Chlidonias leucopterus

BB, M

Species seasonal life history at a given site:

YR-R = Year-round resident; breeder, present throughout the year.
YR-V = Year-round visitor; non-breeder, present throughout the year.
BB = Breeding bird; breeder, absent during non-breeding period.
SV = Summer visitor; non-breeder, present in spring and summer.
WV = Winter visitor; non-breeder, present in late fall, winter and early spring
M = Migrant; bird of passage; present primarily in fall and spring.
ND = Not defined; found but its status not known yet.
FB = Former breeder.
Cas = Casual; recorded irregularly; less expected because normal range is far away.