[8] Editors at AllMusic rated this album 4.5 out of 5 stars, with critic Heather Phares writing that "the chance to connect with his music for the first time once again is something like a miracle" and continued that "listening to Bird Machine is a heartbreaking, uplifting experience—in other words, a perfect tribute to the way he moved so many people".

[11] Writing for The Line of Best Fit, John Amen scored the album 8 out of 10, commenting that "Linkous's lyrical dexterity, emotional depth, and gift for dark-pop hooks are once again on glorious display.

[12] Writing for Louder Than War, Tim Cooper characterized the release as "a familiar blend of the fragile and the furious" that is more than outtakes and unfinished work that is "unmistakably a Sparklehorse album from the moment it begins" that is "packed with hummable tunes".

[13] In The New Zealand Herald, critic Peter Baker shortlisted Bird Machine on music that readers needed to listen to that week and called it "an essential addition to [Mark Linkouss'] legacy".

[15] In The Skinny, Tony Inglis gave Bird Machine four out of five stars, stating that "rarely has a posthumous release felt so emotionally fitting, so lovingly rendered", continuing that Linkous' "oft-praised skill of managing to wrench childlike wonder from the depths of pain and self-flagellation runs across this set".

[17] In Uncut, Jason Anderson scored this album 4 out of 5 stars, writing that this release "demonstrates no diminishment of confidence" and that the work "strongly suggests [that Mark Linkous] remained the same restlessly inventive artist that he'd been" in his early career.