Whiskered Screech-Owl

A year ago on the Atascosa Highlands Christmas Bird Count south of Tucson, Alan and I encountered a little Whiskered Screech-Owl at its day roost. The owlet perched at the entrance to its roost cavity, comfortably soaking up the sunshine on that wintry day. A brief Morse code call and its yellowish bill confirmed its identity.

Yesterday that image of the basking owl, shimmering in my awareness for the past year, finally made it to paper. Here's the beguiling little raptor, rendered in watercolor and gouache.

Whiskered Screech-Owl by Narca

Whiskered Screech-Owls are common within their limited habitat in the southwestern Sky Islands. Their abundance in the Chiricahua Mountains helps to boost that area's density of nesting raptors to a dizzying level. Helen Snyder has investigated nesting raptors around Portal and the Chiricahuas for years, and found that when owls are included with the hawks, eagles and falcons, the density of nesting raptors in Cave Creek Canyon far exceeds that known for any other location in North America. The next closest is the Snake River Birds of Prey Area in southern Idaho, and it boasts less than 1/4 of the density of raptors found in Cave Creek Canyon. Helen and others are encouraging the US Forest Service to give Cave Creek Canyon a special designation that recognizes its unique importance to raptors and further protects the region from oddball threats that occasionally arise.

If you will be in southern Arizona in early January and would like to join Christmas Bird Counts for these areas, you can contact the compiler for the count that interests you. For Atascosa Highlands on Sunday January 3, email Rich Hoyer (calliope@theriver.com). For Portal on Saturday January 2, email Jackie Lewis (winjac12@vtc.net). Counts for Portal and the nearby Peloncillo Mountains are run back-to-back, and many people spend the weekend attending both counts. For the Peloncillo Mountains count on January 3, please contact Alan Craig (narca@vtc.net). Yes––the dates for Atascosa Highlands and Peloncillo Mountains do conflict!

Nevada Oasis

The long drive north from Arizona to Idaho brings the perfect opportunity to revisit our favorite refuges in Nevada and to explore new ground. We pick up our friend Rich Hoyer in Tucson, and the three of us set off on a three-day camping trip through the vast, stark Nevada desert.

The Sonoran Desert grades into the Mojave as we exchange Saguaro for bristly, imposing Joshua Trees. The rainfall regime changes as well: Mojave Desert receives mainly winter rain; Sonoran Desert usually receives both winter and summer rains and is lusher.

Just a half-hour north of the glitter of Las Vegas lies a gem of an oasis: Corn Creek Field Station, a part of Desert National Wildlife Refuge. This refuge's 1.5 million acres encompass six mountain ranges, which are home to Desert Bighorn Sheep. Over the years, Alan and I have stopped at Corn Creek every chance we've had. During migration it often produces an impressive array of western migrants and eastern vagrants, such as White-eyed Vireo and Palm Warbler. Corn Creek is also a northerly nesting outpost for several typically southwestern birds, including Lucy's Warbler, Verdin and Vermilion Flycatcher.

Alan Craig & Rich Hoyer at Corn Creek (Photo by Narca)

We arrive in late afternoon, make a quick circuit of the spring-fed ponds, and set up camp not far away. (It's still possible to rough-camp here for free.) The 100-degree day cools with the setting sun, and Coyotes begin to sing. Soon the vast starfield stretches over our two tents, alone in the immensity. A glow to the south marks Las Vegas.

At dawn we're up, break camp, and return to Corn Creek. We meander along the paths through thick vegetation. Cedar Waxwings pluck fruit from the Russian Olive trees. A Red-shouldered Hawk (unusual in Nevada) swoops to a post next to a small pasture. Endangered Pahrump Poolfish fin through the ponds. We find a nice showing of western migrants––Peregrine Falcon; Willow and Gray Flycatchers; Nashville, Virginia's and MacGillivray's Warblers; Yellow-breasted Chats; Lazuli Bunting––before continuing our journey north.

South Hills Crossbills

South Hills Crossbill male (Rather poor photo by Narca)

Dr. Craig Benkman, who gave the banquet keynote talk at Western Field Ornithologists' annual meeting in Boise, has researched the habits and vocalizations of Red Crossbills for years. His work is helping to untangle the confusing crossbill complex. Just how many species of Red Crossbill are there? What distinguishes them? Are we seeing an example of evolving species, and at what point are they sufficiently distinct to be considered separate species?

Benkman recently proposed a new crossbill species: the South Hills Crossbill, a sedentary species known from the South Hills and Albion Mountains of southern Idaho. For more information on his publications and research, go to his website:

www.uwyo.edu/benkman

Here is the gist of his talk:

Red Crossbills in North America are divided into 9 or 10 "types," first recognized by Jeff Groth. Each type has corresponding calls, songs, and seed preferences. These types specialize in foraging on particular species of conifer seeds, and the grooved palates of their bills match perfectly the size of the seeds they eat.

"Type 1" lives in the eastern US and only rarely feeds on hard pines like Ponderosa.
"Type 2" feeds mainly on Ponderosa Pine.
"Type 3" feeds on the small seeds of Western Hemlock.
"Type 4" specializes on the thin seeds of Douglas-fir and is small-billed.
"Type 5" eats the seeds of Lodgepole Pine.
"Type 6" feeds on seeds of pines from the Sierra Madre and southwestern Sky Islands, and is large-billed.
"Type 7" is probably a generalist.
"Type 8" specializes on seeds of Black Spruce.
"Type 9" is the South Hills Crossbill, a specialist on Lodgepole Pine.
"Type 10" has been proposed by Ken Irwin; it specializes on coastal Sitka Spruce.

So why is Type 9 distinct? Only in a small area of southern Idaho does Lodgepole Pine grow in the absence of tree squirrels. Squirrels harvest pine nuts very efficiently, and begin their feeding at the top of the cone, unlike crossbills. Where squirrels feed on pines, they drive the evolution of pine cone structure. These pine cones have developed thicker protective bracts, especially at the tops of the cones. Squirrels harvest whole cones early in the fall, and cache them for winter, making the seeds unavailable to crossbills. Because crossbills must forage on seeds remaining on the tree, their food supply is more erratic where squirrels share the habitat, and those crossbills must become nomads when they run out of food.

Tree squirrels have never managed to cross the surrounding expanses of sage to reach the Lodgepole Pines of the South Hills, and pine cones here do not show the adaptations to squirrel predation found in Lodgepole Pine from other areas. Without squirrels, the supply of pine cones is more reliable, and these crossbills can afford to be sedentary. South Hills Crossbills have evolved large bills to deal with the pine cones, as well as distinctive calls. Researchers have found a very low frequency of hybridization between South Hills Crossbills and other types, which occasionally occur here as well. Indeed the proposed name for this proposed species is Loxia sinesciuris, which translates as the crossbill without squirrels.

In addition to Dr. Benkman's talk, Nathan Pieplow ably moderated the sound identification panel, both of which prepared us very well for Sunday's field trip to the South Hills to look for the crossbills. Sound ID panelist Rich Hoyer described the Type 9 call as "DYUP." That phrase I could remember. If you would like to hear crossbill calls, go to this website and click on the arrow next to each entry's name:

www.xeno-canto.org/browse.php?query=red+crossbill

You can also find more information on calls at Nathan Pieplow's website, www.earbirding.com.

Sunday morning we set out very early in vans, eventually winding our way up into the South Hills of Sawtooth National Forest. No sooner had we arrived at an upper campground near Porcupine Springs, than "Type 9" South Hills Crossbills flew into the Lodgepole Pines next to the parking area, DYUP-ing as they came. For an hour or more, small groups of crossbills arrived and departed, giving everyone exceptionally good views. Yes!!

If this split is accepted by the American Ornithologists Union, Idaho will have gained an endemic bird species.