Assessing the Impact of Urbanization on Grasshopper Behaviour—A Fieldwork Approach

ABSTRACT

Urbanization is one of the most significant land‐use changes globally, profoundly impacting biodiversity across taxa. Insects, including grasshoppers (Orthoptera), are particularly sensitive to urban pressures, often exhibiting both morphological and behavioural adaptations. While laboratory studies suggest that urban environments favour increased boldness and exploratory behaviour, field‐based evidence remains scarce. In this study, we investigated behavioural differences in the bow‐winged grasshopper, Chorthippus biguttulus , a widespread grasshopper species in Germany, across a gradient of urbanization in and around Münster. Using two behavioural assays, a tonic immobility (hand) test and a tunnel‐based dark‐room escape test, we assessed boldness‐related and exploratory behaviour in 126 individuals from nine grassland sites categorized by low, medium, or high urban land cover. Our results showed that grasshoppers from highly urbanized sites escaped significantly faster from the dark compartment than those from medium or low urbanization levels, indicating increased boldness‐related behaviour. However, urbanization did not significantly affect tonic immobility or exploratory behaviour. Ambient temperature significantly influenced exploratory movement, with individuals moving more quickly at higher temperatures. These findings confirm that urban grasshoppers showed shorter escape latencies, consistent with increased boldness‐related behaviour, under field conditions, likely as an adaptive response to novel and stressful environments. However, the influence of temperature and the lack of changes in exploratory behaviour suggest complex interactions between abiotic and biotic factors. Our study highlights the importance of field‐based behavioural research for understanding insect responses to urbanization and informs future conservation efforts in increasingly urbanized landscapes.