50 portrait and action shots of Pronghorn from the North Entrance at Gardiner, Montana
and the Lamar Valley near Buffalo Ranch, taken in autumn at Yellowstone National Park.

Most of the Yellowstone Wildlife images were prepared without Title Bars.

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       Blacktail Plateau and Blacktail Ponds            Lower Mammoth to Floating Island Lake

North Entrance and Lamar Valley

The Banner below leads to the Pronghorn Gallery where images can be selected.

There are 165 images in the Pronghorn Gallery.

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A Pronghorn male and his large harem of females in the grasslands below the Buffalo Ranch in the Lamar Valley.

Pronghorn males who can maintain a territory near a water source often have a larger harem than other males.
The Lamar River winds through the Lamar Valley roughly a hundred yards behind the photographer’s position.

The Lamar Buffalo Ranch was built in 1907 in an effort to increase the herd size
of the few remaining bison in Yellowstone to prevent the extinction of the species.
Although there were 30 to 60 million buffalo (American Bison) in North America in
the early 1800s, market hunting, poaching and the US Army slaughter campaign
designed to remove the food source for Indians to force them onto reservations
had reduced the population to 24 by 1903, all of which were in Yellowstone.

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Male Pronghorns defend territories from March through the end of the rut in early October. Bucks look for a territory with a water source and terrain features which allow them to corner females (does), and males with those features within their territory do better than those without. Some males defend their fixed territory and allow females to enter, while others defend a small harem of females and move. Males change their mating strategy depending on environmental conditions or demographic conditions. In
areas where rainfall is higher, males tend to be territorial and mark the territory with scent from glands on either side of the jaw. They vocalize and challenge other males entering their territory. In areas where rainfall is lower, they tend to defend their harem and move from place to place, looking for water.

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Pronghorn females browse in the grass in front of a stand of Cottonwoods in the Lamar Valley.

Females also have different mating stragegies. “Sampling” females visit several males, remaining with each for a while before switching to the next male. The rate at which they move increases as estrus approaches. “Inciting” females act as “samplers” until estrus, then they incite conflicts among males and mate with the winners of these battles. “Quiet” females remain with a single male in an isolated area throughout estrus. It appears that the “sampling” strategy is often energetically expensive, and that the “quiet” strategy is used by females with lower energy reserves.

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Pronghorn females check out the photographer as the male leads others towards
a stand of Cottonwooods in the Lamar Valley in northern Yellowstone National Park.

Pronghorns form mixed-sex herds in the winter, which disperse in the spring. Young males form bachelor herds, females group together, and adult males live alone, wandering in search of territory. These territories are usually widely spaced and do not overlap. The range size is smaller in the spring through fall than it is in the winter, when pronghorns wander farther for food.

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A Pronghorn male standing in the autumn grass, in the Lamar Valley of northern Yellowstone National Park.

Also called the Pronghorn Antelope, the Pronghorn is the only surviving member of the Family Antilocapridae
and is not a true antelope, but it closely resembles the Old World antelope and fills a similar ecological niche.
The Pronghorn can run exceptionally fast and it is considered to be the fastest land animal in North America.
They evolved their running ability to escape from extinct predators such as the American Cheetah, and they
are much faster than any current North American predators, being the second fastest land animal behind
the Cheetah. Pronghorns can maintain high speeds much longer than cheetahs, and can reach 55 mph
and can sustain this speed for a half mile. They can maintain 42 mph for 1 mile and 35 mph for 4 miles.

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A Pronghorn male smacks its lips in what is usually part of a courtship sequence.

All of the landscape (horizontal) large version images linked from the thumbnails are 1500 pixels wide.
Portrait (vertical) images are 1200 pixels tall (1290 pixels with title bar). Images designated with an “M”
in the shot number are 5:4 aspect ratio, 1500 x 1290 with a title bar, or 1500 x 1200 without a title bar.

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Pronghorns are 4.5 feet to 5 feet long from nose to tail, stand about 3.5 feet tall at the shoulder, and have a barrel-shaped body. The males and females are about the same size, but females typically weigh about 20-25% less than males.

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Pronghorns have dense, coarse, air-filled fur which provides excellent insulation. The dorsal fur is rufous brown, and they have off-white underbellies, rumps and neck patches. Males have dark patches of fur under the ears and a dark stripe running laterally between the horns. Both males and females have a dark patch on the nose, extending higher on the male to just under the eyes.

Pronghorns have very large eyes, a 320 degree field of view, and can discern detail at great distance.

Pronghorns have unusual horns, which grow from two slender, laterally-flattened blades of bone in the front part of their skull. The horns are covered by skin which develops into a sheath of keratin. Unlike other mammals, a new sheath grows under the old one, which splits annually after the rut and is shed. The horns of the Pronghorn are unique in another way: the male horns curve backwards and fork in a forward-pointing tine (the prongs which give the species its name). The horn sheath of the male is 5”-17“ long, averaging about 10”. Females have much smaller straight horns which are very rarely pronged.

Horns differ from Antlers in several ways:

   –  Horns are a layer of Keratin (like fingernails and hair)
       over a living bony core. Antlers are true bone structures.
   –  Horns are slow-growing and permanent (not shed each
        year). Antlers are fast-growing and are shed each year.
   –  Horns are usually grown by both sexes. Antlers are
       usually grown only by males (except for caribou).
   –  Horns are usually single tines, often curved or spiral,
       and exhibit annual growth rings indicating the age.
   –  Antlers are associated with testosterone and are often
       branched. The number of tines do not indicate the age.

The image at right is a resized detail crop from 9968, which is displayed on the Pronghorn 1 page in the section on Blacktail Ponds. There is no larger version of this detail crop, but there is a larger version of the full image shown on that page.

The Banner below leads to the Pronghorn Gallery where images can be selected.

There are 165 images in the Pronghorn Gallery.

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A 300mm telephoto extreme closeup of a Pronghorn female in the autumn grass of the Lamar Valley.

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A Pronghorn male in the shade of a Cottonwood tree protects his harem in the Lamar Valley.

The Pronghorn breeding period in Yellowstone is from mid-September to October
and roughly corresponds to the Elk breeding period, making this a good time to visit.

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A 300mm telephoto closeup of a Pronghorn female standing in autumn shrubs in the Lamar Valley.

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A Pronghorn male with asymmetric horns checks out the photographer in this 300mm extreme closeup.

When a male Pronghorn is alarmed or disturbed it raises its hackles, an erectile patch of fur in front of its
rump to alert others. The white hairs below can be seen for long distances. They also raise the mane hairs
into a stiff brush, which communicates their alarm to nearby individuals. If the male determines that there is
a threat, it warns the others by emitting a scent from glands in its rump and the pronghorns take off running.

In the closeups on this page, the male has not raised its hackles. As I approached, I moved in very slowly and quietly,
taking shots during the approach to accustom the Pronghorns to my presence and the sound of the shutter. While the
Pronghorns were very aware of my presence, they did not consider me to be a threat and remained in their positions.
You can see a number of 300mm closeup images on the Pronghorn 1 page where the male has raised his hackles.

Getting very close to Pronghorns requires patience. They are curious animals, but they can be skittish.
When you get inside 75 yards, you need to move very slowly and not make any sudden noises, thus it
is a good idea to take shots as you approach to accustom them to the sound of the camera shutter.
By the time you get to about 25 yards, they will be used to your presence, but if you go much closer
they will flee, so getting good closeups requires a long telephoto lens and good stalking technique.

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A Pronghorn juvenile resting in the autumn grass in the Lamar Valley.

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A 300mm extreme closeup telephoto portrait of a Pronghorn juvenile.

This juvenile is a nearly mature female, almost as large as the other females.

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300mm telephoto close portraits of a Pronghorn juvenile and female in the Lamar Valley.

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A Pronghorn female shows her astonishment in this 300mm extreme telephoto close portrait.

The Banner below leads to the Pronghorn Gallery where images can be selected.

There are 165 images in the Pronghorn Gallery.

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A Pronghorn male with an unusually wide set of nearly straight horns walks through the autumn grass while
keeping an eye on the photographer in this series of 300mm telephoto closeups taken in the Lamar Valley.

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Pronghorn fawns and weak individuals are preyed upon by coyotes, wolves, mountain lions and other predators.
Pronghorns can use their horns to defend against predators, and they can also use their sharply pointed hooves
in defense, but their primary defenses are a 320 degree angle of view, exceptionally sharp eyesight, and speed.
Pronghorns are capable of sprints up to 55 mph and can maintain speeds of 35-40 mph for very long distances.
The fastest measured sprint of a pronghorn is over 60 mph (the fastest cheetahs can reach 75 mph for 1.3 mile).

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The nearly straight shape of the horns on this male must make them very good weapons.

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A 300mm extreme telephoto closeup of a Pronghorn male in the Lamar Valley in northern Yellowstone.

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In the image above, you can see the unusual width of the nearly straight horns on this Pronghorn male.

The Banner below leads to the Pronghorn Gallery where images can be selected.

There are 165 images in the Pronghorn Gallery.

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A Pronghorn male running in a meadow at the Northern Entrance to Yellowstone in Gardiner, Montana.

This male has the more typical horn shape, curved towards the inside and rearward just above the prong.

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Pronghorn male and female, running through a meadow just inside the Northern Entrance to Yellowstone.

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A Pronghorn male and female running together near the North Entrance to Yellowstone National Park.

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These images were taken at 500mm. Tracking and framing two fast-moving pronghorns who were
filling the frame in the narrow field of view of a 500mm lens was a rather interesting technical exercise.

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Pronghorn limbs have evolved in specialized ways to increase their running ability, giving them exceptional speed and endurance. The formation of their foot allows them to stand on the tips of their hooves. The length of the radius bone is as long as (or longer than) the femur. The ulna and radius have been reduced to eliminate the twisting and rotating of the elbow, and the ulna is reduced and partially fused to the radius. The reduction of bone and associated muscles in the limbs decreases the limb weight, giving them more speed. Pronghorns have modified their joints to act as hinges, allowing only motion in the line of travel. This has been done by introducing interlocking spines and grooves in their joints. These adaptations have made pronghorns into exceptional runners, but they can no longer jump because they have lost their suspension mechanism.

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A 500mm telephoto portrait of running Pronghorns in a meadow just inside the North Entrance to Yellowstone.

The Banner below leads to the Pronghorn Gallery where images can be selected.

There are 165 images in the Pronghorn Gallery.

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Pronghorn females in a meadow just inside the North Entrance to Yellowstone at Gardiner, Montana.

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A female and male Pronghorn running in a meadow near the North Entrance to Yellowstone National Park.

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Pronghorns are built to run, and watching them is a truly marvelous experience.

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A Pronghorn male is captured with all four feet off the ground while running in a grassy meadow.

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The Pronghorn is the fastest North American land animal, second only to the Cheetah.
The Pronghorn evolved its speed to outrun the extinct American Cheetah, and while the
African Cheetah is faster over a very short distance, the Pronghorn was able to elude the
American Cheetah by using its 13 separate gaits, including one in which the Pronghorn
can take nearly 24 foot long strides (8 yards, 7.3 meters) while maintaining much of its
forward speed. The American Cheetah, which evolved from the Cougar (or Puma),
is thought to have had similar speed to the African Cheetah. It went extinct at the
end of the last Ice Age 12,000 years ago, so no one really knows its true speed.

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A Pronghorn male gallops through a meadow near the North Entrance to Yellowstone National Park.

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Compared to its body size, the Pronghorn has a large windpipe, heart and lungs which allow them
to take in and process large amounts of air to provide them with the oxygen they need while running.

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A male and female Pronghorn resting in a meadow near the North Entrance to Yellowstone National Park.

The Banner below leads to the Pronghorn Gallery where images can be selected.

There are 165 images in the Pronghorn Gallery.

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