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General Impact In the Galapagos Islands, known Philornis downsi fitness costs to Darwin's finches include: high nestling blood loss (18-55%), multiple body wounds and infections, grossly deteriorated nasal openings (Fessl et al, 2006a), reduced haemoglobin levels (Dudaniec et al 2006) and reduced growth rates (Fessl and Tebbich, 2002). Consequently, it is not surprising that P. downsi parasitism has been linked with high brood mortality: 16% to 95% (Fessl and Tebbich, 2002; Fessl et al, 2006a; Huber, 2008), and reduced fledging success (Dudaniec et al, 2007). Species with small clutch sizes, e.g. tree finch species are higher impacted than species with bigger clutch sizes (Fessl and Tebbich, 2002). As well, parasite intensity is higher in islands with highlands (Wiedenfeld et al, 2007). Impacts of P. downsi parasitism especially threaten small remaining populations of the 'Critically Endangered (CR)' mangrove finch (see Camarhynchus heliobates in IUCN Red List of Threatened Species) with an approximate population of 100 individuals; the 'Critically Endangered (CR)' Floreana mockingbird (see Mimus trifasciatus in IUCN Red List of Threatened Species), and the the 'Critically Endangered (CR)' medium tree finch (see Camarhynchus pauper in IUCN Red List of Threatened Species). The Darwin's medium tree finch has recently been uplisted from 'Vulnerable (VU)' to 'Critically Endangered (CR)'. Recent estimates put the total population at not more than 1,660 individuals, and it has recently begun declining rapidly owing to the effects of P. downsi (BirdLife International, 2009). No information is available to our knowledge on impacts of P.downsi on other places.          Location Specific Impacts: Galapagos Islands (Ecuador)   Damage to host species: In the Galapagos Islands, known Philornis downsi fitness costs to Darwin's finches include: high nestling blood loss (18-55%), multiple body wounds and infections, grossly deteriorated nasal openings (Fessl et al, 2006a), reduced haemoglobin levels (Dudaniec et al 2006) and reduced growth rates (Fessl and Tebbich, 2002). Consequently, it is not surprising that P. downsi parasitism has been linked with high brood mortality: 16% to 95% (Fessl and Tebbich, 2002; Fessl et al, 2006a; Huber, 2008), and reduced fledging success (Dudaniec et al, 2007). Species with small clutch sizes, e.g. tree finch species are higher impacted than species with bigger clutch sizes (Fessl and Tebbich, 2002). As well, parasite intensity is higher in islands with highlands (Wiedenfeld et al, 2007). Parasitism: In the Galapagos Islands, known Philornis downsi fitness costs to Darwin's finches include: high nestling blood loss (18-55%), multiple body wounds and infections, grossly deteriorated nasal openings (Fessl et al, 2006a), reduced haemoglobin levels (Dudaniec et al 2006) and reduced growth rates (Fessl and Tebbich, 2002). Consequently, it is not surprising that P. downsi parasitism has been linked with high brood mortality: 16% to 95% (Fessl and Tebbich, 2002; Fessl et al, 2006a; Huber, 2008), and reduced fledging success (Dudaniec et al, 2007). Species with small clutch sizes, e.g. tree finch species are higher impacted than species with bigger clutch sizes (Fessl and Tebbich, 2002). As well, parasite intensity is higher in islands with highlands (Wiedenfeld et al, 2007). Threat to endangered species: Impacts of P. downsi parasitism especially threaten small remaining populations of the 'Critically Endangered (CR)' mangrove finch (see Camarhynchus heliobates in IUCN Red List of Threatened Species) with an approximate population of 100 individuals; the 'Critically Endangered (CR)' Floreana mockingbird (see Mimus trifasciatus in IUCN Red List of Threatened Species), and the the 'Critically Endangered (CR)' medium tree finch (see Camarhynchus pauper in IUCN Red List of Threatened Species). The Darwin's medium tree finch has recently been uplisted from 'Vulnerable (VU)' to 'Critically Endangered (CR)'. Recent estimates put the total population at not more than 1,660 individuals, and it has recently begun declining rapidly owing to the effects of P. downsi (BirdLife International, 2009).