Food Habits and Fish Prey Size Selection of a Newly Colonizing Population of River Otters (Lontra Canadensis) in Eastern North Dakota

By Stearns, Cory R.; Serfass, Thomas L. | The American Midland Naturalist, January 2011 | Go to article overview

Food Habits and Fish Prey Size Selection of a Newly Colonizing Population of River Otters (Lontra Canadensis) in Eastern North Dakota


Stearns, Cory R., Serfass, Thomas L., The American Midland Naturalist


ABSTRACT.-The food habits of river otters (Lontra canadensis) on three rivers in the Red River of the North drainage of eastern North Dakota were evaluated using an analysis of 569 scats collected between 4 Oct. 2006 and 26 Nov. 2007. Fish and crayfish were the primary prey items, occurring in 83.0% and 51.1% of scats, respectively. Other prey included insects (26.7%), birds (7.9%), amphibians (6.7%), mammals (6.0%) and freshwater mussels (0.2%). Fish of Cyprinidae (carp and minnows) were the most prominent fish in the diet, occurring in 64.7% of scats. Other relatively common fish in the diet included Ictaluridae (catfish, 17.4% frequency of occurrence), Catostomidae (suckers, 13.0%), and Centrarchidae (sunfish, 11.2%). The diet of river otters changed seasonally, including a decline in the frequency of fish in the summer diet, and a corresponding increase in the occurrence of crayfish. Consumed fish ranged from 3.5 to 71.0 cm total length, with a mean of 20.7 cm (SE ± 0.5, n = 658). Fish 10.1-20.0 cm were the most frequently consumed size class (36.5% relative frequency), with the majority of other consumed fish being ≤ 10.0 cm (24.6%), 20.1-30.0 cm (14.1%), 30.1-40.0 cm (14.0%), or 40.1-50.0 cm (8.2%). The size of consumed fish changed seasonally, with spring having the largest mean prey size.

(ProQuest: ... denotes formulae omitted.)

INTRODUCTION

Historically, the nearctic river otter (Lontra canadensis) occurred on most rivers in North Dakota, and was relatively common into the 1890s (Bailey, 1926; Adams, 1961). River otters still occurred in the 1920s along the major rivers and some lakes but had become rare by the 1960s, and were considered extirpated soon after (Bailey, 1926; Adams, 1961). However, in recent years reports of river otters have increased, with most coming from the Red River of the North (hereafter referred to as Red River) drainage, and Lake Sakakawea in the Missouri river drainage (Hagen et al, 2005).

River otters are opportunistic aquatic predators. Although the diet is diverse, most dietary analyses have shown fish to be the primary prey (e.g., Greer, 1955; Melquist and Hornocker, 1983; Serfass et al, 1990). River otters are presumed to select fish in proportion to their abundance and in inverse proportion to swimming speed and agility (Ryder, 1955). Therefore, the most abundant and slowest swimming fishes tend to be taken most often. Catostomidae (suckers) , Centrarchidae (sunfish and bass) , Cyprinidae (carp and minnows) and Ictaluridae (catfish) are usually among the most frequently occurring fish families detected in river otter diet studies (e.g., Wilson, 1954; Greer, 1955; Hamilton, 1961; Griess, 1987; Serfass et al, 1990; Noordhuis, 2002; Giordano, 2005). When available, crayfish are usually the second most important prey item and in a few studies have occurred most frequently in the diet (Grenfell, 1974; Griess, 1987; Noordhuis, 2002). Other organisms consumed by river otters include amphibians, insects and other invertebrates, birds, mammals and reptiles (Ryder, 1955; Melquist and Hornocker, 1983; Serfass et al, 1990).

Despite many previous food studies on river otters, rarely have studies been conducted to assess the size of their fish prey. Previous studies have made general inferences about prey size, indicating that fish prey ranges from 2-80 cm and that most fish consumed are probably 10-30 cm in length (Lagler and Ostenson, 1942; Greer, 1955; Ryder, 1955; Hamilton, 1961; Toweill, 1974; Melquist and Hornocker, 1983; Stenson et al, 1984; Griess, 1987; Tumlison and Karnes, 1987; Noordhuis, 2002; Giordano, 2005). However, these studies typically did not indicate the methods used in their assessments, or establish predictive relationships between anatomical structures (that are recoverable from the digestive tracts or scats, such as bones and scales) and fish length. Also, inferences have been limited to one or a few species (occasionally only a few individuals) and only provided information on the size range (maximum and minimum) or common prey sizes. …

The rest of this article is only available to active members of Questia

Sign up now for a free, 1-day trial and receive full access to:

  • Questia's entire collection
  • Automatic bibliography creation
  • More helpful research tools like notes, citations, and highlights
  • Ad-free environment

Already a member? Log in now.

Notes for this article

Add a new note
If you are trying to select text to create highlights or citations, remember that you must now click or tap on the first word, and then click or tap on the last word.
One moment ...
Default project is now your active project.
Project items

Items saved from this article

This article has been saved
Highlights (0)
Some of your highlights are legacy items.

Highlights saved before July 30, 2012 will not be displayed on their respective source pages.

You can easily re-create the highlights by opening the book page or article, selecting the text, and clicking “Highlight.”

Citations (0)
Some of your citations are legacy items.

Any citation created before July 30, 2012 will labeled as a “Cited page.” New citations will be saved as cited passages, pages or articles.

We also added the ability to view new citations from your projects or the book or article where you created them.

Notes (0)
Bookmarks (0)

You have no saved items from this article

Project items include:
  • Saved book/article
  • Highlights
  • Quotes/citations
  • Notes
  • Bookmarks
Notes
Cite this article

Cited article

Style
Citations are available only to our active members.
Sign up now to cite pages or passages in MLA, APA and Chicago citation styles.

(Einhorn, 1992, p. 25)

(Einhorn 25)

1

1. Lois J. Einhorn, Abraham Lincoln, the Orator: Penetrating the Lincoln Legend (Westport, CT: Greenwood Press, 1992), 25, http://www.questia.com/read/27419298.

Cited article

Food Habits and Fish Prey Size Selection of a Newly Colonizing Population of River Otters (Lontra Canadensis) in Eastern North Dakota
Settings

Settings

Typeface
Text size Smaller Larger Reset View mode
Search within

Search within this article

Look up

Look up a word

  • Dictionary
  • Thesaurus
Please submit a word or phrase above.
Print this page

Print this page

Why can't I print more than one page at a time?

Full screen

matching results for page

Cited passage

Style
Citations are available only to our active members.
Sign up now to cite pages or passages in MLA, APA and Chicago citation styles.

"Portraying himself as an honest, ordinary person helped Lincoln identify with his audiences." (Einhorn, 1992, p. 25).

"Portraying himself as an honest, ordinary person helped Lincoln identify with his audiences." (Einhorn 25)

"Portraying himself as an honest, ordinary person helped Lincoln identify with his audiences."1

1. Lois J. Einhorn, Abraham Lincoln, the Orator: Penetrating the Lincoln Legend (Westport, CT: Greenwood Press, 1992), 25, http://www.questia.com/read/27419298.

Cited passage

Welcome to the new Questia Reader

The Questia Reader has been updated to provide you with an even better online reading experience.  It is now 100% Responsive, which means you can read our books and articles on any sized device you wish.  All of your favorite tools like notes, highlights, and citations are still here, but the way you select text has been updated to be easier to use, especially on touchscreen devices.  Here's how:

1. Click or tap the first word you want to select.
2. Click or tap the last word you want to select.

OK, got it!

Thanks for trying Questia!

Please continue trying out our research tools, but please note, full functionality is available only to our active members.

Your work will be lost once you leave this Web page.

For full access in an ad-free environment, sign up now for a FREE, 1-day trial.

Already a member? Log in now.