Amazingly enough, two agencies within the U. S. Fish & Wildlife Service have different bird code systems. The codes used by the Bird Banding Lab (BBL) are pretty widely known, but the Breeding Bird Survey (BBS) has its own system. The two are pretty similar in most cases, but there are two main differences:
Below is a list of all the discrepancies between the BBL and BBS codes known to the author:
BBS BBL Name ---- ---- ---- ASPE ASSP Storm-Petrel, Ashy BMNS BACS Sparrow, Bachman's BRDS BAIS Sparrow, Baird's BASP BANP Storm-Petrel, Band-rumped BNKS BANS Swallow, Bank BATG BARG Godwit, Bar-tailed BRBH BBLH Hummingbird, Broad-billed BLTG BLAG Godwit, Black-tailed BGBK BLGR Grosbeak, Blue ABOY BLOY Oystercatcher, American Black BPLW BLPW Warbler, Blackpoll BSPE BLSP Storm-Petrel, Black BTHH BLUH Hummingbird, Blue-throated BCRM BRAC Cormorant, Brandt's BRZC BROC Cowbird, Bronzed BRES BRSP Sparrow, Brewer's BUBH BUFH Hummingbird, Buff-bellied CACO CALC Condor, California CYNW CANW Wren, Canyon CWAX CEDW Waxwing, Cedar CBOW COBO Barn-Owl, Common CGDO COGD Ground-Dove, Common COPO COPW Poorwill, Common COPE CORE Redpoll, Common COPE CPEA Peafowl, Common EWPE EAWP Wood-Pewee, Eastern FPOW FEPO Pygmy-Owl, Ferruginous FLFS FFSH Shearwater, Flesh-footed FWDU FUWD Whistling-Duck, Fulvous GKGF GKIN Kingfisher, Green GRYJ GRAJ Jay, Gray GKNB GRAK Kingbird, Gray GFLM GREF Flamingo, Greater GRNJ GREJ Jay, Green GRYF GRFL Flycatcher, Gray AGWT GWTE Teal, Green-Winged HADU HARD Duck, Harlequin HRMG HEEG Gull, Heermann's HRGG HERG Gull, Herring HLNH HRLH Hawk, Harlan's HAWH HWAH Hawk, Hawaiian JAWH JAWE White-eye, Japanese LRKB LARB Bunting, Lark LESP LCSP Sparrow, Le Conte's LGPL LEGP Golden-Plover, Lesser LCHP LHSP Storm-Petrel, Leach's LSTP LTSP Storm-Petrel, Least MAGW MAWA Warbler, Magnolia MACW MGWA Warbler, MacGillivray's MCBU MKBU Bunting, McKay's NHOW NOHO Owl, Northern Hawk NPOW NOPO Pygmy-Owl, Northern RWSW NRWS Swallow, Northern Rough-winged PKFS PFSH Shearwater, Pink-footed RTDO RITD Turtle-Dove, Ringed RPHA RNPH Phalarope, Red-necked SHTS SHAS Sandpiper, Sharp-tailed STSH SHOS Shearwater, Short-tailed SBOR SPOO Oriole, Spot-breasted STLS STSA Sandpiper, Stilt GULL UNGU gull sp. WWPE WEWP Wood-Pewee, Western WSPE WISP Storm-Petrel, Wilson's ZEDO ZEND Dove, Zenaida