Saltmarsh Sparrow Nest Habitat Associations and Reproductive Success in a Salt Marsh in Rhode Island

Steven E. Reinert^1,*, Katharine J. Ruskin², Deirdre E. Robinson³, James M. O’Neill⁴, Miranda B. Zammarelli⁵, Olivia R. McCarthy⁶, Joel Eckerson⁷, and Kylie Rezendes⁸

¹11 Talcott Street, Barrington, RI 02806. ²School of Biology and Ecology, Climate Change Institute, University of Maine, 200 Clapp Greenhouse, Orono, ME 04469. ³34 Sullivan Lane, Bristol, RI 02809. ⁴74 Aaron Avenue, Bristol, RI 02809. ⁵Department of Biological Sciences, Dartmouth College, 78 College Street, Hanover, NH 03755. ⁶4 Morrison Drive, Lincolnville, ME 04849. ⁷751 Oak Street, North Dighton, MA 02764. ⁸500 W. University Avenue, El Paso, TX 79968. *Corresponding author.

Northeastern Naturalist, Volume 32, Issue 4 (2025): 493–515

First published early online: 27 October 2025

Abstract
We studied the breeding ecology and reproductive success of Ammospiza caudacuta (Saltmarsh Sparrow) in a 10-ha salt marsh in upper Narragansett Bay, RI, from 2017 to 2021. We banded and color-banded 460 Saltmarsh Sparrows (41% adults, 59% males), and monitored 234 nests. We observed low reproductive success compared to estimates elsewhere in the species’ range and within Narragansett Bay 35 years earlier. We estimated a daily nest survival probability of 0.929; thus, sparrows had only a 17% probability of a nest surviving a full 24-day nest interval. We estimated that 33% and 49% of nests failed over the 24-day nest interval due to depredation and flooding, respectively. As is typical for the species, 77% of Saltmarsh Sparrow nest plots were detected in marsh habitats dominated by salt meadow graminoids (Spartina patens [Saltmeadow Cordgrass], Distichlis spicata [Saltgrass], Juncus gerardii [Saltmeadow Rush]). Atypically, we observed multiple positive associations between Saltmarsh Sparrow nesting and Iva frutescens (High-tide Bush); 24% of 234 nests monitored were found in proximity to Iva, with greater nest-rim elevations of nests placed in Iva habitats, and decreased daily probability of nest failure, particularly from flooding, with increasing percent cover of Iva. We discuss these results within the context of management for this species, which is threatened by sea-level rise and predicted to be extinct by 2060s.

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