5. Equipment and field recording

There are many problems to overcome in making good wildlife sound recordings in the field and some special equipment and techniques are necessary.

Most animals are difficult to approach closely enough to record their utterances with an ordinary hand-held microphone. This can be overcome by carefully placing the microphone, which is connected to the recorder by a long lead, near the spot where the animal is expected to utter its sound, such as by the song-post of a bird. Another method is to use a parabolic reflector, which concentrates the sound waves and reflects them onto the microphone, thus effectively amplifying the sound.

Extraneous noise is usually an inherent problem when trying to record any particular sound in an outdoor environment. The amount of background sound may be considerably reduced by the use of the highly directional parabolic reflector, which excludes most of the sound emanating from other than the direction of aim of the parabola. Another directional device is the gun microphone, which similarly excludes sounds other than those coming from a narrow frontal arc. An ordinary directional microphone close to the subject is ideal where possible. The unwanted noise caused by wind is a frequent problem, but there are some fairly effective windshields that can be fitted to the microphone to reduce this.

Field recorders need to be high quality, light-weight, reel-to-reel portables and the choice is limited to the very few machines in the Nagra and Uher categories. Monitoring by headphone is essential and the recorder, preferably, should provide this facility directly offtape. Since wildlife sounds cover a very wide range of frequencies, the equipment's frequency response must be the widest possible (ideally 20 to 20,000 Hz.). Finally, as many animal sounds are of a low level relative to the ambient noise, it is often necessary to use a high gain setting in order to record them loud enough. For this reason it is important the recorder should have as high a signal-to-noise ratio as possible.

For outdoor use microphones need to be robust, have high sensitivity for comparatively low level sounds and a good frequency response. Only dynamic (or moving coil) and capacitor (or condenser) microphones are suitable for fieldwork.

There are particular problems and equipment requirements in some types of wildlife recording, such as that of the ultrasonics of bats and underwater creatures, for which specialist advice should be taken.

As a minimum for fieldwork, the archive will need to have two recorders (preferably Nagras), one directional and one omnidirectional microphone, a gun microphone, a 20 or 24-inch parabolic reflector and monitoring headphones. For archive work (copying, editing and 'processing' recordings), three studio recorders with ancillary equipment and playback machines for discs and cassettes are minimum requirements.

For field recording, long-play tape is probably the best type to use with most portable recorders, although the use of standard-play has the advantage of also being suitable for storage if the original material is being archived.

The special problems, and the requirements for overcoming them, are a considerable hindrance to the acquisition of good quality wildlife recordings. For most scientific purposes, and indeed for most other uses, it is essential that recordings are of high quality, free from distortion and obtrusive extraneous sounds. The very highest technical standards must be aimed at. For more detailed information the reader is referred to the technical chapter and bibliography in this book.