Season 5, episode 7.
From the Northern reaches of the Llano Estacado in Eastern New Mexico to the Big Bend Borderlands of Texas, this is Nature Notes
One of the more mysterious winter birds of the region is the Sage Thrasher. Have you ever stopped and scanned a brushy hillside for birds greeting the morning sun? Have you ever sat near a desert waterhole waiting for the birds to get their daily drink?
From Marfa Public Radio, in cooperation with the Sibley Nature Center in Midland, Texas, this is Nature Notes. Hello, I’m Dallas Baxter.
For such large Robin-sized birds, Sage Thrashers can be extraordinarily hard to find. At least two were at the Sibley Nature Center for a month, but seeing them was always fortuitous. We never found them by purposeful searching. They’re ground dwellers, preferring to run instead of fly. If a birder approaches too closely, the thrasher escapes by running away under cover instead of flushing to a perch where it can be seen. In West Texas and Eastern New Mexico from October 1 to April 20, Sage Thrashers are found in mesquite pastures where there are Christmas Chollas (Opuntia leptocaulis) with berries. The few thrashers that have spent some time in the city have been in gardens where pyracantha and other berry-bearing shrubs grow.
Sage Thrashers belong to the family Mimidae with the Mockingbird, Catbird, and other thrashers. But Sage Thrashers do not mimic other birds. Their song consists of short warbling notes with very little range of pitch and constant repetition of one accented note. Although they are reported to sing all winter long, even with snow on the ground, naturalists in Midland have never heard them do so. Sage Thrashers look just like Mockingbirds with stripes - in fact, young Mockingbirds just out of the nest have frequently been identified as Sage Thrashers by beginning birders, for at that age Mockingbirds have stripes. Sage Thrashers resemble Mockingbirds in some of their mannerisms, too. When running on the ground, they both hold their tail high. When perched, they raise their tail rapidly and lower it slowly. Their pose when perched and their flight are also much alike.
Sage Thrashers have a great fondness for wild currants, gooseberries and service berries. In the Yakima Valley of Washington, a great fruit growing area, Sage Thrashers become an expensive nuisance, eating rasp berries, blackberries and grapes. They do enormous damage in a vineyard, for they eat only part of each cluster, leaving most bunches with an unattractive appearance. But when no berries are available, they eat many varieties of destructive insects. They eat as many Mormon crickets, (actually long-horned grasshoppers) as the fabled Western Gull.
The Sage Thrasher is well named, for in breeding season it is limited to arid regions covered by a sea of gray-green sagebrush. Nests are built on the ground under a sagebrush or in the branches near the main axis of the plant. In 1875, an ornithologist described a Sage Thrasher nest as a "platform of twigs, so placed as to screen the setting bird from the rays of the almost tropical sun". In 1907, another observer reported a nest with a "distinct arch or platform of dry twigs just above it". In 1978, T. G. Rich wrote in "The Wilson Bulletin" about a nest which "was placed under an old nest from some previous year". Does this explain the "platform of twigs" which the earlier observers thought was deliberately constructed? Or did Rich see the platform and mistakenly identify it as an old nest?
The fall of 2010 was an incredible irruption year for sage thrashers over much of the Edwards Plateau and south Texas where they’re not often seen. The drought of 2011 killed so many juniper trees (and even hackberries) that it seems to have caused the thrashers to extend their winter range this year, to throughout the Hill Country and even beyond.
Nature Notes is sponsored by the Dixon Water Foundation and is produced by KRTS Marfa Public Radio in cooperation with the Sibley Nature Center in Midland, Texas. This episode was written by Burr Williams. Visit sibleynaturecenter.org and join Williams' Facebook page where photos are posted daily.
