Monitoring Urban European Hares (Lepus europaeus Pallas) with Citizen Science and a Thermal Spotter

Populations of the European hare (Lepus europaeus Pallas) have declined in agricultural areas throughout Europe, primarily due to habitat loss caused by the industrialization of agriculture. The growth of cities displaces native habitats, and a decline in hare densities would be expected also in cities; however, several medium-sized mammals thrive in urban areas. In this study, hares in two Danish cities, Aalborg and Aarhus (approx. 145,000 and 300,000 citizens, respectively), were monitored using a combination of citizen science and a thermal spotter. Citizen reports of hares (in all 1874) were highest in the center of the city (26 to 33 locations per km²). Hare observation densities declined significantly with increasing distance to the center. Breeding hares were recorded in both cities. The thermal spotter proved to be useful to spot hares in the city and it did not draw attention as the spotlights normally used to detect the light reflected from the hares’ eyes. Based on the hares spotted at 12 locations where citizens had reported hares, densities of 40.3 (±10.8 SE) hares per km² were estimated. The increasing awareness for biodiversity and for not using pesticides in Danish cities allow for wild plants to be established in lawns, which benefits the hares.