Elusive Owl

Son Matt gave me Birding on Borrowed Time by Phoebe Snetsinger. The author was the first person in the world to see over 8,000 different species of birds in over 2,000 genera. I do not know if her record has been broken, but at the time Ms Snetsinger had seen more bird species than any other human. The book recounts her travels over 34 years to all seven continents and innumerable countries. Most of us can only dream about seeing some of the exotic birds she experienced.

As the book and Phoebe Snetsinger’s life drew to an end she was lamenting never seeing a northern pygmy owl (Glaucidium gnoma) despite many attempts. I saw and photographed a northern pygmy owl in the meadow near the Ash Creek Lower Campground in Modoc County CA. The knowledge that I saw a species that this world-class birder was unable to locate filled me with a certain pride, unjustified of course.

Northern pygmy owls feed mostly on small birds. Unlike most owls, they hunt their prey during the day and can be seen sitting atop high tree branches while watching for their next meal. Because they rely on vision, not hearing, northern pygmy owls do not have the asymmetrically located ears and flattened facial discs around their eyes that help most owls locate prey. The pair of spots on the back of the owl’s head look like eyes and may make attackers think the owl is looking at them.

Phoebe Snetsinger did see a northern pygmy owl in Montana the year of her death (1999). That year was spent searching the world and “cleaning up” species that had previously eluded her.

A previous post, Northern Pygmy Owl 11-17-11, discusses the northern pygmy owl more fully.

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Halophytes

Halophytes are plants adapted to living in a saline environment such as seashores, saltwater marshes and sloughs, mangrove swamps and saline deserts. Among halophytes there is a wide range of salt tolerance and several means of classification. Only about 2% of the earth’s plant species are halophytes.

Plants adapt to survival in saline environments through a combination of morphological and physiological means. Large cells with small intercellular spaces, high cell wall elasticity, salt glands and bladders, leaves covered with trichomes (fine outgrowths), smaller relative surface area , extensive development of water storing tissues and low chlorophyll content are a few of the morphological adaptations of halophylic plants. Physiologically, halophyles may exhibit succulence, C4 photosynthetic pathways, compartmentalization of ions in vacuoles and control of ion uptake by roots among other adaptations.

In my previous post I mentioned the alkali chemical crusts that form in desert or semi-desert environments (Chemical Soil Crusts 01-18-22). At Ash Creek Wildlife Area there is a alkali crust east of the Wayman Barn (Lassen County CA). Two halophytes predominate: alkalai saltgrass (Distichlis spicata and greasewood (Sarcobatus vermiculatus).

One adaptation to a high concentration of salinity in greasewood is succulence. As salt ions concentrate in greasewood leaves, more water is transported to the leaves. This dilutes the salt ions and increases the turgidity of the leaves while maintaining osmotic potential.

Alkali saltgrass has salt glands on the surface of its leaves. Excess salts in the leaves are collected in and excreted through these salt glands, which consist of a basal cell and a cap cell. The salt gland is a reservoir from which the excess salts are excreted onto the surface of the leaf. In the photograph, salt crystals are visible on the leaves.

I always am amazed at how organisms can adapt to even the most extreme environments.

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Chemical Soil Crusts

Salt crusts are the most common type of chemical soil crusts. They occur throughout the world in arid and semiarid regions with intense evaporation and little precipitation. Salts accumulate in soils because of limited or reduced leaching. When salt crystals bond with soil particles on the surface or interior of the soil a cementing layer of soil and salt forms.

There are two types of salt crusts: efflorescence and subflorescence. The types of cations and anions available and the porosity of the soil determine the type of salt crust that forms. Efflorescence occurs when there are fine soil particles and quick evaporation. Small salt crystals form and are uniformly distributed on the soil surface resulting in a smooth, crusty appearance. Large soil particles result in slower evaporation and subflorescence. The slower evaporation leads to large salt crystals precipitating on areas of the soil surface and between the soil particles producing an uneven, patchy distribution of salts at and immediately under the soil surface.

Salt crusts improve soil resistance to wind erosion, inhibit soil evaporation and can change the chemical properties of the soil. “Salt-affected” soils are those where the total concentration of salts is high enough to retard plant growth, injure tissues and/or decrease plant productivity.

Most plants avoid areas with salt crusts and an excess of soluble salts while some can resist the salt effects within a certain range. However, a few plants can actually tolerate a high concentration of salts. In the next posts I will note plants that can survive in soils with salt crusts.

This area of salt crust was photographed at Ash Creek Wildlife Area (Lassen County CA) not far from the microbiotic soil crusts mentioned in my previous post (“Microbiotic Soil Crusts” 01-14-22).

In March Leonard and I will be camping at Death Valley where we plan to observe physical soil crusts, the third type of soil crust.

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Microbiotic Soil Crusts

Three types of crusts form on the soil surface: biological, chemical and physical.

Biological crusts are known by many different names including biocrusts and cryptobiotic, microbiotic, cryptogamic or microphytic crusts. I use the term microbiotic crusts. These biological crusts contain communities from diverse taxa: cyanobacteria (blue-green algae), algae, fungi, bacteria, lichens and/or bryophytes. Different ecological sites favor certain taxa thus crusts differ in composition depending on their location. Microbiotic crusts are found in arid and semiarid locations throughout the world.

In the Great Basin, where Leonard and I live, microbiotic crusts are composed primarily of cyanobacteria and green algae. Well developed crusts here are usually darker than the soil beneath and have a sponge-like texture. The density and color of the organisms forming the crust determine their color and physical properties. Microbiotic crusts can cover 10% to 100% of the soil surface.

Microbiotic crusts perform several functions:

*Stabilize the soil: The filamentous nature of cyanobacteria and green algae bind soil particles and aggregate on the soil surface helping to prevent erosion.

*Nutrient contributions: Cyanobacteria can fix nitrogen, particularly useful in nitrogen poor soils of the Great Basin. The soil fines that are bound into the crust are high in phosphorous. The crust organisms may also make carbon and other nutrients available.

*Water regulation: Microbiotic crusts hold water and benefit surrounding vegetation by slowing evaporation. On the other hand, some crusts impede water absorption with the surrounding plants benefiting from water runoff.

*Seed germination: Some seeds experience reduced germination if they fall on a microbiotic crust while others benefit. The surface of the crust holds seeds and the dark color of the crust increasessoil surface temperature promoting germination.

*Plant growth: As with seed germination, some plants do poorly if they germinate on microbiotic crusts. Others exhibit increased growth because of water regulation by the crust and more available nutrients.

*Build up soil: The microbiotic crust captures dust, which builds up the soil. The organic matter from dead crust organisms accumulates and also enhances the soil.

Microbiotic crust organisms are well adapted to very severe environmental conditions. However they and their resultant crusts are poorly adapted to disturbances caused by human activity such as livestock grazing, hiking, biking and off road vehicles. These disruptions cause decreased diversity, the loss of soil nutrients and organic matter and the erosion of the soil itself. Once disrupted, the microbiotic crust is very slow to recover. Care should be taken to protect beneficial microbial crusts.

There is a low area in Ash Creek Wildlife Area (Lassen County CA) containing both microbiotic crusts and the chemical crusts I will discuss in my next post.

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Being Watched

While hiking in Ash Creek Wildlife Area (Modoc County CA) Leonard and I realized a bobcat (Lynx rufus) was watching us. This was the first time we ever saw a bobcat in the Wildlife Area. Bobcats have the greatest range of all the North American felines. However, because they are very secretive and hunt mainly at night, they are not often seen. We kept walking along the trail toward the bobcat. Eventually it stood and ambled off. It definitely was not overly concerned about us.

In addition to their “bobbed” tail, bobcats have distinctive ear tufts, fur growing from the tips of the ears. The most common reasons given for ear tufts are that they help hearing by directing sound into the ears, they help the bobcat detect things above them and ear tufts help keep debris out of the ears. I recently read another theory, ear tufts are used in communication. There is some evidence that by “flipping” their ears bobcats can communicate with other bobcats. For example: one ear being flipped may mean that I see and recognize you. Tufts add size to the ear and make it easier to see the ear and the signals being sent. There does not appear to be a definitive answer for the existence of ear tufts. But the idea that the ear tufts may aid in communication is interesting.

Leonard and I were delighted to see a bobcat in an area where we never saw them before.

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