Extrapolating population size from the occupancy–abundance relationship and the scaling pattern of occupancy

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Date
2009Author
Hui, C.
McGeoch, M.A.
Reyers, B.
le Roux, P.C.
Greve, M.
Chown, S.L.
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Show full item recordAbstract
The estimation of species abundances at regional scales requires a cost-efficient
method that can be applied to existing broadscale data. We compared the performance of
eight models for estimating species abundance and community structure from presence–
absence maps of the southern African avifauna. Six models were based on the intraspecific
occupancy–abundance relationship (OAR); the other two on the scaling pattern of species
occupancy (SPO), which quantifies the decline in species range size when measured across
progressively finer scales. The performance of these models was examined using five tests: the
first three compared the predicted community structure against well-documented macroecological
patterns; the final two compared published abundance estimates for rare species and
the total regional abundance estimate against predicted abundances. Approximately two
billion birds were estimated as occurring in South Africa, Lesotho, and Swaziland. SPO
models outperformed the OAR models, due to OAR models assuming environmental
homogeneity and yielding scale-dependent estimates. Therefore, OAR models should only be
applied across small, homogenous areas. By contrast, SPO models are suitable for data at
larger spatial scales because they are based on the scale dependence of species range size and
incorporate environmental heterogeneity (assuming fractal habitat structure or performing a
Bayesian estimate of occupancy). Therefore, SPO models are recommended for assemblagescale
regional abundance estimation based on spatially explicit presence–absence data.
Collections
- RESEARCH: Chown S [176]
- RESEARCH: Hui C [188]
- RESEARCH: McGeoch M [57]