Frequency Discrimination, Physiology of Bird Song


On Wednesday, Feb. 15, Dr. Bernard Lohr from the University of Maryland, Baltimore County (UMBC) presented a Natural Science and Mathematics Colloquium (NS&M) titled “Physiology of Bird Song.”

An email sent out to all staff, students, and faculty members summarized Lohr’s presentation by saying, “In this lecture, Dr. Lohr examines the influence of noises of different types on both detection and discrimination of bird songs and calls using a simple environmental acoustic model.” James Williams, a senior, responded positively to the email saying, “I got the email, [and I came because] I was just really interested; I’m really interested in birds.”

Loher began by describing one of his own experiments and then compared the hearing of certain birds to humans. Loher said, “They hear quieter sounds than we do,” when he talked about owls. In reference to other birds, he said, “What I think is surprising to most people is that when we look at songbirds… their hearing is dramatically not as good as ours.”

“We hear quieter sounds even in the middle where our best frequencies are,” continued Lohr. “At high frequencies, we hear much better than they do. And if you want to take it to a range of hearing… small song birds hear roughly between 1 and 6 kHz. An octave higher on the piano and they aren’t hearing anything.”

Part of Loher’s presentation focused on the difference between detection and discrimination. At what point can certain birds know another bird is calling, and at what point can it understand the nature of the birdcall? Loher spent a lot of time talking about his work with the Chester River Field Research Center in Chestertown, Maryland, with the assistance of Washington College. His focus was on the calls of grasshopper sparrows, noting two different types of calls.

The first call is a high amplitude call that provides the reason for the grasshopper sparrow’s name; the call seems to sound like it should belong to an insect. Loher also mentioned a second sound of lower amplitude that usually occurs when a parent comes to the nest to feed its young. He ultimately notes that the calls of the grasshopper sparrows became more complex in the nestling period.

For those interested in attending a Natural Science and Mathematics Colloquium, there is another one Wednesday, March 7, titled, “Microfluidic Investigations of Receptor-Mediated Apoptosis.” The Speaker is Dr. Randy Reif from the University of Cincinnati.