Complex sentence: The Yellow Rail are very elusive and seldom seen; generally calling at night as the sound of two stones being clicked together "tik-tik tik-tik-tik" in repetition.
Split into simpler sentences: The Yellow Rail are very elusive and seldom seen. They generally call at night resembling the sound of two stones being clicked together "tik-tik tik-tik-tik" in repetition.