The grasshopper sparrow as an indicator species in tallgrass prairies

Abstract

Funding constraints highlight the need for efficient approaches to manage wildlife habitat. One such approach is to monitor a single species that serves as an indicator of management effectiveness. The grasshopper sparrow (Ammodramus savannarum) is an obligate species of dry, upland prairie that has been proposed as a surrogate species for the Eastern Tallgrass Prairie, USA. To evaluate whether this species (or another) would make a suitable indicator for grassland birds, we examined the strength of associations in the density and occurrence of grasshopper sparrows and densities of other grassland species: sedge wren (Cistothorus platensis), Savannah sparrow (Passerculus sandwichensis), Henslow's sparrow (A. henslowii), dickcissel (Spiza americana), bobolink (Dolichonyx oryzivorus), and western meadowlark (Sturnella neglecta). No single species was a good predictor for all other species, but grasshopper sparrow density was the best predictor of the densities of other obligate upland prairie species. We also compared avian community composition between grassland sites with and without grasshopper sparrows; densities of all species except sedge wren were significantly higher at sites with grasshopper sparrows. Therefore, the grasshopper sparrow is the best choice as a single indicator species for tallgrass prairies within our study area. However, a better approach would be to select multiple, complementary indicator species to ensure that species not well‐indicated by grasshopper sparrows are adequately represented. © 2018 The Wildlife Society.

A global review identifies agriculture as the main threat to declining grassland birds

“…Species within grassland bird communities have varying ecological needs (Maphisa et al 2017, Elliott & Johnson 2018, Budka et al 2019, often making management challenging. Our results generally suggest that management should aim to provide a mosaic of habitat types with different grass height and cover (Maphisa et al 2019), to benefit the greatest range of species; this can be facilitated by ensuring the largest areas possible are under appropriate management, to capture natural variability in habitat types.…”

“…Species within grassland bird communities have varying ecological needs (Maphisa et al . 2017, Elliott & Johnson 2018, Budka et al . 2019), often making management challenging.…”

Identifying mismatches between conservation area networks and vulnerable populations using spatial randomization

“…The sedge wren, a tallgrass specialist, was not represented by either Focal Landscapes or GBCA ensembles relative to the rest of the state. This can be explained by its association with wet prairie and idle planted grasslands (Elliott & Johnson, 2018 ) and its sensitivity to agricultural management practices that reduce late successional patches of dense herbaceous and woody vegetation that sedge wren use for foraging and cover from predators (Marx et al, 2008 ). Overall, our findings highlight the need for spatial planning of grassland conservation networks to account for heterogeneous habitats and integrate multispecies assessments (Elliott & Johnson, 2017 ; Nocera et al, 2007 ; Thogmartin et al, 2006 ).…”

Response of grassland birds to management in national battlefield parks

“…These 2 species were sufficiently common in the study area to study their responses to the same management strategies. Although the grasshopper sparrow has been suggested as an indicator species for eastern tallgrass prairie because of its strong relationship with other grassland species' densities (Elliott and Johnson 2018), we aimed to compare it with a species whose needs are similar but not identical. For example, although woody shrub cover has a well‐supported negative effect on grasshopper sparrow occurrence and abundance (Johnston and Odum 1956, Dechant et al 2002, Chapman et al 2004, Grant et al 2004), eastern meadowlarks, while also intolerant of heavy shrub encroachment, have been observed to tolerate some woody vegetation for use as song perches (Kahl et al 1985, Sample 1989).…”