Transcript Different kinds of development by birds after birth

Different kinds of development
by vertebrates after birth
The two kinds of developmental strategies for birds
after birth, is mainly linked to nest building, feeding
and protecting from predators in their
environment.
• Altricial development (‘requiring nourishment’)
• Precocial development
Altricial development
Altricial refers to species whose newly-hatched or -born
youngs are helpless and require care for a specific amount
of time. They …
• are relatively immobile,
• lack hair or feathers,
• are not able to obtain food on their own,
• must be cared for by adults,
• have closed eyes which are common, though not always
the case.
They cannot leave the nest and are fed by their parents
until their body is covered in feathers and their muscles
have strengthened.
They are unable to regulate their own body temperature.
(kept warm by a parent)
Altricial development (cont.)
Their nest are above the ground in trees or on poles to
protect them from predators.
Amongst birds, for example,
woodpeckers, owls, pigeons, etc.
Among mammals, most rodents (rat, mouse, marmot)
are altricial.
Cats, dogs, humans are
some of the best-known
altricial organisms.
Advantage of altricial
development
With rich diet provided by parents the initial
small brains developed into large adults brains –
leads to greater adaptability and intelligence
Disadvantage of altricial
development
• More demanding on parents (more energy
needed) for protection and feeding
• Parents need to teach them to fly
Precocial development
Precocial refers to species in which the young
are relatively mature and mobile from the moment of
birth or hatching.
They …
• are able to move around soon after hatching,
• are covered with down /feathers,
• can leave the nest within two days,
• are able to regulate their own body temperature,
• Make their nests on the ground
Examples: guinea fowl, geese, ducks,
chickens, cranes, etc.
Advantage of precocial development
• Hatchings are able to avoid predation to some
extent,
• They can see and run around,
• Can feed themselves,
• Less demanding on female/
parents once hatched – they are independent
• Mother stays nearby to protect them and
teach them
Disadvantage of precocial
development
• Hatchlings have relatively large brains and
their brain size does not increase much
• Demanding on female to produce lots of yolk
so that embryo can develop into more mature
chicks
Increasing parental care
Some differences
ALTRICIAL DEVELOPMENT
PRECOCIAL DEVELOPMENT
Woodpeckers, pigeons, guineafowel
Chickens, duck, geese, owls
25% of yolk – less energy needed to
produce
40% of yolk in egg – lots of energy
needed to produce
Nests in trees, caves, on poles
Nests on the ground
Closed eyes
Open eyes
Naked very few or no feathers
Down/feathers present
Cannot leave the nest
Leave nest within two days
Cannot move around
Can move around
Cannot feed themselves
Can feed themselves
Cannot maintain their body temperature
(kept warm by a parent)
Can maintain their body temperature
Parents have to protect them from
predators
Parents may help to protect them
Need a lot of parental care for amount of Very little or no parental care
time