The Real Social Network of Birds

Our researchers aren’t tweeting—but they’re listening in on the forests’ social channels.

A little over a year ago, 200 acres of trees snapped, uprooted, and fell to the forest floor, hundred-year-old giants bowing down to a tornado’s devastating 110 mph winds. Unlike a city, the forest isn’t putting things back to how it once was for the last 200 years. Instead flora waiting in the seed bank are taking advantage of the open sunlight. Fauna that live for forest clearings are flocking, fluttering, and scurrying to the new gaps. And we’re left wondering: How do these creatures know to return to a suitable habitat once it has reappeared? What signals do they hear and follow?  

Mary Medlin, our resident avian research coordinator and master’s candidate at Auburn University, is not asking these questions philosophically but with an intention to find answers. This spring, with support from her academic advisor Dr. Kelsey McCune, Medlin is starting a years-long research project to understand how different species of eastern songbirds respond to their fellow birds’ calls to find new breeding sites. Her insights could help conservationists gain a new tool for attracting specific birds to newly restored habitats. But first, Medlin must play forest spy. 

Medlin has spent the last couple months hunched over a table, eyes trained through a magnifying glass, assembling and soldering the delicate inner workings of playback recording devices (PRDs). These forest green toolkits have a speaker embedded on one side and a tiny microphone at the top. Medlin will hide the units in Paint Rock’s tornado-impacted sites, other logging sites with similar forest structures, and in adjacent undisturbed mature forests. The units have a timer set to start playing vocalizations of target species, to pause the playback, and to then start recording any responses. 

Six bird species are of special interest: from the vulnerable cerulean warbler to ruffed grouse, Baltimore and orchard orioles, and blue-headed and yellow-throated vireos. Ceruleans have been in steep decline across their range due to a number of issues, namely the loss of mature forests with open understories and sweeping canopies. While ruffed grouse have relatively stable populations throughout their range, there haven’t been any confirmed breeding birds in Alabama in some time. Many would like to see them return. 

“This vocal cue playback method can be incredibly useful for attracting species of conservation concern to areas that are being managed for their support, without having to wait for birds to find them all on their own—which can take many years or may never happen at all,” Medlin says. “The cerulean warbler and ruffed grouse are examples of such species in Alabama, and we are very excited to see if this technique will prove useful for them.” Furthermore, with the inclusion of other target species, the researchers may be able to determine how common the use of conspecific cues, the sounds, scents, and sights from the same species, appears across different passerine groups and guilds.

This first year, Medlin plans to develop a baseline of the target birds already present at the test sites. In the following years, she’ll start sending out calls and listening to hear what, and how many, birds respond. This is a social network we’re excited to tap into and report back on. Stay tuned for more “tweets” from Medlin’s work. 

Sequencing a Forest

This spring we’ve begun a first-of-its-kind project—one that will have wide-reaching implications for the future of Southeastern forests. Partnering with HudsonAlpha Institute of Biotechnology through an ADECA grant, we’re developing full DNA sequences for multiple species of trees common on the 150-acre Paint Rock Forest Dynamics Plot.

An ecosystem catastrophe has made our work even more timely and important. Emerald ash borers have infiltrated the Paint Rock Valley, and in many areas that has meant the loss of more than 95% of ash trees. In Paint Rock, ash trees number among the top 5 groups of trees, and their loss will be a blow to the forest.

There’s reason to believe that Paint Rock’s unusually diverse ash populations may have a bit more fighting power than ash in many places. So we’ve focused this season on collecting DNA from as many trees as possible in the ash genus (Fraxinus), which will allow researchers to dig into the genetics between the population of trees succumbing and those surviving this threat. We may also be able for the first time to accurately identify some “hidden” ash species that are difficult to distinguish by leaves alone.

We’re not looking at just a dozen or so samples either. We’re sequencing 700 to 800 samples before June. We have our work cut out for us.  

What collection means for our team at Paint Rock these coming weeks is many hours in the plot, navigating a rocky terrain and the inherent hazards of being in the brush in the springtime when other life is bursting forth. 

Our task comes with a timeline, too: We must gather samples of fresh growth from the tops of trees as soon as possible after they emerge to protect the genetic integrity of the leaves. Some of these collections are straightforward. We can pluck samples with a Hastings pole (a long 30-foot pole used by utility crews)—or a massive “slingshot” designed to carry lines over limbs. Trees with leaves only in the crown, often a hundred feet in the air, dominating the overstory, will require some creativity and cutting-edge technology—such as sending a robot into the sky (we’ll share more on that later this month). After we’ve collected the branches, we freeze the leaf samples in liquid nitrogen and place the tubes on dry ice to keep them frozen until we can deliver them to HudsonAlpha.

We’re just getting started here too. This will be an ongoing project for the next several springs as we continue to work through the species list. Our ambitious plans for a DNA census in our forest dynamics plot will be critically important to the future of trees facing fast-paced threats and environmental changes. 

By Landon Rakestraw, Research Staff & Aquatics Coordinator