Estimating species relative abundances from museum records

Abstract

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The ‘Meidum geese’ revisited: Early historical art is not a suitable basis for taxonomic speculation

“…Given this temporal bias, our knowledge of most taxa is reliant on relatively modern specimen material. This is often abundant for widespread species, but can be extremely limited in the case of very rare or extinct species, despite some evidence of collection bias in favour of the latter (Gotelli et al 2021). Between at least 80 and 100 described species are generally considered to have become extinct in relatively modern times (post-1600; an arbitrary date selected by several authors for such analyses) (e.g., Fuller 2002).…”

Crop visitation by wild bees declines over an 8‐year time series: A dramatic trend, or just dramatic between‐year variation?

“…First, when sampling effort is not standardised over time, a species can erroneously appear to decline because less effort was made to sample it (or its habitat) in the recent period. Second, a rarer species can appear to decline because early collectors targeted rare species, whereas later collectors tended to use passive collection methods that sample species in proportion to their abundance and thus collect mainly common species (Gotelli et al, 2021). Third, a species can appear to decline if other species in the same dataset increased over time and therefore constitute a larger proportion of the more recent samples (Bartomeus & Winfree, 2013).…”

“…Third, a species can appear to decline if other species in the same dataset increased over time and therefore constitute a larger proportion of the more recent samples (Bartomeus & Winfree, 2013). Although calibration methods have been developed that can make museum and field‐data comparable (Gotelli et al, 2021), this does not negate the importance of having local scale time series for which sampling effort is standardised over time, and thus declines in abundance can be detected directly (Goulson et al, 2015).…”

Six years of wild bee monitoring shows changes in biodiversity within and across years and declines in abundance

“…However, these types of studies are typically only able to investigate changes in a subset of species that are relatively common or popular among collectors (like bumble bees) and are most informative to detect changes in species’ geographic distribution (Cameron et al, 2011 ; Mathiasson & Rehan, 2019 ; Wood et al, 2019 ). While it is possible to estimate changes in species' relative abundance over time from museum collections data (e.g., Bartomeus et al, 2013 ) these estimates can be skewed by changes in collection methods over time (Gotelli et al, 2021 ). Furthermore, relative abundances are a community‐level pattern and do not give direct measures of species' population‐level changes over time (Gotelli et al, 2021 ).…”

“…While it is possible to estimate changes in species' relative abundance over time from museum collections data (e.g., Bartomeus et al, 2013 ) these estimates can be skewed by changes in collection methods over time (Gotelli et al, 2021 ). Furthermore, relative abundances are a community‐level pattern and do not give direct measures of species' population‐level changes over time (Gotelli et al, 2021 ). An alternative approach is to conduct standardized sampling, often using passive traps, in the same locations across multiple years (Gezon et al, 2015 ; Graham et al, 2021 ; Iserbyt & Rasmont, 2012 ; Martins et al, 2013 ; Onuferko et al, 2018 ).…”