An adjective is needed to describe the ‘ivory tusks’. ‘Valuable’ (from value) means worth a great deal of money.
An adverb is needed to modify the verb ‘sold’. ‘Unlawfully’ (from law) means in a manner that is not permitted by law.
A past participle/verb is needed after the auxiliary ‘has’. ‘Shortened’ (from short) means to make something shorter in duration.
A past participle is needed here to complete the parallel structure with ‘shortened’. ‘Interrupted’ means to stop the continuous progress of an activity or process.
A plural noun referring to people is needed as the subject. ‘Poachers’ (from poach) are people who illegally hunt or catch animals.
A plural noun referring to people is needed. ‘Caretakers’ (from care) are people employed to look after a place or person.
A noun is needed after the adjective ‘maternal’. ‘Interaction’ (from act) refers to reciprocal action or influence.
A noun is needed after the article ‘the’. ‘Reintroduction’ (from introduce) is the action of putting a species of animal or plant back into a former habitat.