bison | The Prairie Ecologist

I took our Hubbard Fellows up to the Niobrara Valley Preserve in north-central Nebraska last week. While we were there, I spent quite a bit of time in the east bison pasture, where the recovery of prairie plants from last year’s summer wildfire was in full swing.

Prairie grasses such as sand bluestem (front left) and many others were growing well across the bison pasture during the first growing season since last July’s wildfire.

The lush green growth was in strong contrast to the burned prairie’s appearance back in late April when only a few sedges and yucca looked alive – and both were being cropped short by hungry bison.

These sedges were about the only green in the bison pasture on April 23 of this year. Since the bison were mainly eating brown grass and hay all winter, anything green was pretty attractive.

We knew the prairie would survive the fire, but it was still good to see the quick strong growth after some nice rains this spring. The Preserve staff reduced the size of the east bison herd last year because more than 90% of the bison pasture had burned. The biggest concern was getting the bison through the winter with very little residual grass available to eat. With the help of a little fall growth and some supplemental hay, the bison survived just fine.

The bison are enjoying having a wide selection of green plants to choose from after a long winter of sparse brown grass.

The drought and wildfire definitely weakened the vigor of perennial plants in the prairie, and there is a flush of annuals and other short-lived plants taking advantage of that this year. Species such as goosefoot (an annual Chenopodium species), annual sunflower (Helianthus petiolaris) and six-weeks fescue (Vulpia octoflora) are abundant throughout the grassland. At the same time, however, perennial plants such as prairie wild rose (Rosa arkansana), spiderwort (Tradescantia occidentalis), cutleaf ironplant (Haploppus spinulosus), and many more are having a great year too.

Flower species such as cutleaf ironplant (left) and spiderwort (right) are coloring the sandhills in the burned bison pasture.

Goosefoot (the tall skinny light blue plants) and other annuals are abundant, but so are perennials such as wild rose (pink) and hairy puccoon (yellow).

Besides the bison, we saw numerous other creatures throughout the prairie. I wandered through the area where I’d seen sharp-tailed grouse displaying back in May, and flushed up a couple birds. Upland sandpipers, western meadowlarks, and lark sparrows were all over the place. Insects, of course, were easy to find too, including a number of species feeding on the pollen of the ubiquitous flowers.

Grasshopper nymph on annual sunflower.

Adult antlions were EVERYWHERE during my morning walk in the prairie. A few were feeding on the pollen of spiderwort flowers.

A lesser earless lizard (Holbrookia maculata) near a small sand blowout.

This spring brought a big new batch of bison calves, a testament to the toughness of the females, who were able to get through a hard winter of sparse brown grass and a little hay. There should be plenty to eat now – not only did the Preserve staff reduce the herd size to about 150 adults after the fire, they also increased the pasture size to about 10,000 acres. While the prairie grasses are still weak, that light stocking rate should give those plants plenty of opportunity to recover, depending upon the consistency of rainfall during the remainder of the season, of course. The staff will allow the herd size to grow again over the next few years, aiming for an eventual stocking rate of about 30 acres per animal.

This year’s bison calves looked as cute and healthy as always.

The big bulls looked healthy too…

In other news, the extent of erosion on the ridges where the pine woodland burned last year didn’t look any worse than the last time I was there. In addition to a lot of deciduous trees re-sprouting from their bases, we saw a fair number of oak trees with at least some leaves on last year’s branches – though it’s not clear whether they’ll actually survive long-term or not. Most importantly, we haven’t yet found any invasive plants moving into those burned woodland areas, which is good.

The burned woodlands will be significantly different – but fine – in the coming years. The prairies, however, have been able to absorb the impacts of the drought and wildfire without breaking stride.

It’s like they’ve done this before…

Last week, I got to help our Niobrara Valley Preserve staff round up and sort bison from the Preserve’s east bison pasture. Ok, I actually only helped with the sorting part because the bison were already in the corral by the time I got there…

Richard Egelhoff, our bison manager, had decided that, even with good grass regrowth this fall, we were going to have to reduce the herd size in order to get them through the winter. His plan was to sort off the yearling and two-year-old bison and keep the rest. Many of bison to be sold would have been sold anyway, but not until November. Richard hopes that shipping them off early will save enough forage to keep the rest of the herd fed. In total, the east herd was reduced from 475 animals to 355.

The corral system for the east bison herd is essentially a series of gates along a chute. The process starts by moving a group of bison from the larger corral into the chute. Once there, gates are opened and closed to let a few bison at a time down the chute until they are finally winnowed down to a single animal (or a few of the same kind). At that point, Richard opens one of two gates at the end, and the bison either goes left (back to the pasture) or right (into the sale pen).

If you’ve ever been to similar event with a corral full of cattle, it’s a noisy dusty mess. With bison, it’s dusty (especially in a drought) but not noisy. Bison mainly communicate with a series of low grunts. Because of that, there’s no loud bawling of mothers and calves or bellowing of bulls – just the pounding of lots of bison feet on the dirt, accentuated by grunts and the occasional BANG of a gate. It can be a violent process at times, as bison ram into each other or into gates – they ARE wild animals, after all – but we tried to get them through as quickly and calmly as we could. They’re amazingly tough animals.

The bison were pushed down to the corral last Wednesday afternoon and the sorting was finished shortly after lunchtime on Thursday, so the “keepers” spent less than a day in the corral before they were back in their pasture. The bison selected for sale were run through the chutes one more time on Friday morning so the neighborhood vet could check their tag numbers (little clips on their ears) or add a tracking number to any that were missing one. That number is required to be on any animals moved across state lines so that a buyer can track health records for each individual animal.

Now if we can get a few more rains, maybe we can grow enough grass to keep those bison happy and healthy until next spring. By then their 7,200 acre pasture should have plenty of grass again. Come on rain!

Below is a series of photos from last week’s roundup. You can click on an image to see a larger version of it, then click on the arrows to move through the remaining photos. When you’re done, just close the window by clicking on the X in the top left corner. To see more on this subject, click HERE to see a short story from the Omaha World Herald, along with fantastic photos and video by Alyssa Schukar.