Roseate Burrow #18

In the Summer of 2019 I worked on Stratton Island in Maine for National Audubon's Project Puffin. There were no puffins but many birds bred on the island including four species of tern. While Common Terns were the most...common, there was a sizeable Roseate population in the center of the colony, a few Arctic Terns scattered throughout, and Least Terns on the sandy beach landing.

We had many intimate and intense interactions with the terns that summer. We regularly checked nests, counted eggs, weighed, measured and banded chicks all while the adult terns screamed in our ears, pecked the tops of our heads with surprising force, and aggressively covered us with tern excrement.

Typical tern greetings in slow motion

It wasn’t all chaos though. We also spent a lot of time in platform blinds throughout the colony which allowed us to observe the birds in relative peace. Courtship dances, copulation, eggs hatching, chicks hopping up and down awkwardly flapping their wings. We watched certain chicks get fed over and over while others starved. We watched curious birds wander too far from their nest only to get pecked viciously by their neighbors. We also watched many birds take to the sky on fresh wings, over time gaining the grace and buoyancy of their parent's flight.  The blinds allowed us to observe the entire breeding process in all its messiness.

A view from the blind

The blinds were still a bit removed though. Towering several feet over the colony, we watched through binoculars and spotting scopes. With nearly four thousand terns before eggs even started to hatch, the sound of the colony was, in a word, extra. Any attempt to hear one specific bird was masked by the sounds of hundreds of other vociferous squawkers. What we couldn’t hear were the quiet tern sounds – not necessarily an oxymoron.

Partway through the season we were visited by Bob McGuire (a world class sound recordist, just check many of the audio credits on the Sibley Birds app), who helped open my eyes to the magic of remote recording or "drop rigs." One morning at camp he excitedly passed around his headphones for us to listen to what he had just recorded. The concept was simple enough, he had hidden small omnidirectional microphones in the rock burrow of a Roseate Tern then watched from a distance. When we slipped on the headphones we heard the terns like we never had before.

Omnidirectional mics have several benefits: They’re small and hideable, have low self-noise, and are less susceptible to wind noise. However they have one drawback for isolated species recordings: omnidirectional mics record in all directions equally so the passing lobster boat or obnoxious bird or any other noise will be picked up as if the microphone is pointed directly towards it. What I hadn’t considered was the inverse-square relationship between distance and intensity of sound: if you half the distance between a mic and a sound source, the intensity of sound will be four times greater. The trick is getting the mic close enough to the subject.

The next evening I tried it out myself:

Birds Make Sound · 190701 - 212009 rost18

(Headphones Recommended) -- Recorded with Zoom H5 and FEL Clippy XLR EM172s

The recording starts with the sound of a typical alarmed tern colony. Common and Roseate Terns yell in the distance and then return to their nests all riled up. It is past sunset, fiery clouds fading into the dark blue night. We hear the parent Roseate Tern return, giving its piercing alarm call and aggressive chatter just outside the rock burrow, making sure neighbors keep their appropriate distance. Switching to the more social "chevink" call at 1:03, it heads into the burrow. Moving from left to right in the stereo field, the adult is greeted by its 3-5 day old chicks with quiet scratchy calls. After the initial excitement they all quietly mutter to each other. When I hear this I imagine the adult tern settling down as the chicks huddle and squeeze underneath to rest in the warmth of their parent’s puffed out body feathers. All is calm in burrow #18. Neighboring terns also quiet down and we hear the distant rhythmic crashing of ocean waves. Of course, it never fully settles for long – tern colonies are only varying levels of raucous at all hours and trouble is never too far off.

This is likely the first of many posts about the sounds of Stratton Island and is just one of many examples of this recording technique. Normally field recording attempts to capture and recreate what we can hear, but remote "drop rig" recording can allow us to hear what we otherwise couldn't. Paradoxically, the technology that removes us can also embed us more deeply with our subject, allowing a peek into intimate social interactions with the emotional salience afforded by sound. We hear what birds whisper when we're not around.

Disclaimer: I was trained and permitted to work with these birds and their safety and well-being was always my top priority. One should not approach nests if doing so would cause undue stress or have an adverse effect on nesting success. It is illegal and morally reprehensible to disrupt the nesting of birds for any reason.