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Altricial vs. Precocial Development

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patrick hallis

on 5 December 2013

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Transcript of Altricial vs. Precocial Development

Altricial vs. Precocial Development
What Do They Mean?
Advantages and Disadvantages....
Variables That Influence The Choice of an Optimal Strategy...
"Precocial" and "altricial" are just scientific jargon for the degree of development in birds.
Altricial Development....
Hatch with eyes closed
Little or no down*
Cannot leave the nest
Fed by parents
Cannot maintain their own body temperature.
Precocial Development....
Hatch with eyes open
Covered with down
Can leave the nest (within two days)
Feed themselves
Can maintain body temperature on their own
Benefits of Altricial Development....
Rapid growth (fed large nutrient-rich food items by parents)
chicks become independent relatively quick
minimizes young mortality
allow the brain to grow well in size
capable of growing into an ultimately more more developed state
Disadvantages of Altricial Development.....
Fast growth rate = high food demand
Extended nestling* period (confined to their nests)
Parents have to incubate the chicks
Benefits of Precocial Development...
Slower growth rate = lower food demands
shorter nestling period (minimizes the vulnerable nestling period)
chicks are more independent
less time spent being incubated
Disadvantages of Precocial Development...
slow growth rate = higher young mortality ( Long time to avoid predators without the benefit of flying)
Food Supply...
If food is difficult to obtain, then altricial development is favored
If food is relatively easy to obtain, precocial development is possible, and in some cases, favored.
If food is in high supply, then altricial development is favored
If food supply is low, then precocial development is favored
Nest Accessibility...
If nests are inaccessible, then altricial development is favored
If nests are very accessible, then precocial development is favored
If nest predation is a less of a limiting factor than predation of freely moving young birds, then altricial development is favored
If nest predation is more of a limiting factor than predation of freely moving young birds, then precocial development is favored
*Down: layer of fine feathers under the tough exterior feathers
Left: House Sparrow hatchling (
- naked, eyes closed, helpless). Right: Ruffed Grouse hatchling (
- down, open eyes, mobile, follows parents and is shown food by parents)
*nestling: baby bird in nest. ( too young to leave the nest)
Nature of Young Bird Predation...
Summary of Patterns...
Precocial Development
Altricial Development
species whose foods require flight and/or experience
species whose foods are abundant (predation > starvation), and
species whose nests are relatively less vulnerable to predation.

species whose foods can be obtained by inexperienced, flightless young,
species whose foods are scarce (predation < starvation), and
species whose nests are vulnerable to predation.

Altricial Development
Precocial Development
Summary of Patterns cont'd...
Woodpecker nestling
Kingfisher nestlings
Chick nestlings
Barn owl nestlings

The End...
Thank you!
Patrick H. & Joanne S.
Joanne Sabra & Patrick Hallis
, they cannot fly yet!
"Precocial versus Altricial Development." Maine Birds RSS. Wordpress MU, 6 Aug. 2009. Web. 27 Nov. 2013.
"Precocial and Altricial Young." Precocial. Paul R. Ehrlich, David S. Dobkin, and Darryl Wheye, n.d. Web. 27 Nov. 2013.
Works Cited:
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