerges from sheath.
By day 17 the contour feathers start to push out prepennae and only pale (buffy) tips of rectrices have emerged but growing at about 2 mm/d (since day 13).
By 10 days of age the second down is complete and uniform and outer rectrices are breaking skin. At 10 days, primaries growing at 2–3 mm/d, rectrix sheath not yet split.
At 14 days the second down is dense and long, rectrix sheath about 2 mm and typically ninth primary emerges from sheath.
By day 17 the contour feathers start to push out prepennae and only pale (buffy) tips of rectrices have emerged but growing at about 2 mm/d (since day 13).
At 20 days while still with heavy coat of second down, brown contour feathers are visible on margins of wings, tail, and faintly around the eyes.
By 30 days young appears about half down-covered and half feathered; while side of face well feathered, crown still covered with down.
At 35 days while mostly feathered, large conspicuous patches of down around legs, under wings, and on crown.
At 40 days almost fully feathered with traces of down on crown and under wings and outer several remiges; rectrices not fully grown but bird capable of weak flight.
From my Peregrine falcon website:
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Nijmegen: picnic on the grid
The Nijmegen juvi's are 37 days old and on the grid. Running around, flapping their wings. And the parents are feeding on the grid as well. Our little eyases are growing up! Just a few more days and they will leave and start the thing they where born to: fly
Brightom Sussex Heights: on the ledge
It's often around day 30 that the chicks seem to turn into "real" peregrines almost overnight, very rapidly losing much of the down on their breast, thus revealing the heavily streaked breast feathers they will be carrying for the next year.
Lessons to learn
Without any doubt the most exciting thing about the peregrine falcon is the way it catches it's prey. The falcon feeds on fresh caught prey like small birds,or small mamals. He is a raptor, or bird of prey. No picking little seeds here but killing to survive.
In order to catch a prey, a peregrine needs intelligence. He has to be able to anticipate immediately in a split second on the escaping behaviour of it's prey. No hunt is the same. It will not come as a surprise to know that the peregrine is one of the most intelligent avians. Together with raven it is on top of the Bird IQ list.
Every raptor has a special technique to catch a prey. Just think of the lion, or a shark, a cheetah. The peregrine falcon is beyond compare, but if we have too, we'd best compare it to the cheetah. The peregrine falcon however is faster than the cheetah. In a stoop the peregrine can reach speeds over 350 km/hour. And that's dazzling.
Evolution has streamlined the body of the peregrine falcon, gave it highspeed wings in order to reach the perfect form of a falling waterdroplet. Even the wings have this special airfoilform.
Without making it to technical with aerodynamics, somethings can be said about the stoop techique. And the very unique adaptions to the peregrine body.
Everybody knows how difficult it gets to breath when you're walking in a heavy storm. You have to turn your head to be able to breath. The peregrine falcon does not walk in the storm, it dive-bombs at 350 k/hour. Breathing would be absolutely impossible without special adaptions. The air pressure from a 200 mph (320 km/h) dive could possibly damage it's lungs, but small bony tubercles in a falcon's nostrils guide the shock waves of the air entering the nostrils (compare intake ramps and inlet cones of jet engines), enabling the bird to breathe more easily while diving by reducing the change in air pressure. To protect their eyes, the falcons use their nictitating membranes (third eyelids) to spread tears and clear debris from their eyes while maintaining vision.
The peregrine falcon searches for prey either from a high perch or from the air. Once prey is spotted, it begins its stoop, folding back the tail and wings, with feet tucked.It tumbles and dive-bomds downward. But not in a straight line.
It approaches it's prey in a curved flight path because of it's sideway vision.When diving at prey straight ahead from great distances at high speeds, a peregrine has a conflict between vision and aerodynamics: it must turn its head approximately 40 ° to
one side to see the prey with maximum visual acuity at the deep fovea of one eye, but the head in this position increases aerodynamic drag and slows the falcon down. The falcon could resolve this conflict by holding its head straight and flying along a logarithmic spiral path that keeps the line of sight of the deep fovea pointed sideways at the prey. Wild peregrines, observed with binoculars, telescopes and a
tracking device, did approach prey from distances of up to 1500 m by holding their heads straight and flying along curved paths that resembled the logarithmic spiral.
Prey is struck and captured in mid-air; the Peregrine Falcon strikes its prey with a clenched foot,kind of a fist, stunning or killing it, then turns to catch it in mid-air. The Peregrine will drop it to the ground and eat it there if it is too heavy to carry. Prey is plucked before consumption. The juveniles have to learn all these things: the stoop, how to knock a prey dead, how to kill, and how to pluck. In the months after they fledge they will learn this from their parents, It are hard lessons. We have been able to watch how parents leave prey in the nestbox to force them to try in order to get food. As soon as one of the juveniles has left the nestbox the other ones have to as well. The parents will feed outside. So if they want food they have to step out as well. It seems tough and it is. Next stage is getting them all up in the air. When the first is in teh air, the feeding takes place far from teh nestsite. It's obvious the left-behinds have to fly in order to get food.
When all are airborn, lessons start. With food once more. One of the parents flies in with food in the talons. One of the juvi's will be the first one to take it over the prey and this is his or hers. So it is constantly a competition. The winner takes it all.
Copyright Froona ©
In order to catch a prey, a peregrine needs intelligence. He has to be able to anticipate immediately in a split second on the escaping behaviour of it's prey. No hunt is the same. It will not come as a surprise to know that the peregrine is one of the most intelligent avians. Together with raven it is on top of the Bird IQ list.
Every raptor has a special technique to catch a prey. Just think of the lion, or a shark, a cheetah. The peregrine falcon is beyond compare, but if we have too, we'd best compare it to the cheetah. The peregrine falcon however is faster than the cheetah. In a stoop the peregrine can reach speeds over 350 km/hour. And that's dazzling.
Evolution has streamlined the body of the peregrine falcon, gave it highspeed wings in order to reach the perfect form of a falling waterdroplet. Even the wings have this special airfoilform.
Without making it to technical with aerodynamics, somethings can be said about the stoop techique. And the very unique adaptions to the peregrine body.
Everybody knows how difficult it gets to breath when you're walking in a heavy storm. You have to turn your head to be able to breath. The peregrine falcon does not walk in the storm, it dive-bombs at 350 k/hour. Breathing would be absolutely impossible without special adaptions. The air pressure from a 200 mph (320 km/h) dive could possibly damage it's lungs, but small bony tubercles in a falcon's nostrils guide the shock waves of the air entering the nostrils (compare intake ramps and inlet cones of jet engines), enabling the bird to breathe more easily while diving by reducing the change in air pressure. To protect their eyes, the falcons use their nictitating membranes (third eyelids) to spread tears and clear debris from their eyes while maintaining vision.
The peregrine falcon searches for prey either from a high perch or from the air. Once prey is spotted, it begins its stoop, folding back the tail and wings, with feet tucked.It tumbles and dive-bomds downward. But not in a straight line.
It approaches it's prey in a curved flight path because of it's sideway vision.When diving at prey straight ahead from great distances at high speeds, a peregrine has a conflict between vision and aerodynamics: it must turn its head approximately 40 ° to
one side to see the prey with maximum visual acuity at the deep fovea of one eye, but the head in this position increases aerodynamic drag and slows the falcon down. The falcon could resolve this conflict by holding its head straight and flying along a logarithmic spiral path that keeps the line of sight of the deep fovea pointed sideways at the prey. Wild peregrines, observed with binoculars, telescopes and a
tracking device, did approach prey from distances of up to 1500 m by holding their heads straight and flying along curved paths that resembled the logarithmic spiral.
Prey is struck and captured in mid-air; the Peregrine Falcon strikes its prey with a clenched foot,kind of a fist, stunning or killing it, then turns to catch it in mid-air. The Peregrine will drop it to the ground and eat it there if it is too heavy to carry. Prey is plucked before consumption. The juveniles have to learn all these things: the stoop, how to knock a prey dead, how to kill, and how to pluck. In the months after they fledge they will learn this from their parents, It are hard lessons. We have been able to watch how parents leave prey in the nestbox to force them to try in order to get food. As soon as one of the juveniles has left the nestbox the other ones have to as well. The parents will feed outside. So if they want food they have to step out as well. It seems tough and it is. Next stage is getting them all up in the air. When the first is in teh air, the feeding takes place far from teh nestsite. It's obvious the left-behinds have to fly in order to get food.
When all are airborn, lessons start. With food once more. One of the parents flies in with food in the talons. One of the juvi's will be the first one to take it over the prey and this is his or hers. So it is constantly a competition. The winner takes it all.
Copyright Froona ©
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