The occurrence and nesting phenology of Ardeidae species and other wading birds were documented from 2009–2013 in the Bahía Kino bioregion of western Sonora, México. Two active colonies were surveyed: in a mangrove (Avicennia germinans; Rhizophora mangle) estuary and on a nearshore desert island. Thirteen species of nesting wading birds were recorded, 11 of which are year-round residents and two occurring only during the breeding season; two additional species were documented only in migration. The most abundant species was the Snowy Egret (Egretta thula), which had a peak of 234 nests in 2012. Of particular conservation interest is the Reddish Egret (E. rufescens), which had a peak of 149 nests in 2012. Potential prey of wading birds in the estuary was also sampled, with special focus on brachyuran crabs, which constitute the main prey items of the Yellow-crowned Night-Heron (Nyctanassa violacea). The rapid development of the region, and especially the establishment of largescale mariculture operations along Estero Santa Cruz, has the potential to impact local wading bird populations, and thus an understanding of wading bird diversity, abundance and habitat use may prove critical to inform future management and conservation initiatives.