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1 October 2000 Birds of Bolivia 2.0
Thomas S. Schulenberg
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Birds of Bolivia, 2.0.—Sjoerd Mayer. 2000. CD-ROM for Windows 95 and higher. Bird Songs International B.V., Wierengastraat 42, NL-9969 PD Westernieland, The Netherlands. ISBN 90-75838-04-2. Ca. $52.00.—South America may be the “Bird Continent,” but learning how to identify South American birds remains a tough slog. Knowledge of voice is critical to identification, but voice is difficult to describe in a field guide. The commercial recordings of Bill Hardy and of John Moore and associates have gone a long way toward meeting this demand, but many gaps remain. One of the more glaring such gaps has been Bolivia, a country with immense diversity in topography, habitats, and birds (more than 1,300 species recorded).

In 1996, Sjoerd Mayer released a CD-ROM, Bird Sounds of Bolivia 1.0, that contained vocalizations from more 500 Bolivian species (see Auk 115:819–820, 1998). The present disk is a greatly expanded version of the earlier product. The number of sounds has been increased to 2,530 recordings from 941 species (and about 19 hours of sound!). A new feature is the addition of photographs (see below). Therefore, an extraordinary amount of new information is included in the revised edition.

The CD-ROM is easy to install (with the option of choosing English or Spanish), and the programs are easy to operate. Clicking on the variety of symbols and underlined text brings up lists of included families or species, photographs or recordings, details on the location of the recording or photo, and additional information.

To me, the most important feature of the disk remains the sound recordings. These selections usually are long, often 30 or 40 seconds, and sometimes longer than a minute. Another nice feature is that there usually are two or more recordings for each species, thus providing many more examples of each species' vocalizations than is standard in other cassette or compact disk compilations. Each recording is identified as to vocal type (usually song or call, sometimes other variations such as alarm calls). Each vocalization also is rated as to quality (“A” through “E”). “A” recordings usually are quite good, with the subject coming through loud and clear with few interfering noises. Many “B” and even “C” cuts are quite good as well. “D” cuts are very few, but based on the one that I listened to (the song of Xiphorhynchus spixii), these probably do not merit inclusion at all, with the target sound buried in the background. I noticed no “E” cuts at all, and I suspect that recordings of quality “D” and “E” primarily are associated with background sounds (perhaps exclusively so for “E”). Many of the recordings are by Mayer, but he has rounded out the selection with cuts from many other contributors. That Mayer has been able to assemble the range of vocalizations presented here without falling back on an established sound archive says a great deal about the volume of tape-recorded material that has been accumulated in recent years by active field workers. We can only hope that all of these recordings eventually are added to an existing collection.

These recordings do a good job of covering the taxonomic and geographic diversity of the avifauna of Bolivia. Suboscines are particularly well represented, with vocalizations of more than 350 (!) species of ovenbirds, antbirds, tyrant flycatchers, and the like. Included on the disk are a good number of rare or poorly known Bolivian endemics such as Bolivian Earthcreeper (Upucerthia harterti), the recently described Bolivian Spinetail (Cranioleuca henricae), Yungas Antwren (Myrmotherula grisea), Bolivian Blackbird (Oreopsar bolivianus), and Citron-headed Yellow-Finch (Sicalis luteocephala). Other recordings of particular interest are those that document the first and second records, respectively, for Bolivia of Rufous-fronted Antthrush (Formicarius rufifrons) and Red-billed Tyrannulet (Zimmerius cinereicapillus). A particular treat in these recordings is that all background sounds are identified as well (and even assigned a quality rating). In a departure from most compilations of bird sounds, some vocalizations of uncertain or unknown identification are presented. Proposed identifications to some of these, in turn, already have been posted on the Internet <>.

A good deal of supplemental information accompanies each recording. The date and often the time of day are given for most recordings. And, not only is the location of each recording provided (with the elevation), but one can call up a map that shows the location of the site, along with brief notes on the habitat(s) present and its geographic coordinates.

The disk contains almost 1,400 photographs, representing more than 750 species. The subjects of the photographs (taken by a variety of photographers, Jon Hornbuckle foremost among them) include both birds in the hand and free-ranging birds. The photographs show the usual variation in quality, ranging from well-lit, close-range, spectacular images (e.g. Sunbittern [Eurypyga helias]) to dark or backlit selections that may serve little purpose (e.g. Yellow-billed Nunbird [Monasa flavirostris]). As with the sound recordings, for most (but not all) of the photographs one can call up a map that highlights the location where the photograph was taken. A surprise is the inclusion of photographs of more than 100 species that have not been recorded in Bolivia. A few of these are known to range to the very borders of Bolivia, so their inclusion here seems reasonable (e.g. Ornate Flycatcher [Myiotriccus ornatus], Chestnut-capped Brush-Finch [Burarremon brunneinuchus]). Most of the extralimital species shown in the photographs, however, do not occur within hundreds of kilometers of Bolivia; that said, this set includes some of the most arresting photographs on the disk, such as a male Marvelous Spatuletail (Loddigesia mirabilis) in flight. For any users who are seriously offended by the inclusion of these photographs, there is an option that will “hide” from view the names of these species.

The disk has two other interesting features. A program that presents a succession of sounds, slides, or slides and sounds in conjunction can be used as a test of one's identification skills or as review (or simply as a treat). In addition, one can open several windows at the same time, which is useful in facilitating comparisons between the sounds or photographs of different species.

The reviewer of the first edition of this disk wrote, “my biggest criticism is that I want more.” Mayer rose to the challenge and has provided much more: more songs, more photographs, the works. Although this may not seem fair to Mayer, it remains the case that “my biggest criticism is that I want more.” For example, perhaps at least some of the site descriptions could be supplemented with photographs of the habitat(s) present; maps, even crude maps, of the distribution of each species within Bolivia could be presented; and the photographs could be supplemented with a little bit of text, perhaps something to call attention to field marks.

These suggestions should take nothing away from my favorable impressions of what Mayer has created: an important tool for anyone interested in the vocalizations, field identification, and distribution of Neotropical birds. Everyone, regardless of level of expertise, will learn something from this disk, and most users will find it a very handy learning tool indeed.

Thomas S. Schulenberg "Birds of Bolivia 2.0," The Auk 117(4), 1087-1088, (1 October 2000).[1087:BOB]2.0.CO;2
Published: 1 October 2000
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