The Amazon basin is the largest tropical rainforest in the world covering almost 40 per cent of the South American continent. For centuries, its vastness and inaccessibility have been protecting this area. The general belief is that the Amazonia region has unparalleled biodiversity which means that one in five of all bird species known in the globe lives in the Amazon Jungle. The author is testing this claim against the known occurrence of the world owl species. There are fewer owl species in Amazonia than expected namely 34 (against 54 expected). Two possible reasons are that our knowledge of the Amazon region species is still incomplete as may be indicated that new owl species have been found recently. The other reason could be that the rainforest is not after all the most wanted biotope for many of the owl species which often depend on the prey available in the bottom tier of the forest which is flooded during the wet season. Whatever the reason is, more detailed research is needed on all species of the Amazon region as there must be many new owls and other animal species out there waiting to be discovered. We have no idea how many of those new species have been or will be lost due to the rainforest destruction before they can be discovered. Therefore, it is necessary to stop deforestation in the Amazonia, be it due to forest logging, uncontrolled fires (often deliberately set) agriculture expansion or industrial development. Deforestation is not the only reason that the Amazon basin is changing. The rainforest suffers also from the global climate change when the higher temperatures reduce the rainfall in the tropical Atlantic region, causing drought and increasing the fire susceptibility of the rainforest. Luckily the owls are not so sensitive to surrounding forest cover as many other tropical forest-dependent bird species, like the large-bodied avian frugivores. Impacts of forest fragmentation on owls will need additional research.
- owl species
- number of wildlife species
- climate change
The history of geology tells us that at one time Amazon River flowed westward when it was still inside the Gondwana continent and part of the proto-Congo River system . Later the African and South American continents separated and the Atlantic Ocean widened enough to provide a moist and warm climate to the Amazon region. The rainforest formed during the Eocene era between 56 and 34 million years ago . The Andes have formed 15 million years ago and some 5 million years later the Amazon River began to flow eastward .
Now the Amazon River is the largest of the world’s rivers in terms of water volume discharged into the sea, carrying more than five times the volume of the Congo River or twelve times that of the Mississippi River . The Amazon River basin covers almost 40 per cent of the South American continent and the main river is some 4080 miles long, second only to the River Nile in length . The Amazon river and its 1100 tributaries have a drainage area covering 2.7 million square miles belonging to nine nations: (the percentage share of each nation is shown in brackets) Bolivia (7.7%), Brazil (58.4%), Colombia (7.1%), Ecuador (1%), French Guiana (1.4%), Guyana (3.1%), Peru (12.8%), Surinam (2.5%) and Venezuela (6.1%) . Even in this book, the percentages vary as the perceived extent of the Amazon depends on the definition. Often people as well include areas outside the basin and that biogeographic Amazon ranges 3–3.2 million sq. mi, of which just over 80 per cent is forested . Whatever definition is used the Amazon basin has the world’s largest rainforest, bigger than the next two largest rainforests – in the Congo River basin and Indonesia – combined. The moist broadleaf forest comprises an estimated 390 billion individual trees representing some 16,000 species . Billions of trees pump daily huge quantities of water vapour into the atmosphere. A large part of this water rains down locally, but part of this moisture is carried in the air to other areas including the agricultural heartland of South America. It has been estimated that two-thirds of Brazil’s national product comes from the areas that receive Amazon rainforest generated rainfall .
It was for a long time a general belief that the Amazon rainforest has been always only sparsely populated by the humans due to the poor soils. Recent archaeological findings, however, suggest that the Amazon was earlier densely populated and that up to 5 million people were living in the region in 1500 AD. However, by 1900, the population had fallen to one million and by the early 1980s, it was estimated to be less than 200,000. Indigenous civilizations were devastated by the spread of new diseases like smallpox and typhus after the arrival of the first Europeans, in 1542 and after . The UK broadcaster BBC 4 presented evidence that the Amazon rainforest has been shaped by humans for at least 11,000 years through activities like forest gardening and’terra preta’ indigenous soil management, instead of being only a pristine wilderness . In recent decades the human population has accelerated and incoming people have introduced mechanised agriculture and integrated the region into the global economy. Large quantities of the Amazon-produced commodities like cattle beef and leather, timber, soy, oil and gas, and minerals are sold to China, Europe, Russia and the U.S. .
The wet forests in Amazon have consistently higher species diversity than any comparable forests in Africa and Asia . The Amazonia Region is home to a large collection of living plants (40,000 or more) and animal species in the world. However, Table 1 above shows considerable discrepancies in the stated species diversity.
|Number of plants/and animal group species||Butler/Mongabay|
|Wikipedia ||WWF ||Ascent of the Amazon |
|Plant species||40,000||At least 40,000||40,000||Na|
|Mammals||430+||427||427||More than 1400|
|Amphibians||1000+||428||Over 400||More than 1000|
|Invertebrates||Na||96,660 – 128,843|
|Insects||Na||2.5 million||Na||90% of all animal species are insects|
The largest discrepancies seem to be in the numbers of mammals and amphibians whilst the number of birds and reptiles is relatively uniform. It is possible that the highest numbers represent the number of South American species in its entirety and not just in Amazonia.
It has been said that one in ten known species in the world occurs in the Amazon region and one in five of all bird species are found in the Amazon rainforest . The author knows best “Owls of the World”  and compares here how these statements hold for the world owls.
2. Material and methods
The history of owls in the Amazon region is far less known than that of human history. Fossil records of the Amazon owls are very few if any  so we do not know what kind of owls lived in the region before the present species. Even today, Amazonian owl species are not well known, and few studies have focused on the species from the region (see [14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24]. In the nine countries sharing the Amazon basin the number of owl species is on average 22 species ranging from 13 to 30 per country (Table 2).
However, it is important to note that only part of the above-listed owl species lives in the Amazon basin of that country. In the following, the scientific names are in the same form as in the “Owls of the World”  to avoid the complicated taxonomic discussions. In Bolivia, the tropical lowland evergreen forests are found in all the Amazonian ecoregions of the country. They represent the habitat with the second highest diversity of owls, with the following species:
Unfortunately, there is no available specific study on owls in Guyana, Peru and Venezuela. Also in the French Guiana and Surinam the total of 13 and 15 owl species sounds very small and it is equally not well defined which owls live in the Amazon basin of the country.
The occurrence of different owl species in the comparison of this chapter is based entirely on the latest known distribution maps [12, 13] and no new field research was undertaken in the region. Therefore, especially in the Andean region, it was not so easy to decide which “Pacific side” owls may or may not belong to the Amazonian fauna. As all these owl distribution maps are still in a state of flux so one can expect that the total numbers may hold up very well as any mistakes have most likely been made in both directions.
There are some 268 owl species in the world  and as Table 3. shows that a new Pygmy Owl (yet to be validated) has been discovered by Luis Fabio Silveira, Curator of Birds at the Museum of Zoology, the University of São Paulo by its call during an ongoing expedition to the Neblina National Park area, in Brazil. Provisionally this new owl has been named the ‘Neblina Pygmy Owl’ . That brings the total of the world owl species to 269, so 34 species listed for Amazonia represent 12.6 per cent. Similarly, 88 owl species of the world lives in the Neotropical zone of the world. This is 32.7 per cent of the world species. Amazon Region owls make 38.6 per cent of the Neotropical owls, respectively [12, 13]. There is only one owl species that has been nominated due to the region as Amazon Pygmy Owl
|1. American Barn Owl |
|2. Tropical Screech Owl |
|3. Maria Koepcke’s Screech Owl (Koepcke’s Screech Owl) |
|4. Peruvian Screech Owl |
|5. Rufescent Screech Owl |
|6. Cinnamon Screech Owl |
|7. Cloud-forest Screech Owl |
|8. Northern Tawny-bellied Screech Owl |
|9. Southern Tawny-bellied Screech Owl |
|10. Roraima Screech Owl (Foothill Screech Owl) |
|11. Rio Napo Screech Owl |
|12. White-throated Screech Owl |
|13. Great Horned Owl |
|14. Magellanic Horned Owl (Magellan Horned Owl or Lesser Horned Owl) |
|15. Spectacled Owl |
|16. Band-bellied Owl |
|17. Mottled Owl |
|18. Rufous-banded Owl |
|19. Black-and-White Owl |
|20. Black-banded Owl |
|21. Crested Owl |
|22. Amazonian Pygmy Owl |
|23. Ferruginous Pygmy Owl |
|24. ‘Neblina Pygmy Owl’ |
|25. Subtropical Pygmy Owl |
|26. Andean Pygmy Owl |
|27. Yungas Pygmy Owl |
|28. Chaco Pygmy Owl (Tucuman Pygmy Owl) |
|29. Long-whiskered Owl (Long-whiskered Owlet) |
|30. Burrowing Owl |
|31. Buff-fronted Owl |
|32. Stygian Owl |
|33. Striped Owl |
|34. Short-eared Owl |
Based on the assumption that one in five, i.e. 20 per cent of the world owl species should live in the Amazon Region we can see that the rainforest has twenty species less (34
|Compared with other avian groups, owls are difficult to study||[13, 38, 39]|
|Studying them is a challenge because.........|
Owls are typically not covered by land bird monitoring programmes because of
|they are uncommon|
their low densities
|nocturnal habits||[13, 38]|
|usually go unnoticed|
incomplete detectability or false absences
|and live in places difficult to access|||
The second reason could be that the rainforest may not be the most ideal biotope for many of the owl species which often depend on the prey available in the bottom tier of the forest which is flooded during the wet season. The wet rainforest prey availability and catch-ability can be very different from the dry forest environment. In Ecuador, it has been noted that owl diversity is higher in forested ecosystems than in open areas and in humid forests than in dry forests. However, even in Ecuador the Pacific lowlands harbour more species than the Amazon lowlands  somewhat supporting my second reason. It gains further support at the end of the conclusions.
More detailed research is needed on all species of the Amazon region. Only a small percentage of the basin’s plant life has been documented or studied for their potential medicinal value . Much of the ecology of this ecosystem remains unknown, and one can suspect that there must be many new owls and other animal species out there waiting to be discovered. It may be the only area in the world where you can still hope to find a new owl species, as the recently found and not, yet, officially described new