Zia Crytser: Restoring the melody of bird songs

This piece was written in the fall of 2024 by GRAD 5144 (Communicating Science) student Olaitan Bobade as part of an assignment to interview a classmate and write a news story about her research.

Although she grew up spending time in nature without ever hearing the songs of birds, young Zia Crytser did not think anything was amiss. As a child, Crytser had always nurtured a love for the outdoors, engaging in activities such as snorkeling and fishing with her dad, but a trip to countries outside of her hometown on Guam when she was 15 years old made her realize that birds were abundant in other places – and that they made melodious sounds. The absence of birds on Guam and her love for nature would end up coming together to influence her choice of a major as an undergraduate and, many years later, her research as a graduate student.

    Through her undergraduate coursework as an integrative biology student at the University of Guam, Crytser soon came to learn that the limited presence of birds on Guam was the result of the accidental introduction of the brown tree snake shortly after World War II. This invasive species preyed on birds and their eggs, and, within 30 years, caused the loss of about 90 percent of the birds on Guam.

    Crytser knew she wanted to do something about this problem. During her time as an undergraduate student, she worked as a field biologist for an organization called the Ecology of Bird Loss Project. This work gave her the opportunity to assess and better understand the impact of reduced bird activity on Guam’s ecosystem. Without birds facilitating seed dispersal and pollination, she learned, there was likely to be more loss of biodiversity. She was actively involved in this project for five years, but she was not done with birds yet.

    After graduating from the University of Guam, Crytser moved to the United States to further her learning through a master’s degree program in fish and wildlife conservation at Virginia Tech. Not many people come into graduate school knowing the exact project that they want to work on. Crytser, however, knew exactly what she wanted to do: study how the dietary trends of vertebrates and arthropods, such as birds and insects on Guam, has changed in response to invasive species.

    To achieve this goal, she will collect feather samples from birds via non-invasive methods such as mist-netting, a technique whereby birds are carefully removed from a net, a tip of their feather is clipped, and they are then released to fly away. Crytser will determine the ratio of carbon to nitrogen present in the samples she collects. This ratio will provide insight into the kinds of food that the animal feeds on and their trophic role in the food web.

    Armed with this information, Crytser will then compare the kind of foods eaten by the animals on Guam to those eaten by animals in neighboring islands that are snake-free and still have their bird populations. To compare how the diet of these animals has changed in the presence of invasive species, she will take a trip back in time by using clippings from Guam specimens housed in a German museum since the 1800-1900s. Through this, she will be able to determine the baseline dietary pattern of birds prior to when the invasive brown tree snake was introduced to Guam. By conducting this comparative analysis, she will be able to see any shifts that may have occurred in the dietary trends of these animals through the years and in the presence of invasive species.

    In the long run, Crytser’s research will produce findings that can help inform conservation management practices and promote forest restoration on her home island. And hopefully, in some time, the melodious songs of birds will be heard again on Guam.