North American River Otters Followed by Piscivorous Birds, and a River Otter Parental Distraction Display

Abstract

We observed 2 Lontra canadensis (North American River Otter), likely an adult female and her nearly-grown pup, on a fall 2018 afternoon at a remote lake in Piscataquis County, ME. We witnessed 2 notable animal behaviors, a possible bird-otter foraging association and a River Otter parental display, serendipitously while canoeing. An Ardea herodias (Great Blue Heron) and a Megaceryle alcyon (Belted Kingfisher) watched and followed the River Otters as they fished along the shore of a small cove of the lake. Although neither bird was seen to strike directly at or eat a fish during this episode, the behavior of the piscivorous birds was suggestive of a foraging association with the River Otters, a novel observation in North America. After fishing, the River Otters began traveling along the lake shore and noticed the canoeing human observers. Upon becoming aware of the canoe, the pup apparently hid as the adult female swam toward the canoe while noisily blowing. She then dove and resurfaced farther away from her pup's last-seen position. This routine was repeated several times until the observers paddled away from the female. Despite the large behavioral repertoire known for otters generally, this parental distraction display has not been previously reported.