Complex sentence: Care must be taken to distinguish raccoon sign from that of river otters ("Lutra canadensis"), another mammal that forages extensively in the marshes, and is infrequently observed in the salt hay along the edges of tidal creeks.
Split into simpler sentences: Care must be taken to distinguish raccoon sign from that of river otters ("Lutra canadensis"), another mammal that forages extensively in the marshes. River otters are observed infrequently in the salt hay along the edges of tidal creeks.