If you have not seen a bird climb before, you've never seen a parakeet. Anyways, many birds clime, such as woodpeckers, parakeets, etc. Because ofdifferent varieties, each bird has a different types of feet (grasping foot, scratching foot, swimming foot, perching foot, running foot, etc.). Different feet are designed for different habitats.
Big birds, like ostriches, can't fly because their wings are too small, and their bones are not hollow.
they are too heavy or have different habitats
Some are too heavy, others may be injured..
because some birds don't have the wing power to with stand very much pressure
They are too heavy and the wings are too small.
They are happy
a penguin cannot fly and others can
Bird can fly while the other animals cannot.
Some flightless birds are the kiwi, ostrich, emu, cassowary, rhea, penguin.
Penguins cannot fly, nor did the dodo, which is why it is extinct. Also the emu and the ostrich. Neither of those two birds can fly.
Emus, ostriches, and kiwis are three birds that cannot fly.
Birds cannot fly at all without their feathers.
There are many different drawings of flightless birds. Some of these drawings reflect birds who naturally cannot fly such as penguins for example.
they cannot fly
The hummingbird hovers, as with a helicopter, but a different chassis .
To say that birds use wings and feathers to fly, so all birds can fly, would be false. Not all birds can fly. An ostrich is an example of a bird that cannot fly.
some birds are to big for their wings to make them fly
The swimming bird that cannot fly and whose name begins with letter P is Penguin. As your question also states 'what are some birds that begin with letter P, so some common such birds are Peacock, Peahen, Peafowl, Pelican, Pheasant,Parakeet and Parrot.