Wildlife watchers now can wield unnatural powers, playing actual birdcalls on smartphones and other mobile devices. The practice, called playback, is effective for attracting elusive species but can harm nesting birds if overused.
"It's kind of a balancing act," said Jeffrey Gordon, president of the American Birding Association in Colorado Springs.
"If you're bringing a common bird into view for a group of kids or showing people how habitat is really good for birds, then a case can be made that it's a good tool for making birds visible. Caution is most warranted when you have a rare species or a species when a lot of people want to see it at the same location."
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, however, 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 might 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."