Good question, John.
From what I can tell, most of what we know about Yellow Rail behavior and vocalizations comes from the work of Scott Stalheim, who in the early 1970s created a type of outdoor pen in a marsh in Minnesota so that he could observe captive Yellow Rails under conditions that closely simulated their natural situation. He never reported a female giving the clicking song. His sample size wasn't huge, but it would seem that females are unlikely to give the clicking song. In Rallus rails, female songs sound quite different from male songs. Stalheim never reported any kind of female song in Yellow Rail.
If there are two rails giving the clicking song at Monte Vista, they would seem to be territorial males. Birds of the World says "In Michigan, males cease calling about mid-Jul (Stenzel 1982), but in Quebec they call as late as 25 Aug (Robert and Laporte 1993)." It will be interesting to see how long the Colorado birds persist.
The San Luis Valley is much farther south than the species has ever been known to breed before. It puts me in mind of the still-difficult-to-explain phenomenon of Baird's Sparrows and even a Sprague's Pipit or two being found singing and nesting along the Front Range in recent years. Have they always been there and we just never noticed? Are they reclaiming their historical range? Or is this some kind of weird southward expansion? Why would ranges expand so far south when the general tendency of climate change is to push ranges north?
If the rails are indeed nesting at Monte Vista, it may be their highest-ever nesting elevation (7600 feet). The highest populations I was previously aware of are at the Klamath Marsh NWR in Oregon, at an elevation of about 4500 feet. Climate change is known to drive species upslope. But upslope-and-a-thousand-miles-south? That's pretty weird.
Nathan Pieplow
Boulder
Does anyone know if both male and female make the clicking sounds? You can see where I am going with this and wondering if this mght be a breeding pair?John RawinskiMonte Vista, CO--
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