Rodent, snake and raptor use of restored native perennial grasslands is lower than use of unrestored exotic annual grasslands

Abstract

In California's Central Valley, most native grasslands have been destroyed or degraded due to invasion, farming and development. Grassland restoration is often assumed to provide improved wildlife habitat, ostensibly increasing the abundance and diversity of at least some native wildlife species relative to unrestored, invaded annual grasslands. We compared rodent, snake and raptor activity and species richness at paired unrestored and restored grasslands across four blocked locations in the Central Valley using trapping and observational surveys in up to four seasons per guild from 2014 to 2015. Restored treatments were planted with native perennial grasses 13–24 years prior to study initiation but were partially re‐invaded by Mediterranean annual grasses and forbs. Unrestored treatments contained similar non‐native plant species assemblages as restored treatments, but did not contain any native grass. Rodent, snake and raptor activity was generally higher in unrestored relative to restored treatments. For rodents, the non‐native Mus musculus (house mouse) showed the greatest disparity in abundance, while greater raptors and snakes likely responded to greater rodent abundance. Within treatments, species‐specific rodent responses were related to structure of physical vegetation. In particular, Peromyscus maniculatus (native deer mouse) was associated with more bare ground and shorter vegetation, while the house mouse was associated with less bare ground and taller vegetation, regardless of treatment type. Substantial changes in rodent species composition were observed over short periods of time (<3 months) after unplanned manipulation of vegetation structure via livestock grazing, with patterns reflecting the species‐specific response to physical vegetation structure. Synthesis and applications. Our results reveal that while grassland restoration may promote persistence of native plant communities, restoration may not be beneficial to some higher trophic levels, and in fact may reduce habitat value for some native predators in grasslands invaded by Mediterranean plant species. Changes in vegetation structure can strongly impact wildlife species composition, suggesting a more nuanced approach is required for the restoration of desired wildlife communities. Thus, species‐specific goals should be carefully considered to ensure improved alignment of restoration methods with expected restoration outcomes.

Responses of grassland snakes to tallgrass prairie restoration

“…Colonization by snakes is not unique to grasslands restored from row‐crop agriculture; shrubland and grassland habitats created following mountain‐top removal mining in West Virginia were inhabited by seven snake species 10–18 years post reclamation (Williams et al ). In contrast, snake encounters were lower in restored than in unrestored perennial grasslands in California's Central Valley (Wolf et al ) and ground cover attributes had greater effects than restoration treatment (remnant, revegetated, cleared) on squamate reptiles in Australian agricultural landscapes (Jellineck et al ).…”

Demographic and genetic viability of a medium-sized ground-dwelling mammal in a fire prone, rapidly urbanizing landscape

“…Dense, weedy areas can be used for dispersal and shelter by I . obesulus and other ground-dwelling vertebrates in modified landscapes [ 55 , 81 ]. This demands thoughtful spatial and temporal planning in weed management and restoration practices, so that critical habitat is not removed before appropriate (structurally complex and dense) habitat is available.…”

Novel resources: opportunities for and risks to species conservation

“…In altered ecological environments, with a blend of novel and traditional resources, the novel resource may influence habitat use (MacClagan et al 2018) and subsequent community composition (Wolf et al 2018). For instance, native rodent-feeding raptors and snakes were more abundant in unrestored Californian grasslands dominated by exotic annuals that also contained more non-native house mice (Mus musculus) than comparable restored grasslands dominated by native perennials but fewer mice (Wolf et al 2018). resource use by species, illustrated here by a gray-tailed mountain-gem (Lampornis cinereicauda) in Costa Rica feeding on the flower of an introduced ornamental plant, Callistemon sp, which is native to Australia (WebFigure 1).…”

“…Novel resource use can also impact species by altering community composition (Wolf et al 2018) or by promoting new species interactions (Buettner et al 2013). In the tropical rainforests of northern Australia, foraging by the threatened spectacled flying fox (Pteropus conspicillatus) on a novel food source (fruit from the non-native wild tobacco bush, Solanum mauritianum), which grows lower to the ground than traditional food sources, increased their exposure to a ground-dwelling ectoparasite (the native Australian paralysis tick, Ixodes holocyclus), leading to occasional paralysis in and mortality of flying foxes (Buettner et al 2013).…”

“…2018; Wolf et al . 2018). Urban areas in particular offer a range of novel resources, and are also characterized by greater rates of phenotypic change in animals and plants (leading to contemporary evolution) than non‐urban anthropogenic and natural systems (Johnson and Munshi‐South 2017; Thompson et al .…”