There is a basic and centuries old principle familiar to anyone who has taken a class in economics; something called the law of diminishing returns. Simply stated, it says as one factor of production is increased while others are kept constant, a point will eventually be reached when output per unit of input begins to decrease.
In an odd sort of way, the search for birds can suffer a similar mathematical fate. Let me explain. Let's say a person is just discovering the rewards and joys of the outdoors - specifically birding - and has decided to keep a log of every new species encountered. During the first weeks and months of this budding hobby the list expands almost daily. The second year is comparable but growth begins to noticeably slow. Time passes and a chilly reality sets in, new birds are getting harder to find. Soon a year elapses without seeing any newbies. The birder has discovered that for every mile driven and every hour spent looking, fewer and fewer new species are being tallied. For some, this is indeed diminishing returns.
I've been living in Cass County for well over forty years and have seen roughly 290 species within its borders. At this point, adding a fresh bird to the county list is tough. So it becomes particularly gratifying to stumble across one.
Late one afternoon last week I was looking at birds near Absaraka when I noticed one sitting on a fence. Its near total gray appearance and bold eye ring had me thinking Townsend's solitaire. That is until it flew and flashed a blue tail, a rather specific powder blue found only on one bird around here: Mountain bluebird (Sialia currucoides), the first I'd ever seen in Cass County.
Mountain bluebirds are not particularly hard to find in North Dakota...if you're in the Badlands. Bob O'Connor, author of the book, 'Birding the Fargo-Moorhead Area,' said of last week's encounter, "You may very well have found the first live mountain bluebird in Cass County" (a reference to a dead specimen recovered in Oak Grove Park in 2002).
Identifying adult males is not difficult. One source described them as "breathtakingly brilliant sky blue." There is little else to add other than its back is darker than its front. Females and young birds present more of a challenge with a dull tan-gray color dominating most of the bird. A white eye ring is obvious. Closer examination should reveal a certain bluish hue in the tail and wings, a distinctly pale powder blue.
Of the three bluebird species found in North America, this one is the open country champion. A person encounters mountain bluebirds with ease while traversing the ranch country of the American west (often at fairly high altitudes) where it is often seen perched on fence posts. Pete Dunne describes the bird as the "prairie bluebird." Well, prairie, maybe, but not the tall grass prairie of the Red River Valley. The classic 100th meridian comes fairly close to defining the eastern edge of this western specialty's range.
Like its cousins, the mountain bluebird is a cavity nesting species and will readily occupy a nest box. Curiously, studies of this species so heavily involve nest boxes that its natural cavity requirements are not well understood.
Finding a mountain bluebird in the county was exciting and particularly fulfilling given the bird's normal range. Moreover, as my list of possible new species candidates shrink, the returns become increasingly diminished per unit of effort.
Or do they? That's true only if a person is placing a lopsided value upon new species or lists; the wrong tack to take in my opinion. It's the birds which should draw us outdoors, not some list. The real value lies on the far side of the binoculars, not on the viewing end.