Many species are extending their leading‐edge (cool) range margins polewards in response to recent climate change. In the present study, we investigated range margin changes at the northern (cool) range margins of 1573 southerly‐distributed species from 21 animal groups in Great Britain over the past four decades of climate change, updating previous work. Depending on data availability, range margin changes were examined over two time intervals during the past four decades. For four groups (birds, butterflies, macromoths, and dragonflies and damselflies), there were sufficient data available to examine range margin changes over both time intervals. We found that most taxa shifted their northern range margins polewards and this finding was not greatly influenced by changes in recorder effort. The mean northwards range margin change in the first time interval was 23 km per decade (N = 13 taxonomic groups) and, in the second interval, was 18 km per decade (N = 16 taxonomic groups) during periods when the British climate warmed by 0.21 and 0.28 °C per decade, respectively. For the four taxa examined over both intervals, there was evidence for higher rate of range margin change in the more recent time interval in the two Lepidoptera groups. Our analyses confirm a continued range margin shift polewards in a wide range of taxonomic groups.

Range shifting is vital for species persistence, but there is little consensus on why individual species vary so greatly in the rates at which their ranges have shifted in response to recent climate warming. Here, using 40 years of distribution data for 291 species from 13 invertebrate taxa in Britain, we show that interactions between habitat availability and exposure to climate change at the range margins explain up to half of the variation in rates of range shift. Habitat generalists expanded faster than more specialised species, but this intrinsic trait explains less of the variation in range shifts than habitat availability, which additionally depends on extrinsic factors that may be rare or widespread at the range margin. Similarly, while climate change likely underlies polewards expansions, we find that more of the between-species variation is explained by differences in habitat availability than by changes in climatic suitability. A model that includes both habitat and climate, and their statistical interaction, explains the most variation in range shifts. We conclude that climate-change vulnerability assessments should focus as much on future habitat availability as on climate sensitivity and exposure, with the expectation that habitat restoration and protection will substantially improve species’ abilities to respond to uncertain future climates.

Abstract. 1. Abundance data are the foundation for many ecological and conservation projects, but are only available for a few taxonomic groups. In contrast, distribution records (georeferenced presence records) are more widely available. Here we examine whether year-to-year changes in numbers of distribution records, collated over a large spatial scale, can provide a measure of species' population variability, and hence act as a metric of abundance changes.2. We used 33 British butterfly species to test this possibility, using distribution and abundance data (transect counts) from 1976 to 2012.3. Comparing across species, we found a strong correlation between mean year-to-year changes in total number of distribution records and mean year-toyear changes in abundance (N = 33 species; r 2 = 0.66). This suggests that annual distribution data can be used to identify species with low versus high population variability.4. For individual species, there was considerable variation in the strength of relationships between year-to-year changes in total number of distribution records and abundance. Between-year changes in abundance can be identified from distribution records most accurately for species whose populations are most variable (i.e. have high annual variation in numbers of records).5. We conclude that year-to-year changes in distribution records can indicate overall population variability within a taxon, and are a reasonable proxy for year-to-year changes in abundance for some types of species. This finding opens up more opportunities to inform ecological and conservation studies about population variability, based on the wealth of citizen science distribution records that are available for other taxa.