AbstractIntroductionOur purpose was to assess how pairs of sibling horseshoe bats coexists when their morphology and echolocation are almost identical. We collected data on echolocation, wing morphology, diet, and habitat use of sympatricRhinolophus mehelyiandR.euryale. We compared our results with literature data collected in allopatry with similar protocols and at the same time of the year (breeding season).ResultsEcholocation frequencies recorded in sympatry forR.mehelyi(mean = 106.8 kHz) andR.euryale(105.1 kHz) were similar to those reported in allopatry (R.mehelyi105–111 kHz;R.euryale101–109 kHz). Wing parameters were larger inR.mehelyithanR.euryalefor both sympatric and allopatric conditions. Moths constitute the bulk of the diet of both species in sympatry and allopatry, with minor variation in the amounts of other prey. There were no inter-specific differences in the use of foraging habitats in allopatry in terms of structural complexity, however we found inter-specific differences between sympatric populations:R.mehelyiforaged in less complex habitats. The subtle inter-specific differences in echolocation frequency seems to be unlikely to facilitate dietary niche partitioning; overall divergences observed in diet may be explained as a consequence of differential prey availability among foraging habitats. Inter-specific differences in the use of foraging habitats in sympatry seems to be the main dimension for niche partitioning betweenR.mehelyiandR.euryale, probably due to letter differences in wing morphology.ConclusionsCoexistence between sympatric sibling horseshoe bats is likely allowed by a displacement in spatial niche dimension, presumably due to the wing morphology of each species, and shifts the niche domains that minimise competition. Effective measures for conservation of sibling/similar horseshoe bats should guarantee structural diversity of foraging habitats.