Even though I’ve been a bird-watcher most of my life, nothing prepared me for the experience of witnessing—on my phone—the entire process of birds being born in my own backyard.

I’ve maintained a regular “dumb” nest box for years, the birthplace of generations of black-capped chickadees. I’ve seen them going in and out, but I always wondered what was happening in there, especially the year I opened up the box in the fall and found five deceased fledglings at the bottom. How could this have happened? I wondered.

Thanks to the Birdfy Nest Duo smart nesting box and its built-in thermometer and hygrometer, I now at least have an educated guess. (The poor things likely overheated during an early season heat wave.) Being able to watch the entire nesting operation from all angles, starting with excavation and egg-laying and ending in hatching and fledging, has been one of the most educational and entertaining bird-watching experiences I have ever had, and something I’d recommend to anyone interested in birds, nature, or just life science in general.

Eye Spy

Birdfy makes three smart nest boxes in addition to the Duo. The original, the Birdfy Nest, has one camera—located inside the box—and can only hang from an eye hook screwed into the top. There’s also a version made out of solid fir in contrast to the others’ lightweight bamboo. I have also tested Birdfy’s artful Polygon, but persistent connection issues prevented me from using it this season.

I have not tested the first two single-camera versions, but I can’t imagine not having a second camera outside the hole to see who’s unexpectedly poking their head in. (At one point in my testing, it was a confused flicker; another, a curious starling—this is when I learned chickadees can hiss). It’s also critical to be able to pole-mount the box to keep it away from predators.

SCREENSHOT: Kat Merck

The Nest Duo is substantial—16 inches tall and about 8 pounds—with one 1080p HD camera facing the nest entry hole on the exterior and another tucked discreetly inside the nest box itself. There’s also an internal hygrometer (humidity) and thermometer (temperature) that show readings on the live view in Birdfy’s easy-to-use app. There are four easy-to-install, screw-on entry hole sizes for different species, from 0.9 inches for wrens up to 2 inches for starlings or bluebirds, along with corresponding metal predator guards to prevent chewing. The entire side of the box opens with a latch for easy cleaning and access.

In the app, each screen capture appears as a split-screen image, which you can tap to view 20-second videos (with audio) of both the inside and the outside of the box. The videos are immediately downloadable and shareable—no subscription is needed.

The screen captures work much like one of Birdfy’s smart bird feeders, but with images shunted to sections labeled “Prelude,” “Nesting,” “Brooding,” “Nestling,” “Fledgling,” and “End.” There seemed to be no rhyme or reason for what process the app thought was happening at the time (for example, if a nestling was simply turned around, the app asked if it should label it as “Fledgling”), but this story format was easy enough to ignore onscreen.

House Hunters

In March of this year, at the beginning of nesting season on the West Coast, I installed the Duo with the 1-inch entry hole on a pole stand and mounted the included solar panel below the box with hose clamps. Black-capped chickadees were consistently interested, popping in and looking around, but something was preventing them from staking a claim. It took me a while to realize they were looking askance at the holes on the metal tray “floor,” which is perforated for drainage. The idea is that this tray can be inserted into one of a series of slots to increase or decrease the nest cavity depth, depending on your local species’ preference.

Photograph: Kat Merck