For many Eastern North American birders the King and Clapper rails are similar, but usually not a huge identification issue as King is brighter and keeps to fresh water marshes, and Clapper duller and keeps to salt marshes. But leave the east and things become more complicated. There are bright colored large rails in fresh water marshes in the highlands of Mexico, often classified as Kings, but sometimes as Clappers. On the West Coast, such as in California Clappers are in salt marshes, but they are relatively small and bright colored, not as dull as birds from the east. Then in South America Clappers are small and dull, and restricted to mangroves. Neotropical Birds has a range map and info for the King and Clapper rails. Very recently James Maley and Robb Brumfield of Louisiana State University tackled this problem by looking at the genetic relationships of these birds. They found that they sorted out into various groups, and that the eastern Clapper Rails were the closest relatives of the King Rail; interestingly the California Clapper Rail is not as closely related to the eastern Clapper Rail, it is related to the rails in the highlands of Mexico! They make the proposal to divide the complex into five species, based on each being genetically related to each other, and morphologically identifiable. Voice was not analyzed in the group, but King and Clapper rails are not all that different from each other vocally. For more information on voice, head over to earbirding.com. So the five species suggested would be:
1) King Rail (Rallus elegans) of fresh water marshes of the East and Cuba.
2) Clapper Rail (Rallus crepitans) of the East and Gulf Coast, Caribbean and Yucatan.The bird in the photo above is in the Caribbean subgroup of the Clapper Rail.
3) Mangrove Rail (Rallus longirostris) of mangroves of South America.
4) Mexican Rail (Rallus tenuirostris) of the highlands of Mexico, living in fresh water marshes.
5) Ridgway’s Rail (Rallus obsoletus) of California, Arizona, Baja and NW coast of Mexico. This is the one you can see in the San Francisco Bay Area. Note also that if this taxonomic change, this would become a federally endangered species, rather than endangered subspecies. I wonder if folks will warm up to the English name or if another will be proposed, we shall see.
This link from the original publication shows museum specimens of members of the groups, from left to right: Mexican Rail, Ridgway’s Rail, Mangrove Rail, Clapper Rail (Caribbean), Clapper Rail (US), King Rail.
Assuming the South American and North American committees of the AOU vote and accept this proposal, we could have several additional rail species to look for. But importantly, another reason to come to California – to see Ridgway’s Rail. Great place is Palo Alto Baylands on a high tide. – Alvaro.