Fig 1.
Geographic distribution of the White-breasted Thrasher.
(A) White-breasted Thrashers are restricted to the islands of Saint Lucia and Martinique, shown in red. Data source: CIA World DataBank II. (B) Approximately 80% of the species’ global population inhabits the central east coast of Saint Lucia within the Mandelé range. This range is a mix of dry forest habitat and human land use. Twenty percent of habitat within the range was lost due to resort construction beginning in 2005; the approximate area of forest remaining on the development property is shown in light gray. Only 4% of the Mandelé range overlaps with federal forest reserves. Data source: Recreated and modified from [33, 34].
Table 1.
Parameters used to build individual-based models for the White-breasted Thrasher population viability analysis.
Table 2.
Comparison of White-breasted Thrasher population viability measures across scenarios.
Fig 2.
White-breasted Thrasher perturbation sensitivity analysis.
Populations were projected at extant carrying capacity (1K) for 200 years. The hashed vertical lines and boxes show mean vital rates ± 1 SD before habitat loss (black outline; [34]), after habitat loss (light gray filled; [33]), and across both time periods (dark gray filled). Breeding success is the proportion of breeding females that produce at least one successful brood per season. Mean population size includes only the iterations that persisted over the entire time frame.
Table 3.
Sensitivity of population growth and persistence to changes in White-breasted Thrasher parameter estimates.
Fig 3.
Effects of carrying capacity and annual adult survival on White-breasted Thrasher quasi-persistence over 200 years.
We varied carrying capacity from 0–1500 in increments of 100, and also depict the four habitat loss scenarios discussed in the text–from left to right, 1.2K, 1.0K (extant), 0.8K, and 0.17K. The bars on the x-axis represent the mean and 95% CI of adult survival before (black bar) and after (gray bar) habitat loss. Adult survival is truncated below 0.5 because all simulations at lower survival values resulted in a quasi-extinction (defined as a population size < 100) of 1. Note that while simulations were run using adult mortality, survival (1-mortality) is shown here for ease of viewing.
Table 4.
Summary of published sensitivity analyses of avian cooperative breeder vital rates relative to different metrics of population persistence.