An invasive parakeet is killing off Europe’s biggest native bat.

At the turn of the century, the largest colony of greater noctule bats (Nyctalus lasiopterus) in Europe occupied a park in Seville, Spain. Between 2003 and 2017, the number of park trees used by bats fell by 81%, according to a study by Dailos Hernández-Brito at the Doñana Biological Station in Seville and his colleagues. Conversely, the number of nests of rose-ringed parakeets (Psittacula krameri), which are native to Asia and Africa, increased by a factor of 20 over the same period.

The team documented parakeets nesting in tree cavities previously occupied by bats. The researchers also observed the 120-gram parakeets chasing the 50-gram bats out of their nests, and found dead bats bearing wounds from parakeet beaks.

The authors warn that, without further action, the already rare bat could become endangered within a few years.