英文關鍵字
alert
animal
are
beak
beautiful
biology
bird
birds
black
close
coastal
colony
common
community
entering
environment
europe
european
feather
feathers
feeding
flight
furrow
group
hole
image
leaving
many
martins
mud
nature
nest
ornithology
outdoors
riparia
sand
singer
spring
swallow
their
tunnels
wild
wildlife
wing