(a) – acoustic comparison species
(v) – visual comparison species


M – male
F – female


JUV – juvenile
IMM – immature
AD – adult
1CY – 1st calendar year
1W – 1st winter
1S – 1st summer


SUM – summer plumage
WIN – winter plumage
BREED – breeding plumage
NBREED – non-breeding plumage
ECLPS – eclipse plumage
DARK – dark morph
IMED – intermediate morph
PALE – pale morph


element – single element
syllable – tiny units consisting of elements
phrase – a series of similar/different syllables

monotone – steady frequency curve
upslur – increasing frequency curve
downslur – decreasing frequency curve
overslur – increasing and than decreasing frequency curve
underslur – decreasing and than increasing frequency curve

monophonic sound – sound produced just by one voice box
polyphonic sound – sound produced by two voice boxes or body parts

partials – bands of spectral sound energy produced simultaneously with the 1st partial (often wrongly referred to as fundamental)

1st harmonic partial
2nd harmonic partial – 1st even-numbered multiple
3rd harmonic partial – 2nd even-numbered multiple
1st inharmonic partial
2nd inharmonic partial – 1st uneven-numbered multiple
3rd inharmonic partial – 1st uneven-numbered multiple

side-band – a band of frequencies higher or lower than the carrier frequency (as a result of amplitude or frequency modulation)

bandwidth – the range between the lowest and highest pitch of a bird’s song or call
narrowband (simple) sound – sound with energy in a narrow band of multiple frequencies
broadband (complex) call – sound with energy in a broad band of multiple frequencies
noisy sound – sound of variable acoustic structure in a broad band of irregularly spaced frequencies

slow modulation – single or just a few modulations
fast modulation – many modulations
narrow modulation – modulations in a narrow frequency band
broad modulation – modulations in a broad frequency band


flight call – call only used in flight or to show flight motivation
call in flight – call used in flight, but also in other contexts
call during migration – call sound recorded during migration
nocturnal flight call – call sound recorded during nocturnal flight
social call – call in flight with a non-defined social meaning
wing sound – sound from resonating wing feathers, accidentally or ‘purposly’
mimicry – imitation of the call of another species