Abstract
The mule deer population in Mexico declined severely during the early 20th century but recovered due to public policies centered on sport hunting. Sonora is considered the main reference for mule deer management in Mexico; however, the conservation status of the species in the state remains unclear. This study aimed to estimate the relative abundance and population structure of mule deer in Sonora. An aerial survey was conducted from 4 to 24 November 2019 using linear transects distributed across 62 sampling quadrants (30 × 30 km each). Over 82 flight hours, a total of 1376 deer were observed, with a male:female:fawn ratio of 24:100:12. The number of sightings and deer observed per quadrant followed a normal distribution, with averages of five sightings and twenty-two deer per sampling unit. The quadrants with the lowest abundance corresponded to areas containing towns and agricultural fields, whereas the areas with the highest deer numbers coincided with those containing a high concentration of Wildlife Conservation Management Units, where habitat improvement actions were implemented. The results falls within the limits of a stable population of desert mule deer; however, the low proportion of fawns suggests that limiting factors may be exerting pressure on the population. These findings highlight the importance of continued habitat management and monitoring to promote population stability and support recruitment in Sonoran mule deer populations.