The University of Southern Mississippi The Aquila Digital Community Dissertations Spring 2020 Regional Differences in Wild North American River Otter (Lontra canadensis) Behavior and Communication Sarah Walkley Follow this and additional works at: https://aquila.usm.edu/dissertations Part of the Biological Psychology Commons, Cognitive Psychology Commons, Comparative Psychology Commons, Integrative Biology Commons, and the Zoology Commons Recommended Citation Walkley, Sarah, "Regional Differences in Wild North American River Otter (Lontra canadensis) Behavior and Communication" (2020). Dissertations. 1752. https://aquila.usm.edu/dissertations/1752 This Dissertation is brought to you for free and open access by The Aquila Digital Community. It has been accepted for inclusion in Dissertations by an authorized administrator of The Aquila Digital Community. For more information, please contact [email protected]. REGIONAL DIFFERENCES IN WILD NORTH AMERICAN RIVER OTTER (LONTRA CANADENSIS) BEHAVIOR AND COMMUNICATION by Sarah N. Walkley A Dissertation Submitted to the Graduate School, the College of Education and Human Sciences and the School of Psychology at The University of Southern Mississippi in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy Approved by: Dr. Hans Stadthagen, Committee Chair Dr. Heidi Lyn Dr. Richard Mohn Dr. Carla Almonte ____________________ ____________________ ____________________ Dr. Hans Stadthagen Dr. Sara Jordan Dr. Karen S. Coats Committee Chair Director of School Dean of the Graduate School May 2020 COPYRIGHT BY Sarah N. Walkley 2020 Published by the Graduate School ABSTRACT This study focuses on the vocalization repertoires of wild North American river otters (Lontra canadensis) in New York and California. Although they are the same species, these two established populations of river otters are separated by a significant distance and are distinct from one another. River otters are semi-aquatic social predators that can be found throughout North America. This is the first study to examine the vocalizations of wild river otters, and results are compared across field sites in the different regions. River otter vocalizations and behaviors in New York were recorded using Bushnell Aggressor trail cameras that were placed in areas of moderate to high river otter activity. The River Otter Ecology Project, a nonprofit organization studying river otter populations in Marin County, provided the otter videos from California. Recorded vocalizations were separated into categories based on their appearance on a spectrogram and parameters including frequency and duration were measured for each call. Behaviors were identified in all New York videos and during vocalizations in both New York and California videos. Four call types (chuckle, hah, chirp, and whine) were recorded in both California and New York otters. An additional call (chirpwhine) was recorded only in the California population. Otters in both populations produced chuckles while traveling, scentmarking, and investigating. Hahs were produced during disturbance, food, play, and rub behaviors. Otters were most likely to produce chirps when they were stationary and alone. Hahs were most likely to occur in pairs, and chuckles and whines were more likely to occur among groups of 3 or more otters. This study not only contributes to the limited knowledge that exists on the North American river otter vocalization repertoire, but also bridges the gap between animal acoustics and ii behaviors, providing behavioral context for this elusive species’ most common call types in the wild. iii ACKNOWLEDGMENTS This project could not have been completed without the help of many. Thank you to my advisor Dr. Heidi Lyn, for your guidance and support, always given generously and especially when it was needed most. Thank you also to my committee chair, Dr. Hans Stadthagen-Gonzalez, and committee members, Dr. Carla Almonte and Dr. Richard Mohn, for your feedback and support. Thank you to my friends and family, especially my parents Rebecca and Steve Walkley, for your encouragement through the completion of this project. Essential to this research was my friend and colleague Dr. Maria Zapetis - Thank you for your constant support in so many aspects of our research with river otters. Thank you to Megan Isadore and the River Otter Ecology Project for sharing your data on river otters in California as well as Mike Bottini for your help researching otters in Long Island. Thank you to the county of Westchester, the town of Suffolk, and the Mianus River Gorge Preserve for allowing data collection on their land. Additional thank you to Mianus River Gorge for providing funding for field equipment and travel. iv TABLE OF CONTENTS ABSTRACT ........................................................................................................................ ii ACKNOWLEDGMENTS ................................................................................................. iv LIST OF TABLES ........................................................................................................... viii LIST OF ILLUSTRATIONS ............................................................................................. ix LIST OF ABBREVIATIONS ............................................................................................. x CHAPTER I - INTRODUCTION ...................................................................................... 1 Otters ............................................................................................................................... 1 Threats to Otters .............................................................................................................. 1 North American River Otters .......................................................................................... 3 Life History ................................................................................................................. 3 Behavior ...................................................................................................................... 6 Otter Vocal Communication ........................................................................................... 9 Chirps ........................................................................................................................ 10 Hahs .......................................................................................................................... 11 Variable Frequency Calls .......................................................................................... 11 Low Frequency Calls ................................................................................................ 13 Combination Calls .................................................................................................... 14 Whistles..................................................................................................................... 15 Current Study ................................................................................................................ 16 v CHAPTER II – METHODS ............................................................................................. 18 Participants .................................................................................................................... 18 Procedure ...................................................................................................................... 18 Site Selection ............................................................................................................ 18 Trail Cameras ............................................................................................................ 19 Behaviors of New York Otters at Latrine Sites ........................................................ 19 Vocalizations............................................................................................................. 20 Behavior and Vocalization Interaction ..................................................................... 21 Data Analysis ................................................................................................................ 22 Behavior .................................................................................................................... 22 Vocalizations............................................................................................................. 22 Behavior During Vocalizations................................................................................. 23 Reliability .................................................................................................................. 23 CHAPTER III - RESULTS ............................................................................................... 24 Behaviors in New York at Latrine Sites ....................................................................... 24 Vocalization Repertoire and Associated Behaviors ...................................................... 27 Vocalization Repertoire ............................................................................................ 27 Behaviors During Vocalizations ............................................................................... 34 Vocalization and Behavior Interaction ..................................................................... 36 CHAPTER IV – DISCUSSION........................................................................................ 39 vi Behavior in New