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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 collector’s 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 night’s 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 informant’s 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.