Assistant Professor University of Southern California, United States
Background/Question/Methods
Ectotherms are expected to be disproportionately affected by rapid climate change, resulting in both range reductions and population declines. This increases the urgency of closely monitoring existing species of concern as well as identifying species that may be at risk in the future. However, when assessing uncharismatic, rare or difficult-to-access species, it can be difficult to determine whether a lack of distribution data is related to a lack of search effort, or true population/range declines. As such, many species of conservation concern lack high-quality distribution maps and thus assessing their extinction risk is limited.Occupancy modelling can leverage data from across many species (including charismatic and data-rich species) and sites. This optimizes past search effort, while identifying areas of uncertainty to prioritize for future searches. We use Canadian butterflies as a study system for a number of reasons: i. insects often lack comprehensive survey data found in better-studied groups but have ample museum and citizen science data which can improve occupancy modelling attempts; ii. Canada is an understudied region, and so occupancy maps are currently unavailable for this group; and iii. many species are predicted to shift northwards as climate change progresses, making Canada an increasingly important player in their conservation.
Results/Conclusions
We used a curated database of over 1 million records that span 2000-2019 to build preliminary multi-species hierarchical occupancy maps for each of Canada’s ~300 butterfly species over the past 20 years. We highlight changes in occupancy across their full North American range, both at the individual species level (particularly for species of conservation concern) as well across species to examine spatial and temporal trends in occupancy. Preliminary results indicate that average occupancy probability across species nor detection probability has not changed significantly over the past 20 years, though there is much variation between individual species. We also examine where losses and gains in occupancy are clustered in Canada. Future steps will examine whether external anthropogenic drivers (e.g. pesticide use, climate change, land use change) have mediated these responses.
