[EBB Sightings] Calling Black Rail

? When I first got to Hayward Shoreline I thought I was hearing calling Black Rails.? Later, I read that a female Clapper Rail, on the nest, can make a similar sound.? Listening again, I heard Kik-kik-brrr not Kik-kik-grrr. Black Rails in both places are rare, Clapper Rails are not.? Peter