Regional faunal decline - reptile occurrence in fragmented rural landscapes of south-eastern Australia

Abstract

Many species of reptiles are sedentary and depend on ground-layer habitats, suggesting that they may be particularly vulnerable to landscape changes that result in isolation or degradation of native vegetation. We investigated patterns of reptile distribution and abundance in remnant woodland across the Victorian Riverina, south-eastern Australia, a bioregion highly modified (>90%) by clearing for agriculture. Reptiles were intensively surveyed by pitfall trapping and censuses at 60 sites, stratified to sample small (<30 ha) and large (>30 ha) remnants, and linear strips of roadside and streamside vegetation, across the regional environmental gradient. The recorded assemblage of 21 species was characterised by low abundance and patchy distribution of species. Reptiles were not recorded by either survey technique at 22% of sites and at a further 10% only a single individual was detected. More than half (53%) of all records were of two widespread, generalist skink species. Multivariate models showed that the distribution of reptiles is influenced by factors operating at several levels. The environmental gradient exerts a strong influence, with increasing species richness and numbers of individuals from east (moister, higher elevation) to west (drier, lower elevation). Differences existed between types of remnants, with roadside vegetation standing out as important; this probably reflects greater structural heterogeneity of ground and shrub strata than in remnants subject to grazing by stock. Although comparative historical data are lacking, we argue that there has been a region-wide decline in the status of reptiles in the Victorian Riverina involving:(1) overall population decline commensurate with loss of >90% of native vegetation; (2) disproportionate decline of grassy dry woodlands and their fauna (cf. floodplains); and (3) changes to populations and assemblages in surviving remnants due to effects of land-use on reptile habitats. Many species now occur as disjunct populations, vulnerable to changing landuse. The status of reptiles in rural Australia warrants greater attention than has been given to date. Effective conservation of this component of the biota requires better understanding of the population dynamics, habitat use and dispersal capacity of species; and a commitment to landscape restoration coupled with effective ecological monitoring.

Landscape and local influences on patterns of reptile occurrence in grazed temperate woodlands of southern Australia

“…Brown, Bennett, & Potts, 2008;Driscoll, 2004;Fischer, Fazey, Briese, & Lindenmayer, 2005;Fischer, Lindenmayer, & Cowling, 2003;Michael, Lunt, & Robinson, 2004), not least because so little is known about the impacts of many agricultural practices on the distribution and abundance of this diverse animal group, and the prospects that altered management, such as extensification, hold for it. Broadly, reptiles in these agri-landscapes are thought to be in decline Driscoll, 2004).…”

Tropical reptiles in pine forests: Assemblage responses to plantations and plantation management by burning

“…Reptiles are an important element of the fauna in tropical forests worldwide, but their responses to tropical forest management are poorly understood (Alcala et al, 2004;Trainor and Woinarski, 1994;Gardner et al, 2007b;Cunningham et al, 2007). Reptile populations are especially sensitive to manipulations of the structure of vegetation communities (Vitt et al, 1998;Kavanagh and Stanton, 2005;Gardner et al, 2007a;Brown et al, 2008). Because plantation management strongly alters vegetation structure (McCullough, 1999), solar radiation levels, and environmental temperatures (Yirdaw and Luukkanen, 2004;Lemenih et al, 2004), the response of reptiles to plantations may be driven by their response to these environmental changes (Jä ggi and Baur, 1999;Valentine, 2006).…”

Drought-driven change in wildlife distribution and numbers: a case study of koalas in south west Queensland

“…Habitat loss and fragmentation were identified as one of the main causes of extinction of woodland birds in Australia, related to poor dispersal to isolated patches, increasing nest predation, changes in habitat quality and resource availability, and increasing interspecific completion from aggressive bird species (Ford 2011). Brown et al (2008) found that reptiles in Victoria, Australia, had declined significantly with loss of habitat and changes in woodland structure, with declines in species richness even in remaining large patches. For howler monkeys in the Central and South American Neotropics, loss of habitat was more important than fragmentation on distribution and abundance, probably because howler monkeys are highly mobile and resistant to initial habitat disturbance (Arroyo-Rodriguez and Dias 2010).…”