By Vincenzo Penteriani and María del Mar Delgado
Poyser (Bloomsbury), 2019
Hbk, 368pp; eight colour plates, many black-and-white illustrations and figures
ISBN 978-1-4729-0067-8; £60.00
Given that the Eagle Owl Bubo bubo is one of the world’s largest owls and occurs in most Western Palearctic countries, it comes as something of a surprise that this is the first book dedicated to it. These authors have brought together everything that is currently known about the species from studies across its range, not least from their own research, spanning 30 years in Spain, Italy, France and Finland.
Having outlined the species and its many races from western Europe to eastern Siberia, the authors provide extensive details of distribution and population density in each country, including the UK. In some cases, populations have been augmented through official and unofficial releases, and as a result the species has returned to countries such as Denmark and Luxembourg from which it had been extirpated. The evidence suggests that Eagle Owls once formed a part of the UK’s avifauna, and perhaps the tiny population of escapees and released birds will eventually spread. After widespread declines in Europe in the last century due to falling Rabbit Oryctolagus cuniculus populations, numbers are now increasing in Spain, France, the Netherlands and Belgium, still decreasing in Finland, Switzerland and Russia, while in many countries the population trend is simply unknown.
There is a chapter assessing the diet of Eagle Owls, and those who thought they ate just Rabbits and Hedgehogs Erinaceus europaeus may be surprised to learn that around 800 prey items have been recorded. The authors investigate interspecific interactions with other birds and describe the breeding year. Causes of mortality are explored – Eagle Owls are frequently electrocuted on power lines, and sadly still widely persecuted. Eagle Owl territories are often difficult to locate so it is surprising to learn that the authors have found them breeding at high densities in southwest Spain with as many as 40 pairs per 100 km2.
This is a species that avoids dense forest and prefers relatively open country, and although birds generally avoid living alongside humans there are some locations where they have moved into cities, often because of the plentiful rodent prey associated with rubbish dumps, and can be found nesting on buildings. The book explores all aspects of the species’ life, including the breeding process, nest success, home-range behaviour and post-breeding dispersal. There are chapters on visual and vocal communication, and the significance of the white feather patches below the bill and on the breast in visual signalling is explored; apparently the owls call more when their throat patch contrasts most with their surroundings.
There is a huge amount of detail in this book and the authors are thoroughly rigorous in their approach to reporting what is known. The text is quite dense (with few paragraphs, and some of more than 1,000 words), but the authors have brought together a huge amount of information, drawing on more than 1,300 references, of which they were involved with almost 60. This book provides the background to the success of Eagle Owls in a world where the odds are often stacked against them.