Monica Birkenes opens her debut full-length singing like a bird celebrating its bird-ness: cooing and twittering in sweet and playful tones, swooping and dipping and gliding for the fun of it. It’s the best kind of pop, in the vein of Cardigans and Brunettes. But slipping into the duskier tones of “Mercy,” it’s clear that Pocketknife is more than pop confection. Her super-chill and somewhat spooky cover of Arcade Fire’s “The Suburbs” garnered the Norwegian singer a few million new YouTube fans, and her morphing from pop to moody electronica and back again hasn’t seemed to bother them a bit. Mr Little Jeans (she took the moniker from a character in the quirky and beloved film “Rushmore”) seems quite comfy in pants of all kinds: the sleek Knife-nod “Good Mistake” is as sexy and cool as black leather; the kids’ choir on “Oh Sailor” is as carefree as summer capris; the drowsy “Mercy” ebbs and flows like a silky pair of harem pants. Birkenes is a confident and strong writer and arranger, a fabulous performer, and an artist ready to join Lorde and Lykke Li on the big stage.