Point transect distance sampling data collected during the 2010 surveys of Alamagan, Commonwealth of the Northern Mariana Islands (CNMI). Data were collected at points along transects where trained observers recorded the detection type (heard, seen, or heard then seen) and horizontal distance (exact distance in m) from the station center point to individual birds detected during an 8-min count. To increase the numbers of detections, survey data from 40 detections from the CNMI Division of Fish and Wildlife (DFW; 2000) surveys of Alamagan, and 46 detections from Saipan surveys described in Camp et al. (2009). The count length of the DFW surveys was only 5 minutes; therefore, we included detections from the first 5 minutes of the 2010 survey. The data set also includes covariates that may influence the detectability of birds. Camp, R. J., Pratt, T. K., Marshall, A. P., Amidon, F. and Williams, L. (2009) Status and trends of the land bird avifauna on Saipan, Mariana Islands, with emphasis on the endangered Nightingale Reed-warbler (Acrocephalus luscinia). Bird Conservation International 19: 323–337. Division of Fish and Wildlife (2000) Wildlife and vegetation surveys: Pagan 2000. Technical Report 7. CNMI Division of Fish and Wildlife, Saipan, MP.