Wild Mammals of the Santa Rosa Plateau

By Rick Bramhall

This is a guide to the wild mammals known to be found on the Santa Rosa Plateau Ecological Reserve, located in southern California, just west of Murrieta CA. It includes a physical description of each animal, along with notes on habitat, daily activity, reproduction, death and where each is usually found on the Reserve. This online version does not include the illustrations found in the printed version of 2003.

• Language: English
• Publisher: Rick Bramhall
• Release date: May 6, 2015
• ISBN: 9781311275905

Rick Bramhall

I was born in 1952 and grew up Hawthorne, California. Served in the US Air Force from 1975-79. My longest gig was working in Medical Information at the Loma Linda VA from 1979-89. Got my BA from Cal State San Bernardino in 1989. Taught 8th Grade Language Arts 1990-94. Volunteered at the Santa Rosa Plateau Ecological Reserve from about 1997-2004. I moved to San Diego in 2009 to be nearer family. In 2019 I moved to Yuma AZ, as rent became too high in SD. In 2021, my place in Yuma burned down and I moved to Tucson to be nearer my childhood friend, Carl Harrison. I'm currently involved as a community activist.

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Wild Mammals of the Santa Rosa Plateau

by Rick Bramhall

Copyright 2003 by Rick Bramhall

printed edition 2003

Smashwords edition 2015

This ebook is licensed for your personal enjoyment only. This ebook may not be re-sold or given away to other people. If you would like to share this book with another person, please purchase an additional copy for each recipient. If you’re reading this book and did not purchase it, or it was not purchased for your use only, then please return to your favorite ebook retailer and purchase your own copy. Thank you for respecting the hard work of this author.

#sci

Table of Contents

Acknowledgments

Introduction

Scientific Names

Mammals in General

Badgers

American Badger

Bats

Big Brown Bat

California Myotis

Canines

Coyote

Gray Fox

Cats

Bobcat

Mountain Lion

Deer

Mule Deer

Opossums

Rabbits and Hares

Black-tail Jackrabbit

Desert Cottontail

Raccoons

Rodents

Brush Mouse

Cactus Mouse

California Ground Squirrel

California Mouse

California Pocket Mouse

California Vole

Deer Mouse

Desert Woodrat

Dusky-Footed Woodrat

Pacific Kangaroo Rat

Pocket Gopher

Western Harvest Mouse

Shrews

Gray Shrew

Skunks

Striped Skunk

Weasels

Long-tailed Weasel

Other Mammals That May Be On the Reserve

References

Acknowledgments

First and most importantly, I want to thank Rob Hicks, Interpreter for the Santa Rosa Plateau Ecological Reserve, without whose encouragement I never would have become so involved in the Reserve. He has given me advice and much information.

Reserve Ranger Kevin Smith has also been a good friend and source of much aid.

From the Nature Conservancy, I want to thank Resource Manger Carole Bell and Project Ecologist Zachary Principe, who have given me both information and access to further sources.

Jenny Duggan, biology researcher from San Diego State University, has been very generous in sharing with me her knowledge of the Reserve's rodents.

Grover and Ethel Bramhall kindly helped with proofreading. Any mistakes, errors or omissions herein are the sole responsibility of the author.

Special thanks to my sisters Robyn Bramhall and Ellen Silver for the computer this was first written on.

Introduction

This book is meant for the general public and as such contains as little scientific jargon as possible. the last thing I want is for anyone to be intimidated or scared away from gaining knowledge. It is hoped that the information provided here leads to greater understanding of nature, and respect for it.

Why Wild?

I believe every living organism has a set of biological, or natural rules which are meant to govern its life. Animals that are not wild -- that is, domesticated by humans (Homo sapiens) -- live partly by rules imposed on them by another species and therefore often do not act or live according to their genetic programming. It seems their lives do not provide us much insight into nature, or at least not as much as their wild counterparts.

Why Mammals?

Humans seem to be interested in, and care the most about, mammals. Much is made about such features as fluffy fur and big eyes. But let's face it: we care the most about them because we, too, are mammals. They look more like us than other animals, and they act more like us.

The word 'mammal' comes from the word 'mamma.' We are all raised on milk (preferably mother's) and we are all looked after in our infancy by one or both parents. We look more alike than perhaps we are willing to admit: head, eyes,ears, noses, hair, legs, feet. And internally we all have pretty much the same bones and organs.

However, there are a number of ways other mammals differ from Homo sapiens. These are equally instructive.

Why the Santa Rosa Plateau?

My desire is to create a book that covers each species in as much depth as possible and yet is not so large as to be unaffordable to most people. So I had to find a basis to limit the number of species.

I was a volunteer for the Santa Rosa Plateau from 1998 to 2005. This book is specially meant to serve both as a memento and encouragement to further explore this super natural place.

Scientific Names

Badger...................................Taxidea taxus

California Myotis..................Myotis californicus

Big Brown Bat.......................Eptesicus fuscus

Coyote....................................Canis latrans

Gray Fox.................................Urocyon cinereoargenteus

Bobcat.....................................Felis rufus

Mountain Lion........................Puma concolor

Mule Deer...............................Odocoileus hemionus

Opossum.................................Didelphis marsupialis

Black-tailed Jackrabbit...........Lepus californicus

Desert Cottontail....................Sylvilagus audubonii

Raccoon..................................Procyon lotor

Brush Mouse...........................Peromyscus boylei

Cactus Mouse..........................Peromyscus eremicus

California Ground Squirrel.....Spermophilus beecheyi

California Mouse....................Peromyscus californicus

California Pocket Mouse........Perognathus californicus

California Vole........................Microtus californicus

Deer Mouse.............................Peromyscus maniculatus

Desert Woodrat........................Neotoma lepida

Dusky-footed Woodrat.............Neotoma fuscipes

Pacific Kangaroo Rat...............Dipodomys agilis

Pocket Gopher..........................Thomomys bottae

Western Harvest Mouse............Reithrodontomys megalotis

Gray Shrew..............................Notiosorex crawfordi

Striped Skunk..........................Mephitis mephitis

Long-tailed Weasel..................Mustela frenata

Mammals in General

There are some aspects of wild mammal behavior that many readers will find alien, or even gross and disgusting. But it must be understood that wild animals do not live for a religion or cause, nor do they search for their identity, make career decisions or seek to make their mark on the world. Their morals come down to one principal: to pass on their DNA. They will do whatever it takes to do this as often as possible, and to make sure their progeny are as capable as possible of continuing the line.

This does not mean they all adopt the same strategies to achieve this goal. For example, only 3% of all mammalian species are monogamous. While having both parents assist in raising young may seem clearly advantageous, it must be kept in mind that every action is a trade-off of energy. And the bottom line is that, whatever the behavior strategy, these species have been successfully passing on their DNA for millions of years.

Mom's Milk

Not all mammals have hair or fur, and there are animals other than mammals who are warm-blooded. What all mammals have in common and is unique to us is that, under natural conditions, we start our lives receiving our sole nutrition from the milk of our mother.

The strategy of lactation means that mothers can ingest food when and where they can and then reform their nutrients into a form easily digested by her young. And she can feed them at another time and place than her feeding ground, keeping them safe.

Lactation is just one aspect of the complicated set of behaviors that lead one or both parents to care for their offspring until they have the size and knowledge to survive on their own. These behaviors are largely triggered by two hormones: prolactin and oxytocin.

Prolactin first evolved in fish for the purpose of maintaining a bodily balance between salt and water. In mammals it triggers care-taking behavior in both males and females.

Oxytocin not only produces the trigger of muscle contractions necessary for uterine birth and mammary gland secretions, but is needed to cause a mother to bond with her newborn. Since it is also found in mother's milk, it is suggested that it also bonds offspring to their mother.

The make-up of milk varies from species to species but all contain, in some percentage, water and protein, either in the form of sugar or fat, or both. Also transmitted from mother to child are hormones necessary for the physical development of the young. Opiates in the milk give babies a sense of contentment.

Perhaps the single most important component of mother's milk is antibodies, helping to immunize the newborn against a number of diseases.

Sense of Sight

Most mammals, including almost all found on the plateau, are nocturnal. The sensory problems with this is that, even on the brightest moon-lit night, there is millions of times less light than during the day.

The most obvious way nocturnal mammals deal with this problem is that they have proportionately larger eyes, with pupils that can open wide. However, this causes a problem when they do have to see during the day, because too much light coming in can cause temporary blindness and damage to the retina. One way some mammals protect against this is with a layer of opaque skin that can slide into place over the eye like a clear eyelid.

The way we all deal with too much light is to make our pupils smaller. However, some nocturnal have to make theirs so small that the amount of muscular effort involved is too great. Instead, they have a slit pupil -- what we commonly refer to as a cat's eye.

The mammalian retina is made up of two kinds of light-receptive cells: cones and rods. Cones tell us the color of things, but require a lot of light to do their job. Rods only process black and white, but are able to function in much lower light by pooling their information. Nocturnal mammals have retinas mostly, sometimes entirely, made up of rods. They see the world mainly in shades of gray. The only way they can differentiate colors is by degrees of brightness. this means that the shorter the wavelength, the brighter it is perceived. In this system, green is bright than yellow and these animals often see green vegetation as a whiteness.

Besides all the above-mentioned adaptations to night sight, most nocturnal mammals have another: a layer of reflective cells located right behind the retina. This layer, called the tapetum (accent on the second syllable, long 'e'), is what causes these animals' eyes to glow in the dark.

Most wild animals are far-sighted, with predators usually having better vision than prey. This, along with the fuzziness of rod-dominated vision, means that they have trouble seeing detail. It is often only by smell, at closer range, that they can differentiate between two species.

Depth perception varies greatly. Information received by the left eye goes to the right side of the brain and information from the right goes to the left side. So, getting a three-dimensional picture is a matter of the two halves of the brain sharing visual information. Among dogs, one quarter of this information is shared, while in cats one third is shared. Among primates like Homo sapiens one half of the visual information taken in my one side is shared with the other.

The sense of sight in all mammals is keyed around movement. So when a mammal doesn't want to be seen it stays as still as possible.

Eating Plants

Vegetation is very difficult for mammals to digest -- in fact, technically speaking, we don't. The walls of plant cells are so tough to break down that we have to have bacteria that live in our digestive tracts do it for us. Even then, it takes longer. The upper intestines of mammals who eat plants, either solely or along with some meat, are longer in relation to body size than those who are chiefly carnivorous. In most, this digestive process takes place in the cecum, where the small and large intestines meet.

(Plant cell walls are made of cellulose, whose molecules are bound to each other by a shared hydrogen atom. This means, in order to split two molecules, an atom has to be torn apart -- a very hard task.)

Mammals who rely solely on plants for their energy have several different ways, depending on the species, to wring as much nutrition as possible out of their food. As you will see in the chapters on these animals, they do so by putting the material through their digestive system twice.

On the Reserve

Except for coyotes, rabbits and ground squirrels, mammals are seldom seen the Ecological Reserve. This is mainly because they are chiefly nocturnal but also because they don't want to be seen.

There are a number of ways to know they here, though, such as footprints and scat. However, it is mainly coyotes who use the trails and so most of these signs are theirs.

Evidence of burrows is another sign but doesn't tell who, if anyone, is currently residing in them. Visitors, staff and docents report infrequent sightings, usually from early in the morning. Most knowledge of what species live here comes from field researchers. For example, small mammal traps tell us what rodents live where on the Reserve. Cameras triggered by motion are located in several restricted areas on the Plateau and are sometimes the only verification of certain species' residency here.

American Badger

Physical Description. Badgers have short legs on a rather stout body. They are either gray or reddish-brown with yellowish-white undersides. They have a black or dark brown face with a white stripe running from the nose over the top of the head, sometimes traveling all the way back to the tail. White cheek hair stand out like old-fashioned mutton-chops. Their ears and feet are black or dark brown, the tail short and yellow-white. The length of head and body is approximately 18-22 inches, the tail 4-6 inches and they normally weight from 13-25 pounds. Males are longer and heavier than females.

Their claws are very sharp, with the front ones considerably longer than the back. They cannot contract them. The feet are wide -- the back ones smaller -- and each has five digits, which are partly webbed to keep the claws close together for more effective digging. When walking, their heels and wrists don't touch the ground. They walk on their soles, not their toes.

The head is relatively small, on a short, thick neck. The end of the snout is very flexible and has long stiff whiskers, shorter than those on the domestic cat. Their ears are small and can be closed off while digging. The ears are further protected by long, stiff hairs. They have an inner eyelid that covers most of the eye, protecting and keeping it clean. Their upper and lower canine teeth are situated so that they sharpen each other.

Coarse guard hairs hold the badgers' coloring near their tips and are longest on the sides, shortest on the belly. In fact, the belly of a lactating female may be practically naked. They molt in the spring, starting with the felt-like undercoat, and finishing by fall. The young and very old are generally lighter in color.

A scent gland is located just below the tail and just above the anal opening. The musk secreted from this gland is cream-colored and fatty. It is used in courtship and marking of territory. The scent can also be used as a last line of defense, its offensive odor driving off an attacker, or even blinding if gotten in the eye.

Senses. The areas of the badger brain dealing with smell and hearing are large and well-developed, while the vision area is relatively small.

Their most important sense is smell. Smell tells them where they are and who is around. The first thing they do on leaving the burrow is to lift their snout and smell in all directions. When they walk, it's with their nose to the ground.

As they walk they regularly stop to lift their head to smell the air because when smelling the ground that's all they can smell. Often they snort as they smell, as this concentrates scents. They can smell better in humid weather and at night, when the ground temperature is higher than that of the air.

Badgers use their sense of smell to identify other, individual badgers. They depend on smell so strongly when on a path that they an follow that path even when its visual signs have been changed. They have been known to detect the scent of a human up to 11 hours after it has passed by.

Like almost all mammals, badgers an hear higher frequency sounds than humans can. Low frequencies are felt by them as ground vibrations, which will cause them to immediately stop. Cubs up to 12 weeks old are startled by any noise, but after that they become used to sounds they hear regularly and will only be upset by the unexpected.

Since they are almost entirely nocturnal, their retinas are mainly made up of rods, and they have a tapetum. They see entirely in black and white. As might be expected, they avoid bright light. They see shapes and movement, but not detail. An adult can see an outline up to approximately 55 yards away.

Habitat. American badgers prefer dry, open grassland and can live far from water. They can also be found among sparse scrub. In west Riverside county they occur in a low population density of 2-6 per square kilometer (about 1-3 per 123 acres). Each has a range anywhere from 593-2,100 acres, which means they overlap extensively. However, they are very solitary animals (except during breeding season) and do their best to avoid each other. Also, the larger the territory, the vaguer the border lines.

Males (known as boars) have larger territories than females (sows), and expand them even farther during breeding season. All must travel farther during the summer, when food is scarer. While avoidance is the behavior of choice, they do occasionally fight. This is much more common among males, who will defend well-defined boundaries. Females fight mainly in defense of their burrow, especially when they have cubs. Surveys show that most males and half of all females have wounds or scars from fighting with other badgers. The wounds of males are more severe.

Besides secretions from their anal gland, they also mark their territory with feces and urine. Don't expect to find their scat, though, since they mark by smell not sight. Their deposits are more likely than not to be made under a bush or overhanging rock, or inside their burrow.

Because they make their living digging, the type of soil is very important to their choice of habitat. They prefer ground that is dry