Making Animal Sound Recordings

Making animal sound recordings An introduction to the science-- and art--of recording and annotating bird and other animal sounds by Richard Bradley• Introduction Nearly all early work in bioacoustics, as well as much of the current literature, deals with three major groups; insects, anuran B IOACOUSTICS,has come intothe activestudy of focusanimal relatively sounds, amphibians,and birds. A quick tally of papers recently. Although some valuable work was dealingwith acousticcommunication in birds done on a variety of species prior to the demonstratesthe rapid growth in this field 1940s, most of the research in this field (Fig. 1). With the tape specimensin hand, beganwith the introductionof easilyportable workerscan carefullyand objectivelyanalyze soundrecording equipment in the mid-1950s. acoustic signals used by animals for com- munication. Currently, work in bioacoust•cs isexpanding rapidlyinto almost everytaxon 300 - and most environments. New recording equipment has opened up the underwater acoustic environment as well as the ultra- sonic and subsonicranges. Amateurs as well as professionals are 200- producingan increasingnumber of new recordings,many of which have great poten- tial value. Unfortunately, few workers are careful to include all pertinent data neces- sary to complete a specimen. This paper 100- is meant to serve as a guide for both the serious student and the casual recordist to insure that their recordings are valuable scientificspecimens. Many people are familiar with recordings 44-48 49-53 54-58 59-63 64-68 69-74 of animal sounds now available on commer- YEARS cially publishedphonograph discs. Although Figure 1. Growth in bird song research as indi- cated by the number of technicalpapers published x Associate in Natural Sciences, Florida State since 1944 Museum, Gainesville, Fla 32611 Volume 31, Number 3 279 these discs perform a useful service, they stantly changingtheir machinery and tech- are of secondaryimportance to scientific niques to conform to the flux in the "state investigators. Most of them are produced of the art" in electronics. This does not from recordingshoused in various private mean that others limited to less sophisti- and institutional sound archives, and are cated equipment cannot produce valuable usually presentationsof typical examples of recordings. On the contrary, excellent re- well documented sounds. Perhaps the most cordings can now be made by the serious famous sound archive, established by Peter amateur on equipment that is readily avad- Paul Kelloggand Arthur A. Allen, is housed able on the retail market for under $300. at the Laboratory of Ornithology, Cornell Two basic types of tape recorders are in University. Many other fine archives exist, use today. One type uses nalTOW(¬ in.) and scientificanimal sound specimencollec- magnetic tape enclosed in a sealed unit tions have mushroomed in recent years. A called a cassette (not to be confusedwith preliminary list of sound specimencollec- a cartridge). Another type usestape threaded tions is presentedby Boswall (1974). Sound between two separate plastic reels, and is specimensare cataloguedin the samegeneral usually referred to as open reel or reel- way as in otherscientific collections. Complete to-reel recorder. I will discuss the relative recordingdata are kept with the specimens, characteristics of these two groups below. including notes on the specific behavioral Although investigatorsoccasionally make re- context in which the vocalization was given. cordings of their subject in a laboratory, The material in sound archives is used this paper deals with equipment and tech- by investigatorsin a variety of fields in- niques for work in the field. In addition cluding ethology, ecology, taxonomy and to the many different tape recorders, an evolutionary biology. Although hundredsof equally confusingalTay of microphonescan field recordists have recorded miles of tape be used in bioacousfics. The specific type specimens,much basic information remains of recorder and microphone appropriate for to be documented.In fact, sound specimens any given situation depends upon the type have probably been obtained for fewer than of organism being recorded as well as Its half of the known speciesof birds, the best surroundingenvironment. documentedtaxon. The vocal performances Naturally most workers would like to pro- of myriads of tropical insects, amphibians duce "clean" recordings of an organism's and mammals are totally undocumented. sound, i.e. without extraneous background Recorded specimensfrom aquatic animals noise. However, some noise is usually un- are barely represented.Many of these forms avoidable. In fact, weak recordings of a have complex and interesting acoustic be- rare phenomenonare often more valuable havior. Amateurs can perform a valuable than beautiful clear tapes of more common service by contributing well documented sounds. The use of modern laboratory audio recordings of animal sounds to scientific equipment can often transform so-called collections. "useless" recordings into valuable speci- [Definitions of technical terms italicized mens. m the text may be found in the glossary, Field Notes page 285]. General Methods UTTINGperhapsDATAthe singleWITH most a important specimen step is in bioacousticrecording. It is critically im- RACTICALLYwork in bioacousticsSPEAKING involvesALL MODERNrecord- portant that as much data as possiblebe lng of animal soundsonto magnetic tape. recorded onto the tape at the time of re- The great variety of tape recording equip- cording.In this way the actual specimenand ment now available ranges from barely associateddata are physically linked and suitable to highly sophisticated.The type of confusion or transcription errors are far equipmentused dependstipon convenience less likely. Some identificationinformation of operation,portability as well as monetary should be included on the tape to avoid hnutations. Professional recordists are con- confusion, although notes put on a tape may 280 American Birds, May 1977 often be supplementedby written field notes. TapeRecorders Objections to this technique involve "wast- lng" tape for voice comments by the re- HE TWOBASIC TAPE systems used •n cordist, but experience with reels of "no bioacoustics are the cassette and open data" recordings has convinced me of the reel systems. Cassette recorders have been importance of putting data on the original shunned for many years for high quahty field tape. recordings because of several inherent prob- The minimum data that should be re- lems. corded on the tape includes: the name of Early cassettemachines had several d•sad- the organism, the location, date, time and vantages. The most important was the slow weather data where possible. Additionally, tape speed which is used for all cassette it is important to add notes on the context recorders--1.5 inches per second (ips). The of the vocal behavior. In some cases a upperfrequency responsewas usually limited statement like "singing from the top of a to about 8000 Hz. Tape speed control was bare tree" is sufficient. In other cases a also poorer than open reel machinesoperat- description of a particular display or inter- ing at higher speeds. The thin tape used •n action may be more appropriate.The more cassette recorders often resulted in a poor relevant data that are included, the more signal-to-noise ratio. These two problems valuable is the specimen. Most recordists have been largely eliminated in cassette will not wish to •'talk on top of" their technology,and modem high quality portable recordings. Unless one has the facility cassette decks are available that y•eld for recording a separate voice track simul- superior results. These are often more com- taneously, it is customaryto wait for a pause pact and convenient than the standard open •n or the end of a recording for notes. A reel machines. short note giving the name of the organism One important factor in this improvement •s often inserted near the beginning of a has been the development of chromium particular cut. This will aid during the dioxide cassettes. The chief complaint re- cataloging procedure. maining is that cassette tapes are difficult Use of an organism's scientific name is to edit compared to open reel tapes. Open preferred over its common or vernacular reel machines are usually heavier and less designation. If the vocalizer is not seen, convenient to operate. The finest open reel th•s should be noted because, at least in machines still maintain somewhat superior the case of birds, imitation is often a pos- quality to the best cassettemachines. sible source of misidentification. The loca- When selecting a tape recorder one must non should be described as the distance and balance quality and convenienceagainst eco- d•rection from a town or city, or other nomic factors. In general, inexpensive open geographic landmark, or coordinates. The reel machines give better performance than country, state and county should be in- inexpensive cassette machines. RelaUvely cluded where appropriate. Weather data inexpensive cassette recorders such as the should indicate sky and wind conditions Sony C-108 (ca $150) are probably the and air or water temperature. In the case best bet for the occasional recordist. For of amphibians it is particularly important more serious investigators who wish to have to take temperature readingsfrom the water good quality at a reasonable price, the ff the subject is partly submerged. Uher 4200 (ca $675) and Tandberg II (ca For conveniencea shorthandnotation may

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