This data release includes metadata and tabular data from a field study of avian diseases (malaria and pox virus) that threatened recovery of the last extant population of ‘Alalā (Corvus hawaiiensis) before it went extinct in the wild in the early part of the 21st century. The study focused on habitat occupied by the last remaining wild ‘Alalā and determined prevalence of avian malaria (Plasmodium relictum) in native and non-native forest bird reservoir hosts (Atkinson et al. 2005), oviposition trap captures of Culex quinquefasciatus (the primary vector of avian malaria and pox virus) and Aedes albopictus across an altitudinal gradient, prevalence of malaria within the vector population, wing lengths of Culex quinquefasciatus and Aedes albopictus at different elevations, primary larval habitats and abundance of those habitats across an altitudinal gradient, environmental factors (temperature, humidity and rainfall) that might affect vector distribution and longevity, details about reduction in larval habitat after management actions to drain feral pig damaged tree ferns (Cibotium spp), and pre- and post-treatment oviposition trap catches before and after habitat management.