Megapode Mania Down Under

October 26, 2023
Science Magazine

Written by Maddy Ganz (Duke University), Gayatri Singla (Rice University), Millie Spivey (Wofford College), and Ali Power (Scripps College), this article highlights students research conducted abroad in Cairns, Australia at the School for International Training (SIT) program focused on Australia: Rainforest, Reef, and Cultural Ecology. This semester program focuses on the interaction between humans and the environment in North Queensland, Australia, an area known for significant biodiversity. This observational study investigated variations in the density of megapoes, a family of mound-building ground birds, across the region.

It’s a Sunday afternoon: you’re lying on a blanket with your friends, basking in the Australian sun and listening to the chatter of the visitors at Lake Eacham and the faint but distinctive squawks of orange-footed scrub fowl piercing the air. You’ve just finished a refreshing swim in the crater lake and can’t wait to take a bite of the sandwich you put together this morning. Suddenly, a big bird with a bald, red, and warty head struts over and snatches the sandwich right out of your hand. You gasp, looking around for any witnesses to the crime, and see other birds picking at food scraps left and right. You’re surrounded. What are all these brush turkeys doing here?

Above: Brush turkey. Image courtesy of The Queensland Government.

The Australian brush turkey and the orange-footed scrub fowl are two of the three species of megapodes found across Australia. Known as “mound builders,” males of this bird family spend their days kicking leaves into piles that are just the right temperature for the females to lay their eggs in. Males can move up to two to four tons of material into these mounds. When not working on their mounds, the Australian brush turkeys feed on insects, fruit, seeds, and even human food crops and trash. They also dig for food, often harming farms and gardens. For this reason, many Australians consider them pests. Over the years brush turkeys have become a common sight around parks due to their increasing comfort around humans, whom they see as an easy source for food. On the other hand, orange-footed scrub fowls aren’t nearly as friendly. They eat insects, fruit, and seeds within the rainforest—usually away from humans. 

Above: Orange-footed scrub fowl. Image courtesy of Thala Beach Nature Reserve.

Lake Eacham and Lake Barrine, the two Crater Lakes in North Queensland, are popular homes for these megapodes. Despite similar locations, these lakes differ in their amount of exposure to humans. Lake Eacham is a more prominent tourist spot, with heaps of trash left behind each day by picnickers. With a smaller recreational area that includes the local cafe, Lake Barrine, has much less litter and human interference to impact these birds. In our study, we sought to investigate how megapode communities differ in density at each site. 

Above: Crater Lake located within Australia. Image courtesy of Google Maps. 

To collect our data, we traversed both lakes to seek out brush turkeys and scrub fowl. We collected data in six groups during the early morning and late afternoon over the course of two days. In total, we surveyed over 150 km of trail. We standardized our data by completing our surveys at the same time each day, using even walking paces, and staying quiet during our walks to see and hear as many birds as possible. Our survey area included the circular paths around each lake in dense forest cover, a picnic area filled with people in clearing with less vegetation, and the main roads around the park entrances. After two days of searching in the rain with terrestrial leeches and wet clothes, we didn’t blame the brush turkeys for wanting to steal a sandwich or two.

Above: Bird’s-eye view of Lake Eachem and Lake Barrine. Image courtesy of Google Maps.

At the Lake Eacham picnic area we listened for scrub fowl and watched more than eight brush turkeys pick at trash and scraps. After one of our group members valiantly collected the empty sandwich wrappers, she searched the whole picnic area before discovering the complete lack of trash cans—even in the bathrooms! As we walked home from the park, we passed by a sign that read, “No trash cans, take your trash with you.” In discussion with our professor, we learned that the Queensland Parks Department lacks proper funding to keep the parks sufficiently staffed for a garbage removal system.

Lake Barrine, however, sees significantly fewer visitors than Lake Eacham and also has a cafe. While we surveyed this lake we saw no picnickers—only people eating at the small cafe near the trail. We concluded that most visitors frequented the cafe rather than bringing their own lunches, as we saw barely any trash on our walk around Barrine.

After compiling the data collected from each park, we observed that the numbers of orange-footed scrub fowl at Lake Eacham and Lake Barrine were almost identical. However, we recorded almost three times as many brush turkeys at Lake Eacham versus Lake Barrine. While scrub fowl were consistently difficult to spot in all of our forest surveys, we found shockingly high numbers of brush turkeys congregating in Lake Eacham’s picnic area, which is riddled with trash and food scraps.

Even in the pouring rain, brush turkeys were hungry for garbage left behind by Lake Eacham visitors. Since brush turkeys have broadened their diet to include scraps of food and litter, people are constantly, inadvertently feeding the animals. Similar numbers of scrub fowl at Lake Eacham and Lake Barrine suggest a lack of food competition between scrub fowl and brush turkeys. Brush turkeys now rely on human leftovers and have moved away from eating natural resources that the scrub fowl rely on as their main source of food.

Unless you want to keep feeding brush turkeys the second half of your sandwich, something needs to be done to rectify this situation. The parks service at Lake Eacham doesn’t have the means for a garbage removal system, so the change needs to come from visitors. Make sure to bring all your trash with you when leaving the park area so that you are not unintentionally making this ecological dilemma worse. As the nature-lover’s mantra goes: leave no trace! 

Brush turkeys are ecosystem engineers: their actions can have long-term, dramatic effects on the environment. Their mound building digs up seedlings, roots, and young trees. As their numbers continue to rise, their impact on the forest ecosystem will only become more prevalent. All it takes is one simple step—not leaving behind your trash—to help save the rainforest that Australians are so proud of. 

Above: Lake Barrine with a brush turkey in the foreground. Image courtesy of Gayatri Singla.

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