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

Ff Rivera-Milán,H Diaz-Soltero,D Guzmán,A Matos,Aj Martínez,Cr Ruiz-Lebrón,Ea Ventosa-Febles

doi:10.3354/esr01166

Ff Rivera-Milán, H Diaz-Soltero + Show 5 more

Open Access

https://doi.org/10.3354/esr01166

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Abstract

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 María in September 2017 (category 4). María 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 pigeonPatagioenas inornata wetmoreiand the abundant scaly-naped pigeonP.squamosaand red-tailed hawkButeo 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 usedN-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 estimatesN̂= 1043 ± 476 island-wide andN̂= 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 María makes landfall on the island during the current decade.

Highlights

Hurricanes can cause abundance declines, give rise to negative interspecific interactions and increase the risk of extinction of Caribbean island birds with restricted distribution ranges and small population sizes
Because María has been the most devastating hurricane to make landfall on the island since the 3 major hurricanes that occurred in 1899−1932 (Boose et al 2004, Uriarte et al 2019, Hall et al 2020), we expected plain pigeon abundance to decline below the lowest estimate since monitoring started, which had occurred in April to June 1990 (Rivera-Milán et al 2016)
While the process model in the state-space formulation accounted for our incomplete understanding of pigeon and hawk population dynamics, we related true abundance state to the distance sampling abundance estimates and standard errors (SEs) to account for observation variance (Knape 2008)

Summary

INTRODUCTION

Hurricanes can cause abundance declines, give rise to negative interspecific interactions and increase the risk of extinction of Caribbean island birds with restricted distribution ranges and small population sizes. Because María has been the most devastating hurricane to make landfall on the island since the 3 major hurricanes that occurred in 1899−1932 (Boose et al 2004, Uriarte et al 2019, Hall et al 2020), we expected plain pigeon abundance to decline below the lowest estimate since monitoring started, which had occurred in April to June 1990 (Rivera-Milán et al 2016). We used the term ‘interaction’ in a statistical sense, meaning that δ and φ = 1 would suggest that the 3 species tended to occur independently of each other, based on estimates of detection, abundance and occupancy for the surveyed areas in the east-central region of Puerto Rico in April to June 2015−2019

Distance sampling

N-mixture and two-species models

Bayesian state-space logistic model

Findings

DISCUSSION