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Home » 2009 - Issue 2, In the Wild, Issue

The Evolution and Behaviour of the Extraordinary Eclectus Parrot

By Jessie Zgurski


Eclectus Enigma
High in the canopy of the dense rain forests of Australasia lives one of nature’s most extraordinary and beautiful birds, the Eclectus Parrot (Eclectus roratus).  Although their strange behavior sets them apart from other birds, they are most well known for their brilliant and unusual colors.  The handsome males are a vibrant emerald green, while the elegant females are a dark ruby red, usually with a vest of violet or cobalt feathers.

The two birds are so different that it wasn’t immediately apparent to biologists that the males and females belonged to the same species.  The males were first discovered and described by a Western biologist, PLS Müller, in the spice islands of Indonesia in 1776.¹ However, the females, who are harder to see in the wild than the males, were not described until 1837.¹ It wasn’t until 1874 that the two sexes were finally united under the same scientific name, Eclectus roratus.¹

That the males and females are completely different colors makes the Eclectus an oddball among its kin.  While there are other parrot species that have males and females that look different (are sexually dimorphic), none shows such extreme colour differences between the sexes.  For instance, mature male Ringneck Parakeets (Psittacula krameri) have a black ring around their necks, while the females do not.  And, in most sexually dimorphic parrot species, males do not develop their adult plumage until they have molted a few times.  Eclectus are different in that the chicks are very easy to sex as soon as their feathers start appearing: boys are green and girls are red.

The form of sexual dimorphism seen in Eclectus Parrots is strange even when they are considered against all other bird species.  It is not unusual for male birds to be much more extravagant looking than females - peacocks are the perfect example of this - but in the Eclectus, neither sex is really more colorful than the other, although it’s the female who would stand out more in nature due to her red colouring.  Males would blend in well against green, leafy tree tops.

The reasons for the differences among male and female Eclectus Parrots eluded biologists until very recently.  In fact, one of the most influential evolutionary biologists of the 20th century, the late Dr Bill Hamilton, was so puzzled by the Eclectus, that during lectures, he would often show a slide with a photo of a male and female Eclectus and proclaim that once he knew why one was green and the other one red, he would be ready to die. ² Dr. Hamilton often talked about this most unusual parrot species, and despite having contributed to solving many difficult problems in biology, he could not explain why Eclectus are colored the way they are.

However, a long term project investigating the behavior and ecology of Eclectus Parrots was started in 1997 by Dr Robert Heinsohn of the Australian National University.  Dr Heinsohn was alerted to the unsolved mystery surrounding the Eclectus by Dr Bill Hamilton’s lectures, and he decided to study this species because they display a form of sexual dimorphism unparalleled in the bird world.  Since no one could satisfactorily explain why this is, it was a perfect biological mystery just waiting to be solved.

Few field biologists had done much work on wild Eclectus Parrots before the start of this project, most likely because studying them in the wild comes with many logistical difficulties.  Eclectus nests are usually situated very high in trees, at an average of 22.2 meters off the ground.³  Additionally, Eclectus nest holes are often situated very far apart, and for Australia’s population of Eclectus, there is only one suitable nest hole per square kilometer of forest.⁴  That means that any biologist interested in studying Eclectus Parrots must be willing to travel across many miles of dense rainforest, and up trees that tower tens of meters above them, all in an oppressively hot, humid environment.

Dr Heinsohn decided to take on this challenge, and he and his team managed to find forty Eclectus nests in his first two field seasons, studying the birds in a thick rainforest on the Cape York Peninsula of the northeastern tip of Australia.  Traveling around a rainforest is difficult work and the researchers had to rely on creek beds and ridge lines to get around.  The fact that Eclectus can be very noisy around their nests can help people spot them, although the birds often flee once they spot people.  Time spent in an aircraft also helped Dr Heinsohn find potential nest sites, because Eclectus like to nest in tall, emergent trees that are easy to spot from the air.

Once nest sites were found, more gruelling work began.  Since Eclectus nests are typically 15-30 meters up trees, Dr Heinsohn and team had to use single rope technology to climb up the trees to examine the nests, take small blood samples from nestlings, and take any shed feathers left by the female.  These feathers were used as a source of DNA.  Climbing ropes in a humid, hot, tropical forest is incredibly physically demanding, and Dr Heinsohn estimates that if one stacked up all the trees he’s climbed end to end, he’s climbed the equivalent of a tree ten times taller than Mount Everest.

Climbing the nest trees can get one access to Eclectus chicks, but catching the adult males so they could be banded to allow for individual identification was also a big challenge.  Dr Heinsohn and team had to string mist nets about thirty meters above the ground to catch adult Eclectus Parrots. And, once caught, the adult parrots were not easy to handle.  As any parrot owner knows, they can bite very hard!  The researchers also had to build viewing blinds 20 meters off the ground up in trees, so they could observe the birds without disturbing them.

In the end, all that exhausting and challenging field work allowed researchers to gather data that demystified many of the unusual traits of Eclectus Parrots.  Dr Heinsohn first tested hypotheses regarding the evolution of different colors in male and female Eclectus Parrots by taking optical measurements of the birds and their surroundings, using a spectroradiometer.⁵

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