{"id":3889,"date":"2012-08-16T18:55:09","date_gmt":"2012-08-17T00:55:09","guid":{"rendered":"http:\/\/earbirding.com\/blog\/?p=3889"},"modified":"2012-08-21T12:41:03","modified_gmt":"2012-08-21T18:41:03","slug":"king-and-clapper-rails","status":"publish","type":"post","link":"http:\/\/earbirding.com\/blog\/archives\/3889","title":{"rendered":"King and Clapper Rails"},"content":{"rendered":"
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King Rail, Pike County, Missouri. Photo by Jim Rathert, USFWS (public domain). Click to enlarge<\/figcaption><\/figure>\n

The two largest rails in the United States are so similar in appearance and vocalizations that they have at times been considered a single species.\u00a0 In general the King Rail is a more brightly-colored bird of freshwater marshes, while the Clapper is a duller bird of coastal salt marshes.<\/p>\n

But even this statement requires a few caveats. For one thing, Gulf Coast Clappers are brighter than East Coast Clappers, and the disjunct populations of “Light-footed” and “Yuma” Clappers in California and Arizona are brighter still, bright enough to have been considered subspecies of King Rail by some authors. Furthermore, King and Clapper Rails have been known to hybridize in brackish marshes where their ranges meet, spawning the dreaded “Cling Rails” — birds presumably intermediate in all respects, and not safely identified in the field, even when you can see<\/em> them — which is not very often, for these ghosts of the cattails.<\/p>\n

Most of the time, the presence of one of these rails is announced solely by their loud, unmusical calls, leaving us to identify them solely by voice. It isn’t always possible, but today we’ll talk about when and how it can be done.<\/p>\n

The “Kek” Series<\/h4>\n

For humans, this vocalization is about as exciting as listening to a six-year-old incessantly rap a stick against a wooden fence.\u00a0 For female rails, it must be quite an aphrodisiac, because it’s the primary way that males attract mates in early spring.\u00a0 It’s typically heard for a fairly brief period out of the year, and given only rarely after the singer is paired.<\/p>\n

Male Kings and male Clappers “sing” with the same notes — the key to identifying them is to listen to the speed of their calls.\u00a0 Here’s a useful snippet from the Sibley Guide to Birds<\/em><\/a>:<\/p>\n

a series of unmusical kek<\/em> notes, slower at beginning and end; the tempo of the fastest portion is useful for species identification. […] Individuals may give faster or slower calls depending on mood, but such departures are usually brief.\u00a0 Long, consistent bouts of typical calls can be reliably identified.<\/p><\/blockquote>\n

According to Sibley, eastern Clapper Rails “kek” at about 4-5 notes per second, while Kings are slower, usually 2 notes per second.\u00a0 In a careful survey of all the rail recordings I could find online, I found the differences to be consistently smaller than this. I found some very excited Clappers reaching 5 notes per second, but an extended listen to most birds will find them averaging between 3 and 4 notes per second in the fastest parts of their series.<\/p>\n\n\n\n
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