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Thorns, Leeches and Bowerbirds...Oh My!

CBS undergraduate Reid Gamble's research project while studying in the rainforests of Australia.

Reid Gamble

Many people envision Australia as a vast desert filled with kangaroos and koalas. While there are large populations of these two species, Australia also includes a rainforest bursting with rare fauna and beautiful flora. One such animal is the tooth-billed bowerbird, which is known for its theatrical displays and great artistic feats. These birds can be found in the Wet Tropics region, specifically around Lake Eacham and Lake Barrine. Both of these areas are characterized by complex rainforest and high diversity of organisms.

The tooth-billed bowerbird species is endemic to Papua New Guinea and Australia. They are recognized for building bowers that are identified as a cleared area strewn with leaves specifically chosen by the male in order to attract a female tooth-billed bowerbird. Their mating habits are based upon female choice. In one area multiple males will set up their bower, or stage, and perform for a female. The female will then choose a mate based upon a male’s stage and display dance.

As part of our study abroad experience, we recently spent a morning observing how these birds build their bowers and the differences between bowers in the Lake Eacham versus the Lake Barrine area.

Our morning started off on foot with a sharp turn off the road into dense rainforest. There were no trails. We collected data on Bowerbird Hill near Lake Eacham, which has been previously studied by former researcher Caroline Bailey under the advisement of Dr. John Grant in 2012. Bailey found and marked 20 stages around the Lake Eacham area with pink tape. Dr. Grant led us to five of these stages based on the marking tape, past knowledge, and the call of the bowerbirds. This rainforest trek can be best described as an uphill battle. Our enemies included an inconspicuous thorn covered climbing palm called “Wait-a-while”, dozens of leeches, and a steady rainfall that erased any hopes of good footing. After an hour of steady climbing, we found two of the marked stages abandoned, three in use, and one new unmarked stage. We collected data on abundance and leaf species used to build the stage along with the stage length. We also measured the diameter of the stage tree. This tree is used as the starting point for the stage and as a prop in the courtship dance. These variables would be compared to other groups in the area, in hopes that we may gain some insight into the preferences used in courtship of this exceptional species.

Upon completing our data collection, we started to head home, but we soon after found ourselves somewhere on Bowerbird Hill without any tape markers in sight. Needless to say, the journey back gave a new meaning to the term “bush whacking.” Instead of us whacking the bushes, the bushes whacked us. We found ourselves sliding down a hill into wait-a-whiles and monkey climbing down trees to finally arrive at the bottom of a ravine. We looked up to see yet another uphill battle unlike our previous trek. This time, we scaled the hill pulling ourselves up by any roots or trees within grasp, many of which were dead and simply fell to the side. After 30 minutes of climbing, the road magically appeared.

Despite the treacherous conditions, we were able to collect insightful data. Twenty-nine bowers were found within the six areas sampled. Bowerbird Hill had significantly higher total leaf count and stage length compared to the other five sites, including areas around Lake Barrine, Lake Eacham and Gadgarra National Park. These sites are exposed to increased amounts of human interaction and disturbance due to walking paths and nearby parks. However, Bowerbird Hill is isolated from human activity. Therefore, the bowerbirds may be able to build more elaborate stages. Although human disturbance may have had an impact on leaf abundance and stage length, it seemed that display tree diameter was not. The average diameter of the display tree did not differ between all six sites. This could be accredited to the tooth-billed bowerbird’s body size, which is consistent among mature males.

Six different species of leaves were used in the four stages on Bowerbird Hill: rusty laurel, tamarind, milla milla, needlebark, and two unidentified species. An important species found by Bailey at many sites around Lake Eacham was wild tobacco. However, the Bowerbird Hill sites did not have any tobacco present, which is consistent with our findings three years later. During our study, only one site at Lake Barrine found wild tobacco being used on a stage. This could be due to a decline in wild tobacco populations around Lake Eacham and Lake Barrine. On Bowerbird Hill, wild tobacco seems to never have been established.

This small project on the tooth-billed bowerbird gave us the chance to immerse ourselves in true fieldwork, which is important to us as future scientists. Few people have the opportunity to observe such a unique creature in its natural habitat. Our findings have contributed to the database of knowledge on this animal, which is only one of the many understudied fauna of the Wet Tropics. Like many areas around the world, a lot is unknown. Everyday new species are discovered and more species go extinct. Without research—like our tooth-billed bowerbird project—spectacular species could go missing without anybody ever knowing of their uniqueness. While this experience was an amazing opportunity for us, it is important to remember that there is so much more to learn about the natural world. 

—Reid Gamble, Cassie VanWynen and Emily Cafaro