You’re out birding at the local marsh, facing a sea of cattails and reeds. Somewhere in that vast expanse is a Black Rail. How in the world are you going to find it? What are the odds of it sauntering out of the dense growth right in front of you? If left to their own devices, very few Black Rails—and other very secretive birds—would show up on any birders’ life lists.

Birders do check off rails—and Swainson’s Warblers, nocturnal owls, and other hard-to-find species. Frequently these birds are prodded into announcing their presence by the use of recordings.

Birders tend to fall on a broad spectrum when it comes to using recordings. Some use them to excess. Others refuse to use them at all. As in other things, sanity probably lies somewhere in the middle.

I was recently with a group of birders at a scene similar to the one I describe above. We knew a Black Rail was somewhere in the marsh. Many other birders had seen it, some the night before. The trip leader opted to play a recording, hoping to lure it out from the cattails. In reply, we heard one soft answer, then silence. The rail decided it had had enough, and refused to show itself. Disappointed, but in sympathy with the bird, we left.

In this case, the bird had probably been subject to repeated tape playing over the course of our weekend birding convention, and was “played out.” Like the story of the boy who cried wolf, it had been bothered once too many times, and no longer bothered to respond. As we were the last group to look for it, I comforted my conscience by the fact that normally, birders don’t frequent that site. The bird would have its peace for months to come.

There is a lot of concern over what these recordings do to the bird hearing them. The idea is that by playing the sound of an intruding male, the resident male is forced to speak up in defense of his territory and his mate. Of course, this interrupts whatever else he may have been doing at the moment—perhaps feeding, nesting, sleeping, or showing off for the ladies. Physiologically, the birds may experience several hours of elevated stress hormones. It seems that this can’t be good for the birds, but very few studies have been done.

I read the small number of the studies that were available online. Most of the studies used male Song Sparrows, an easy-to-find, non-threatened species. The males are known to aggressively defend their territories against other males, making them ideal for this type of research.

I expected to find a negative effect on the birds subjected to “simulated territorial intrusions” (by either introducing caged birds or recordings). Surprisingly, the results were completely different from what I’d anticipated.

For one, there was significant variation between individual Song Sparrows in how they reacted to the recordings. One bird might become agitated and move in aggressively, singing and even pecking at the speaker, whereas another would ignore the recording completely.¹ There is also a marked difference between rural and urban individuals, with the city birds being both bolder and more aggressive than their country cousins, yet maintaining lower levels of stress hormones.²

 The playback of tapes could result in an upheaval in the social hierarchy of neighboring male chickadees. In some cases, the lower ranked males moved upward—presumably because the dominant males were seen as unable to drive away the “intruder.” In other species, the reverse occurred.³

Different species react in different ways. Some birds experience a rise in testosterone levels when another male intrudes, while others do not. In a study of Dark-eyed Juncos, the males exhibited “robust” aggressive displays and singing that continued even after the tapes were stopped, but “playback did not elicit any detectable elevation of testosterone or corticosterone”!⁴

Finally, repeated exposure to recordings leads to habituation as the birds learn to ignore the sounds. This is probably what happened to the Black Rail I’d hoped to see. How might this affect the ability of a male bird to defend his territory against an actual intruder?⁵

With all this in mind, what should we birders do? Should we continue to use tapes (or pishing, or hooting, or other sound effects) to draw out birds out into the open where we can see them? It seems that, while using these tools can be disruptive, it bothers the birds less than we might have imagined. My conclusion is to keep recording use to a minimum. I’ll avoid using it during the breeding season, or on threatened or endangered birds, or in areas frequented by birders. It’s important to weigh our need to see the bird against the bird’s comfort and safety.

The American Birding Association shares my opinion. In their guide to birding etiquette, they state:

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.

A 2011 article by David Sibley takes a balanced and sensible approach to using recordings. Rather than repeat his points here, please read what he has to say:

The Proper Use of Playback in Birding

As birding becomes an ever more popular activity, hopefully we can all take care to promote the well-being of our favorite subjects.
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Black Rail photo from the USGS via Wikipedia.

References:

1. http://jstor.org/stable/3677592?seq=1#page_scan_tab_contents
2. http://www.science20.com/anthrophysis/different_personalities_urban_and_rural_song_sparrows-85052
3. http://www.hras.org/sw/Swjune02.html
4. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3477244/
5. http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0077902