| 1. |
Because chicks of the same clutch hatch over several days, the older, larger chicks are better able to compete for food. As a result, the youngest chick(s) in the nest often dies of starvation or is killed by a larger nest mate. Scientists believe asynchronous hatching is an adaptation to unpredictable food supplies. If food is plentiful, all the chicks survive. If food is scarce, the brood is rapidly reduced.
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| 2. |
The nestling period (the time from hatching to fledging, when a bird is able to fly) lasts from four to seven weeks. As with incubation, large species have proportionately longer nestling periods than small species. |
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Chicks gain weight slowly at first, then increase rapidly, leveling off around the time of fledging. |
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Small species grow more rapidly than large species. Small species may reach adult weight by fledging, while large species may not reach adult weight until sometime after leaving the nest. |
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As contour feathers replace downy ones, chicks begin to preen after meals. |
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Once wing feathers have developed, chicks spend a considerable amount of time flapping them at the nest. |
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| 3. |
Postfledging periods (the period between fledging and complete independence) range from two to three weeks in small falcons, five to ten weeks in Buteo hawks, and up to several months in large eagles and vultures. |
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After fledging, young birds begin to make short flights to nearby trees or perching sites. They usually return to the nest when a parent returns with food. |
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Later, the young may intercept a parent further and further away from the nest, sometimes screaming loudly or even attacking the parent for food. |
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When the fledglings can hunt independently, they may leave the nest area on their own or wait until the parents stop feeding them, drive them away, or leave to migrate. |
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