Chilling with the endemic Australian Chowchillas: using bird populations to assess environmental health
By Samantha Siomko, Staff Writer
Additional Writers: Natalie Pitman, Katrina Cordseen-David, Shelby Downes
Deep in the heart of the Australian rainforest, braving leeches and swarms of mosquitos, four students intensely listen for the distinct sound of a Star Wars-era blaster being fired. This sound belongs to none other than the Chowchilla bird, an avian species that exists only in the damp Australian rainforest, as indicated by the abundance of biting insects. These students are none other than four Gettysburg juniors, currently studying abroad in Cairns, Australia and focusing on the rainforest ecology.
Their quest: to unearth knowledge about the health of the Chowchilla populations, a species vulnerable to climate change.
The Chowchilla is a robin-sized Australian bird that feeds on insects and small animals. The males have a white chest while the females have orange chests, and they can live and call in group of about four birds. This species is known to have dialects based on where they were born, much like the accents people would encounter when traveling across the United States.
Because these birds exist in such a small area, when critical habitat is lost or damaged the population density of these birds can decrease, which can be dangerous with an already diminishing population.
In order to assess the density of the birds, we listened for the distinctive “pew pew” sound characteristic of the Chowchilla. If heard, we would determine where the call was coming from and how many groups of Star Wars battles were taking place, or would attempt to draw the birds out of the forest with a recording of the call.
Two beautiful Australian sites were used: Lake Eacham and Lake Barrine, both of which are located in the Atherton Tablelands in Northern Queensland, smack in the center of rainforest country. Both sites have become fragmented habitats, making it difficult for species to travel to other patches of rainforest, since farmland and houses separate them.
There were 18 groups of birds per square kilometer at Lake Barrine while no groups of birds were heard at Lake Eacham properly. Clearly, the Chowchillas prefer the Lake Barrine habitat over Lake Eacham. So, why are the Chowchillas disappearing from Lake Eacham, just like Anakin abandoned Obi Wan? Or is it that the Chowchilla population is being held captive at Lake Barrine, similar to how Princess Leia was prisoner to Jabba the Hutt?
There was a high density of brush turkeys, which are another endemic bird species in the Wet Tropics. Brush turkeys dig up the leaf litter in search of food and to make their nests with, which can reach up to 6 feet in height. The disturbance of the ground layer causes the soil to dry up more quickly since the upturned leaves can be exposed to the air. Less insects tend to live in these dry environments, making it hard for the Chowchillas to find food.
Just as Luke wanted to flee his dry and desolate home of Tatooine, the chowchillas prefer to live in moist environments and will leave areas of increased dryness.
However, at Lake Eacham there was a small creek, Wright’s Creek, which displayed a density of 8 groups of birds per square kilometer. This is much different than at the actual lake, where no Chowchillas were heard over the two days. This is because this creek is a refugial area, or a favorable section of rainforest where certain organisms will go when the surrounding area is unsuitable. Due to the fact that Wright’s Creek is one of these refugial sites, some Chowchillas live here while they cannot be found around Lake Eacham.
In comparison to a past study conducted in 2002, the density of birds has not changed much. The population at Lake Eacham is still smaller compared to Lake Barrine, and Wright’s Creek still remains a refuge for Chowchillas. From studies like this, we can see the effects of climate change by studying how it impacts those that are most vulnerable to rainforest fragmentation.
The populations of Chowchillas can represent the health of the ecosystem overall, making them an indicator species. This means that other species could likewise be decreasing with the Chowchilla population. So, in order to avoid losing more critical rainforest species, save the Chowchillas, we must.