Assortative mating of Carrion Corvus corone and Hooded Crows C-cornix in the hybrid zone in eastern Germany

Mating patterns in hybrid zones may be important for maintaining a stable hybrid zone. Theory suggests that hybrid zones are stable due to assortative mating outside the zone. To test whether assortative mating occurs in the crow hybrid zone in eastern Germany, I studied pairs of crows. The study area between Magdeburg and Dresden was divided into a grid and in each grid cell I recorded paired crows between 8 April and 12 July 2006. Carrion Corvus corone and Hooded Crows C. cornix mated assortatively given that the composition of observed pairs deviated significantly from what was expected by random mating; homotypic pairings, i.e. Carrion x Carrion or Hooded x Hooded Crows, were observed more and heterotypic pairings less often than expected. These findings contradict previous suggestions for this region but are in accordance with studies in other parts of Europe.