Yellowfield Biological Surveys

09/07/2025

A new post on Substack

We cannot believe our ears

09/01/2025

I put up a new post at Substack.

Is it genetic or choice?

08/07/2025

https://open.substack.com/pub/davidschmoller/p/the-descent-of-man?r=3p81uz&utm_campaign=post&utm_medium=web&showWelcomeOnShare=true

Wave as we pass by the Apes

06/28/2025

Coming next spring

05/26/2025

I am migrating my writings to Substack. I will be writing about the ecology of the Great Plains, much of what you see here, plus some fiction/short stories. I will be at

My personal Substack. Click to read David’s Substack, by David Schmoller, a Substack publication. Launched a day ago.

06/26/2022

Sandhill Lakes.
Amy took this photo yesterday. It's Hackberry Lake in Valentine National Wildlife Refuge in central Nebraska.
The Sandhills.
The novelist Jim Harrison called the Sandhills, "without a doubt the most mysterious landscape in the United States."
Covering some 25,000 square miles (1.5 million acres) - six times larger than Yellowstone - they are the largest dune formations in the western hemisphere. They cover about one-quarter of the state of Nebraska. They are unsuitable for crops, so very little of it has been plowed. As a result, 85% of the landscape is in near-native condition.
Non-native plant species are only half as common as on other prairie systems in the US.
It's a prairie system, the mixed-grass prairie, with thousands of interdunal lakes. You see similar lake formations on the west coast of Lower Michigan, around Glen Arbor or Beulah, but nothing on this scale.
The interdunal lakes are an important part of the Central Flyway for migrating birds. The lakes are filled with waterfowl in April. Only a few remain by June.
Imagine Sandhills National Park...
The current science says that dunes were created at the end of the Pleistocene when glacial meltwaters deposited sand on the Great Plains. Core samples show that the dunes were formed as strong, prevailing, northwesterly winds swept over the sand deposits, much like you see forming along the shores of the Great Lakes at Sleeping Bear Dunes, Indiana Dunes, and Grand Sable Dunes.
The Sandhills sit atop one of the world's largest aquifers, the Ogallala. Covering some 174,000 square miles, it stretches from Texas to South Dakota. It has the same amount of water as Lake Huron.
Yep, that's Ogallala water in the picture.
But civilization has a drinking problem. Crop irrigation has drawn down much of the southern half of the aquifer to dangerous levels. There is little restraint being shown. If the whole aquifer were depleted, it would take rainfall about 6000 years to replenish it.
Drinking problem? Time for an intervention.

06/26/2022

Platte Thistle (Cirsium canescens)
A native Great Plains thistle, found on sandy and gravely sites. This one was taken in Valentine NWR in the sandhills of Nebraska. It's found from MT to CA to CO and NE.
There are not many human uses of thistles other than symbols of a failed landscape. The fact that this species is found in 'waste areas, roadsides, and overgrazed lands' does not do much to dispel that notion.
Nevertheless, thistles are favored by butterflies, some of which are rare. So the point about a land given to thistles isn't about some inherent evil of these plants, but is fundamentally about human land mismanagment, which creates those failed conditions under which it takes over the land.
These plants are just doing what they do best, which is stabilize a broken land.
Huh. I guess that means when someone is complaining about thistles, he may actually be complaining about himself.

06/26/2022

Shell-leaf penstemon (Penstemon grandiflorus)
This is one giant penstemon. Grows four feet tall. Those flowers are two inches across. It's a short-lived perennial or biennial. It is found from Wyoming to Wisconsin to Missouri to Texas.
It grows in sandy, alkaline soils. Hence, it's widespread in the Nebraska Sandhills, which is where this specimen was found, south of Valentine.
One common name is showy beardtongue. As mentioned earlier, the penstemons have what is called a staminode. That's a stamen that is non-functioning, that does not put out pollen. You can see it in this picture, it's the long white tube in the throat of the flower. They are usually covered with hairs, hence "beardtongue."
The staminode leads the pollinator deeper into the tube of the flower. Some of the penstemons also have hooks on the inside of the flower that make the pollinator struggle to get out. When he does, he gets tangled in the stamens and gets dusted with pollen. When he gets out, he takes that pollen to the next penstemon.
This is floral equivalent of a drug mule, where the bee is tricked into carrying the contraband pollen to another location. I don't think that is what is meant by biomimetics.

06/26/2022

Northern hawthorn (Crataegus chrysocarpa)
A very complex genus, because the species hybridize freely. Apple-like flowers and thorns characterize this species. No fragrance. Many are cultivated as ornamentals. They put out a bland, starchy fruit during the summer.
Speciation refers to the development of unique characteristics in a subset of a population of a species. This is driven by reproductive isolation as by a mountain range or unique environmental conditions. Often this develops to the extent that the species becomes relatively reproductively exclusive, tending to reproduce only with like species. Think bison and cattle.
So the species within this genus interbreed freely, which makes it very hard to identify individual species. The characteristics merge, mix, and divide. Often you just call it a hawthorn and go home.
This was taken in the northern Black Hills by Bear Butte about a week ago.
Why some species within a genus freely hybridize and other species within another genus do not freely hybridize is another subject that I will avoid because it is late and we just got home and the two of you readers are probably sleeping as you read this anyhow.