Avian Communities of the Northern Jaguar Reserve East-Central Sonora, Mexico
Situated near the northern extent of subtropical thornscrub and among oak woodlands of the foothills of the Sierra Madre Occidental, the Northern Jaguar Reserve of east-central Sonora supports a diversity of environments and wildlife of both Nearctic and Neotropical affinity. Isolated by the Sierra Madre to the east and surrounded by deep rugged canyons of the Río Aros and Yaqui on three sides, the reserve is at the core of one of the largest and least fragmented wildlands in northwest Mexico. Due in part to its inaccessibility, this region supports fairly large and potentially viable populations of Jaguar (Panthera onca) and other wide-ranging predators yet its remoteness has made it difficult to obtain detailed information on the status of many organisms including birds.
Birds are one of the better studied groups of animals in Sonora (e.g. van Rossem 1945, Marshall 1957, Russell and Monson 1998, Flesch 2008a, Molina Freaner and van Devender 2010) yet information on birds in areas on and around the Northern Jaguar Reserve have only recently been made available. Thomas Clark (1984) reported notable birds he detected near Sahuaripa in April and May 1978 and Steve Russell (Russell and Monson 1998) worked in the mountains east of Sahuaripa in March 1984, and these efforts provided perhaps the first bird records for the region. Bryan Brown studied nesting Bald Eagles (Haliaeetus leucocephalus) along the Río Aros, Bavispe, and Yaqui (Brown and Warren 1985, Brown 1988), yet it was not until 1998 until his data on species other than raptors (Rodríguez-Estrella and Brown 1990) were summarized (Russell and Monson 1998). More recently, biologists from the University of Arizona recorded 80 species of birds along a 185 km stretch of the Río Aros below Natora and Río Yaqui above Sahuaripa in July and August 2005 (O’Brien et al. 2006). In mid April 2007, Peter Warshall and others visited several portions of the Northern Jaguar Reserve and recorded 99 species including a variety of Neotropical migratory species (Warshall 2007). During approximately four weeks of field work that spanned portions of July, September, and January 2007-2009 (Flesch 2008b, 2009), I observed 152 species of birds that included 92 potential breeding species, 43 (47%) of which I confirmed breeding. During that effort I also estimated bird abundance along eight transects that were representative of important habitats on the reserve and recorded data on habitat use by birds.
At the request of Northern Jaguar Project, I surveyed the reserve for birds during the fall and spring migratory periods in September 2009 and April 2010 and during winter in January 2010. This report summarizes observations from these three field trips, summarizes the residency and breeding status and relative abundance of all bird species detected on the reserve based on information collected since 2007, and provides information on local habitat use by migratory birds.