The prevalence of these small, inexpensive tools is increasing at a rate that concerns many recreational birders, said Michael Webster, a professor and director of Cornell University's Macaulay Library archive, the repository for more than 200,000 bird-call recordings — 150,000 of which people can use online.
"The main negative? It can stress the birds, especially if overdone," Webster said. "On the positive side? These are devices for people to get out there and experience nature. It's educational engagement."
People should adhere to a wildlife-watching code of ethics, he said.
The American Birding Association's Principles of Birding Ethics includes: "Limit the use of recordings and other methods of attracting birds, and never use such methods in heavily birded areas, or for attracting any species that is Threatened, Endangered or of Special Concern, or is rare in your local area."
That language soon may be updated, Gordon said.
"I don't know if that will make it more restrictive, though, just more thorough — spelling out a little better that not one size fits all. There are so many birds in so many situations that common sense and courtesy will be a better fit."
Here, then, are some common-sense suggestions for minimizing playback disturbance to birds and other birders, from noted field guide author David Sibley's website (www.sibleyguides.com):
• Have a plan. Choose your spot and know your quarry, don't just play sounds.
• Play snippets of sound — less than 30 seconds at a time — with a long pause before the next snippet. After five minutes or so, give it a rest.
• Be subtle. You are trying to coax a bird into the open, not stir up a fight (among competing males during mating season).
• No surprises. Announce your intention to play a recording and hold the device above your shoulder so other birders can see the source of the sound.
"Any potential negative impacts of playback are more likely to occur in areas with a lot of birding pressure, so avoiding playback in those places is a good idea," Sibley writes. "Where and how to use it in other situations is up to the individual birder."