Development of a rapid demographic monitoring protocol to assess tidal marsh sparrow productivity

Abstract

Salt marshes in the northeastern United States provide critical breeding habitat for tidal marsh specialist birds like the Saltmarsh Sparrow (Ammospiza caudacuta) and Seaside Sparrow (Ammospiza maritima). Saltmarsh Sparrow population estimates have declined by nine percent annually, which elevates the importance of immediate conservation actions for this vulnerable species. However, estimating species vital rates across a large geographic region is logistically challenging and cost prohibitive. I developed and tested a time-efficient rapid sampling protocol focused on reproductive metrics to enhance future conservation planning. I used three years (2018, 2019, and 2021) of intensive demographic data from 17 sites to estimate daily nest survival, nest period success, fledglings produced per female, and successful broods per female. I implemented the rapid protocol co-located at intensive sites in the same years to estimate the number of captured females and juveniles. I used general linear models to determine if I could predict intensive metrics with rapid metrics. I found that the sum of Saltmarsh Sparrow female and juvenile captures predicted daily nest survival (R2 = 0.37, β = 0.605, P = 0.01), nest period success (R2 = 0.49, β = 0.700, P = 0.002), fledglings produced per female (R2 = 0.67, β = 0.818, P < 0.001), and successful broods per female (R2 = 0.67, β = 0.819, P < 0.001). My analysis demonstrates that the rapid demographic protocol is an informative and time-efficient sampling method that can aid in making informed management decisions related to sparrow conservation.