Habitat use and behaviour of birds in areas invaded by buffel grass (Cenchrus ciliaris L.) and in restored habitat

Abstract

Context Buffel grass (Cenchrus ciliaris L.) is an introduced pasture grass that has spread over large areas of semiarid Australia with potentially significant negative consequences for biodiversity. Previous studies suggest that the response of bird communities to the changes in habitat associated with buffel grass invasion is complex. Aims This study compares the behaviour of birds between sub-sites with predominantly native vegetation where buffel grass had been removed and control sub-sites with buffel grass, which were left unmanaged, at two locations in central Australia. Our objective was to evaluate whether removing buffel grass at small scales had measurable benefits for local bird species and to better understand how the presence of buffel grass affects bird behaviour. Methods We assessed differences in microhabitat use and behaviour of all species combined and when separated into above ground, flexible and ground foraging guilds. We also tested for direct correlations between different cover types and the microhabitat use and behaviour of birds within guilds, with some further analyses of three common species individually. Key results Management of buffel grass was associated with changes in the microhabitat use and behaviour of birds when all species were combined and for all foraging guilds. Buffel grass cover was negatively correlated with the proportional time birds spent on the ground and with proportional time spent foraging. However, of the three species examined individually only the behaviour of white-winged trillers (Lalage tricolor) was consistently correlated with ground vegetation cover. Our observations also suggest birds spent less time overall at sites with high buffel grass. Conclusions Managing buffel grass in small areas creates islands of habitat that provide important opportunities for foraging at a localised scale. Buffel grass and other ground cover affects the behaviour of birds collectively, but individual species responses vary. Implications Management of buffel grass in small areas with high conservation value should be considered. Our study will help to inform land managers of the benefits of controlling buffel grass on a localised scale.

Buffel grass (Cenchrus ciliaris) eradication in arid central Australia enhances native plant diversity and increases seed resources for granivores

“…The estimated mean mass of buffel grass seed at infested sites (1.2 kg/ha) was much lower than the combined mass of non-buffel grass seeds at buffel-removed sites (46.26 kg/ha). This finding may partially explain previous observations that link buffel invasion to depauperate populations of granivore guilds of birds, harvester ants and rodents (Ludwig et al, 2000;Friedel et al, 2006;Smyth et al, 2009;Young and Schlesinger, 2014). However, it is possible that results from these studies also reflect that granivores benefit from the generally more open site attributes of native plant communities, which may facilitate easier foraging and/or better nesting or breeding sites than weed-invaded habitats (Antos and Williams, 2015).…”

“…Several competitive traits promote buffel grass invasion into new habitats: its ability to establish and grow under low‐rainfall conditions (Hodgkinson et al, 1989); prolific seed production with or without outcrossing (i.e. buffel grass is agamospermic) (De Lisle, 1963; Franks, 2002); the ability to chemically suppress the growth of native species via the leaching of allelopathic chemicals into soils (Cheam, 1984); bristly burrs that are easily dispersed over long distances by wind, water and/or animals (Goldsmith et al, 2008; Fensham et al, 2013); and the capacity to capture nutrient resources and rapidly regenerate from a deep root system after disturbance (Stevens and Fehmi, 2009; Young and Schlesinger, 2014).…”

Ranking buffel: Comparative risk and mitigation costs of key environmental and socio‐cultural threats in central Australia

“…Buffel directly suppresses (Abella, Chiquoine, & Backer, 2012; Eilts & Huxman, 2013) and threatens the persistence of many native plants (Clarke et al, 2005; Edwards, Schlesinger, Ooi, French, & Gooden, 2019; Eyre, Wang, Venz, Chilcott, & Whish, 2009; Fairfax & Fensham, 2000; Friedel et al., 2006) including threatened species (Griffin, 1993; Jackson, 2005). Changes in vegetation composition and structure following buffel invasion also affect species and assemblages of fauna (Bonney, Andersen, & Schlesinger, 2017; Pavey & Nano, 2009; Read & Ward, 2011; Smyth, Friedel, & O’Malley, 2009; Williams, Mulligan, Erskine, & Plowman, 2012; Schlesinger, Kaestli, Christian & Muldoon, 2020; Young & Schlesinger, 2014) and may increase the risk of extinctions. There is substantial evidence that buffel establishment in arid and semi‐arid communities has negatively affected native biodiversity (Bonney et al, 2017; Griffin, 1993; Marshall et al., 2012; Schlesinger, et al, 2020), even at comparatively low cover levels (Eyre et al., 2009; Friedel et al., 2006) though the mechanisms driving these impacts are not yet well understood.…”

Not All Roads Lead to Rome: A Meta-analysis of Invasive Plant Impact Methodology

“…While most studies do not investigate the relationship between invader abundance and impact (Barney et al 2013), some have shown a linear increase in magnitude with grass (Olsson et al 2012), forb (Hulme and Bremner 2005), shrub (Gooden et al 2009), and tree (Ruwanza et al 2013) cover. It has also been shown that abundance–impact relationships can be nonlinear (Tekiela and Barney 2015; Toth 2016; Truscott et al 2008; Young and Schlesinger 2014), and others have shown more complex relationships (Fried and Panetta 2016; Thiele et al 2011). Here we show that impact magnitude increases with invader abundance across all studies.…”