WyoPanama: Intruder Alert!

Post by Terri Higgins

Understanding the distribution of animals across the world is essential to researching animal interactions and ecological systems. The distribution and isolation of a species is especially important. This is because when one population of a species is separated from another population of the same species for a long period of time, there can be changes in behavior between these populations that could eventually lead to speciation. The Tropical Mockingbirds (Mimus gilvus) of Panama are a particularly interesting subject, as their population is small and isolated compared to its counterparts in Central and South America. Mockingbirds were introduced to Panama in the 1930s from Colombia. 

Terri holds a microphone to capture mockingbird responses to her playback experiments, conducted in Gamboa, Panama. (Image © 2020, Priscilla Wigington/WyoPanama 20.0)

I am interested in how mockingbirds in Gamboa, Panama, respond to the calls of mockingbirds throughout this wide range of distribution. This can help us better understand the effects of isolation on behavior and song recognition.

The distribution of Tropical Mockingbirds across Central and South America (Image: screenshot from Cornell’s Neotropical Birds website)

Tropical Mockingbirds are blue jay-sized birds that live in pairs or family groups. They are known to defend their nesting and foraging territories by singing (done by the dominant male), scolding with harsh “fussing” noises, and, if necessary, attacking the intruder (Botero et al. 2007). In my study site, these birds are found in and around developed areas such as neighborhoods, churches, and playgrounds.

A map of the territories of Gamboa mockingbirds, as Terri mapped them during her research project (Map adapted from Mapas Owje.)

Typically, when mockingbirds hear the song of an unfamiliar bird of their own species, they believe that their territories are being invaded by an intruder. Their responses may consist of singing back to the recording, making “fussing” noises, venturing closer to the speaker or “intruder”, or flying close to, or over, the speaker (Botero et al. 2007).

A pair of mockingbirds in Gamboa, Panama (Image © 2020, Patrick Kelley)

My project consisted of playing pre-existing recordings of mockingbirds recorded in locations 0-5000km away from Gamboa to the Gamboa mockingbirds and measuring their response. This recording or “playback” simulates the presence of an intruder. I will use the reactions of the mockingbirds to assess whether there are varied reactions from the Gamboa birds to calls from nearby sites as opposed to birds from different areas of the global Tropical Mockingbird distribution. This study will add to the knowledge of how distribution and isolation impact the social interaction of a species over time.

Working with these birds was a fun game of hide and seek. The territory map (pictured above) was put together by walking around the town in search of mockingbirds, marking where I saw them, and then hoping they would be there again the next time I came around. In some cases, where the borders of territories meet, it was hard to determine which birds belonged to which territory. There was one instance where we even, unknowingly, set up the experiment right on the edge of two territories and accidentally caused a little border war between two groups of mockingbirds.

This was an exciting project to be a part of. I think my favorite part was just walking around every day, watching the birds, getting to know them, figuring out their territories, and, in some cases, accidentally finding their nest sites. I had never done field research before, much less gone out on my own to do it. This project gave me the opportunity to interact with science in a hands-on way, and to make some of my own decisions about how to do the research. 

For more about Terri’s research and the WyoPanama program, visit the following links: WyoPanama course on Facebook | The UWyo Biodiversity Institute’s spring 2020 series on WyoPanama research | WyoPanama course website

Terri (Austin, TX) is a junior majoring in Zoology and Physiology at the University of Wyoming. She developed and led her own, independent research project as part of the WyoPanama study abroad course supported by the UWyo Honors College and Travel Abroad program. The course is led by Department of Zoology and Physiology faculty Patrick Kelley and Bethann Garramon Merkle, with invaluable support from TA and international master’s student Laura Gomez-Murillo.


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