Grasshopper country before and after: a resurvey of Ken Key's collecting expeditions in New South Wales, Australia, 70 years on

Recent reports of insect declines across Europe and other parts of the world have emphasised the generally poor baseline that exists for assessing changes in biodiversity. One important source of untapped baseline distribution data is field notebooks, which are often associated with the collection activities of museums and other scientific institutions and may be decades or even centuries old. Over 220 field notebooks are associated with the grasshopper (Caelifera) collection in the Australian National Insect Collection, containing detailed notes on the times and places species were collected as well as vegetation and soil descriptions. In 2019, we resurveyed 45 locations from three of these notebooks from the 1940s, to assess the potential value of larger‐scale efforts in the future. We found substantial differences in grasshopper species richness and composition between the surveys; richness was generally higher in our survey, and some species showed dramatic increases in range and occurrence, whereas others remained relatively static. There was also evidence for vegetation state transitions in some areas, including increased weediness and shrub thickening, which may be associated with changes in the grasshopper fauna. We developed approaches for comparing environmental conditions across surveys and found that our species richness and abundance estimates were positively correlated with rainfall in the year preceding each survey. We conclude that further resurvey work on these field notebooks will provide a strong baseline picture of the diversity, distribution and abundance of the Australian grasshopper fauna for assessments of future change and may also give new insights about associated vegetation changes.