than seven hundred North American species, simply by downloading one of a number of smart-phone apps. Unfortunately, most of these apps don't come with instructions, so some novices will play the songs repeatedly until a bird appears for that perfect photograph or for checking off on a life list. And since birders tend to share hot spots and unusual sightings via the Internet, some birds may be blasted with the artificial calls over and over again. The problem is that if a call is overplayed, birds may become overly excited and quickly fly back and forth, wasting their energy. They may get distracted from crucial activities, such as feeding and nesting. When males hear another male's call, they perceive it as a threat. Those birds may then expose themselves to predators and leave their nests vulnerable. Recently, in fact, federal biologists scaled back the use of recordings in spotted-owl surveys after it became clear that the birds that "whoo"-ed in reply were subject to attack by the more aggressive barred owls. Both the American Birding Association Code of Ethics and National Park Service regulations disallow the harassment of wildlife. And most national parks (not to mention state parks and national wildlife refuges) regard the consequences of playback (heart-pumping anxiety, undefended nests and mates, and exposure to predators) as harassment, thereby prohibiting the use of birdsong playback by smartphone. In fact, on Yosemite National Park's website is the statement: "Refrain from using broadcast bird calls to elicit responses." You make the