With human expansion continuing at its relentless pace — and deforestation, soil erosion, species extinctions, and climatic changes, accompanying it — there are a significant number of animals nearing the brink of extinction.

While listing all of them here would be impossible — there are far, far too many — I still think that it’s worth going over some of the more prominant of the many critically endangered animals in the world today.

And, to that end, the article below will highlight 5 of those critically endangered animals — the Giant Leatherback Sea Turtle, the Siberian Tiger, the Mountain Gorilla, the North Pacific Right Whale, and the Philippine Eagle.

The Brink of Extinction — Top 5 Critically Endangered Animals

Giant Leatherback Sea Turtle

The Giant Leatherback Sea Turtle (Dermochelys coriacea) is the largest turtle species still in existence. As you can probably guess from its looks, the species is quite ancient — and has been around in relatively unchanged form since around the time of the dinosaurs.

And it’s now very near extinction — largely owing to human activities. Such as: egg/nest poaching, commercial fishing (where it’s caught as by-catch), plastic pollution (which resembles the jellyfish that the turtles eat), boat collisions, and other forms of chemical pollution (causing hormonal/reproductive problems).

They are bigger than any other reptiles still in existence in the world other than the last remaining species of crocodilians.

In contrast to most other extant turtles, the Giant Leatherback Sea Turtle doesn’t possess a hard shell — and instead is covered in a thick “leather” covering for protection/insulation, hence its name.

Out of all the turtles they possess the most hydrodynamic body design — which allows them to swim at speeds of up to 22 mph, which makes them (very arguably) the fastest reptile in the world.

As far as size goes, like the name implies, they are giants. On average they grow to be 6-7 feet long and weight up to 1500 lbs — but they can get much, much larger than that. The largest individual on record in modern times was measured as being over 9.8 feet long, with a 7.2-foot-long shell — and weighed well over 2000 lbs. that individual was found on a beach on the west coast of Wales.

As alluded to before, the species is considered to be critically endangered — there are less than 26,000 to 43,000 mature females left (as of 2007), spread out thinly across all of the oceans of the world (they’re a cosmopolitan species).

Overall population numbers have fallen drastically over the last 100 or so years as a result of human activity. The biggest declines have been seen in Southeast Asia, where some previously important nesting sites have collapsed completely. While the meat of the turtle isn’t considered to be appetizing to most people, they are regularly caught and killed as by-catch by commercial fishers (they are too big for “turtle excluder setups” to work).

Research has shown that during the 1990s, roughly 1,500 mature females were being caught accidentally every year.

Pollution is also a significant issue, with many of the turtles experiencing sometimes fatal health issues as a result of eating plastic debris that resembles their primary prey, jellyfish. This ingested plastic pollution causes intestinal blockages and malabsorption of food — leading to “starvation” and sometimes death. The ingested plastics also causes health issues through the effects of the phthalates in the plastics — developmental and hormonal/reproductive problems are reportedly becoming more and more common in the species.

There’s something important to note here in that regard, Giant Leatherback Sea Turtles are one of the only animals to consume/prey on large quantities of jellyfish. Overfishing of the species tends to result in jellyfish numbers climbing dramatically.

Below I’m going to highlight a couple of the notable qualities of the species:

• Giant Leatherback Sea Turtles are nearly unique amongst reptiles in that they can maintain very high body-temperatures, despite being “cold-blooded”. They are effectively “warm-blooded” animals owing to their sophisticated internal body design making use of counter-current heat exchangers. In addition to this “clever” internal architecture, the species also is simply active all the time — research has shown that they rest for as little as 0.1% of the day. The rest of the time they are swimming — at up to 22 mph. The internal temperatures of adults can be more than 18 °C (32 °F) warmer than the temperature of the water that they’re swimming in.
• Dermochelys coriacea is one of the deepest diving animals in the world currently. They have been observed at depths of over 4200 feet below the surface of the ocean.
• They regularly make incredibly long journeys all the way across the world. Researchers tracked a leatherback turtle that “swam from Indonesia to the US in a 12,000 mile foraging journey over a period of 647 days” once.
• They possess very long lifespans. Some researchers estimate that they can live to be over 80-100 years old in the wild. This is something that they have in common with many other turtle species — many are quite long-lived.
• Part of the reason that they can grow to be so old is that once they have reached a large size there are few animals willing to pick a fight with them. They are also surprisingly very aggressive and quick when provoked (while in the ocean, not on land). While there have been observations of individuals being “overwhelmed” by killer whales, great white sharks, and tiger sharks, these are thought to be relatively rare events — and not ones involving the older, larger turtles.
• They’re actually known to aggressively attack boats sometimes when struck by one, and can actually do quite a bit of damage to small/mid-sized boats.

At current rates of population decline the species could very well be extinct in less than 20 years — and almost entirely as a result of industrial/human activity.

Siberian Tiger

The Siberian tiger (Panthera tigris altaica) is a type of tiger currently found mostly in the Sikhote Alin mountain region of the Russian Far East. Until relatively recently though, the subspecies was found throughout much of Eastern Asia.

As of the last widespread survey (back in 2005), there were roughly 331–393 adult + subadults left. Partial surveys done after 2005 have suggested that population numbers are continuing to decline, despite “intensive conservation efforts”.

The Siberian Tiger is one of the largest cat species still in the world. Research done on the individuals caught/killed in the earlier part of the 1900s indicate that it was at that time the largest cat species in the world — extensive hunting has apparently killed off the genetics for the larger individuals of that time though. The Siberian Tigers of today are thought to be notably smaller than they were during these earlier times.

As it stands, most individuals grow to be 130-140 inches long, and reach weights of 400-700 lbs for males, and 200-400 lbs for females. Reports of wild individuals as large as 11.4-feet long, and 850 lbs, have been made bough. In captivity, somewhat obese individuals often reach weights of over 1000 lbs.

Siberian Tigers prey on a wide range of animals, including: red deer, musk deer, wapiti, moose, roe deer, pigs/boars, sika deer, black bears, smaller brown bears, salmon, rabbits, hares, pikas, etc.

The killing of brown bears appears to be a two-way deal though, as brown bears are also known to regularly kill Siberian tigers, especially the females.

When prey animals are abundant Siberian tigers paper to prefer to take it easy, and target the smaller prey animals. They are capable of taking down very large animals, such as bull moose though — this is dangerous though, even for them.

With regard to the interactions between brown bears and Siberian tigers — brown bears are known to regularly “appropriate” kills from the tigers. Often of prey-animals that they themselves don’t hunt.

“During telemetry research in the Sikhote-Alin protected area, 44 direct confrontations between the two predators were observed, in which brown bears were killed in 22 cases, and tigers in 12 cases.”

With regard to the limited numbers of the tigers still left, inbreeding appears to be a real issue:

Broad genetic sampling of 95 wild Russian tigers found markedly low genetic diversity, with the effective population size extraordinarily low in comparison to the census population size, with the population behaving as if it were just 27–35 individuals. Further exacerbating the problem is that more than 90% of the population occurs in the Sikhote Alin mountain region, and there is little movement of tigers across the development corridor, which separates this sub-population from the much smaller sub-population found in southwest Primorye province.

Poaching has remained as one of the primary threats to the continued survival of the species — both regard to poaching of the tigers themselves, but also their prey.

As far as the danger that Siberian Tigers pose to humans, here’s this:

In the Far East, during the middle and third quarter of the 19th century, attacks on people were recorded. In 1867 on the Tsymukha River, tigers killed 21 men and injured 6 others. In China’s Jilin Province, tigers reportedly attacked woodsmen and coachmen, and occasionally entered cabins and dragged out both adults and children.

According to the Japanese Police Bureau in Korea, a tiger killed only one human, whereas leopards killed three, wild boars four and wolves 48 in 1928. Only six cases were recorded in 20th century Russia of unprovoked attacks leading to man-eating behaviour. Provoked attacks are however more common, usually the result of botched attempts at capturing them.

So while it’s clear that in the past they have not hesitated to hunt humans, the numbers aren’t exactly on the same scale (with regard to threats to humans) as many far more common animals.

Such as: hippos (more than 3000 people killed annually), mosquitos (more than half a million annually), deer (hundreds killed every year in the US alone, mostly via auto accidents), bees (50-100 a year in the US alone), feral dogs (50-100 a year in the US alone), ants (hundreds every year), jellyfish (hundreds to thousands annually), cows (hundreds to thousands every year), horses (hundreds to thousands annually) etc.

So while the image of a tiger dragging your half-eaten kid off into the wilderness may not be pleasant, they simply don’t kill anywhere near the same number of people as common “safe” animals do. It would be unfortunate for them to go extinct simply because of their popular image as a killer (that’s not to say that they aren’t dangerous of course).

North Pacific Right Whale

The North Pacific right whale (Eubalaena japonica) is one of the largest species of whale still extant in the world. But it isn’t looking too likely that it’ll be in the world for all that much longer — as it is critically endangered, and it has many factors working against its continued survival.

As far as the population numbers go — the Northeast Pacific subpopulation (the one that summers in the southeastern Bering Sea and Gulf of Alaska) constitutes no more than 50 individuals; and the western subpopulation (the one that summers in the Sea of Okhotsk between the Kuril Islands and Sakhalin Island) is made of a few hundred individuals at the most.

Prior to commercial whaling in the North Pacific (ie pre-1835) the populations in the North Pacific probably were over 20,000 animals. The taking of right whales in commercial whaling has been prohibited by one or more international treaties since 1935. Between 1962 and 1968, illegal Soviet whaling killed 529 right whales in the Bering Sea and Gulf of Alaska as well as 132 right whales in the Sea Okhotsk.

The North Pacific Right Whale (E. japonica) is a very big, robust whale — like most of the other baleen whales are. The species looks a great deal like the other species of right whales — the North Atlantic right whale (E. glacialis), and the southern right whale (E. australis) — but apparently tends to be a bit larger. The species are quite distinct genetically though. As with the other baleen whales species, the females tend to be a bit larger than the males.

They can grow to be over 60 feet in length, and to weight over 110,000–180,000 lbs. The largest recorded individual measured 65 feet in length.

North Pacific Right Whales feed mostly on small copepods, in particular on the species Calanus marshallae. They feed in the same way that other right whales do — by skimming water continuously while swimming. As you can imagine, it takes an mm credible number of copepods to meet the energy needs of the North Pacific Right Whale. As a result, the species needs to find large concentrations of them (greater than 3,000 per cubic meter) in order to remain in good health.

As far as historical population numbers and the effects of industrial whaling go, here’s a good overview:

One can consider 1835 as a good year to use as a baseline for the historic population. In Japanese shore-based net whaling, right whales were considered to be the primal target, and the industries were devastating to the stocks as catch quantities had been reduced dramatically in relatively short periods, and the effect of the industries were more notable on the whale populations than the later American whaling, resulting not only in financial solvencies of many industrial groups but also in disputes between feudal domains in western Japan that required the shogunate itself to settle. Among this, it has been revealed that Japanese people have been trying to shift responsibility of whale declines to the later American whalers by creating a tragic story of the “semi-nagare”, to control public opinions since at the end of the Edo period.

In the single decade of 1840–49, between 21,000–30,000 right whales may have been killed in the North Pacific, Sea of Okhotsk and Bering Sea. This suggests that right whales may have been as abundant as the gray whale in the North Pacific.

Owing to the fact that the population was greatly diminished by the time the scientific community developed an interest in the animals, the behavior of the species is something of an unknown in many ways.

Based on limited observations in the 19th century, it was noted that the more extensive whaling was conducted, the more aggressive and harder to approach the whales became. These traits correspond with many recent observations in which whales seemed to be very sensitive to vessels, and swam away while staying submerged for far longer than normal, presumably in order to avoid being followed.

North Pacific Right Whales like many/most other Eubalaena species is known to interact extensively with other whale species.

Several observations of North Pacific Right Whales interacting with groups or solitary Humpback Whales have been recorded in both Eastern and Western North Pacific. A record of a pair of Gray Whales showing signs of aggression towards a Right Whale and chasing it, off the coast of California was made in 1998. And an observation of a sub-adult Right Whale swimming in a group of critically endangered Western Gray Whales and demonstrating social behaviors was made off of Sakhalin’s northeast coast in 2012.

Growing levels of noise-pollution in the oceans (shipping, drilling, etc) are though to be a growing issue for the species, as is the case with many other whale species — owing to their highly sensitive and developed hearing systems.

While the general theory is that North Pacific Right Whales generally live to be 80-100 years old, the fact that they are relatively closely related to bowhead whales raises some questions — as there is strong evidence that bowhead whales can live to be more than 200 years old (and perhaps considerably longer than that).

Here’s a somewhat humourous anecdote on that count:

In May 2007, a 15 m (49 ft) specimen caught off the Alaskan coast was discovered with the head of an explosive harpoon embedded deep under its neck blubber. The 3.5-inch (89 mm) arrow-shaped projectile was manufactured in New Bedford, Massachusetts, a major whaling center, around 1890, suggesting the animal may have survived a similar hunt more than a century ago.

Hmm…

Mountain Gorilla

The Mountain Gorilla (Gorilla beringei beringei) is one of the 2 remaining subspecies of the eastern gorilla, and one of the most endangered species of primate in the world. The subspecies currently exists as only 2 small populations — one in the Virunga volcanic mountains of Central Africa; and one in Uganda’s Bwindi Impenetrable National Park.

Altogether these populations only total about 880 individuals (as of November 2012).

The subspecies is, true to its name, well adapted to living in the relatively cold mountain regions of central Africa — possessing particularly thick, long fur. Male Mountain Gorillas typically grow to reach heights of around 5’6-5’9, and weights of 430-490 lbs. Females are typically notably smaller. Despite the norms, particularly large individuals can be as tall as 6’4, and as heavy as ~600 lbs.

The high-altitude forests where these gorillas live (7,200–14,100 feet up) are generally quite cloudy and misty. Depending on the time of year, the subspecies is somewhat nomadic — family bands will often travel to different areas at different times of the year, to feed on whatever food is particularly desirous at that time of year.

Mountain gorillas are herbivores — the vast majority of their diets come from the leaves, shoots and stems (85.8%) of over 142 different plant species. These are supplemented “by bark (6.9%), roots (3.3%), flowers (2.3%), and fruit (1.7%), as well as small invertebrates. (0.1%).”

Mountain gorillas are very social, as most primates are — and they spend much of their time in “relatively stable, cohesive groups held together by long-term bonds between adult males and females. Relationships among females are relatively weak. These groups are nonterritorial; the silverback generally defends his group rather than his territory. In the Virunga mountain gorillas, the average length of tenure for a dominant silverback is 4.7 years.”

The subspecies is threatened mostly as a result of deforestation; bushmeat hunting (both intentional trophy hunting for heads, hands, and feet, etc, but also accidental deaths via snare traps); the illegal wildlife trade (mothers are killed so that the infants can be sold to zoos, as pets, etc); and habitat loss.

On the subject of the illegal wildlife trade, here’s a good summary:

The abduction of infants generally involves the loss of at least one adult, as members of a group will fight to the death to protect their young. The Virunga gorillas are particularly susceptible to animal trafficking for the illegal pet trade. With young gorillas worth from $1000 to $5000 on the black market, poachers seeking infant and juvenile specimens will kill and wound other members of the group in the process. Those of the group that survive often disband. One well documented case was that known as the ‘Taiping 4’. In this situation, a Malaysian Zoo received four wild-born infant gorillas from Nigeria at a cost of US$1.6 million using falsified export documents.

And on the subject of deforestation and habitat loss, and loss of genetic diversity:

The forests where mountain gorillas live are surrounded by rapidly increasing human settlement. Through shifting (slash-and-burn) agriculture, pastoral expansion and logging, villages in forest zones cause fragmentation and degradation of habitat. The late 1960s saw the Virunga Conservation Area (VCA) of Rwanda’s national park reduced by more than half of its original size to support the cultivation of Pyrethrum. This led to a massive reduction in mountain gorilla population numbers by the mid-1970s. The resulting deforestation confines the gorillas to isolated deserts. Some groups may raid crops for food, creating further animosity and retaliation. The impact of habitat loss extends beyond the reduction of suitable living space for gorillas. As gorilla groups are increasingly geographically isolated from one another due to human settlements, the genetic diversity of each group is reduced. Some signs of inbreeding are already appearing in younger gorillas, including webbed hands and feet.

With the pressures of expanding human settlements/populations, deforestation, the illegal pet trade, and geopolitical instability in the region, looking unlikely to change anytime soon the future existence of the Mountain Gorillas is very questionable.

Philippine Eagle

The Philippine eagle (Pithecophaga jefferyi) is an eagle of Accipitridae family, and is endemic to the forests of the Philippines. The species is occasionally referred to as the “monkey-eating eagle”.

The species generally grows to sizes of ~3-3.5 feet in length (wingspan of ~6-7.5 feet), and 10-18 lbs in weight. It’s considered to be the longest eagle species still in the world — it’s more lightly built than the harpy eagle or the Steller’s sea eagle though. It’s actually the second-later gets eagle known for the fossil record as well — the only eagle known to have been longer was the truly gigantic Haast’s Eagle that lived in New Zealand until colonization by modern humans relatively recently.

It’s one of the rarest birds in the world currently, with no more than 500 individuals thought to live in the wild (and perhaps as few as 150). The species has seen its numbers plummet in recent decades — largest as a result of widespread deforestation and habitat loss. It’s currently illegal in the Philippines to kill a Philippine eagle — and is punishable by 12 years in jail and/or large fines.

While the species will indeed hunt monkeys as it’s common name implies, it possesses a varied diet — regularly taking large snakes, colugos, civets, monitor lizards, and other large birds, as prey.

Based on genetic evidence, the species closest relatives are the snake eagles (Circaetinae).

The species is known to communicate using loud, high-pitched whistles ending with inflections in pitch.

Each breeding pair requires a large home range to successfully raise a chick, thus the species is extremely vulnerable to deforestation. Earlier, the territory has been estimated at about 100 km2 (39 sq mi), but a study on Mindanao Island found the nearest distance between breeding pairs to be about 13 km (8.1 mi) on average, resulting in a circular plot of 133 km2 (51 sq mi).

Despite its size, the Philippine Eagle is actually very agile and fast — rivalling smaller hawk species in these qualities.

Juveniles in play behavior have been observed gripping knotholes in trees with their talons and, using their tails and wings for balance, inserting their heads into tree cavities. Additionally, they have been known to attack inanimate objects for practice, as well as attempt to hang upside down to work on their balance. As the parents are not nearby when this occurs, they apparently do not play a role in teaching the juvenile to hunt.

In the wild the species is thought to typically live to be 30-60 years old if food availability is good.

Eagle pairs sometimes hunt troops of monkey cooperatively, with one bird perching nearby to distract the primates, allowing the other to swoop in from behind, hopefully unnoticed, for the kill. Since the native macaque is often around the same size as the eagle itself, at approximately 9 kg (20 lb) in adult males, it is a potentially hazardous prey, and eagles have been reported to suffer broken leg due from a fall after struggling and fell along with a large male monkey.

Like most other species of eagles, the Philippine eagle is monogamous. After the pair-bond forms the two eagles remains together for the rest of their lives. If/when one of the pair dies, the still living one will generally look for a new partner.

The beginning of courtship is signaled by nest-building, and the eagle remaining near its nest. Aerial displays also play a major role in the courtship. These displays include paired soaring over a nesting territory, the male chasing the female in a diagonal dive, and mutual talon presentation, where the male presents his talons to the female’s back and she flips over in midair to present her own talons. Advertisement displays coupled with loud calling have also been reported. The willingness of an eagle to breed is displayed by the eagle bringing nesting materials to the bird’s nest. Copulation follows and occurs repeatedly both on the nest and on nearby perches. The earliest courtship has been reported in July.

The greatest threat to the continued survival of the species is deforestation and the accompanying loss of habitat. The remaining old-growth forests of the Philippines are currently being lost at a rapid rate — as much of the remaining forests are actually now owned by logging companies. Other threats include: growing mining operations, growing use of agricultural pesticides (which causes reproductive problems in the species), and the illegal wildlife trade/poaching.

Image Credits: Public Domain; Screen Capture