The canariesí nails grow too long or curl in. This can cause the toe to bend unnaturally and at its worst can stop a bird from standing properly.
It is natural for your birds toenails to grow. Being too long can be caused by perches being too thin and or perches that are too smooth.
Catch your bird and hold him as per the picture on your left then using a sharp pair of scissors or clippers cut off the excess about 1.5mm beyond the pink blood vessels that can be seen in the nail, as per the photo on your right. If you accidentally cut a blood vessel in the nail donít panic just touch with some antiseptic and it will repair by itself.
It also helps to have a cement floor on your aviary as this will help to keep the toenails short, by abrasion.