Petrels Night and Day by Magnus Robb, Killian Mullarney and The Sound Approach (iBook edition)

For many the subject matter of the latest iBook from The Sound Approach team will be uncharted territory, although some birders may have as a benchmark for petrel calls a visit to a ringing session with an ear-splitting European Storm-Petrel tape vibrating through an audio system at decibel levels normally found at a Motörhead concert.

I'll admit to watching the download of Petrels Night and Day thinking that maybe this time those guys have gone too far, pushed so far into a niche that there will be little that resonates for the average birder. Then I read Magnus Robb's preface — "Nothing I have experienced is as intoxicating as total immersion in a petrel colony at night" and "Petrels Night and Day is a celebration of hidden diversity" — plugged in the earphones, and closed my eyes.

At the sound of the wings passing close and then the first slow moans of Zino's Petrel, I was taken out of body to a darkness-enveloped mountainside in Madeira. This is The Sound Approach secret: gently coaxing you on a journey into a new world, filling your ears with sounds you have never imagined and guiding you flawlessly to understanding. Magicians or alchemists, blending words, sounds and perfect pictures into a mind-expanding trip that leaves you addicted and seeking another hit.

From the barking of Bulwer's Petrels to the crying Cory's Shearwater chicks, Petrels Day and Night shares the authors' experiences and exploration of 21 petrel species through a rich soundscape crammed with hidden meaning. Beautifully written and illustrated, supported by the slick tech that allows every sketch to be enlarged and sonogram explored at a click or finger swipe and personalises the experience with user-generated notes, it is yet another extremely impressive product.

In keeping with previous offerings, there is some cutting-edge material such as the call differences between Boyd's Shearwater and Barolo Shearwater and the probable separation of male and female Boyd's based on call pitch. In fact every chapter throws up interesting depth and detail.

Touch-screen technology was made for The Sound Approach; throw in adventures on the high seas, intricate and thorough analysis of the vocal outpourings of an enigmatic group of ocean wanderers that only occasionally offer glimpses of a life utterly wild, and Petrels Night and Day will draw you in, amaze, inspire and make Sound Approach disciples of you all — if you aren't already — in equal measure.

More information

• Petrels Night and Day by Magnus Robb, Killian Mullarney and The Sound Approach (iBook edition, The Sound Approach, Poole, 2015).
• To view this book, you must have an iPad with iBooks 2 or later and iOS 5 or later, an iPhone with iOS 8.4 or later, or a Mac with OS X 10.9 or later.
• £19.99. Download from iTunes: bit.ly/bw281PetrelsNightDay