Tests of the impact of Philornis downsi on Darwin's Finches.

(Y, impact of parasite on host parameter detected; N, no impact detected; -, not tested).*Observational data suggest P. downsi responsible for nestling mortality.†Correlational data show a negative relationship between parasite abundance and fledging success.‡Experimental nests fumigated to reduce parasite abundance.αDifferent islands pooled for analysis.βDifferent species pooled for analysis.ΩGeospiza fuliginosa, Camarhynchus parvulus, Cam. psittacula, Certhidea olivacea.θGeospiza fuliginosa, G. fortis, Camarhynchus parvulus, Cam. psittacula, Cactospiza pallida, Certhidea olivacea.