# Unrecorded Butterfly Species and Potential Local Extinctions: The Role of Citizen Science and Sampling

## TL;DR

This study uses historical and citizen science data to assess butterfly extinction risks in the Aosta Valley, showing that citizen science helps fill data gaps but professional sampling is still needed for certain species.

## Contribution

The study combines multiple data sources to evaluate butterfly extinction risks and the role of citizen science in high-altitude regions.

## Key findings

- 2.9% of the butterfly community in Aosta Valley is at risk of extinction.
- Butterfly extinction risk increases with a decrease in altitudinal range.
- Citizen science contributes significantly to data collection but professional sampling is essential for species with specific traits.

## Abstract

Estimating species extinction risk is crucial to reverse biodiversity loss and to adopt proper conservation measures. Different sources may play a pivotal role in prioritising species conservation. Recently, citizen science demonstrated a substantial role, especially when it comes to butterflies. This study examines species records and richness in Aosta Valley, which represents one of the highest mountain areas in Europe. Through 30,351 data points from 1825 to 2022, the impact and efficiency of three groups of data sources were investigated: literature (i.e., publications and collections), sampling (butterfly experts' recording), and citizen science (open‐source databases). The study also aims to assess the extinction potential of the butterflies in relation to functional traits. The results showed that even if there were significant differences in the number of records between the three sources, there were no significant differences for species recorded. Moreover, 2.9% of the butterfly community risks extinction, and it is related to some response traits. Indeed, extinction risks increase when the altitudinal range decreases and for multivoltines. In conclusion, citizen science has a strong impact on the amount of data and could be exploited to fill data gaps at low/medium altitudes. However, professional sampling is needed to focus on species no longer reported, and in particular on species that are difficult to identify, have specific distributions or particular traits (e.g., limited altitudinal range). Using different data sources, extinction risk estimation, and trait analysis, it is possible to prioritise studies on some species using different efforts (sampling and/or citizen sciences).

30,351 data from 1825 to 2022 were used to assess community changes in Aosta Valley. 2.9% of the butterfly community risks extinction. Butterfly extinction risks increase when the altitudinal range decreases.