Perhaps the most ambitious amateur music-archiving project on the internet is Jeff Glenn’s Lost Jukebox series. Glenn, a musician and collector who died in 2009, put together 240 CD-Rs containing forgotten ’60s pop tracks. Some of the names are familiar or semi-familiar (the Association, Bobby Sherman, the American Breed); the vast remainder is composed of the forgotten hopefuls. Plowing through the set is a neat experience: While few songs could be considered hidden gems by sunshine pop neophytes, the collection affords a deeply satisfying, unified aesthetic experience. Thousands of musicians working in dozens of studios pursuing varying creative and financial goals somehow creates a body of work that can be reconstituted as a dialogue — it’s the story of genre in every age.

Such is the story I heard when listening to Local Natives’ first record. The SoCal act — now a quartet with the departure of Andy Hamm; Taylor Rice picks up bass duties — released their debut, Gorilla Manor, in 2009. It was a record that will in a few years likely be viewed as very much of its time: slightly obtuse indie pop with gently reverbed guitar, keening tenor vocals, modest string touches, and harmonies that stick more than they stack. That’s not intended to be a backhanded compliment. The album, though widely acknowledged to be a familiar-sounding document, was received warmly, possibly indicating an audience unmooring from the idea that worthwhile music must push boundaries or offer some brand-new sonic concept. The Grizzly Bearish pleasures of the waltz-time “Stranger Things” and the Fleet Foxy skitter of “Wide Eyes” didn’t need to define their time or put the game on notice; they were their own reward. Their sound was sturdy enough to translate the nervous spell of Talking Heads’ “Warning Sign” into a darkly pretty big-city chorale. Gorilla Manor was an assured debut, studiously intricate yet uncluttered.

Hummingbird finds the band in a new situation: new to them, but as old as wax cylinders. They parted with an original member and moved to the opposite coast, ending up in Brooklyn (as bands do), under the eye and roof of their co-producer, the National’s Aaron Dessner. Gorilla Manor was named for the Orange County house in which the band wrote the album. Allegedly, it was a raucous environment; by contrast, the craziest thing the guys cop to this go-round is an exploding kombucha bottle in Dessner’s kitchen. But Local Natives’ devotion to their foundational sound is such that the venue change (and three-year-plus gap) can’t be intuited from the record. Hummingbird’s introductory element is a buzzy, ambient synth bed, which for them counts as an instrumental departure.

You can, however, detect an increased confidence. The aforementioned album opener (“You & I”) uses that nagging guitar ping familiar to fans of the genre, but also fits in clanging, metallic patches and a rhythm section that burbles like Yoshimi Battles The Pink Robots, or “Little Faith” from the National’s High Violet. At its peak roar, the reverb becomes a compositional element, rather than a byproduct. “You & I” also tips the listener to another change: the harmonies have been dialed back, allowing Kelcey Ayer to occasionally uncork a Jeff Buckley-style yawp (here and on “Black Spot,” especially). As someone who’s admittedly never had much use for Buckley, believe me, I mean this as praise. The Fleet Foxes’ style of Maximum Harmonies works in small doses; massed vocals can quickly become an oppressive opacity. When Ayer rocks back on his heels for a phrase, he manages Buckley’s pure tone without approaching his tremulous megalomania. Even largely harmonized tracks like lead single “Breakers” tend to use the supplemental vocals more for timbre than tone.

There’s also a newfound faith in their ability to … if not rock, then at least rattle. Whether due to the influence of their locale, their producer, or recent tours with louder acts like the National and Arcade Fire, Local Natives are beating slow tracks from a placid palette. “Black Balloons” throws Hammond organ textures and a thick guitar topline over the pinging stuff, against which the bass hacks out a counterpoint. “Wooly Mammoth” showcases a sticky riff worthy of Shields (if not Shields), frantic percussive patter, and a brief out-of-body chorus. A few years ago, a song like “Black Spot” might have been an inert bit of prettiness. Now, fidgety piano block chords maintain tension until Ayer leads the band into a soaring coda, where a constantly-ascending midrange riff observes the proceedings.

The beefier tone seems to have come at the expense of the looser moments on Gorilla Manor: You won’t find anything here like the goofy warm-up hollers at the beginning of “Airplanes” or the arresting dance-punk break in “Sun Hands.” Instead, you’ll find a lot of synth textures and programmed drums. (“Three Months” uses sampled drums from Ryan Hahn’s vinyl collection.) On “Ceilings,” Local Natives allow themselves a bit of fun. It opens with a familiar pastoral six-string figure, but after the dreamy chorus, a subtle, mimicking synth line pokes fun at the guitars while four-on-the-floor scratch yields something you can stomp to (while still keeping in mind the downstairs neighbors). The band builds a lyrical bridge too far (“Haven’t stopped you smoking yet/ So I’ll share your cigarette” and “Walk around till 3 AM/ Tell me what I know again” are dead-on, while “Hold the summer in your hands/ Till the summer turns to sand” is a bit on-the-nose), but to a guy who leans pop these days, it’s the standout track.

In one sense, Hummingbird’s full sonic immersion is a standard follow-up procedure, the natural result of a band finding its legs during a rigorous touring schedule. In another, it’s a reasonable reaction to a hectic, often heartbreaking few years. The split with Hamm was painful; worse still was the passing of Ayer’s mother, Patricia. “Colombia” — named after her native country — invokes the titular hummingbird in its opening verse. (It falls to the ground before the singer, recalling the cardinal in Sufjan Stevens’ “Casimir Pulaski Day.”) As the piano paces and the city goes about its business in the deep background, Ayer addresses his mother: “Patricia/ Every night I ask myself/ Am I giving enough/ Am I giving enough/ Am I giving enough/ Am I?” It’s utterly heartrending, made even more devastating by a cliffjump of an ending that leaves behind siren-like strings and organ drone.

While “Ceilings” is probably Local Natives’ most immediate song to date, it lies beyond my meager powers to predict whether they’ll develop a knack for pop songcraft like their peers in, say, Real Estate. But on their sophomore album, the band has capably expanded their sonic and emotional palettes. Formalist niceties are giving way to resonant songwriting. One of us may compile the Lost Jukebox for the ’10s, and with luck, Local Natives will keep us stocked for years to come.