Eurasian otters are becoming urbanized

The Eurasian otter (Lutra lutra) is often associated with pristine or restored habitats in Europe. Increasingly, however, this species is occupying suboptimal urban environments. Between 2018 and 2021 we monitored otters along the Spanish coast from Tarifa to Málaga, the western-most region of the Mediterranean Sea. We found otters prospering in urban environments such as golf courses, ports, and highly polluted streams. In 2012, in the port of Estepona, two otters were observed consuming fish unintentionally dropped while fishers were unloading their catches from boats. Nine years later, otters there continue to display a commensalism-like behavior toward the ships as they await their arrival to port. In San Roque, another port, otters use nets on boats to help remove dried salt from their fur, occasionally even while in close proximity to people. Likewise, in Puerto Banús, otters nonchalantly traverse the port’s mooring docks and inner waters to take advantage of the rocky breakwaters and the fish around them. This pattern is repeated at other leisure ports, between the Royal Gibraltar Yacht Club in Gibraltar, the Sotogrande in San Roque, and La Duquesa in Manilva, as well as at the industrial port of Algeciras – the largest in Spain. To reach Gibraltar, otters must cross several ecological communities: traveling across 10 km of coast from the nearest river, then moving along beaches and into the Bay of Algeciras, then cutting across the grounds of the Gibraltar International Airport to access the Yacht Club, as there are no rivers or wetlands in Gibraltar. These findings demonstrate how otters are undisputed opportunists. Some individuals have developed exploratory behaviors that have led them to exploit “urban oases” where they can live successfully. The challenge is how to manage and conserve this species outside of its natural habitat.