It wasn’t long before we moved to southeast Arizona for good—at last. Alison and I were coming down Miller Canyon after a quick pre-breakfast walk, and we ran into a group of binocular-wearing colleagues headed up. The usual greeting: “Seen anything?” The group’s apparent leader responded with the disyllabic question: “Sulfurs?”

Alison hesitated, puzzled, then pointed to the Sulphur-bellied Flycatcher squeaking its loud matins from the tree right above our heads. “Sulfurs?” was the bemused response.

They weren’t talking about birds.

Birders and lepers have a lot in common. Indeed, most of the latter started out as the former before discovering the pleasures of late rising and warm climates. As a result, the culture of butterflying, in North America at least, has closely mimicked the development of birding, with the signal exception of the big year: though well established in birding circles, the attempt to record as many species in a single annual cycle had never been attempted by a lepidopterist.

Until, that is, Robert Michael Pyle’s scaly-winged run in 2008.

Pyle—not to be confused with Hawaii’s ornithologist—is a highly respected butterflyer, an eloquent and influential conservationist, and a fine writer, and I was prepared to love Mariposa Highway, the account of his 2008 North American butterfly big year. Unexpectedly, however, the book (all 400+ pages of it!) never really catches fire, its gentle prose and unhurried rhythm descending—I hate to say it—into the monotonous after the first 100 pages or so.

Why?

Like most critics, I usually find it easier to identify the causes of failure than the sources of success; that’s what reviewers are for, right? It was harder this time, though, given Pyle’s long record of wonderful publications. Soon enough I found myself concentrating more on the book’s failure to excite than on the events it recounts. What happened?

It wasn’t just the occasional editorial lapse, as when the well-known state park in southeast Arizona is called “Pacheco” rather than “Picacho Peak” or when Tom Beatty of hummingbird fame is called “Bentley.” Instead, I think Mariposa’s failure to excite lies in its single-mindedness, in the static nature of its subject, and in a certain narrative solipsism. Let me explain:

Peterson and Fisher’s Wild America, which Pyle takes as his express model here, was the account of a birders’ big year—and much, much more. There was little the two friends did not stop to think about, feathered or not, natural or cultural: they spent April 19 in Concord and Lexington, they made a pilgrimage to the abandoned cabin of a Sonora Desert hermit, they ended the book with an appendix on the history of the fur seal trade. Mariposa, in contrast, gives the impression of being about butterfly twitching and very little else. I haven’t counted, but my sense is that far more words and far more pages are filled with the lister’s veni, vidi, vici in Pyle’s work than in its great predecessor; this means that a reader who is not quite as enthusiastic a lepidopterist as the author may succumb before finishing the book.

There’s something about butterflies themselves, too, that makes it much harder to keep the non-specialist reader’s attention. Put simply, they don’t really give a listing writer much to say: they may be beautiful, they may be rare, but beyond hilltopping, sucking manure, and copulating, they just don’t do much. This challenge is visible in its extreme in Pyle’s accounts of finding (and listing) butterfly eggs for his big year; I admire the author’s observational skills, but it would take a finer writer even than Pyle to generate much narrative tension out of such a find.

Finally, and perhaps most importantly, Pyle’s big year was conducted largely on his own. Not even when he is butterflying with others does the hopeful reader find much in the way of interpersonal interest. Pyle is as dutiful as he is obviously sincere in thanking those who helped him, but I can’t say that at the end I had any sense at all of having got to know the secondary “characters” in his story. Not even Pyle’s wife, whose illness is a moving theme running through the book, ever really takes narrative shape here. Contrast this with the complicated relationship so charmingly drawn by the authors of Wild America, or with the priceless character sketches that punctuate the account of another solo big year, Kenn Kaufman’s Kingbird Highway. In Mariposa, we learn nearly as little about the author as we do about his friends; Pyle resembles Kenny Rogers, he went to Yale, that seems to be enough.

Butterfly devotees will read this book differently and probably with greater pleasure. The rest of us may come away disappointed that Mariposa doesn’t do a better job of spinning a more interesting story around the author’s year on the butterfly road.