    Sentence 1: Kempenaers said some  species are still faithful , notably swans  and sea birds such as the albatross .  which mate for life and are never  unfaithful to their partners .    Sentence 2 HKempenzers said fidelity still  exists in some species , notably swans and  sea birds such as the albatross that mate  for life and are never unfaithful to their  partners