Sunday, December 8, 2013

Horned Larks are tough as nails

A wintertime country road in rural Ohio. Frigid temperatures, a landscape blanketed in snow, and brutal winds conspire to make this a habitat unfit for man or beast. But even such a seemingly stark environment does indeed have its beasts, even if overall biodiversity of living species can often be tallied on one hand.
I spent this morning searching backroads in Pickaway and Ross counties for Snowy Owls. Even though none of the big Arctic visitors put in an appearance, I saw scores of another bird species not put off by tough winter conditions. Horned Larks. These sleek Fox Sparrow-sized members of the Alaudidae share familial ties with the fabled Sky Lark of Eurasia, and are - in my estimation - just as special.
As I cruised roads similar to the above, small flocks of Horned Larks scurried mouselike along the verges of the lanes, seeking sustenance at the interface of gravel, blacktop and snow. When fields become smothered in the white stuff, the larks are forced to the roads to find feed, and an observer can get an idea of just how common they are. But what, in such a barren landscape, are they eating?
This gravelly tract is superficially similar to most Ohio roadsides, and shares the same plants. Several species of small spindly grasses find a foothold in such sites, and much of their biomass is of species in the genera Sporobolus (dropseeds) and Aristida (triple-awned grasses). The fruit of these plants is tiny, but is nutritious and produced en masse.

A Horned Lark, Eremophila alpestris, examines your narrator. To most people, if they notice these birds at all, the larks are just fleeting shadows; brownish wisps flushing from the roadside and coursing out over the surrounding fields. Birders notice them, and those up on field ID know to look for the lark's flag, a conspicuous black tail. Sometimes the rarer Snow Bunting and/or Lapland Longspur are intermingled.

After a bit, I came across a lark flock that was fixated on a section of vacant roadway, and slowly coasted my car up close. Using the vehicle as a blind and exercising a bit of patience, a couple of the larks eventually moved in close to feed. We - or at least I - may marvel at the hardiness of these songbirds, as well we should. It was about 20 degrees F and breezy when I made these photos, and the larks routinely endure FAR colder temperatures. The wide-open spaces of a barren corn field on a sub-zero winter night might seem to be about the most inhospitable place in the world, but that's typical of where the larks bed down. They shun all but the most open places.

Anyway, it doesn't seem like there would be much of sustenance in the above shot. But there is, although few animals could successfully exploit such a niche. This Horned Lark, fat and all afluff, was feeding on the grasses springing from that crack in the asphalt between it and the snow. The aforementioned Sporobolus grasses had found a home in this fissure, and the lark was gobbling down their fruit.

A first-year Horned Lark joins the adult on the right, both busily milking that crack in the road for all it's worth. This is what all those roadside larks are doing: harvesting the seed of grasses and other plants that survive along the roadsides, or have blown in from nearby fields. If passing grain trucks leak some cargo, all the better. As befits a bird that habitually feeds on the ground, the larks walk, not hop. It's a more efficient mode of locomotion.

In the relatively brief period that I watched these larks and their companions, scads of tiny seeds were plucked and consumed. Grass seed is tough stuff, and some of those grains are destined to run through the larks' digestive tracts intact. They'll be expelled somewhere else, maybe  near, maybe far.

Horned Larks have been harvesting grass seed for eons, and play a valuable role in dispersing native plants.


Lisa Rainsong said...

I love Horned Larks and have wondered for yeras what they are finding to eat in and right next to the road. Thanks for the detailed explanation!

Anonymous said...

Jim you gave the Larks a stage today, good post! Gary Wayne

Jim McCormac said...

Thanks for your comments, Lisa and Gary, and yes, someone needs to give the larks a voice! Maybe next, I'll advocate for meadow voles - it's their arch-enemies the snowy owls that are getting all the limelight!