Action: Remove midstorey from savannas
A controlled study in Argentina found that in summer, but not overall, a control area had higher bird abundance and species richness than an area where shrubs were removed. There were also differences in community composition between treatments.
Conservationists may wish to remove shrubs from savanna if they are dominating the habitat and excluding some open-habitat species. However, shrubs can also provide habitat complexity and additional niches for species.
Supporting evidence from individual studies
A controlled study in 1998-1999 in one treatment (where shrubs were manually removed) and one control (shrubs left unmanipulated) area (both 200 ha) within the same Chacoan forest in Santiago del Estero, Argentina (Codesido et al. 2009) found that, overall, there was no difference in bird abundance or species richness between the two areas. However, the treatment area contained significantly lower species richness and abundance than the control area in summer. At the guild level, bark-feeding insectivores were more abundant in the treatment area; whereas foliage-gleaning insectivores and arboreal seed-eating species were less abundant in the treatment area. In December 1998, terrestrial insectivores were less abundant in the treatment. Birds were surveyed four times at 30 points within each area. In the treatment area, saplings of species that form the tree layer were not removed.