Marsh bird response to restored shallow lakes: Implications for future management

Abstract

The restoration of shallow lakes has the potential to provide habitat for obligate breeding marsh birds, including secretive marsh birds. However, the degree of marsh bird response to wetland restoration may vary over time as prairie wetlands are subject to variation in water depth and vegetation characteristics (e.g., height, density, distribution) because of management and biotic and abiotic factors. We investigated the effects of shallow lake restoration age and habitat covariates on the abundance of 3 secretive marsh bird species and marsh bird species richness at shallow lakes in northern Iowa from 2009-2010 and again from 2016-2017. We found that the interspersion of water and emergent vegetation, shallow lake area, and water depth influenced the abundance of pied-billed grebes (Podilymbus podiceps). Restoration age (β = −0.52, 95% CI = −0.87, −0.18) had a quadratic effect on abundance of piedbilled grebes, peaking at 6 years post-restoration. Percent cattail (β = 1.95, 95% CI = 0.55, 3.35) and restoration age (β = 0.51, 95% CI = 0.14, 0.87) were important predictors for Virginia rail (Rallus limicola) abundance. Species richness was greater at restored shallow lakes (R ˆ= 2.72, 95% CI = 2.23, 3.23) compared to non-restored shallow lakes (R ˆ= 3.91, 95% CI = 3.41, 4.56) and at shallow lakes with a greater percentage of cattail (R ˆ= 2.54, 95% CI = 2.13, 3.07 at 0% cattail to R ˆ= 4.27, 95% CI = 3.47, 5.15 at 100% cattail). Restoration age did not significantly influence least bittern (Ixobrychus exilis) abundance or species richness, but both variables tended to peak between 5 to 8 years after restoration. Our findings illustrate the need

King Rail ( Rallus elegans ) response to audio playback: implications for population estimation, monitoring methodology, and trapping approach

“…Progress has been made toward using SNAMBM survey data to model King Rail occupancy (Glisson et al 2015, Stevens and Conway 2019, though little advancement has been made toward estimating population density for this species, likely due to its low abundance, occupancy rate, and detectability in many regions (Steidl et al 2013). Population density has been estimated for other marsh birds (e.g., Harms and Dinsmore 2012, Wiest et al 2016, 2019, Vanausdall et al 2022) despite the high potential for these oftensecretive species to remain undetected at or immediately adjacent to the observer, which is a violation of a distance sampling assumption (Buckland et al 1993). N-mixture models can produce reliable population density estimates via repeated surveys at locations, though are known to overestimate population size where densities are low (Neubauer et al 2022), as is often true for King Rails.…”