Birds as surrogates for mammals and reptiles: Are patterns of cross-taxonomic associations stable over time in a human-modified landscape?

Abstract

a b s t r a c tCross-taxonomic surrogates can be feasible alternatives to direct measurements of biodiversity in conservation if validated with robust data and used with explicit goals. However, few studies of cross-taxonomic surrogates have examined how temporal changes in composition or richness in one taxon can drive variation in concordant patterns of diversity in another taxon, particularly in a dynamic and heavily modified landscape. We examined this problem by assessing changes in cross-taxonomic associations over time between the surrogate (birds) and target vertebrate taxa (mammals, reptiles) that demand high sampling effort, in a heterogeneous mosaic landscape comprising pine monoculture, eucalypt woodland remnants and agricultural land. Focussing on four study years (1999, 2001, 2011, 2013) from a dataset collected over 15 years, we: (1) investigated temporal changes in cross-taxonomic congruency among three animal taxa (2) explored how temporal variation in composition and species richness of each taxon might account for variation in cross-taxonomic congruency, and (3) identified habitat structural variables that are strongly correlated with species composition of each taxon. We found the strength of cross-taxonomic congruency varied between taxa in response to both landscape context and over time. Among the three taxa, overall correlations were weak but were consistently positive and strongest between birds and mammals, while correlations involving reptiles were usually weak and negative. We also found that stronger species richness and composition correlations between birds and mammals were not only more prevalent in woodland remnants in the agricultural matrix, but they also increased in strength over time. Temporal shifts in species composition differed in rate and extent among the taxa even though these shifts were significant over time, while important habitat structural correlates were seldom shared across taxa. Our study highlights the role of the landscape matrix and time in shaping animal communities and the resulting cross-taxonomic associations in the woodland remnants, especially after a major perturbation event (i.e. plantation establishment). In such dynamic landscapes, differing and taxon-specific shifts in species diversity over time can influence the strength, direction and consistency of cross-taxonomic correlations, therefore posing a 'temporal' problem for the use of surrogates like birds in monitoring and assessment of biodiversity, and conservation management practices in general.

Effectiveness of woodland birds as taxonomic surrogates in conservation planning for biodiversity on farms

“…Findings from these studies contribute to the evidence-base for conserving a broad array of biodiversity on farms. However, other research shows that other groups of vertebrate taxa that are more difficult to survey, for example mammals and reptiles, can respond differently to vegetation composition and structure compared to woodland birds (Cunningham et al 2007;Jellinek et al 2014;Michael et al 2014;Yong et al 2016). Such a discrepancy in responses to the landscape calls into question whether woodland birds are as good taxonomic surrogates for biodiversity on farms as they are supposed.…”

“…Agricultural landscapes, despite their highly modified state, can support high numbers of species (Yong et al 2016), and systematic survey data on multiple taxonomic groups are rare (underscoring the necessity of using taxonomic surrogate approaches). We took advantage of the South West Slopes Restoration Study (Cunningham et al 2007;Lindenmayer et al 2016), which gathers detailed multitaxon data across an extensive agricultural region of southeastern Australia.…”

“…However, we did not expect that the degree of spatial concordance or incidental representation would be identical between taxa (Lentini and Wintle 2015). For instance, we predicted that conservation planning for all woodland birds in our agricultural landscape would be: (i) less effective than conservation planning targeted at a subset of threatened woodland birds (Beger et al 2003), and (ii) more effective at representing arboreal marsupials, which may use the landscape at similar scales to birds and thus may have similar ecological requirements, compared to reptiles, which may use the landscape at smaller scales (Yong et al 2016).…”

Established and empirically derived landbird focal species lists correlate with vegetation and avian metrics

“…similarity in habitat requirements; Senzaki and Yamaura 2016). Understanding whether focal species lists adequately represent vegetation will inform potential linkages with other taxa; while some useful correlations exist across taxa, not all important habitat characteristics are shared among taxa (Yong et al 2016). We found correlations between both PIF and empirical focal species lists with vegetation metrics at select parks, suggesting that in some cases birds adequately represent coarse metrics of vegetation structure and composition (e.g., conifer vs. hardwood, canopy cover).…”

Implications of vegetation clearing biases for the interpretation of landscape-scale species-area relationships

“…As has been highlighted by numerous authors, measures of species richness (and analyses of changes thereto) can mask how the composition of assemblages compare, or vary in response to environmental change (i.e. vegetation clearing) Bennett et al, 2006;Fleishman et al, 2006;Villalobos et al, 2013;Matthews et al, 2014b;Lindenmayer et al, 2015;Yong et al, 2016). This is potentially problematic because a small (or no) change in species richness may obscure a large conservation impact, such as compositional changes that mask the loss of highly-sensitive species , or species that have disproportionately important functional roles in an assemblage De Coster et al, 2015).…”