Eavesdropping on passing songbirds

Bird monitoring station records nighttime activity to help track migrations

By Mike Lynch

Brian McAllister has wanted an auditory nighttime bird monitoring station at Paul Smith’s College for years. 

Finally, the pieces have fallen into place and the adjunct professor has gotten his wish. 

Bill Evans, an ornithologist known for his decades of work recording nighttime bird traffic, has been collaborating with McAllister to install a station at the college. Evans donated his time and several hundred dollars worth of equipment to the college over the past year. He put the station in place last summer and visited again in May to make some adjustments. 

Evans, who is in his sixties, is hoping a new generation will take up what has been his passion for years. 

The station consists of a microphone, which sits on the roof of the science building in a waterproof container, and a hard wire feed that connects to a laptop. The bird calls can be heard through the laptop speaker or headphones, but also seen using a program that displays spectrograms, which are visual representations of the calls. 

The microphone can pick up the calls of birds flying thousands of feet overhead, with the distance depending on a number of factors, including the volume of the call. 

For instance, for Canada geese, the range is probably 5,000 feet, Evans said. For small to medium size songbirds, like thrushes, the microphone can pick up birds up to a couple thousand feet above the building.

On a mid-May night, a pair of students joined McAllister and Evans to observe the birds passing by. 

“I’ve been interested in nocturnal flight calls before but this has really opened my eyes,” said student Nik Main. 

Main said the station has him considering doing a capstone project on nighttime bird calls. 

“It opens up a whole new area of study for students that we’ve never had here before,” McAllister said. 

Large numbers of birds migrate into or through the Adirondacks at night, navigating by the stars and other means. Nighttime is a good time to travel for songbirds, in particular, because the smaller birds can avoid predators and the weather is often calm and cooler.  

“Most of the songbirds move at night because it’s safer,” Evans said. 

The bird calls  picked up by the microphone are used by birds to communicate about things such as flight spacing, so the winged creatures don’t run into each other as they fly through the night. The calls typically last between one-tenth to one-twentieth of a second long. 

There were some nights last August when hundreds to thousands of birds were picked up by the monitoring station. In addition, the microphone detected some surprising birds, such as a dickcissel. 

McAllister said dickcissels are generally found in  Minnesota and elsewhere in the Midwest. 

“When we get one, it’s really rare,” he said. 

Evans and McAllister see value in continued listening to the night skies. 

“I think the thing that interests me the most is the potential for long-term monitoring,” Evans said. “If this station at Paul Smith’s is run for 100 years, you’ll have a 100-year data set.”