Deep in the Amazon rainforest, in southeastern Peru, lies the Tambopata River, located in the department of Madre de Dios, a large tributary of the world's longest river, the mighty Amazon. The department of Madre de Dios, with its diverse regions, is the most biodiverse place on the planet and has such popular exotic species as the jaguar, the giant otter or the harpy eagle.
However, in the case of Tambopata there is one animal for which this magical land is most famous... the macaws. These large, colorful and charismatic birds have long captivated the attention of tourists and researchers, attracting people from all over the world to marvel at their beauty and better understand their fascinating way of life. In my opinion, Tambopata is undoubtedly the macaw capital of the world, as the combination of the region's proximity to the Andes Mountains and the bird's need to forage through clay licks means that macaws can be seen in greater variety and numbers here than anywhere else in the Neotropics.
There are six species of macaws that can be found in Tambopata. They are the red-and-green macaw (Ara chloropterus), the scarlet macaw (Ara macao), the blue-and-yellow macaw (Ara ararauana), the chestnut-fronted macaw (Ara sevrus), the red-bellied macaw (Orthopssitaca manilatus) and the blue-headed macaw (Primolius couloni).
Programs such as Wired Amazon and the Tambopata Macaw Project promote the care, study and observation of this beautiful animal, which we will discuss below.
Scarlet Macaw flying by Paul Bertner
The population of these birds has gradually declined over the past 30 years. Anecdotal reports state that in the 1990s hundreds of macaws could be seen at the clay licks, and it was not uncommon to see 300-400 macaws almost daily during the months of August through February.
Sad to say, nowadays, I consider seeing 50 macaws at the clay lick to be a VERY good day. So why is it that in the bastion of planet Earth for macaws their populations are in decline? Simply put, there are not enough nesting sites for the birds to breed, and here in Madre de Dios, and throughout the Amazon, these potential nesting sites are being stripped from the forest every day. Therefore, through a series of short blogs, I would like to explore the reasons behind these developments and bring to light the challenges faced by the macaws. In this first article, I will explain the different nests used by Tambopata macaws, hoping that you, the reader, can understand why macaws need these types of nests to reproduce, and continue the life cycle of some of nature's most beautiful and spectacular birds.
In Tambopata there are in effect two variations of macaw nesting sites. The first is in the cavities of emergent trees high in the rainforest canopy, and the second is in dead/rotting palms. Let's start with the first, macaws are “secondary cavity nesters”. Of the six species, it is the red and green macaws, the scarlet macaw and occasionally the chestnut macaw that fit this category. You may now be wondering what exactly a cavity is. Well, imagine a giant tree in the rainforest with several spreading branches that are extremely heavy. After many years, as a result of extreme weather conditions such as strong winds, torrential rains and intense dry heat, these branches sometimes fall off, exposing a hole in the tree where the branch was once connected. This hole is called a “cavity”.
Scarlet Macaw in Tambopata Research Center by Carlos Gonzales
Although not scientifically proven, the strongest theories revolve around the idea of “protection”, both from the natural elements and from predators (of which there are many). As expected, it rains a lot in the “rainforest” and, since Tambopata macaws nest in the rainy season (November-March), it is desirable to have a roofed nest. The cavities left in these giant trees often go deep into the trunk/fork thus protecting the eggs and chicks from the onslaught of persistent rain at this time of year.
Now, while having a waterproof home is obviously nice, it is believed that more importance may be placed on the protection from predators that a cavity can provide. As mentioned above, these cavities can go deep into the interior of the tree, and the deepest nest ever discovered goes 18 meters into the trunk. As I'm sure you can imagine, a deep, dark chasm acts as a natural deterrent to many macaw predators, especially diurnal predators such as capuchin monkeys and toucans. In the case of Toucans, one of the most prolific predators of Macaw chicks/eggs, they are simply unable to climb back out of the deepest cavities with their oversized beaks, a problem not faced by Macaws being such strong and agile climbers.
Scarlet Macaw on natural nest
Quickly examining the other extreme, a very shallow cavity acts more like a buffet for macaw predators, trapping the chicks in an easily accessible place with only one entrance and exit, leaving the parents as the only line of defense. Now we can see the importance of depth for macaw nests, another crucial factor to consider is the width/size of the cavity.
In short, the smaller the hole at the cavity entrance, the better. If we now consider some of the larger predators of macaws, such as the Kinkajou, they have the problem of needing to fit not only their heads, but also their shoulders into these holes. Macaws are more than happy to force and squeeze their way into very small cavities, as this subsequently translates into successfully eliminating the potential risk of larger mammalian predators. In addition to the depth and width of the cavity, the last two factors that macaws seem to like are the height of the cavity in the tree and how isolated the tree is from neighboring conspecifics. The higher the cavity, the less chance a hungry terrestrial predator, such as a Tayra, will decide to venture in for a quick snack, and the more isolated it is, with fewer connecting branches, the less chance an arboreal mammal will be able to get through from nearby trees.
Now, let's consider how dead palms serve as suitable nesting sites for macaws. Species such as the Blue-and-yellow Macaw, Red-bellied Macaw, and Chestnut-fronted Macaw typically nest in decaying palms. Although it may seem unappealing, these rotting trees are favored nesting sites for various parrot species throughout Latin America, indicating that they offer significant benefits.
Why do macaws choose to nest in rotting wood, with the constant risk of getting wet and surrounded by crawling creatures? It might seem surprising compared to the more desirable tree cavities that larger macaws like Red-and-Green and Scarlet Macaws often occupy. The reason is competition. However, palms offer a solution. These trees are abundant in the Amazon, especially in swampy areas, where dead palms provide ample nesting opportunities with less competition. Additionally, the fruits of these palms are a major part of the macaws' diet, allowing them to nest and feed in the same area without the need for long flights in search of food.
And so, to conclude, I hope that now, after reading the above, it is clear how/why macaws in Tambopata use tree cavities and dead palm trees to breed. Join me next time where I will write about which trees specifically can provide macaws with these types of nests, and examine the darker issue of how they are disappearing from Madre de Dios through illegal logging and fruit farming.
