Rodent Pest Management

Ishwar Prakash

• Publisher: CRC Press
• Year: 2018
• ISBN:
  9781351093354
• Edition: 1
• Topic: Medicine
• Subtopic: Veterinary Medicine

The objective of this multi-authored compendium is, therefore, to bring together the state of arts reported in one place. Written by specialists by specialists in various fields of rondentology, and to suggest future lines of research. It is also felt that this work on rodent pest management will trigger more research effort for the benefit of mankind and help certain countries and organizations in revitalizing serious work in this field which, it appears, has dampened during the last few years.

Chapter 1

RODENT PROBLEMS ON THE NORTH AMERICAN CONTINENT

Rex E. Marsh

TABLE OF CONTENTS

I.	Introduction
II.	Rodent Pests
	A.	Pocket Gophers
	B.	Ground Squirrels
	C.	Prairie Dogs
	D.	Woodchucks
	E.	Chipmunks
	F.	Tree Squirrels
	G.	Voles or Meadow Mice
	H.	Muskrats
	I.	Nutria
	J.	Beaver
	K.	Mountain Beaver
	L.	Porcupines
	M.	Deer Mice
	N.	Woodrats
	O.	Cotton Rats
	P.	Kangaroo Rats
	Q.	Rice Rats
	R.	Norway Rats
	S.	Black Rats
	T.	House Mice
	U.	Minor Rodent Pests
III.	Nonrodent Species Causing Similar Damage
References

I. INTRODUCTION

Rodent problems on the North American Continent are highly varied as they are on most other continents and involve both introduced as well as native species. Many of the species found in North America have counterparts of the same family or closely related genera on other continents, and the problems they cause or damage they do is often similar. Rodent problems can be categorized in many ways, but for the purpose of this chapter they will be discussed on the basis of taxonomic classification and how they affect man’s interest or impact on humans.

Although certain rodent species or groups of rodents are discussed as pests in this chapter, relatively few of the numerous existing rodent species are considered pests. Few species are detrimental all the time as might be unintentionally implied by categorizing them as “pests.” Some good or benefit can be attributed to most every species, if nothing more than serving as food for animals of a high trophic level.

Many factors may contribute to whether a rodent species becomes a pest, including its geographic distribution, preferred habitats, feeding habits, reproductive propensity, population dynamics, and other biological or behavioral characteristics; but most important is its adaptability to man-made or modified environments.

Rodents are considered pests in many situations and for a variety of reasons. They damage food crops, such as sugar cane, rice, sugar beets, and vegetables, and trees or vines that produce fruit, nuts, or berries; they compete with livestock for forage, or damage forage or hay crops; they damage oil and fiber crops such as cotton and flax; and they damage forest trees and hamper reforestation efforts. Rodents of one species or another may cause damage at most any stage of plant growth from the seed to the harvestable commodity. Often crop damage does not stop there, and some of the most serious damage and losses through rodent contamination occur postharvest in transportation and storage.

Our most serious postharvest or stored-food rodent pests are three introduced species: the black or roof rat (Rattus rattus), the Norway rat (R. norvegicus), and the house mouse (Mus musculus).

Rodents are implicated in the transmission of a variety of diseases to man and his domestic animals. In other situations, especially around habitations, rodents are nuisance problems. They cause considerable structural damage to buildings and other man-made or engineered structures.

The major pest genera or species are discussed individually in a general order of importance to provide an overview of the problems in the North American Continent, including the crops and other damage they cause. Space permits only a brief discussion of pest rodent groups and the nature of their damage. As a convenient reference, important rodent pests of North America, their taxonomic classifications, types of damage, and magnitude and severity of damage are presented in Table 1. Important pest rodent species are managed or controlled as needed to reduce animal damage, health-related problems, and other conflicts with man’s activities. Control success varies with the pest species. Management and control methods are discussed in other chapters. More complete taxonomic information and distribution maps for the species discussed are found in The Mammals of North America.¹⁴

II. RODENT PESTS

A. Pocket Gophers

Pocket gophers are fossorial rodents that spend much of their lives in their extensive burrow systems. They are represented by five genera of the family Geomyidae and are found only in North America, from Central Canada to Panama. The thick-set bodies, about 6 to 12 in. (15 to 30 cm) long, show little external evidence of a neck. Highly adapted for living below ground, they have small eyes and ears, a good sense of smell, and stout forelegs with strong claws. The gopher’s incisors protrude through an opening in its lips to enable their use for digging. A pair of furlined external cheek pouches are used for carrying food items.⁵

Table 1
IMPORTANT RODENT PESTS OF NORTH AMERICA, TAXONOMIC CLASSIFICATION, TYPES OF DAMAGE, AND MAGNITUDE AND SEVERITY OF DAMAGE

^a The magnitude of the problem is indicated by the following letters: (L) localized; (MW) moderately widespread; (W) widespread. The severity of the problem is indicated by numbers or a range of numbers: (1) occasional damage; (2) light damage; (3) moderate damage, (4) heavy damage.

^b Introduced species, not native.

Pocket gophers feed mostly below ground on seeds, roots, bulbs, tubers, and the bark of trees. After consuming the roots of a plant, they often pull the smaller plants into their burrows and devour them entirely. The various species have somewhat different preferences for plants, but they include both grasses and forbs. Many agricultural crops, ornamental plants, and newly planted forests suffer severe damage from root and seedling clipping. Damage to older trees involves basal debarking. The major economic losses occur to landscape plantings, young transplanted forest trees, fruit trees, and alfalfa production. On rangeland and pasture, pocket gophers compete for forage and greatly reduce the carrying capacity for livestock.¹³

In their burrow construction, pocket gophers push up numerous earthen mounds that may exceed 3000 per ha.³⁰ These mounds bury other vegetation as well as interfere with mowing of alfalfa and other hay crops. In irrigated crops or pastures, considerable water is lost because of extensive burrow systems, and in hilly terrain burrowing may accelerate soil erosion. Damage to earthen dams and levees can be extensive and costly.

B. Ground Squirrels

As a group, the ground-dwelling genera of the squirrel (Sciurid) family are of considerable economic importance in western U.S., especially as competitors of livestock for forage and damage they do to grain crops. Though the three groups, i.e., ground squirrels, prairie dogs, and woodchucks or marmots, have similarities, they differ considerably in biology, behavior, population densities, and the degree with which they affect man’s livelihood.

Ground squirrels belong to the genus Spermophilus and range from Canada to Mexico, with 20 of the 23 species found in the U.S., mostly west of the Mississippi River. Over half of those species are considered significant pests to agriculture and forestry.²⁷ These species generally inhabit open grassy plains and valleys, slightly wooded areas, or openings in forests. Several species are relatively adaptable and thrive in and around a variety of agricultural crops, principally grain, alfalfa, and other forage crops, but they also attack sugar beets, vegetable, and fruit crops. In some regions of western U.S. they compete extensively with livestock for range forage^12,17,22,23 and, to a much lesser degree, cause reforestation problems by consuming tree seed and clipping small seedlings.³⁴ As diurnal rodents of substantial size that feed above ground, their presence and damage seldom go unnoticed. Some species colonize and reach high population densities. They are implicated in the transmission of several diseases to man, including the plague.

C. Prairie Dogs

Prairie dogs, the local name given to rodents belonging to the genus Cynomys, are found mostly in the Plains area of the U.S. One of the four species extends into Canada a short distance, and a fifth species is found well into Mexico. Larger than most ground squirrels and smaller than woodchucks or marmots, it is a stocky rodent with a short tail about one-fourth its total length. They are very social animals and thrive in large colonies called “towns”, which may contain a few to thousands of individuals. Once widely distributed and abundant, particularly over the short-grass prairies of the Great Plains,³⁵ agricultural and grazing practices, plus control measures, have greatly reduced inhabited areas, yet they are still...

Table of contents

• Cover
• Title Page
• Copyright Page
• Table of Contents
• Chapter 1 Rodent Problems on the North American Continent
• Chapter 2 The Rodent Problem in Latin America
• Chapter 3 Rodent Problems in Europe
• Chapter 4 Rodent Problems in Africa
• Chapter 5 Rodent Problems in Asia
• Chapter 6 Rodent Problems in Selected Countries in Southeast Asia and Islands in the Pacific
• Chapter 7 Rodents and Human Disease: A Global Appreciation
• Chapter 8 Population Principles
• Chapter 9 Changing Patterns of Rodent Populations in India
• Chapter 10 Prevention of Plagues of House Mice in Rural Australia
• Chapter 11 Reproduction
• Chapter 12 Behavior
• Chapter 13 Methods for Estimating the Losses Caused in Rice and Other Crops by Rodents
• Chapter 14 Selection of Baits and Their Distribution
• Chapter 15 Large-Scale Evaluation of Rodent Control Technologies
• Chapter 16 Rodent Pest Management: The Principles
• Chapter 17 Exploring, Sampling, Neophobia, and Feeding
• Chapter 18 Bait Shyness and Poison Aversion
• Chapter 19 Nonanticoagulant Rodenticides
• Chapter 20 Anticoagulant Rodenticides
• Chapter 21 Chemosterilants for Rodent Control
• Chapter 22 The Potential for Pheromonal Involvement in Rodent Control Programs
• Chapter 23 Biological Principles, Development, and Perspectives of the Use of Bacteria and Viruses
• Chapter 24 Natural Resistance of Plants to Pest Rodents
• Chapter 25 Chemical Repellents
• Chapter 26 Ultrasound Devices
• Chapter 27 Predation
• Chapter 28 Nonlethal Methods in Rodent Control
• Chapter 29 Integrated Pest Management, Principles in Rodent Control
• Chapter 30 Transfer of Rodent Pest Control Technology
• Chapter 31 Areas of Further Research
• Chapter 32 Ecology and Economics of Rodent Pest Management: The Need for Research
• Index