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The Mammals
of Texas - Online Edition
Appendix II.
Observing and
collecting mammals.
Whether to satisfy the interest of the
casual outdoorsman or to fulfill the needs of scientific
research, the observation and collection of mammals are
exciting occupations. Practically all that is needed to
make interesting and useful observations of mammals is a
good pair of binoculars, and the inclination to rise
early and stay late. Unlike birds, most mammals are
either crepuscular (twilight active) or nocturnal (night
active) in nature, making prolonged observation of
behavior, feeding habits, and other aspects of natural
history more difficult. Additionally, many species are
fossorial (dwell underground) and cannot be directly
observed except during the rare and brief moments these
animals may appear at their burrow entrances.
For these reasons, the observation of
mammals is often done indirectly, by evaluating the
tracks, scats, scrapes, rubs, and other such
"sign" that mammals leave behind as evidence of
their activities. Locating sign and drawing accurate
deductions of animal activity is an art that for the most
part has been lost as people rely less and less on
understanding nature to fulfill basic needs.
Nevertheless, "reading sign" is a fascinating
occupation, many aspects of which can be learned simply
through interest and perseverance. Acquiring one or more
of the numerous field guides now available on this
subject will speed up the learning process and allow for
a more complete understanding of the outdoors.
For scientific purposes, collections of
mammals are sometimes made. The collection of mammals and
their subsequent preparation as museum specimens is a
complicated process that often requires a great deal of
equipment and planning. Numerous techniques and types of
traps are available depending on the animals to be taken,
the region studied, and the type of information being
sought. For smaller mammals, such as mice, mouse traps of
the variety that snap shut on the animal can be purchased
in almost every hardware store. However, the larger
"Museum Special" is best because the wire that
strikes and kills the mouse is far enough from the
treadle to keep the head of the mouse from being struck
and crushed. For study purposes, broken skulls are less
desirable than unbroken ones.
The still larger rat trap is stocked in
most hardware stores and is suitable for taking animals
the size of wood rats and small ground squirrels. Steel
traps in sizes 0 to 4 are used in many areas to secure
other animals. McAbee gopher traps are the best yet
devised for taking pocket gophers. Several mole traps are
on the market; the stabbing variety is preferred by most
collectors.
Many specimens are most effectively
taken by shooting. For smaller and medium-sized kinds, a
shotgun is recommended but shot of small size should be
used in order to avoid unnecessary mutilation of the
animal. Nets of silk or nylon may be useful to the mammal
collector, especially in capturing bats. Pitfall traps
are often set for shrews by burying a can up to the rim
in mammal runways and other likely spots.
In addition to traps that kill the
mammal, numerous styles and sizes of live traps are
offered for sale by various manufacturers. These include
the popular "Sherman" live trap frequently used
for mouse and rat-sized mammals, up to the equally
popular "Havahart" traps useful for capturing
raccoon-sized mammals. Large drive nets, drop nets, and
similar traps, often used in conjunction with other
equipment such as helicopters and immobilizing drugs, are
used by specialists to capture larger mammals for study,
such as deer and even elk.
Properly preparing mammals as museum
specimens requires skill, patience, and training. The
labeling, skinning, and stuffing of mammal skins, as well
as preparing skeletal material, are demanding, sometimes
tedious tasks that require attention to detail and a lot
of practice. Several handbooks and guides are available
to introduce the mammal enthusiast to this necessary
aspect of mammalogy.
For safely storing prepared mammal
specimens in accessible fashion a museum cabinet that
excludes insects, dust, and light is essential. A visit
to the nearest museum known to maintain a collection of
study specimens of mammals, or a letter of inquiry
addressed there, will yield all needed information about
the type of container best suited to the needs of the
collector. Advice concerning the preparation of mammals
as specimens, including the preparing of skins and
cleaning of skeletal material, can be obtained from the
same sources.
The trapping of mammals, even for
scientific purposes, requires a scientific collecting
permit. Every state has its own laws relating to hunting
and trapping, and the collector should obtain and read
these laws so as to carry on collecting in conformance
with the law. In Texas, scientific collecting permits are
issued by the Texas Parks and Wildlife Department; advice
and clarification on collecting regulations can also be
obtained from this department. Collecting on federal
lands, such as national parks and monuments, requires a
permit from federal authorities. Government personnel at
the site to be studied should be contacted for
information on obtaining federal collecting permits. Of
course, if mammal collecting is to be done on private
lands the permission of the landowner is also required.
Next to conducting mammal collection
and observation activities in a lawful and responsible
manner, the most important obligation of the mammalogist
is to take accurate and complete field notes. Only in
this way can new information eventually be provided for
the benefit of others. Field notes can usefully be
divided into a catalog of specimens, itinerary or
journal, and accounts of species. For convenience all
three sections of the notes ordinarily are kept in a
single binder, but separate binders may be used. Enter
the name of the collector and the year in the upper
left-hand corner of every page but far enough from the
margin to permit binding of the pages. Each page should
be filled before another page is started.
In the catalog, all specimens of
vertebrate animals should be given consecutive numbers.
Never repeat a number; for instance, do not begin a new
series each year. One line of the notebook page should be
devoted to the precise locality. Include airline distance
from some well-established town. Include also elevation,
county, and state. Devote one line to each specimen. If
not a conventional specimen, indicate the nature by entry
directly above the field number whether (if)
skeleton, skull-only, skin-only, or alcoholic. Toward the
end of line it may be desirable to enter, on occasion,
color of iris and soft parts. Use the vernacular name of
the species if you are not sure of the scientific name.
On the first line of the itinerary
enter date and locality. Follow with a concise account of
route and travel area and habitats studied, and record
number and kinds of traps set, distance between traps,
number of vertebrates collected, as well as other
pertinent information. For example, record number of
traps set in each type of vegetation and numbers and
kinds of animals caught therein. Section, township, and
range comprise useful information.
Accounts of species should be headed
either with the scientific or common name, as preferred.
The date and locality for the account should be given on
the first line. Only one species should be written about
on a single page. Information in the account should not
be a repetition of material given in the itinerary or
journal. Include not only facts but also interpretations
and generalizations. The accounts should be written in a
style suitable for quoting in any publication. Accounts
of species need not be restricted to kinds collected. If
the account is about animals collected it is wise to
refer to the animals by your field numbers.
Head each and every notebook page with
collectors name and year, page number (if number
system is used), locality (in detail the first time
used), and date. Write full notes, even at risk of
entering much information of seemingly little value. One
cannot anticipate the needs of the future when notes and
collections are worked up. The following are suggested
topics, but do not restrict yourself to these alone. Be
alert for new ideas and new facts. Special data sheets
may be helpful.
Describe vegetation (saving plant-press
samples of species not positively known), nature of
ground, slope, exposure, and drainage in each belt of
animal life sampled. Describe exact location of trap
lines, referring to your topographic maps, and also enter
a sketch, in profile or surface view or both, to
illustrate the location and relations of the different
habitats crossed. Properly marked maps for each region
worked should ultimately be bound in with the field notes
of at least one member of your field party.
Keep record of closeness of settings of
traps, distance covered, and results of each nights
trappings; give number and type of traps put out in each
habitat and number of animals of each species captured in
each habitat (whether or not preserved). It is advisable
to record the sex, age, and breeding condition of each
animal. We have found special data sheets helpful.
Keep full record of breeding data;
number and approximate size (crown-rump length) of
embryos, or of young found in nests. Dig out burrows if
practicable; make drawings to scale, plan, and elevation;
describe fully.
Record food plants; keep specimens for
identification where not known by a definite name;
preserve contents of cheek pouches and stomachs. If these
are not saved, identify and record contents.
Note regularly in notebook all
"pick-up," that is, odd skulls or fragments of
animals of whatever sort or source, serially numbered
along with specimens of the more usual sort. Give full
information, as with odd skulls secured from trappers.
Label all such specimens adequately, as elsewhere
described.
Keep frequent censuses of diurnal
mammals, with habitat preferences indicated. These
censuses, if short, need not be entered on formal census
sheets. When leaving a well-worked locality, enter a
summary of species observed, with remarks of a general
nature, such as relate to local conditions of terrain,
human activities, and other pertinent conditions.
Where feasible interview residents,
trappers, state wildlife biologists, National Forest and
National Park rangers at each locality visited. Always
record accurately the name, official position, or
occupation and address of each person giving information;
give also your opinion as to his/her reliability. Note
general attitude of person interviewed as to game laws,
conservation, and effects of settlement by man, and
record specific comments, complaints, and criticisms.
Ascertain present numbers and
distribution of large mammals as compared with former
status. As far as possible get definite statements
expressing ratio of abundance now, compared with a
definite number of years back. Seek such information
where feasible, by indirect query. Do not risk
influencing your informants statements by leading
questions. Record fully all evidence as to human
influence upon original or "natural" balance.
Record present economic relations of vertebrate animal
life; that is, effect on agriculture and stock raising,
with full details. Note opinions of persons interviewed
as to whether species should be protected or destroyed.
Describe local methods of capture or destruction; give
your opinion as to their effectiveness and justification.
Opportunity offering, record detailed
observations on effects upon mammals of severe storms;
floods; forest, brush or prairie fires; overgrazing; tree
cutting; road-building; or tree-planting.
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