Complex sentence: The common coquí is the most abundant frog in Puerto Rico with densities estimated at 20,000 individuals/ha, and as an invasive species can reach up to 91,000 individuals/ha in Hawaii.
Split into simpler sentences: The common coquí is the most abundant frog in Puerto Rico with densities estimated at 20,000 individuals/ha,. As an invasive species, it can reach up to 91,000 individuals/ha in Hawaii.