Inspired by Terry Masear’s book about her work with the world’s smallest birds, Sally Aitken’s documentary follows her during a busy caretaking season in Los Angeles.

When she first appears onscreen, Terry Masear, the plainspoken hero of Every Little Thing, is driving through Los Angeles and carrying on a jokey banter with her passenger. If there’s no return banter, that’s understandable: Riding shotgun, in a minuscule nest inside a lovingly built coop, is a hummingbird named Wasabi.

Masear’s book Fastest Things on Wings is the inspiration for the film by Sally Aitken, who captured another woman’s dedication to misunderstood animals in Playing With Sharks: The Valerie Taylor Story. Every Little Thing acknowledges the ways hummingbirds have been endlessly poeticized, and it offers stunning visual poetry of its own as it zeroes in on rehabilitation, an undertaking both practical and spiritual. The way Aitken and her ace team have made a handful of these birds, each a few inches long and weighing a couple of grams, into compelling screen characters is, well, no small thing.

Masear has run a hummingbird rehab hotline since 2008, and the doc follows her through 2022’s busy spring-summer season (lots of newborns). Elegant drone camerawork over the hills and canyons of Los Angeles paints the setting, while amazing macro shots offer a rare chance to admire the usually fast-moving birds, whether through slo-mo footage of them suspended in air or ultra-close-ups of nonflying patients on the mend. (Nathan Barlow and Dan Freene were the DPs for the rehab story, and Ann Johnson Prum handled the birds-in-the-wild angle.)

In the homespun ICU, Masear tends to damaged wings and feeds motherless nestlings using the slenderest of syringes. It’s not hyperbole when she says, “Their lives depend on me.” As to why the caretaker role has profound meaning for her, Aitken offers hints, drop by drop, as if from that tiny syringe. When, eventually, the pertinent facts are revealed, there’s no need for lurid details; the clarity and concision of Masear’s words, and the quiver in her voice, tell us all we need to know.

The question of how she came to inhabit the huge, sparsely furnished hilltop home where Angelenos bring her suffering hummingbirds is never clearly explained in the film; you’d have to read the production notes to know that this is a rental house chosen for the documentary (Masear was just returning to L.A. after relocating during the pandemic). Nagging questions about fiscal realities aside, the setting, with its natural surroundings and outdoor aviaries, feeders and fountains, is a kind of spa retreat for hummingbirds. In the indoor infirmary, Masear conducts such procedures as “physical therapy flight training,” complete with a cherished twig she calls a magic wand. But it’s a magic born of commitment and focus and hope against hope.

“It’s not just this one bird,” Masear says with emotion. Her lament takes in “a whole way of viewing the world that a lot of humans have.” In her regard for these smallest of winged creatures, in the laser-focused, unfussy way she talks to them, and in the way, after all these years, they still amaze her, Every Little Thing is not just a deeply affecting portrait — it offers a vision of compassion as a way of life. In a world where we’ve doubled down on war rather than outgrown it, that’s a lot.

When Masear buries the birds who don’t make it, placing flower petals beside their corpses, some might scoff. Some might ask if it matters that Sugar Baby has a few days or weeks of attentive care and loving kindness before she dies. In its quiet way, Aitken’s effortlessly riveting film provides a resounding response: It matters, yes.