An Automatic Bat-Collecting Device

Abstract

Previous methods of collecting bats are satisfactory in many situations, but each has inherent limitations in usefulness. Shooting requires considerable experience and produces damaged or dead specimens. Nets of the insect-catching variety (Lyman, 1926) and modifications of the same produce only one bat per thrust in most situations and are usually effective only in close quarters. Gill (Jackson, 1926) are useful in some instances, but Japanese mist nets (Dalquest, 1954) are particularly effective. However, the latter require constant attention, for captured bats quickly become entangled, requiring considerable time to extract them, and if unattended, the net is soon damaged by bats that attempt to and frequently succeed in escaping by chewing their way to freedom, producing gaping holes in the net. My experience has shown that, if large numbers of bats are captured at one time, the bats and net become a hopelessly entangled mass. Griffin (1940) described the use of tunnel nets and metal or celluloid cylinders for capturing bats as they leave small openings in buildings, and he introduced the use of smooth-sided trap receptacles for housing captured bats, eliminating the necessity of cage doors. Similarly, the author has used glass or plastic sheets, placed in a vertical position at building roost exits, such as Spanish tile roofing openings; bats strike the obstruction and slide into a smooth-sided container below. Borrell (1937) captured bats by tripping them with taut wires, arranged horizontally just above the water surface of open water tanks, from which flying bats drink by scooping mouthfuls of water. This remarkable method requires constant attention, or the bats will escape or drown. Bats may be extracted from roosts with long forceps, a hooked wire, or by hand. Numerous modifications of the above procedures, as well as less satisfacto y techniques, have been employed. T ese methods, each being desirable under certain circumstances, lack ad ptability to all situations, and none fully satisfie the need arising when thousands of flying bats must be captured unharmed in pen space or in such places as large cave entrances. Furthermore, most of these techniqu s require considerable experience in the field and the presence of an operator. The discovery of bat rabies in the United Stat s (Venters, et al., 1954) and subsequent developments in this field stimulated the author to devise an automatic