The Malagasy forms gracilis (Madagascar) and griveaudi (Comoro Islands) of African Palm Swift Cypsiurus parvus have very different vocalisations (short insect-like single buzzy notes and occasional drawn-out rising buzzes) from mainland African taxa (twitters and staccato notes, the former sometimes in longer series). They also have heavier dark markings on the throat and upper breast, paler bellies and distinctly shorter tail extensions. These characters in combination are here considered to demarcate the Malagasy forms as a species, Madagascar Palm Swift C. gracilis, separate from both the remaining taxa of C. parvus and Asian Palm Swift C. balasiensis.
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15 March 2019
Species limits in the African Palm Swift Cypsiurus parvus
Michael S. L. Mills,
Peter Boesman,
N. J. Collar