largest bat rookery hibernates deep underneath the ground they represent the redbook species and mount seir bat and the horseshoe nosed bat more than two thousand bats gather here in the winter they cuddle together in order to survive the cold weather in summer they fly to the foothills and return again in autumn they start preparing for migration in early spring and when they split up into smaller groups. sometimes i find that all of about it's covered with jew. and they look very nice like covered in tensile. ok visit closed ecosystem the humidity is one hundred percent and the temperature in the caves is constant which is exactly what bats need cumin should avoid staying in the caves for long as they start to have an impact on the special climate conditions. feedback that with you know we keep the good guys and you hear them calling. you know this means we've warmed up they're confined have a job. if they start flying around they will use up their funds and may not survive until spring. so let's get out of here. on the way back the rangers run into an unexpected obstacle to our riverbed