Puerto Rico plain pigeon, scaly-naped pigeon and red-tailed hawk: population dynamics and association patterns before and after hurricanes

Since the 1980s, 3 major hurricanes have made landfall on Puerto Rico: Hugo in September 1989 (Saffir-Simpson scale, category 4), Georges in September 1998 (category 3) and Maria in September 2017 (category 4). Maria was the most devastating hurricane since the 3 major hurricanes that occurred in 1899-1932. Major hurricanes can cause severe abundance declines and population bottlenecks by decreasing survival and reproductive rates and increasing predation and competition for limited resources. In April to June 1986-2021, we used distance sampling to estimate abundance and monitor the population dynamics of the endangered Puerto Rico plain pigeon Patagioenas inornata wetmorei and the abundant scaly-naped pigeon P. squamosa and redtailed hawk Buteo jamaicensis. Here, we fit a Bayesian state-space logistic model with distance sampling abundance estimates to generate posterior estimates of maximum population growth rate and population carrying capacity, and predict abundance in April to June 2020-2030. In addition, we used N-mixture and 2-species models to assess association patterns in April to June 2015-2019. The scaly-naped pigeon and red-tailed hawk populations did not decline, or recovered faster from their declines than the plain pigeon population after the hurricanes. The association patterns between species were positive but variable for the 2 pigeon species and negative but variable for the plain pigeon and red-tailed hawk. At lowered abundance (i.e. mean +/- SE estimates (N) over cap = 1043 +/- 476 island-wide and (N) over cap = 522 +/- 157 at the centre of abundance in the east-central region in April to June 2018-2021), the plain pigeon may become extinct if another hurricane with the path and intensity of Maria makes landfall on the island during the current decade.

Automated summary

Since the 1980s, Puerto Rico has experienced three major hurricanes, with Hurricane Maria in 2017 being the most devastating. These hurricanes have had significant impacts on the bird populations, with the plain pigeon being the most vulnerable to extinction if another hurricane of similar magnitude occurs in the coming years.