Definitely screech-owls. I was able to see 4 of them last night, after running into dodo on Saturday night who kindly pointed out the right location. They emerged from an area of dense vegetation about 8:50, sat in a more open forested area and took some short flights for about 15 minutes, then zoomed across the ravine and out of sight. The sound they are making is actually rather quiet and would be easy to miss unless you are very close to them.