The photographic equipment consisted of a digital Canon 20D camera with an EF 200 F2.8L lens and an EF 300 F2.8L IS lens.
The mp3 files available for download from this site were generated with lame version 3.97 and 3.98.
Apart from the mobile hides, I also have hides in permanent positions. An example is shown here.
Sometimes, bait was used to attract birds to the vicinity of a hide. For doves and finches, seeds were scattered on the ground. Vultures were lured with sheep intestines.
Species were identified visually, by combining visual and acoustic clues, or by their vocalizations alone.
I found the following books most useful for species identification:
For Passeriformes: "The Birds of South America", by Ridgely and Tudor, vol. 1 (1989), and vol. 2 (1994); later substituted by "Field Guide to the Songbirds of South America" by Ridgely and Tudor 2009; also "Handbook of the Birds of the World", vol. 8 and vol. 9.
For Cerrado birds: the new field guide by Gwynne et al. 2010.
See also References.
Many thousand sound recordings of Brazilian birds can be found in the websites wikiaves and xeno-canto. Both sites were tremendously useful. To identify unknown voices, I frequently use the Pai-Luiz-system, a computer program which proposes IDs based on similarities between a template sonogram, and sonograms with known IDs from a database. I started developing this system in 2009, and a preliminary version of Pai-Luiz was available from September 2010 to November 2010 on xeno-canto. At present, Pai-Luiz runs only on my home PC, awaiting further development.
Most software used in this project is open source software, gratis and easily available. Digital picture processing was done with the gimp. Acoustic data were processed with the wavesurfer, a free sound editor from the Center for Speech Technology, Stockholm, Sweden; with the standard linux programs lame and sox; and, until 2009, also with Raven Pro (the only comercial package used), by Cornell Lab of Ornithology. Spectrograms were generated with Raven Pro or wavesurfer.
The web pages were created and maintained on a linux system (OpenSuSE with KDE), directly in HTML, with standard unix tools (vim, bash scripts) and perl. I use a mysql database as a register of the bird species. Many thanks to the Open Software community for their excellent systems and programs.
My standard browser, for site development and testing, is firefox, and apart from this, I have only tested with Microsoft Internet Explorer (more or less recent versions) and a little with Chrome. No testing was done with other browsers, mainly because of time constraints. If you find bugs, please notify me (contact).