Appearance of a population of the mangrove rail Rallus longirostris (Rallidae) in salt marshes invaded by the exotic tanner grass Urochloa arrecta (Poaceae) and its disappearance after plant management

Abstract

Biological invasions cause species extinction but can also provide benefits. Wetlands, such as salt marshes, include little-known but important ecosystems that are sometimes severely invaded by exotic plants. Salt marshes in eastern South America are increasingly impacted by invasions of the African grass Urochloa arrecta . This study investigated the appearance of a population of the mangrove rail Rallus longirostris in areas dominated by U. arrecta and its disappearance with the eradication of this plant. We monitored four areas (54.47 ha) in the Guaratuba Bay estuary in southern Brazil, from 2006 to 2022, two of which contained four patches of U. arrecta as the dominant species. In 2012, we started to eradicate U. arrecta with mechanical management, and in 2020, it was eradicated locally. We recorded R. longirostris for the first time within a patch of U. arrecta in 2007. In subsequent years we saw the species in two other patches of the exotic plant. Rallus longirostris was no longer observed once U. arrecta was eradicated. Differences in patch occupancy between invaded and uninvaded habitats observed for R. longirostris and Pardirallus nigricans , and the disappearance of R. longirostris following the exotic plant management suggest competitive advantage and/or differential habitat preference and population density as hypotheses to explain observed patterns. The invasion of U. arrecta can increase the local populations of R. longirostris . Since this bird is not endangered, we encourage the management of U. arrecta because of its impact on salt marshes, including an endemic endangered bird. Supplementary information The online version contains supplementary material available at 10.1007/s13157-022-01642-7.

Population of the Paraná AntwrenFormicivora acutirostrisreassessed as being 64% smaller: Revision of its conservation status and assessment of its Green Status, with management proposals

“…It is quick and relatively expensive to eradicate 1 ha of exotic grasses in estuaries where no seed bank is formed (Bornschein et al . 2022).…”

“…2022). Invaded tidal marshes take 10 months to recover, from the start of management to the return of native vegetation (Bornschein et al . 2022), although with a reduced number of species.…”

“…2022), although with a reduced number of species. The cost of managing 1 ha is 13,404–29,356 USD, depending mainly on the distance of the management areas from the workers’ homes (Bornschein et al . 2022).…”

Short-term extinction predicted by population viability analysis for a Neotropical salt marsh endemic bird

“…et al 2006). Subtropical salt marsh birds also lose nests due to ooding by high tides (Bornschein et al 2022), but climatic conditions and the proximity of this environment to forests potentially exacerbate nest predation, which is a primary cause of reproductive failure in tropical birds (Oniki 1979;Winkler 2016).Additionally, salt marshes and other estuarine environments are generally vulnerable to sea-level increases, rising temperatures, changes in precipitation patterns, and alterations in river ows (Marengo 2006). Climate change models have predicted that sea levels will rise by up to 2 m by 2100 (IPCC 2013; Sweet et al 2022), which could lead to drastic habitat reductions for estuarine species (Erwin et al 2006; IPCC 2007).…”

“…et al 2006). Subtropical salt marsh birds also lose nests due to ooding by high tides (Bornschein et al 2022), but climatic conditions and the proximity of this environment to forests potentially exacerbate nest predation, which is a primary cause of reproductive failure in tropical birds (Oniki 1979;Winkler 2016).…”