Factors associated with local and statewide population trends of the Florida Sandhill Crane ( Antigone canadensis pratensis )

Breeding Bird Survey (BBS) data indicate that the Florida population of the nonmigratory Florida Sandhill Crane (Antigone canadensis pratensis) has been increasing for 50 years despite substantial habitat loss and a recent period of extended drought. We generated BBS route-specific population trends for 1966-2016 to identify locations in Florida that had experienced significant increases or declines to better understand the statewide population growth. We also assessed whether changes in land cover over time were correlated with local increases or decreases in the Sandhill Crane population. Finally, we explored how drought during the breeding season affected the number of cranes detected during the BBS and the number of young cranes detected in a fall post-reproductive survey we conducted during 1991-2016. Of the 42 BBS routes on which cranes were observed in >= 4 years, populations increased on 17 (40%) and declined on one (2%), and no change was detected on 24 (57%). Routes with positive population growth occurred throughout the breeding range, with one hot spot of growth occurring in the northwest region of central Florida. Change in five primary land cover types (grassland, wetland, scrub/successional, woodland, urban) during 1985-2016 did not predict changes in Sandhill Crane populations. Drought conditions during a prior year's breeding season were negatively correlated with BBS counts, and within-season drought conditions were negatively correlated with juvenile crane counts on the post-reproductive surveys. Productivity rates in all but the driest years were similar to those associated with stable or growing crane populations. Continued monitoring is warranted because the longevity of adult cranes could mask an impending population decline and because little is known about the cranes that reside in the suburban landscapes that make up an increasingly large proportion of Florida's landscapes.