I learned about a bird I have never heard of before my Colorado trip earlier in July. While hiking up Deer Mountain in Rocky Mountain National Park, an obvious woodpecker-type bird landed in a tree not far off the trail, I zoomed in on him and took some photos, not knowing exactly what type of woodpecker it was. Upon research I identified it a Williamson's Sapsucker - thank you David Allen Sibley, author of Field Guide to Birds of Western North America. (And Thank you to Val for giving it to me as a gift.)
In most species of Woodpeckers or Sapsuckers the sexes have only subtle differences in appearance, usually with the male having red somewhere the female doesn't. Williamson's Sapsuckers are unusual in having the male and female looking drastically different. The two sexes look so unalike that they originally were described as different species. The female looks more like a Flicker with a brownish head. The Williamson's Sapsucker was first described in 1852 by John Cassin, an American ornithologist, who named the female - Black-breasted Woodpecker, before they were discovered to be the same species. The species took its common name from Lieutenant Robert Stockton Williamson, who was the leader of a surveying expedition which collected the first male.
An interesting bit of information - a group of sapsuckers are collectively known as a "slurp" of sapsuckers. That seems to make a bit of sense - "slurp" and "sucker."