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To acquire wisdom, one must observe

Litter and leeches: the ideal environment for Australian brush-turkeys (not so much for other megapodes)

As the rain patters down the leaves of the canopy above, falling onto the foliage-filled ground, a swish of leaf litter flies onto the path in front of you. Quickly, you look up and see a large, red-faced bird kicking up piles of leaf litter to make his nest. What you are witnessing right now is an Australian brush-turkey. This bird is a common sight to Australians living throughout the eastern part of the country. Though, they were not always such a common sight. For thousands of years, these native birds had been sustainably hunted by the indigenous Aboriginal people, who maintained a healthy equilibrium of the birds. However, as European settlers began to arrive in the area, this balance was disrupted; by the end of the Great Depression, brush-turkeys were hunted to endangerment, to such a degree that these megapodes were barely spotted until recent years. 

However, in 1992, the Queensland government passed the Nature Preservation Act which granted Australian brush-turkeys, along with other native Queensland species, protection from non-Aboriginal hunting. Following this act, the brush-turkeys regenerated incredibly fast, and in 2023, no one bats an eye as they stroll through parks and hiking trails in search of edible litter left behind by humans. However, the smaller, orange-footed cousin of these brush-turkeys remains a rare sight in the rainforest. Like the Australian brush-turkey, the orange-footed scrubfowl is a megapode: a ground-dwelling bird that builds mounds to incubate their young. Considerably smaller than the brush-turkey, they are also less flashy than the red-faced, yellow wattled bird, and instead, remain inconspicuous with brown feathers that blend in with the forest’s shrub layer. While it is common knowledge that the population of brush-turkeys has been steadily increasing since the passing of the Nature Preservation Act in 1992, few studies have concluded what their numbers actually are, including how they compare with the population numbers of scrubfowl. With this in mind, we conducted a survey of the populations of both Australian brush-turkeys and orange-footed scrubfowl in two distinct sites: Lake Eacham and Lake Barrine. 

Lake Eacham and Lake Barrine are both located within the Crater Lakes National Park, Northern Queensland. These freshwater lakes, each about 65 meters deep, are the result of ancient volcanic activity which created deep catchments. Both lakes contain gorgeous, clear blue water which draws the attention of tourists and locals alike. We conducted our studies in the terrestrial-leech filled rainforest (and yes, we said terrestrial leech, as in they travel on land to find their hosts, yikes!) surrounding each lake, where both Australian brush-turkeys and orange footed scrubfowl make their homes. During three separate periods, students monitored the numbers of perceptible birds for each species at the two sites. Since the scrubfowl are much 

shyer than the brush-turkeys when it comes to human contact, we accounted for this by spending 20 minutes listening for the distinct scrubfowl call at the beginning of our transect. After this, students walked through the rainforest (key word: ‘rain’!) surrounding either Lake Eacham or Lake Barrine, during which we made note of each instance a brush-turkey or scrubfowl was spotted. At Lake Barrine, students listened either just outside of the rainforest or within 30 meters of its bounds before embarking on a five-kilometer circuit. At Lake Eacham, students employed the same listening regime, then went on one of three different paths with close proximity to the lake. Over this two-day study period, the group walked a total of 45 kilometers at Lake Barrine, and nearly 25 kilometers at the Lake Eacham site. 

After compiling our data from the two sites and picking numerous leeches off our soaking clothes, we found that there were significantly more brush-turkeys compared to orange footed scrubfowl observed at the sites, which was expected. Additionally, we found that there was about 3 brush-turkeys per kilometer at Lake Eacham, while Lake Barrine hosted an average of one brush-turkey per kilometer. Interestingly, there was also a noticeable discrepancy between the ratios of brush-turkey per kilometer to scrubfowl per kilometer at the two sites. At Lake Echam, there was around a 6:1 ratio of brush-turkeys to scrubfowl, whereas at Lake Barrine, there was a more balanced 2:1 ratio of brush-turkeys to scrubfowl. 

Because of the notable difference in the number of brush-turkeys per kilometer between the two sites, we deduced that the higher foot traffic at Lake Eacham, a more popular tourist site than Lake Barrine, could provide an answer to why this is. To elaborate, more tourists mean more trash. Brush-turkeys, with no fear of human interaction, gladly consume this litter. This is further exacerbated by Lake Eacham’s garbage policy, which assumes that visitors will take their trash with them, since bins are not provided on-site. However, the reality of the situation is grimmer, with litter sprawled around the lake’s picnic tables and restrooms. Because of the greater amount of litter at Lake Eacham, the brush-turkeys are enabled to increase their population sizes at this location. At the same time, this has put the scrubfowl at a disadvantage at Lake Eacham, where we see that the ratio of brush-turkeys to scrubfowl is about three times larger than it is at Lake Barrine. Because brush-turkeys can operate as they normally would around people, which includes performing mound-building, they effectively have a larger amount of available forest to use at Lake Eacham, while their shyer counterparts, the scrubfowl, are left in a limited area. The scrubfowl also do not feed on the litter left by humans, which again, puts them at a disadvantage. This lack of human-related fear possessed by the brush turkeys, coupled with the increase in edible litter left behind by people has become a threat to the small scrubfowl it shares its niche with. 

While a two-day study is not enough to serve as gospel, its implications go beyond our findings. Brush-turkeys have a disproportionate effect on the ecosystem due to their rapidly growing population at Crater Lakes National Park. Orange-footed scrubfowl is just one example of an organism that is being negatively affected by this. Likely, there are a plethora of organisms that also find themselves suffering the consequences, perhaps organisms even more elusive than the orange-footed scrubfowl. While initially it may not appear that there is such an ecological difference between the sites at Lake Eacham and Lake Barrine, which are both lush rainforests teeming with life (including leeches!), all it takes is a closer look (and listen) to begin to understand the discrepancy between them. Ultimately, more studies must be done to determine the extent of human influence on the ever-growing brush-turkey population in Eastern Australia, how they influence scrub fowl populations, and the further ecological impacts yet to come.

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