sentence: vigorously chewing , it is important to provide a constant and regular supply of any non-toxic materials such as non-toxic tree branches ( i.e. apple , aspen , birch , pear , pine , willow ) that has never been treated with any type of chemical products ( i.e. disinfectant , fungicide , insecticide , javel , pesticide ) the species is hardy & vigorous when acclimatized .