Seabirds are the most threatened marine group with nearly 28% of extant species considered at risk of extinction. Managers and researchers face considerable financial and logistical challenges when designing programs to monitor the status of any of the 97 species listed as critically endangered, endangered, or vulnerable by the IUCN. These challenges are exacerbated by the fact that these birds breed in isolated/inaccessible locations, many have cryptic nest sites, and most return to colonies only at night. Acoustic sensors are an effective tool for monitoring the presence, distribution, and relative abundance of rare and elusive seabirds. We have developed new, cellphone-based wireless acoustic sensors that 1) are comparable to state-of-the-art sensors, 2) are affordable (~US$500.00 per hectare), 3) can sample continuously over months, 4) can telemeter data from remote locations via a cellular, microwave, or satellite link, and 5) can be reprogrammed remotely. To date we have deployed our wireless acoustic sensor networks to monitor seabirds of conservation concern including - Ashy Storm-petrel, Oceanodroma homochroa, on Southeast Farallon Island (CA), Tristram’s Storm-petrel, O. tristrami, on Tern Island (French Frigate Shoals), as well as Newell’s Shearwater, Puffinus newelli, and Hawaiian Petrel, Pterodroma sandwichensis, at the Upper Limahuli Preserve (Kaua’i, HI).