Clumping litter contains ingredients which can absorb moisture and swell to over 10 times their size, possibly causing crop impaction, gastrointestinal tract obstruction and death. Even if not eaten, there is a possibility of inhalation of the powdered portion of kitty litter. These products absorb liquid and make poop examination difficult. Paper Products - Paper products are the safest materials to use for bedding. Unprinted newspaper, printed newspaper, paper towels, any plain paper and even brown paper bags can be used.
Paper towels are expensive and very absorbant and are a better choice for chicks.
If using printed newspaper, don't use the glossy pages or the pages with colored ink as these inks may contain lead and other harmful chemicals. Paper and paper products are very easy to change and allow you to visibly monitor droppings. They are also relatively inexpensive. So for your bird's sake, use paper materials to line your bird's cages. Limit pine shavings to nesting material.