Pronghorns_LowerMammoth_FloatingIsLake

39 portrait and action shots of Pronghorn from Lower Mammoth, Lava Creek and Floating Island Lake,
taken in autumn between Mammoth Hot Springs and the Lamar Valley in 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

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There are 165 images in the Pronghorn Gallery.

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Pronghorn_LowerMammoth_7542


Pronghorn Lower Mammoth 7542

A Pronghorn male in the grasslands just to the east of Lower Mammoth in 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.

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.

Pronghorn_BlacktailPonds_9968detail
Pronghorns_LowerMammoth_7547


Pronghorns Lower Mammoth 7547

A male and two female Pronghorns at rest in the grasslands east of Lower Mammoth.

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.

Pronghorn_YoungMale_LowerMammoth_7584


Pronghorn Young Male Lower Mammoth 7584

Pronghorn_LowerMammoth_7552


Pronghorn Lower Mammoth 7552

A young male Pronghorn with unusually forked horns still in the process of erupting from the cancellous bone.
Compare the look of the young male’s horns with the adult male shown at right. There are several closer shots
of this young male displayed further below with greater detail of the unusually shaped horns of this individual.

Pronghorn_LowerMammoth_7556


Pronghorn Lower Mammoth 7556

A Pronghorn male running in the grasslands just east of Lower Mammoth in northern Yellowstone National Park.

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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Pronghorn Juvenile Lower Mammoth 7592

A Pronghorn juvenile crossing the grasslands just east of Lower Mammoth in Yellowstone National Park.

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.

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Pronghorn Juvenile Lower Mammoth 7597

A Pronghorn juvenile prancing across the grasslands just east of Lower Mammoth in northern Yellowstone.

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Pronghorn Young Male Lower Mammoth 7601

Pronghorn_YoungMale_LowerMammoth_7625


Pronghorn Young Male Lower Mammoth 7625

The young male with the unusually forked horns in the scrub just east of Lower Mammoth.

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Pronghorn Young Male Lower Mammoth 7623

A closeup of the young male allowing detail examination of the unusually forked horns which are still erupting
from the cancellous bones. It is possible that the continued growth of these horns will yield a similar structure
to a typical horn, but some adult pronghorns have oddly shaped or asymmetrical horns as you will see later.

Pronghorn_LowerMammoth_7617M


Pronghorn Lower Mammoth 7617 M

A 500mm telephoto close portrait of a Pronghorn male in the grasslands east of Lower Mammoth.

While the typical shape of adult horns curve inward and to the rear, this adult’s horns curve
directly towards each other. Further below, you will see individuals with asymmetrical horns.

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.

Pronghorns_LowerMammoth_7621


Pronghorns Lower Mammoth 7621

Pronghorn males browsing in the scrub to the east of Lower Mammoth in Yellowstone National Park.

Pronghorns eat mostly stems, leaves, shrubs and grasses, preferring to eat small amounts of a wide variety.
They have a particular fondness for flowers, including spring flowers, daisies, paper flowers and woolly senecio.
Paper flowers are poisonous to sheep, and woolly senecio are poisonous to cattle, but pronghorns can eat them.

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There are 165 images in the Pronghorn Gallery.

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Pronghorn_LavaCreek_8843


Pronghorn Lava Creek 8843

Pronghorn_LavaCreek_8923


Pronghorn Lava Creek 8923

Pronghorn males in the Lava Creek area, a little further east between the Gardiner River and Blacktail Ponds. The male on the left has typical horns curving inwards and to the rear, while the male on the right (nicknamed “Snagglehorn”) has asymmetrical horns, with one in the typical shape and the other curved forwards and outward. There are closer images of Snagglehorn below.

PronghornFemale_LavaCreek_8910


Pronghorn Female Lava Creek 8910

PronghornFemales_LavaCreek_8911


Pronghorn Females Lava Creek 8911

Pronghorn females browsing and resting in the Lava Creek area of northern Yellowstone National Park.

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Pronghorn Female and Juvenile Lava Creek 8916

A Pronghorn female and juvenile in the Lava Creek area of northern Yellowstone National Park.

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.

PronghornScratching_LavaCreek_8936M


Pronghorn Scratching Lava Creek 8936 M

PronghornScratching_LavaCreek_8937M


Pronghorn Scratching Lava Creek 8937 M

The Pronghorn male nicknamed Snagglehorn scratches himself on a shrub,
incidentally marking his territory with scent from the glands on the side of his jaw.

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.

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.

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.

Pronghorn_LavaCreek_8965


Pronghorn Lava Creek 8965

Pronghorn_LavaCreek_8941


Pronghorn Lava Creek 8941

The Pronghorn male nicknamed Snagglehorn in the Lava Creek area of Yellowstone.
Note the asymmetric horns, with one typical horn curving almost directly inward, and
one horn curving forward and outward. Some pronghorn males have unusual horns.

Pronghorn_LavaCreek_8947


Pronghorn Lava Creek 8947

Snagglehorn smacks his lips. This action is often part of a courtship sequence.

Pronghorns_LavaCreek_8957


Pronghorns Lava Creek 8957

A Pronghorn female and juvenile with the male nicknamed Snagglehorn in the Lava Creek area of Yellowstone.

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).

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.

PronghornFemales_LavaCreek_8972


Pronghorn Females Lava Creek 8972

PronghornFemales_LavaCreek_8974


Pronghorn Females Lava Creek 8974

Pronghorn females browsing through the scrub in the Lava Creek area of northern Yellowstone.

PronghornFemales_LavaCreek_8977


Pronghorn Females Lava Creek 8977

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There are 165 images in the Pronghorn Gallery.

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PronghornFemale_FloatingIslandLake_0372


Pronghorn Female Floating Island Lake 0372

A Pronghorn female on a hillside near Floating Island Lake, further east from the Lava Creek area.

PronghornJuvenile_FloatingIslandLake_0379M


Pronghorn Juvenile Floating Island Lake 0379 M

A 500mm telephoto close portrait of a Pronghorn juvenile near Floating Island Lake in Yellowstone.

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Pronghorn Female Floating Island Lake 0392

PronghornFemale_FloatingIslandLake_0391


Pronghorn Female Floating Island Lake 0391

A series of 500mm telephoto portraits of a Pronghorn female near Floating Island Lake in Yellowstone.

PronghornFemale_FloatingIslandLake_0396


Pronghorn Female Floating Island Lake 0396

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Pronghorn Female Floating Island Lake 0401

PronghornFemale_FloatingIslandLake_0410


Pronghorn Female Floating Island Lake 0410

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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Pronghorn Juvenile Floating Island Lake 0427

A 500mm telephoto close portrait of a Pronghorn juvenile near Floating Island Lake in Yellowstone.

PronghornFemale_FloatingIslandLake_0432


Pronghorn Female Floating Island Lake 0432

A 500mm telephoto close portrait of a Pronghorn female near Floating Island Lake in Yellowstone.

PronghornFemaleJuvenile_FloatingIslandLake_1141


Pronghorn Female and Juvenile Floating Island Lake 1141

I switched cameras to take this 200mm scenic shot of a Pronghorn female and juvenile on a hillside.

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Pronghorn Floating Island Lake 0435

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Pronghorn Floating Island Lake 0436

A Pronghorn male near Floating Island Lake in northern Yellowstone National Park.

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Pronghorn Floating Island Lake 0442

This pronghorn male has the typical configuration of horns, with his horns curving inward and to the rear.

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