Late mating behaviour in European brown bears

Brown bears (Ursus arctos) usually mate in spring throughout their global range, although a few cases of breeding activity are known in late summer and autumn. In this note, we describe four observations of courtship and copulations of brown bears in the wild in late August and September 2011, 2019, and 2021 in the Cantabrian Mountains (northwestern Spain). These cases extend the published dates on copulations in Europe and the length of the mating season. These couples showed the same behaviour as those recorded in spring. Two females interacted with three different males, but we only saw them copulating with one male. Three of the four courtship cases occurred around a concentrated and seasonal source of food that congregated a large number of bears in restricted areas for a few weeks. We discuss the advantages that these late copulations can have and the uncertainties that still exist about the late reproduction in brown bears.

Automated summary

This study reports four observations of courtship and copulations of brown bears in late August and September in the Cantabrian Mountains of northwestern Spain in 2011, 2019, and 2021. These cases extend the known dates on copulations in Europe and shed light on the possibility of late mating in brown bears. Three of the courtship cases occurred in areas with a concentrated food source, attracting a large number of bears for a few weeks.