top of page
Palm Cockatoo Project official logo
Palm Cockatoo pair at the hollow
CNZ in the trees

Better understanding Palm Cockatoos

Australia's largest parrot by weight, Palm Cockatoos are sadly Endangered, and they need our help. This Project, which I started in 2009, has involved 33 months of remote fieldwork (as of May 2023), 6 scientific papers published (more in preparation), and myriad public engagement activities to increase the public profile of these magnificent birds. 

This Project promotes the preservation and better understanding of Palm Cockatoos in Australia. Our dedicated efforts have resulted in research outputs which indicate that Palm Cockatoos 1) are in steep decline, 2) possess individually unique vocalisations, 3) mix and match vocal syllables like Passerine birds do (unusual for a parrot), 4) have different vocal dialects across their range, with Lockhart River being particularly unique in this regard, and 5) are the only non-human animal to produce rhythmic sound with a tool.

More recently, after witnessing relentless destruction of their ancient (300+ years old) nesting trees by unnaturally large fires, I've turned my efforts to protecting individual irreplaceable nesting trees. Given the lack of funding for annual fire management in the region, I've resorted to making firebreaks around Palmy nest trees.


You can help me save Palm Cockatoos by donating to this cause! 

I've partnered with a non-profit called People For Wildlife to make this happen. 


Latest publication! Setting the gold standard for Palm Cockatoo surveys on Cape York for conservation.

Zdenek, C.N.; Cacho, C. V; Searle, J.B.; Nevard, H.D.; Dibben, L.R. Field Methods to Identify Palm Cockatoo Nest Hollows. Aust. F. Ornithol. 2022, 39, 113–124.

Within Australia, the iconic Palm Cockatoo Probosciger arterrimus macgillivrayi occurs only on the Cape York Peninsula, Queensland, has recently been listed as Endangered, and requires large, old hollow-bearing trees for nesting. Surveys for these trees are crucial for management purposes. Typical surveys rely on following auditory (vocalisations) and visual (sightings) cues to determine the presence of birds or nests. However, nesting hollows can easily be inadvertently overlooked during such surveys because of false absences caused by biennial nesting, decreased vocal activity during nesting, and silent flushing from active nests when approached. We developed a systematic, grid-based transect methodology that maximises the likelihood of identifying potential, used, and confirmed Palm Cockatoo nest hollows and this has been implemented on western Cape York Peninsula since 2015. This method does not rely on bird presence at the time of surveys, but instead relies on multiple, specific signs of recent Palm Cockatoo nesting activity, to the exclusion of other large, sympatric parrots. We tested this method on novice observers and found that it enabled them to rapidly learn how to detect Palm Cockatoo hollows in the landscape. Thus, for ecological surveys on Cape York Peninsula, we propose that this method should supersede previous auditory/ visual surveys to identify Palm Cockatoo nesting sites, and we hope that this improves the conservation of this species in Australia.


Our main publication that enabled us to change the conservation listing of Palm Cockatoos to be Endangered (Nov.2021)

Keighley, M. V, Haslett, S., Zdenek, C.N., Heinsohn, R., 2021. Slow breeding rates and low population connectivity indicate Australian palm cockatoos are in severe decline. Biological Conservation 253, 108865.

Abstract: Dispersal dynamics can determine whether animal populations recover or become extinct following decline or disturbance, especially for species with slow life-histories that cannot replenish quickly. Palm cockatoos (Probosciger aterrimus) have one of the slowest known reproductive rates of any parrot, and they face steep decline in at least one of three populations comprising the meta-population for the species in Australia. Consequently, we estimated demographic rates and population connectivity using data from published field studies, population genetics, and vocal dialects. We then used these parameters in a population viability analysis (PVA) to predict the trajectories of the three regional populations, together with the trajectory of the meta-population. We incorporated dispersal between populations using genetic and vocal data modified by landscape permeability, whereby dispersal is limited by a major topographical barrier and non-uniform habitat. Our PVA models suggest that, while dispersal between palm cockatoo populations can reduce local population decline, this is not enough to buffer steep decline in one population with very low breeding success. The small population size and likely decrease in the meta-population of greater than 50% over three generations (49 years) supports a change of conservation status for Australian palm cockatoos from ‘Vulnerable’ to ‘Endangered’ under IUCN criteria. Our research provides an important demonstration of how PVA can be used to assess the influence of complex meta- population scale processes on the population trajectory of species that are challenging to monitor.

BACKSTORY of The Palm Cockatoo Project

Professor Rob Heinsohn from The Australian National University fell in love with Palm Cockatoos during his 10 years of field researching Eclectus Parrots in Lockhart River on Cape York. Rob later supervised Steve Murphy who finished his PhD on Palm Cockatoo breeding biology in 2007. Then I came into the picture starting in 2008 to do an MPhil (½ PhD) in 2008, and then Miles Keighley continued my vocalisation work for a PhD, finishing in 2018.
Since 2015, my involvement with Palmies has since been largely industry-based, rather than academia (with the exception of some papers still trickling out alongside other full-time work). I've worked on mining sites, training staff on how to properly survey for Palm Cockatoos, have been contracted by numerous film companies (e.g. BBC, NHK, ABC, Netflix) to assist them in documenting Palm Cockatoos, and started The Cocky Cognition Project, a subsidiary of The Palm Cockatoo Project.



In 2008, I won a Fulbright Fellowship which funded me to undertake an MPhil (1/2 a PhD) degree from The Australian National University, under the supervision of Professor Rob Heinsohn. 
This fellowship funded one year of study (not by coursework, but by research), but my research on Palmies required more time and more sacrifice for success (they're difficult to study). So, for two years straight I had to live off of $12,000. I managed this by living out bush for 5-6 months each year in a small place called the Humpy. And also by drinking pasta water for extra calories.
With no prior recording experience or sound analysis skills, I dove into full-on recording fieldwork, digitally recording vocalisations of the elusive and charismatic Palm Cockatoo (Probosciger aterrimus). From June to December of 2009 and 2010, I hiked through shoulder-high grass for hours each morning and afternoon in Iron Range National Park and surrounding freehold aboriginal lands on Cape York Peninsula (far north QLD, 12° 47’S, 143° 18’E). Before long, I made two new best friends: the user manuals of both the Marantz PMD661 (solid-state digital recorder) and RavenPro v.1.3 (sound analysis computer program). 

Screen Shot 2020-05-20 at 08.17.38.png


Living remotely poses many challenges. Being poor while living remotely exacerbates this difficulty. Shelter was a particular challenge for me when running The Palm Cockatoo. This issue never went away either- every year I returned was another year I had to creatively solve this massive problem. It wasn't just me I had to house, but a revolving door of one volunteer at a time for the majority of my time up on the cape. So careful planning was the responsible, field project leader thing to do. 
The Humpy was my shelter solution for 2009 and 2010. With only two walls, the wind, dust, and leaves blew in daily. But this also meant that butterflies, bats, and birds flew through occasionally, and the odd snake slithered in too! One even laid eggs in an old cardboard box on a shelf, and they hatched! Cute little Brown Tree Snakes (Boiga irregularis) they were. 

on arriving to the Humpy_31May2009_PicByChadZdenek.JPG

Dr Christina Zdenek and Prof Rob Heinsohn
at The Humpy (2009)

10min Palmy Documentary!

A short documentary about my research on the tool-using behavior of the Palm Cockatoo in Cape York Peninsula, Australia. By Cintia Garai.


Learning about Palm Cockatoo drumming (!) behaviour

From 2013-2015, thanks to the grant-winning capabilities of Professor Heinsohn and to the support from the Hermon Slade Foundation and National Geographic Society, I was charged with the incredibly challenging task of capturing video footage of a rare behaviour of an elusive bird in a remote area. And not just once, but as many times as possible. Being a scientific study, the more…the better. We needed data, and lots of it, so that we could make quantitative, statistical conclusions about drumming behaviour by Palm Cockatoos. We didn't want qualitative data, we wanted quantitative. Fortunately, Rob Heinsohn is brilliant and won a grant from National Geographic to achieve this goal, and he hired me to carry out the mission impossible. 
Year #1 was a dud. Despite all my efforts, day in and day out, I just missed recording two drumming events, so empty-handed I was. But Rob still had faith in me. He employed me again, a year later, to have another go at cracking the Palmy code. I managed to record eleven drumming events this time- a resounding success! And the following year, 31! I was finally getting the hang of it ; ). I had cracked their code. In total, I managed to record 62 drumming events in four years. One of the hardest things I've had to do, but what an adventure it was! We published the first of our drumming papers in Science Advances (Heinsohn et al, 2017). And we have a few more up our sleeves too, so stay tuned ; ). [L. Hall took this photo.]

Screen Shot 2020-05-16 at 14.53.05.png

Fire and Films

Hot fires that burn intensely at the end of the dry season (Sept-Jan) often destroy Palmy hollows by burning these piped, vulnerable trees to the ground. This is why appropriate fire management is critical to the breeding and survival of this species. Early dry season burns (cold burns) leave a mosaic pattern of lightly burnt landscape, leaving the vast majority of ancient hollows standing. These small fires also create small fire scars at the base of tree trunks, which, with the help of fungus and termites, is a critical step in the hollowing out of tree trunks that can later be use by Palm Cockatoos as breeding hollows. With managed fire in the early dry season out of the way, this leaves much less fuel and chance for late dry season fires to burn hot and out of control. Besides stopping land-clearing of their breeding and feeding habitats, I strongly believe this is the top management action authorities can take to prevent this species from going extinct.
To help promote appropriate fire management and the preservation of Palm Cockatoos, I worked very hard for many months to produce a 10 minute professional documentary on this majestic species. Pictured is Cintia Garai, a wildlife filmmaker from Hungary who helped make this Palmy docco happen. [T. Hunt took this photo.]

Screen Shot 2020-05-16 at 14.52.57.png


I climbed palmy hollows to better understand their nesting preference and drumming behaviour. [A.C. Cowper took this photo.]

Screen Shot 2020-05-16 at 09.42.56.png


Here is an article I wrote in July 2017 for Hearts & Minds, a magazine published by the Australian-American Fulbright Commission in Australia.

Screen Shot 2020-05-13 at 07.31.21.png

Invariably one egg only

This is a photo of a Palm Cockatoo egg at one of my 100+ Palmy hollows included in my 7 years of researching them on Cape York. Unfortunately, it's an unviable egg. It is seven days past the hatch date, and abandoned for four days. Chad Pumpa climbed this tree for me to collect the abandoned, unviable egg for research purposes. 

Dr Steve Murphy's work revealed that females invariably lay only one egg...and this happens very infrequently too. Once every two years on average. This egg also has a high chance of not making to adulthood. Each egg has only a 20% chance of leading to a fledgling. On this basis, and other arguments I put forward in my submission to the government, palm cockatoos were declared Vulnerable by the Australia Government which led to greater legal protection.


Children's Book

Children are the future, and they can't protect or care about what they don't know about. So, I wrote and published a children's book to introduce Palmies to those who don't know them. Before I owned a camera and could take my own Palmy pics, I teamed up with George Gornacz and took him to my sites and he took the photos in this book. I wrote the text. It's out of print now, but if there is great interest, it may be worth the personal financial investment required to get it back into print again.



This photo was taken by my field assistant and associate, John Griffith of Cape Capers Tours. It wonderfully depicts a baby Palmy, about to receive a meal from her mother. This hollow was called Docco Hollow, but sadly burnt down in the 2018 late-dry-season intense bush fires. I gave Docco Hollow this name because I found it during a nature documentary shoot I was contracted to help film in 2018.

One major limitation in Palm Cockatoo breeding biology is the requirement for very large tree hollows. Since Palmies are so large (165cm long), they need very large hollows in which to raise their young. Typically, a side-branch is not large enough. This is why Palmy hollows are often in the trunks of trees...trees which have first been hollowed out by termites that entered the tree via a small fire scare at the base of the tree. Then, a cyclone twists the top of the tree off, exposing the mud-gut in the trunk. This concrete-hard centre then slowly erodes away via rain, hollowing out a large enough space for palmies to raise a chick.

Thus, their hollows are estimated to take 100+ years to form. However, once the centre of the tree is gone, it of course becomes vulnerable to intense fires and strong winds. This delicate balance results in few suitable Palmy hollows in the landscape, making hollows an extremely rare commodity that largely dictates the maximum breeding population size for Palm Cockatoos.


Meet Nina and Nile

Meet Nina and Nile, a delightful pair of Palm Cockatoos, whom I have had the pleasure to follow and get to know over the years. Nina is easy to identify, even with just binoculars, as the right side of her upper bill has a long linear divot. This pair successfully laid an egg in this hollow, but I cannot comment on the success of this breeding attempt, as I do not have that data. 
Nina and Nile are a great team, always working together to fend off intruder pairs trying to steal ownership of their precious hollow (which I called Shifty Hollow, by the way).
This pair is featured heavily in a nature documentary, produced by a famous Japanese filming company called NHK. I spent four weeks with a crew of four NHK employees and we managed to film four Palmy drumming events! Needless to say, the filming crew were ecstatic, and the docco came out great!


Teaching California kids about Palm Cockatoos, via my palmy kid's book. 7 March 2012.



Teaching Lockhart River State School kids about Palm Cockatoos. 21 June 2023. Pic by Daniel Meier. 


bottom of page