Biology in the News Explained

Predator-avoidance behavior in smoke alarms

The coqui frog Eleutherdactylus coqui, a native of Puerto Rico, gets its species name from the shrill call produced by males seeking mates, which is surprisingly loud for a beast the size of a quarter. Anyone from a part of the world with native tree frogs generally appreciates the lovely sound of calling peepers in the spring. Unfortunately, when the coqui was introduced to lands without its native predators to keep its populations in check, the lovely peeping sound in the distance was transformed into an overwhelming, piercing cacophony, which can be heard here at the site for Hawaiian Ecosystems at Risk (HEAR), where there is bountiful information on the hundreds of alien invasive species devastating Hawai`i’s ecosystems. Listen to the recording. Then imagine playing it through your surround sound system at full wattage, and you will begin to get the idea of one of the problems caused by this species. After dusk, one literally has to yell to carry on a conversation at one house I have visited in Kurtistown (which lies between Hilo and Volcano on the Big Island).

Here is a youtube video of a single calling male. Well, puppies are cute too, but no one wants to live next to a kennel, do they? Even from a purely anthropocentric perspective, this invasive has much more direct effects on property values than any other. Control efforts are detailed at the University of Hawai`i College of Tropical Agriculture site.

While the attempted control of a tiny frog meets with far less opposition than previous plans to kill destructive feral cats in Volcanoes National Park, some PETA-types of course object. But even if you can tolerate the highly unnatural, deafening noise, anyone who cares about the ecological integrity of the Hawaiian Islands understands that coquis are a destructive pest that is incompatible with efforts to conserve endemic Hawaiian species (many of which are of course are living animals also).

Although predators in its native land clearly make an impact on coqui populations, it is remarkable how difficult it is, for humans at least, to localize a single calling frog. Apparently this is what the recent producers of smoke alarms were trying to emulate when they designed the system in which a dying battery causes the alarm to beep at long intervals. If your spouse, like mine, believes him- or herself to be the household’s safety police, then you have about a dozen of these things littering your home, in every room. So, being able to find the one whose battery is dying is no trivial task. These contraptions strive to imitate the behavior of chirping frogs: as one attempts to hone in on the sound, they fall silent, in order to confuse and frustrate you, their predator.

As I have stalked around the second floor of the house, frozen for 30 seconds or more at a time, waiting for the next beep, my sympathies fall more into line with my father, who was decidedly not the Safety Monitor of our family. When smoke alarms first became available, my mother, whose very natural fear of house fires was grounded in personal experience, installed a single one in our split-level house. The first time it went off (the usual false alarm, of course, caused by kitchen smoke or whatnot) my father brandished a hatchet at the alarm, threatening over the excruciating whine to chop it to bits. Somehow my mother got the alarm away from him and turned off before he was able to make good.

My patience with the smoke alarms has run thin as well, every time I have to hurl one out the back door because my spouse insists on placing it in the kitchen, in defiance the manufacturer’s instructions. “Ever heard of the smoke alarm that cried wolf?!!” I bellow.

But the Chinese-beeping-torture is the worst. I cannot move on with my life until I have ripped the innards from every alarm in the house, looking for the culprit, which is always the sixth or eighth one I’ve checked. My poor mother though, has seen the karma in her early support of smoke alarms. The Einstein who built the house she moved into several years ago placed a wired-in smoke alarm near the peak on the wall of their two-story living room, with only a narrow stair landing about ten feet below. Wired smoke alarms would seem like a better solution if they too did not have back-up batteries – after all, the power could be out when a fire starts. A note to contractors: even those batteries fail after several years – which my mother and her husband discovered when it started beeping – so, it would be a big help if those alarms were actually ACCESSIBLE! To get to this one required climbing a ladder placed on the landing at an alarmingly steep angle, a task most of us would rather not attempt, given our desire for the smoke alarm actually to save our lives, rather than end it. Thus, the residents had no choice but to wait two days for the services of their local fire department – who sent a fireman to make the climb and deactivate the alarm.

My mother called me shortly after the alarm had been firmly and permanently disconnected, and the haunted tone in her voice made me shudder at her recent trial. “It kept beeping…” she wailed, “Every. Twenty-six. Seconds.” Though driven nearly to their wits end, their German short-hair pointer was clearly the most damaged of the three by the experience. Shortly after the beeping began he found the deepest recess of the downstairs guest room and burrowed within it, refusing to come out for anything but the quickest dash outside to relieve himself, after which he returned to his spot, trying, trying but (being a dog of very little brain) not succeeding in escaping the beeping torture. I witnessed his post-traumatic stress disorder on my next visit, when an inadvertent breaker pull caused one stray beep, and the terrified beast nearly knocked me over skidding to his designated burrow. Despite the fact that no more beeps were heard that night, the dog had to be crowbarred out of the corner of the room when I was ready to go to bed.

Really one of the stranger aspects of the low-periodicity beep torture is that it is not recognized as such by all vertebrates alike. Some friends, a family of four, invited us over for dinner once, and I noticed immediately upon crossing their threshold that they had a smoke alarm on the blink. I politely pointed it out to them, and astonishingly, the response I got was, “We know, it’s been doing that for weeks now.” Agog, I enquired with the grin frozen on my face, how they could stand it, and they just shrugged and said they didn’t notice it after awhile. I tried to bear up under the strain, but by halfway through dinner I just couldn’t keep myself from blurting out conversationally, “Wow, it’s really amazing that the smoke alarm doesn’t bother you.” Being astute students of the subtleties of human communication, they finally got the hint, and one of them laughed as he went immediately to extract the offending battery.

I suppose that answers my question about why smoke alarms are programmed with predator-avoidance response. Those of us driven crazy by one are as likely to take a hatchet to it as a new battery (until we sigh to ourselves that maybe, just maybe it will save our lives one day), while the rest of everyone out there just can’t be bothered to hunt them down (and may be selected out by unalarmed house fires). I just hope the people of Hawai`i have more success with accepting the grating chirp of the coqui than I have had with the grating chirp of a smoke alarm, because they will likely be there forever.


4 Responses to “Predator-avoidance behavior in smoke alarms”

  1. shlogblog says:

    great blog! keep up the good work. Just discovered it today- so will do more reading of yours than posting on mine for a while! (

    re: frogs/toads- Australia has a huge problem with the introduced Cane Toad species.. travelling ever westward. It’s poisonous skin means anything that eats it dies.

  2. Georgfelis says:

    The easy solution (that nobody does) is to buy a box of 9v batteries once per year and replace all the batteries in the little chirpy things across the house. We do ours in December and toss the old batteries into the box of remote control car controllers, works pretty good and the kids get the last goodie out of the expensive little beasts.

  3. joated says:

    Great story! I can imagine the frazzled look on your Mom’s face and that poor dog!

  4. Sofie says:

    I don’t even have a smoke alarm anymore. Being distracted while dealing with burned food, or delaying it to deal with the alarm, seems FAR more likely to result in harm to me than the chance of a fire while I’m sleeping that doesn’t wake me up.

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