Tuesday, February 28, 2017

Streams in the Desert: Red Rock Canyon State Park

On my recent geology field studies trip to Death Valley, we made a side trip to another beautiful and geologically rich place: Red Rock Canyon State Park.  Located on Highway 14 north of the town of Mojave, Red Rock Canyon State Park offers visitors opportunities for hiking, camping and more in a stunning desert landscape of red rock formations.  But due to the incessant rain, our time at Red Rock Canyon was relatively brief.


The impressive layered cliffs at Red Rock Canyon are part of the Ricardo Formation, an assemblage of rock layers that are unique and distinct enough to be separated from surrounding rock.  Looking closely at the layers, you will notice layers of red, brown and gray sandstone, pebbly conglomerate, very fine-textured gray clay, and both light-colored rhyolitic tuff and dark basalt from volcanic eruptions. 

Layers of sandstone and clay indicate that these deposits were laid down in the lakes, rivers and floodplains of a terrestrial landscape.  Conglomerates form as highly energetic water slows down and dumps its load of pebbles and cobbles; they are often indicative of alluvial fans.  In this case, rapid streams flowed from the Sierra Nevada mountains, as indicated by pieces of granite contained in the sediment.  The slight tilt of the layers was caused by more recent movement along the nearby Garlock fault.  Folds in the rock are the result of erosion by wind and water.


From these pieces of evidence, geologists are able to interpret the landscape and can piece together a picture of what this area was like millions of years ago.  5-20 million years ago, during the Miocene Epoch, the area that is now Red Rock Canyon State Park (and surrounding desert areas) was a relatively flat coastal plain, crossed by rivers making their way to the coast.  At that time, the coastline was just east of present-day Bakersfield, near Sharktooth Hill.  The Sierra Nevada had not risen to its present height, which meant there was no rain shadow effect and no desert; the area had a wet, humid and rather tropical climate dominated by a vast grass prairie. 

The prairie supported an array of grazing animals, the ancestors of modern species of horses, camels and deer, as well as their predators, such as an ancestral form of the saber-toothed cat and the amphicyon, a sort of bear-dog.  Red Rock Canyon State Park preserves the most complete Miocene-age (5-24 million years) vertebrate fossil record in North America.

Sunday, February 26, 2017

Plant Profile: Many-headed Barrel Cactus (Echinocactus polycephalus)

If I were to ask you to describe the quintessential desert plant, you would say a cactus, right?  Of course.  So then what is the first type of cactus that comes to mind?  Maybe the grand Saguaro cactus of the Sonoran desert in Arizona.  The tall, branching cactus has become a symbol of the American West, although its distribution is limited to the Sonoran desert of Arizona and Mexico, with a few very isolated populations in the rugged desert mountains of extreme southeastern California.  But we're not talking about the famous Saguaros today, since there are many other fascinating and beautiful species of cacti out there! 


Today, I'd like to introduce you to a lesser-known member of the Cactaceae family, a small cactus known as the Many-headed Barrel Cactus (Echinocactus polycephalus).

Species account from The Jepson Manual, Vascular Plants of California

Other common names for this cactus include Cotton-top and Mojave Mound.  I like the name "Many-headed Barrel Cactus" best, since it is both descriptive and its Latin species name, polycephalus, directly translates to "many-headed."  This cactus is low-growing, forming large clumps of 20-40 heads.  The larger California Barrel Cactus (Ferocactus cylindraceus) occurs singly rather than in clumps, and has a ring of yellow flowers around its top, like a crown, when in bloom.  The spines of the Many-headed Barrel Cactus turn a bright reddish-pink color when they are wet.  (It was raining when I took all of these photos.)


The range of the Many-headed Barrel Cactus includes the Mojave and Sonoran deserts.  In California, look for them largely in Inyo and San Bernardino counties, with some in Riverside, Imperial and San Diego counties; Calflora shows a few specimens occurring in Kern county as well.  Like many cacti, they are found on coarse, gravely and rocky soils, often growing on steep slopes and canyon walls with sharp drainage, up to 6,000 feet in elevation.

Thursday, February 23, 2017

Streams in the Desert: Rain and Rocks in Death Valley National Park

The desert southwest is a captivating place, and Death Valley is certainly no exception!  The largest National Park in the lower 48 states, Death Valley is well-known for being a land of extremes: hottest, driest, lowest.  It is a land of dramatic scenery, hardy desert plants and animals, and an impressive geologic record.

Uplifted and tilted layers of ancient lake sediments, alluvial fans and volcanic ash deposits
 are found in the Furnace Creek formation, exposed at Zabriskie Point.

Over the Presidents' Day weekend, I was able to spend several days exploring Death Valley with a geology field studies class from Modesto Junior College.  (Last September, I went on a similar trip to Northern California where I studied geology at Mount Shasta, Lava Beds National Monument, and Lassen Volcanic National Park, as well as botany on the Modoc Plateau.)  Never pass up a good learning experience!

Water in Badwater Basin (a rare sight)

While we were in Death Valley, an unusual thing happened: it rained!  A storm came through and showered us with rain for two days and two nights, almost without stopping.  But thanks to having the right gear, I stayed warm and dry the whole time.  Don't underestimate the importance of a good tent, raincoat, and waterproof boots, even in the desert!  Being prepared will go a long way toward making a rainy camping trip much more enjoyable.  Seeing rain in Death Valley gave me a much better understanding of flash floods and the geologic effects these massive torrents of water occasionally have on the landscape.  It's hard to imagine that there is ever that much rain in the desert, but as I have learned, it does happen!

Stream channel above Gower Gulch, through which water has been diverted in hopes of preventing floods.  (The
diversion didn't actually work.)

Thanks to the beautiful rain, we were able to experience a side of Death Valley not many tourists get to see.  Streams were flowing, tiny rivulets gathering into larger channels and running across the desert to collect in low spots (low spots like Badwater Basin and the spot right underneath my tent!)  The air was clean and clear, and the rocks were bright and vivid when the sun eventually came out. 

View toward Gower Gulch

Death Valley is in the Basin and Range geomorphic province, an area defined by a series of north-south trending fault valleys and mountain ranges.  The fault valleys are known as grabens, blocks of land that have sunk between parallel mountain ranges, called horsts.  These valleys were formed as the earth's crust stretched over time, breaking and tilting blocks of land into the horst and graben landscape we see today.  (In German, horst means an eagle's nest or eyrie, and graben means grave.)

 
The aridity of the desert preserves an ancient landscape, allowing geologists to reconstruct a vast history of the region as they interpret the rocks.  The Death Valley we see today is really the second fault valley or graben that has formed here.  Extensional forces have been pulling the crust apart to create the horst and graben landscape in the Death Valley region for 15-16 million years.  Around 5-6 million years ago, a northwest-southeast trending fault valley opened.  Mountains rose on either side and erosion filled this "original Death Valley" with layers of sediment that were then lifted by faulting and exposed through erosion.  At times, a lake in the valley deposited layers of silt and clay; at other times, dry conditions left behind deposits of salt, borate and gypsum.  Alluvial fans deposited conglomerates and volcanic eruptions created colorful deposits of ash and tuff.  These layers, part of the Furnace Creek formation, are exposed at Zabriskie Point.  The graben we call Death Valley today formed between 2 and 3 million years ago; a relatively recent addition to an otherwise ancient landscape.

Furnace Creek formation (foreground) and Artists Drive formation (darker rocks in the background), seen from
Zabriskie Point.

20,000 years ago, Death Valley was a grassy savannah with a warm, moist climate.  A large, freshwater lake, Lake Manly, filled the fault valley to a depth of 600 feet with runoff from melting glaciers during the Ice Age.  Mudstone formed at the bottom of the lake.  11,000 to 12,000 years ago, the climate shifted to become warmer and drier, causing the lake to shrink and eventually dry up, leaving salt and mineral deposits behind, which can be seen at the well-known salt flats at Badwater Basin. 

Part of the shoreline of Lake Manly can be seen along the Beatty Cutoff.  Notice the rounded beach pebbles and
linear, rounded shape of the beach berm.


Badwater Basin is a famous tourist destination known for being the lowest point in North America at 282 feet below sea level.  Beneath Badwater, there are between 9,000 and 11,000 feet of sediments that have washed down from the mountains over the millennia.


The Black Mountains, which rise up several thousand feet above Badwater to the east, are composed of ancient rock, 1.7 billion years in age.  Exposed in these mountains is a metamorphic core complex, the literal "roots of the mountain," or basement rocks that were brought to light through uplift and erosion as extensional forces created the Death Valley graben 2-3 million years ago.  Geologists believe the sloping side of these mountains is the fault plane of a detachment fault (a low angle normal fault), and that as younger rock slid off along the fault plane, these mountains slowly rose.  The formations in the picture below, where metamorphic basement rocks are exposed, are called Turtlebacks.

Turtleback at Mormon Point

The Mesquite Flat sand dunes are a beautiful sight, especially with the snow-capped Grapevine Mountains as a backdrop.  A few of my classmates and I explored these dunes at night, climbing one hill after another until we were far enough from the road to sit in silence.  Once we were deep in the dunes, we shut off our headlamps and let our eyes adjust to the darkness.  As clouds drifted across the sky, Venus and familiar constellations blinked on and off.  We sat in the sand dunes for almost two hours, soaking in as much wonderment and awe as we could (which is not a hard thing to do on a starry desert night).  From Mesquite Flat sand dunes, it was about a two-mile hike across the desert back to our camp at Stovepipe Wells.

Mesquite Flat sand dunes at sunset

The Mesquite Flat sand dunes formed as wind carrying fine particles of quartz and feldspar, likely weathered from the Cottonwood Mountains to the north and northwest, sweeps down the valley, only to be interrupted by Tucki Mountain at the northern end of the Panamints.  This interruption in the wind current results in eddies which slow the wind, causing it to drop its load of sand in the area where the dunes have formed.


If you ever get a chance to visit Death Valley (in the cooler months), take it!  It's a wild, remote, fascinating place, with a stark beauty that is sure to captivate.  Geologists, botanists and adventurers alike will find more than enough to enthrall them for days on end.  But remember to be prepared: the desert, for all its beauty, is a harsh and dangerous place.  Carry and drink more water than you think you need, wear sunscreen, sunglasses and a hat.  But also bring warm, waterproof clothes (in layers) and sturdy boots!  A good, properly staked-out tent is important if you plan to camp.  It does rain occasionally in the desert, and strong winds are always likely! 

Happy adventuring!


Tuesday, February 14, 2017

Phainopepla

The Phainopepla (Phainopepla nitens) is an intriguing bird.  It is a songbird of deserts and the arid southwest, and the first time I encountered one was last spring in Joshua Tree National Park.  But it turns out they can also be found closer to home (my home in the Central Valley, anyway!).  Last weekend, I spotted a female Phainopepla in an oak tree along the Stanislaus River, near the town of Knight's Ferry.


The name Phainopepla is Greek and means "shining robe," in reference to the male's black, shiny plumage.  Females are a more subdued gray, but still have the crest and red-orange eyes characteristic of the species.  These birds are found throughout the southwestern part of the United States, and south into Mexico.  Their preferred habitat is desert, chaparral and riparian woodlands.  According to Cornell's All About Birds, Phainopeplas exhibit different breeding behavior in different territories.  In the desert, they are very territorial, but in woodlands, they nest colonially, with multiple nesting pairs sharing one tree.  I wonder if this correlates with resource availability?


Phainopeplas are often seen perching prominently on the tops of trees and shrubs.  In flight, adult male Phainopeplas flash bright white wing patches, which contrast sharply with their black plumage and make identification easy.  They feed heavily on mistletoe berries, eating over 1,000 individual berries per day when they are abundant.  Phainopeplas will also feed on other berries, as well as insects caught in mid-air.

Wednesday, February 8, 2017

Campground Spotlight: Texas Springs, Death Valley National Park

When considering places to explore in the off-season, never overlook the largest national park in the lower 48 states, Death Valley National Park!  Next week, I'll be heading down to spend a few days exploring the geology of Death Valley, and hopefully catching a few of the first spring wildflowers!  Last spring, Eric and I were able to visit Death Valley during the 2016 Super Bloom, making it the first stop on our week of desert camping.

A spectacular view of the sunset from Texas Springs campground, looking southwest toward Telescope Peak

Eric and I left home one morning last March with high hopes and no definite camping arrangements, aside from a list of campgrounds and a vague idea of where each was located on a map.  We made it to Death Valley a couple of hours before dark... during an enormous sandstorm. 

If you've been to Death Valley, you might be familiar with the Mesquite Flat Sand Dunes.  As we drove past Stovepipe Wells looking for a campsite, the dunes were literally airborne; visibility was greatly reduced as sand billowed high into the air.  A few dim shapes could be seen through the billowing sand, tents flapping in the wind as dogged campers desperately re-staked corners.  I can't comment on this campground, as I never actually saw it through all the sand.  But the plan is to camp there next week!

Not to be deterred, we drove on to the next possible campground on our list, Sunset campground, across the street from the Furnace Creek area.  We used the restroom here and immediately returned to our car, mostly for shelter from the wind.  Sunset campground is pretty much just for RVs: a large, exposed expanse of gravel parking lot. 

Just up the hill from Sunset campground, however, we found the perfect spot to camp: Texas Springs.  This campground is nestled in an eroded badlands landscape, surrounded by sheltering hills and mesquite trees growing in low-lying areas; a veritable desert oasis!

Texas Springs campground, on a stormy evening! 

Thanks to the wind, havoc had been wreaked on the campground: tents were blown into trees, sleeping bags, pads, gear and clothing were literally scattered to the winds.  Gusts were strong enough to send picnic tables sailing, flip over a pop-up camper and blow out car windows.  But on the upside, as we pulled into this scene of chaos, not-so-happy campers were jumping ship as fast as they could and a number of campsites became available (always a silver lining, eh?)  We cruised around the campground and found a recently-deserted site, relatively free from broken car window glass, and claimed it as our own, hauling our wayward picnic table out of a thicket of mesquite which had happily prevented it from flying further afield.  And someone had even left behind a whole bundle of firewood!  Talk about a windfall!

By evening, the worst of the wind had died down and big, fat desert raindrops began to fall.  Eric and I went for a walk to get the lay of the land, had our supper, and were considering putting up our tent.  But just as the sun went down, the wind kicked up again, ripping through the badlands with furry.  We slept in our car the first night.

Desert sunrises can't be beat!

In the morning, we were happy to wake to clear skies and no wind.  We put up the tent, got our gear sorted out and headed off to explore the desert.  Texas Springs campground is centrally located in Death Valley National Park, making it a great place to set up a basecamp for exploring more distant reaches of the park.  From Texas Springs, in the Furnace Creek area, it is a reasonable drive to Death Valley's main attractions, such as Artist's Pallet, Badwater Basin, Zabriskie Point and Dante's to the south, as well as the Mesquite Flat Sand Dunes and the Salt Creek area to the north.  (Furnace Creek campground is also centrally located, but we didn't have the chance to look around that area very much.)

Our humble camp at Texas Springs.

Texas Springs campground is open from October 15 to May 10 and is first come, first served.  (For a campground that is open year-round, visit Furnace Creek campground, which also accepts reservations.)  92 sites are available at Texas Springs campground, for $16 per night; each site has a picnic table and fire ring.  Potable water is available, as is that great luxury of campgrounds, flushing toilets.  For additional information, as well as important park alerts and camping regulations, visit the National Park Service's website.

Consulting The Jepson Manual: Vascular Plants of California during a lunch break in camp. 
Also a chance to reapply sunscreen!

Monday, February 6, 2017

Peeps, Plovers, and Other Notoriously Difficult Shorebirds: Central Valley Edition

The following scene is a common cause of despair to many beginning birders: mixed shorebirds. 

They're small and brown, far away and flighty; they're all mixed together and most of them have their heads in the water.  So where to even begin?

What are these?  There are four species here:
 Greater Yellowlegs (in the back, blurry), Killdeer (with prominent black collar), Least Sandpipers (the smallest birds;
one is at the edge of the water toward the right of the photo), and Long-billed Dowitchers (the other brown birds!)

Initial despair can either bolster a birder's courage, causing him or her to rise to the challenge, or torment the beginning birder, allowing frustrations to give way to defeat.  Don't be defeated by shorebirds!  Rise to the challenge! 

Shorebirds are a tricky group to identify, but not entirely impossible.  I've been studying them recently, and would like to offer a few of my beginner's tips (as I am still in the beginning stages of learning shorebirds myself!)

Step 1.  Learn the basic shapes of different groups of shorebirds.

Don't rely heavily on color or markings, since most (if not all) of the shorebirds in California during the winter are in drab winter plumage rather than bright breeding plumage.  Usually the first or largest illustration in a field guide will be of a bird in bright breeding plumage, and not necessarily what you will see in the field in California.  (Good field guides will have illustrations of all plumages!)  Learn the shapes of the different groups of birds instead, including relative bill length and shape, leg length and body shape.  Figure out what makes a plover different from a sandpiper; separate the dunlins from the dowitchers. 

Cryptically-colored plover-shaped birds.  Any guesses? 
These are Black-bellied Plovers; the common name is completely unhelpful outside of the breeding season,
 the only time of the year that adult Black-bellied Plovers actually have black bellies.  So unless you're planning
a summer trip to the Arctic, expect to see this color pattern instead.

A note on size: It's difficult to get a sense of scale from most field guides; I had no idea how small sandpipers are (6 inches long) until I actually saw them in the field!  Remember that the size of one lone bird seen in the field can be deceptive.  But size is useful in the field when several species are seen together in a mixed flock.  When you can note the relative size of various species seen together, much larger or much smaller species become more obvious.

One lone Least Sandpiper; it's impossible to get a sense of size from this photo, as the bird by itself looks much
larger than it actually is.


Another Least Sandpiper, at right, seen here with a Killdeer for scale.  Now we begin to get a sense of relative size.
 For a third example, see the first photo in this post; the Least Sandpiper is the tiny bird at the edge of the water to the
 right, obviously much smaller than any other bird in the photo. 
 
Step 2.  Narrow down your options.
 
Once you have learned to recognize the basic shapes of shorebirds, you can go to the field guides to figure out which species are likely to be in the area at that time of year.  Note which plovers are likely to be seen in your location; do the same for sandpipers (those tiny, tricky, sparrow-sized shorebirds commonly lumped together as "peeps.")  Say you're in the Great Central Valley, in a wetland refuge with some open fields, some shallow water, some mudflats.  It's February (winter).  Flip through a couple of field guides and consult with eBird to get an idea of what you can expect to see (that's not cheating, I promise).  Hint: common species in the Valley during the winter include Least Sandpipers, Dunlins and Long-billed Dowitchers.  That plover-type bird is likely to be a Killdeer, but might also be a Black-bellied Plover.

Dunlins are a common shorebird in the Great Central Valley during the winter; they're larger than a sandpiper and
smaller than a dowitcher, with slightly down-curved black bills and black legs.  Oh, and they're also brown.

Step 3.  Learn the common species well.  Really well.

Once you've sorted out a handful of the most common species for a certain area and time of year, get to know those species really, really well.  After a little practice in the field with binoculars and maybe a camera or sketchbook, and some time spent at home looking through books and the internet for images and descriptions, you'll feel comfortable identifying a few previously confusing species.  You'll probably be able to pick out a Least Sandpiper or Dunlin every time!  Once you are familiar with the common species, it will be much easier to pick out the odd bird here and there that you don't know; you'll know when you see a bird that you don't recognize, maybe one that is a little less common for the area.  Then you can focus on one unfamiliar bird in a flock of known species, rather than be overwhelmed by the entire group of confusing birds.

Long-billed Dowitchers, more likely to be seen in the freshwater ponds of the Central Valley than their
 tidal flat-loving relatives, the Short-billed Dowitchers.

With a little practice, shorebirds will become less intimidating.  Start with a small handful of species common in your area, and gradually add more to your list of familiar faces.  Winter in the Great Central Valley is a good time and place to start learning.  My suggestions for brownish shorebird species to start with are plovers (Killdeer and Black-bellied Plovers, specifically), Greater Yellowlegs, Least Sandpipers, Dunlins, and Long-billed Dowitchers. 

So there's your homework: five (okay, six) species of birds to become familiar with over the next month or so.  Happy birding!

Mixed shorebirds at sunset.  You no longer have to shy away from scenes like this one!

Sunday, February 5, 2017

The Budding Naturalist, Part I: My Mom & Dad

I can't imagine life without nature, life without hiking in the mountains, camping in the desert, swimming in lakes, exploring tide pools.  Because my parents taught me to appreciate the natural world from a young age, my life has been lived largely outdoors, exploring, learning, wondering.  They didn't just teach me how to hike and camp and swim; they taught me to be a naturalist.

My parents are the best parents in the world.  Let me tell you why.

On a road trip with my parents in Grand Teton National Park

                First, they named me after a glorious mountain range, the Range of Light, the Sierra Nevada.  They couldn't have picked a more suitable name.

                Second, they packed me with them all over those mountains in a "baby backpack" when I was still too small of a tot to hike.  I don't remember the first time I went camping and slept in a tent, because that event took place before my first memories were formed.    

                Third, they bought me books.  As a budding naturalist, I loved reading field guides, natural history guides and a magnificent collection of binders known as Wildlife Fact Files.  (At the time, I believed these contained information on every living species on the planet.  Not quite true, but close!)  My first field guide to birds, a Peterson's, was given to me by my dad when I was two years old.  

                Fourth, they took me places.  Lots of places.  They didn't just take me to the woods and to the beach and to the desert to hike and camp.  They took me to museums and interpretive centers and every zoo within a day's drive of our house.  They took me to an open house day at the wildlife care center where I now volunteer.  They took me to wander around inside the science building at the university where I eventually studied and earned my degree. 

                Fifth, they made massive investments in my interests and encouraged my curiosity daily.  They were (are) proud of me, and made me feel like what I love - nature, animals, plants - is important and valuable.  My mom made me a "nature box" in which to store various odds and ends of the natural world I found on outings - rocks, leaves, shells, pinecones and the like.  I still use that box to this day.  My dad got up at 4:30 in the morning with me one day when I was twelve years old to go look for gray foxes because I'd read in my field guide that they're most active at dawn.  We saw an entire pack of gray foxes that morning. 

Backpacking in Yosemite National Park

                My parents are still two of my go-to adventure buddies.  We still go to natural history museums and on hikes; they still buy me field guides for Christmas.  I recently got them both interested in birding.  It was true as I was growing up, and it remains true to this day: my parents are the best parents in the world. 

Friday, February 3, 2017

Great Horned Owls

It's February, and Great Horned Owls (Bubo virginianus) are already nesting in California; in fact, some owls in this area begin breeding as early as January.  These large, nocturnal predators are particularly active at this time of year, and I've seen quite a few Great Horned Owls while I've been out and about this winter, even during the day.  Look for these magnificent birds roosting during daylight hours in thick stands of trees, often near the trunk.   


 
As the afternoon begins to fade to dusk, listen for the distinct and familiar series of mellow hoots that indicate a Great Horned Owl is near.  During the late fall and winter, you will likely hear a pair of owls calling to each other as courtship begins.  The pair may sing (or "hoot") simultaneously in a duet, or alternately, and often part of their songs will overlap.  The male's voice can be distinguished from the female's by its deeper tone, although he is the smaller partner in size.  In late December and January, I heard owls calling to each other as early as 3:00 p.m. on overcast days.  Most commonly, these owls are most vocally active during the first hour after sunset and just before dawn.
 


Great Horned Owls mate for life, though they roost separately apart from the nesting season.  They are quite territorial, with both members of a pair usually remaining on their territory throughout the year.  One pair requires around 2.5 acres of suitable habitat for their territory, which they will defend from neighboring owls through hooting contests.


The Great Horned Owl is North America's most widespread owl.  This species has successfully adapted to a wide variety of habitats, including virtually all California habitats except for the crest of the Sierra Nevada range.  Provided there is ample prey and adequate nesting sites, Great Horned Owls are equally likely to be found in oak woodlands, low-elevation conifer forests, chaparral, desert and riparian habitats; they are less common in high-elevation conifer forests, though not absent.  It is not unusual to find that these powerful predators have even adapted to suburban life; Eric and I have seen Great Horned Owls on several college campuses in the Great Central Valley, where there are stands of mature trees and open fields with plenty of gophers!



Owls in general are not known for their nest-building prowess; most species simply "renovate" an existing nest or cavity that has been abandoned by its previous tenants.  Great Horned Owls will use the past-season nest of other large birds such as crows or ravens, herons and hawks.  They make themselves at home with relative ease: stick nests in trees or on platforms will do, and so will old tree snags and cavities or niches in cliffs.  By utilizing natural cavities or niches in rocky cliffs, Great Horned Owls have been able to establish themselves successfully in desert regions.  The same nest may be used by a pair of owls for multiple years.


Great Horned Owls are formidable hunters, taking whatever prey happens to be available.  Adapting to eat nearly anything of manageable size, from large geese to small Jerusalem Crickets (Stenopelmatus fuscus), has allowed these owls to reproduce successfully and establish themselves in almost every habitat across North America.  They prey on other birds, including other owls, raptors and waterfowl; snakes, frogs and large insects round out the menu.  But by far, the most significant component of the Great Horned Owl's diet is small mammal species, such as rabbits, gophers, woodrats and mice.  Owls have a poor sense of smell, and are known for preying on the occasional skunk.  Swooping down silently on its prey, the Great Horned Owl snatches its victim with long talons, gripping with almost 30 pounds of pressure.  Prey is killed with a quick bite to the back of the neck from the owl's powerful beak.