Examine why some species are vulnerable to extinction than others
Name
PSYC 6552 - Psychology of Motivation at Work
Walden University
2022
Introduction
Extinction
Extinction is the wiping out of a species from the face of the earth forever or simply seizing to
exist due to some unfavorable conditions. Every organism has its place where conditions are
right for its survival. This is the organism's habitat. When the habitat is wiped out, the organism
won't have any place to live. The last two centuries witnessed accelerated rates of animal
extinction and endangerment which took place alongside industrial progress and rapid growth in
human populations. For example, when the forests in Mau were cut down for human settlement
and cultivation, the Colobus monkey, became a threatened species. According to Richard P
(2001) humans have shown an incredible ability to invade, change, and inhabit every habitat type
on the planet. The main fundamental cause of animal extinction in most recent times has been,
without any reasonable doubt, human demand, either for animal resources directly, or for the
natural resources constituting the animals’ habitats. He further agued that, roughly, when 90% of
the habitat is eliminated, 50% of the species will be lost. When natural habitat of animals is
deprived, most of animals die because it’s difficult for them to adapt to new environments.
Selection of the lost species, however, is not random. The larger, wide-ranging species, such as
large carnivores, suffer first. Because those groups often contribute to healthy ecosystem
processes, a wave of secondary losses may follow their decline. Some species are more
vulnerable than others due to several reasons.
Human wildlife conflicts. Animals that conflict with humans are also the victims of concerted
eradication efforts. This is because when animals destroy crops planted by human beings, they
strive to eradicate them to minimize losses this might lead to their eradication. A good example
is that when elephants and hippos invade human crop plantations, they are killed hence reducing
their number.
Species with a narrow geographic range. Animals and plants that are restricted to a relatively
small area, such as an island, are inherently vulnerable to extinction. They have incurred the
greatest number of extinctions in the past 400 years. Changes in their habitat or losses to their
populations can eliminate them. Many of these species were confined to areas that measured
only a few square miles. Mainland species, likewise, can be endemic to small areas. The
Grackle once inhabited a single marsh near Mexico City. The marsh was filled about 1910,
spelling extinction for this bird. Species with a narrow geographic range, or species that were
never common, are vulnerable as well to extinction because may see that niche disappear
quickly. Populations existing in fragments become susceptible to genetic disorders, demographic
problems, environmental variability, and catastrophic events. Species with narrow niche
requirements. And species that live in colonies, or social groups, are often affected when
numbers decline this eventually leads to their extinction. When habitat is destroyed, some
species die as a direct result of lost resources. Species that are not effective dispersers are limited
when their habitat is disrupted. Other species survive in reduced numbers in the habitat
fragments, but their vulnerability to extinction increases.
Poaching and hunting for food. Poaching and (legal and illegal) wildlife trade is another
common threat to animals. But the introduction of ban and or restrictions on international trade
in many endangered species (CITES) several decades ago became an effective measure in
halting this problem. Large animals are often keystone species at the top of their food chains or
play important roles in ecosystems. Their absence is indicative of damaged or incomplete
ecosystems. Elephants are important in spreading seeds of many plants through their dung, and
large predators play a major role in the health and physical characteristics of their prey. The
African savannahs without Lions, Leopards and Cheetahs would soon be overpopulated and
overgrazed by their numerous prey species. The largest lemur and bird species of Madagascar
were killed off by the Malagasy immigrants thousands of years ago, as were many large
flightless birds by the Maori when they first arrived in New Zealand. Large animals are often
killed merely because they make large targets or for trophies for those who enjoy slaughtering
animals. Animals of large size require considerable amounts of habitat and are, therefore,
naturally rarer than species with smaller habitat requirements. When human populations rise and
wilderness is replaced with towns and industry, large animals are the first to disappear, due either
to loss of habitat and prey or because they are killed as potential threats. Most of the largest
mammals on Earth are now on the endangered list Wild animals and plants which have a value
as food, pets, ceremonial objects or marketable products to humans are prime candidates for
extinction. The list of animals that have been hunted to extinction for food is long. Within the
past 400 years, many large land tortoises, the Great Elephant Bird, moas, Steller's Sea Cow,
Auroch and Quagga were all extinguished by hunting for food. The unique Huia bird of New
Zealand had plumes that were sold for large sums, helping to drive its limited population to
extinction. Hawaiian songbirds were hunted to extinction for their colorful feathers, which were
used in ceremonial headdresses and capes. Within the past decade, trade has increased as a
threat to wildlife with the rise in Asian economies. This has fueled the Traditional Medicine
markets, which consume vast numbers of animals, threatening many of them. The vacuuming of
the seas by commercial fisheries has resulted in depletions and endangerments. The once
abundant sturgeon of the Caspian Sea, for example, sources of Beluga and other expensive
caviar, are now critically endangered as a result of unrestricted fishing and poaching for the
luxury gourmet market. The bush meat markets of West and Central Africa sell tons of
slaughtered monkeys, forest antelope, Chimpanzees, Gorillas and other wildlife, devastating
species whose tropical forest habitats are being logged. Hunting for food is also a major threat as
firearms become available to native peoples who once used primitive weapons. Southeast Asian
wildlife is under siege by people who once hunted only for their own purposes but now find that
a wide range of wildlife can be sold in local meat markets or for Traditional Medicine. They set
nooses and traps, killing rare monkeys and antelope, birds, snakes, turtles and tortoises,
pangolins and lorises, clearing out the forests of wildlife. The pet trade is driving many colorful
tropical birds, reptiles and primates to endangered status. Luxury goods, such as high-priced
reptile products, provide an incentive to hunt--legally or illegally--lizards, crocodiles and snakes
for this market, endangering many species. Trophy hunting of endangered species by wealthy
hunters is a major threat to a growing number of animals, especially since the largest specimens
are killed; these are the ones that should be left to breed. The higher the value of the animal or
product, the greater the threat to that species.
High value products e.g. Fur, ivory, skin, medicinal value e.t.c Weidenfeld & Nicolson (2003)
argues that this type of trade was popular as human beings killed animals in Oder to acquire fur
from them.the fur were used for industrial purposes in manufacturing heavy jackets and blankets.
Elephants are at a greater risk of extinction. They carry precious commodities that since early 19
century, they have hunted down for their ivories. In 1987, Kenya witnessed one of the
memorable ivory destruction under the former president Moi. This activity saw many elephant
decrease in number which could otherwise had led to their demise during its peak period.
Climate change. Warmer global temperatures may be affecting animals in different ways.
Global warming leads to desertification in fact, global warming is predicted to put at least 20 to
30 percent of plant and animal species at risk of extinction, and up to 40 to 70 percent in worst
case. Study reveals that global warming depletes the ozone layer which might result to severe
drought and hence leading to animals and plants extinction and demise. This is because animals
depend largely on plants for both food and shelter.
Pollution David (2008) further discuses that Environmental pollution which in many ways
causes global warming is another cause for animal demise. Pollution from industrial wastes,
garbage and poor disposal of domestic wastes emits carbon gas which in turn leads to depletion
of ozone layer hence high chances of desertification which leads to animals and plants demise.
Introduced (Invasive) Species Benton M J (2005) argues that, Invasive species introduced to
biodiversity rich areas damage habitats of native species and destroy their safe existence. A good
example of that is that of the introduction of Nile perch in Lake Victoria which invariably fed on
tilapia leading to its minimization in the lake. Rarity is also another idea of species extinction
when there are very few animals of a species left e.g. Galapagos tortoise. The few animals
available will definitely succumb to death and demise.
Trade for Biomedical Research Weidenfeld & Nicolson (2003) further argues that Almost all
biomedical research is done in industrialized countries which were the main importers of animals
(specifically, primates) for these purposes Until this day, many companies still perform animal
testing for biomedical research purposes including HIV and vaccines if it will persist, It will
some day lead to their decline. . Because of human technology and weaponry, all animals have
become vulnerable. Animals that for thousands of years used natural camouflage, stealth and
intelligence to escape from natural predators, have become easy prey for human hunters and
fishermen. Predators, never in their evolutionary history preyed upon, now find themselves
targeted by hunters, trappers and poisoners. Sonar locates fish schools and whales, and heat
detectors and night-view binoculars observe animals in darkness. Cleverly constructed blinds
hide hunters from view. Animal scents are used to lure wildlife, and hunters imitate animal
sounds or use tape recordings of their calls to lure them to traps or within shooting range. Some
hunters use the signals emitted by radio transmitters placed in wild animal collars by biologists
for tracking, to hone in and pursue them to their deaths. Guns equipped with telescopic sights
can fire at targets mile away, killing animals before they are even aware of the hunter. Other
weapons include sophisticated traps, nets, snares, guns, harpoon guns and high speed vehicles
and boats, with which people can run down, maim and kill even the swiftest and most intelligent
animals. These devices give humans such an advantage that they render the natural protections
animals has evolved over eons completely ineffective. Hunters are able to kill the fittest and
strongest specimens through these means. In the process, we are changing the course of
evolution from survival of the fittest to survival of animals that are tolerated by humans and
those able to persist in an increasingly polluted, damaged and ecologically impoverished natural
environmentThose species whose populations have become greatly reduced are vulnerable to
extinction through genetic impoverishment and inbreeding. Such species usually remain rare or
gradually fade into extinction as fertility declines. The critical low level which results in
extinction is different with each species and cannot be predicted with certainty. Just as the story
of North America's lost species and environments is illustrative of many similar tragedies, the
account below of the civil war in Rwanda and the former Zaire encapsulates the major threats to
wildlife and the environment. It also makes abundantly clear that the survival of humans,
animals and the environment are intrinsically linked. The influences of countries that contribute
foreign aid to poor nations half a world away, and interfere in their politics, are another
important element that can greatly affect the survival of wildlife and the natural world.
Limited dispersal ability. According to Benton (2005) Limited dispersal ability happens when
an animal's habitat is destroyed and it can't adapt to another habitat e.g. the spotted owl in the
Pacific Northwest because of the trees being cut down for logging
Inbreeding. Another cause according to Benton (2005) is Inbreeding. This is when animals mate
too much within their own group the offspring become less able to survive and adapt in a healthy
way e.g. Pandas. This eventually leads to demise of the species since they easily succumb to
diseases. Species breeding in colonies or requiring large numbers of their own kind for
protection, to locate food sources or for other means of survival are vulnerable to extinction. The
Passenger Pigeon was a colonial nesting bird and could only survive among large numbers of its
own species, flocking and seeking food sources over large areas. When flocks were fragmented,
these separated populations declined to critically low levels, even though their total numbers may
have been in the tens of thousands. The Passenger Pigeon may have become critically
endangered as soon as its migrations, feeding and nesting behavior were interrupted, even though
it appeared to observers at the time to be plentiful. These pigeons had longevity of several
decades, and failure to reproduce would take some time to be noticed in the overall population.
But when there is little or no introduction of young into a population over a period, it can
suddenly crash with little warning, as the Passenger Pigeons did. Wild parrots tend to feed, roost
and spend their time preening and in courtship as a flock. For some species, these flocks number
in the thousands of birds. When netted or caught by various means for the pet trade, which
threatens a large number of species, their flocks are broken up and they are no longer able to
function as a group. Their breeding is curtailed or stopped altogether, and they may no longer
fly in groups seeking fruiting trees or mineral licks when they fear being captured. Flamingos
require large numbers of their own kind for feeding, flocking, migrations and breeding, and their
population’s crash if any of their survival requirements are not met. Mammals, reptiles and
amphibians also have male contests of strength, agility or other mark of superiority of species.
Wild sheep and deer vie for females by head butting and challenging one another. Many types of
tropical frogs emerge during the breeding season to form groups that display to one another for
the benefit of females. Male Plowshare Tortoises joust with one another in attempts to upend the
rival and will not breed if only a single male and a female are placed together. Without rivals for
competitions, male breeding behavior may not be triggered, preventing reproduction. Many
species of birds have breeding strategies in which male birds will not breed unless they are able
to display courtship behavior in the company of other males, vying for the approval of females.
Birds of paradise, cocks-of-the-rock in South America, prairie chickens and grouse of North
America are among birds that display for the benefit of females, who choose among them. Such
birds require specific conditions to breed, and habitat alterations, reductions in their populations
or hunting pressure that keeps them from exposing themselves in the open can prevent their
breeding. Zoos and zoologists are only beginning to understand some of the instinctive responses
necessary for breeding. Our traditional concept that a compatible pair of animals will reproduce
is often incorrect, and populations of animals must not be allowed to be so reduced that their
natural breeding behavior and other survival needs are not met. Thus, while population numbers
can provide important information about the status of a species, without additional information,
such as the traits mentioned above, the data can be extremely misleading and inapplicable. The
number of individuals surviving in a species, when known, must also be placed into a context
greater than their rate of decline and habitat status. Unless the entire breeding biology, behavior
and other aspects of species' survival needs are taken into account, extinction cannot be
predicted, or status properly evaluated.
Some species now extinct suffered from several of the above factors, which hastened their
extinction. The Passenger Pigeon, for example, required enormous amounts of food, mainly
from nut-bearing trees in old-growth forests, and was relatively long lived, killed for food and
commercial sale, and lived colonially. Elephants and manatees are among endangered species
with many vulnerable traits, including large size, altruism, slow-reproduction, low natural
mortality and longevity. They are also slow-moving and valuable in trade and as food sources.
These traits indicate only vulnerability to extinction caused by humans, not species likely to
become extinct through natural selection. Sea turtles, for example, have lived on Earth for more
than 200 million years. By any standard, they are a superbly successful, adaptable species that,
prior to recent exploitation, showed no signs of decline. Their vulnerability lies in their inability
to flee rapidly in the water or while laying eggs onshore when preyed on by humans.
Succession loss of habitat According to Benton (2005) Succession loss of habitat, this when an
animal's habitat is slowly destroyed and they have nowhere to live e.g. the Bali tiger which is
now extinct, was forced to move to the mountains when the forests were cut down.
Natural calamity Extinction of reduction of mutuality population when species are dependent
on each other, when one becomes threatened; it affects the other species e.g. when all snakes are
killed in an ecosystem, hawks will reduce since their major source of food has been deprived.
E.g. the island of Krakatau in Indonesia was destroyed by a volcanic eruption and all life on the
island died hence leading to animals and plants extinction
Predators are carnivores that majorly on other animals for food for example lions depend on
antelopes for food when the population of a species of predator in a habitat suddenly increases,
the population of their prey decreases.
Diet Animals that depend on a certain type of habitat or food source and cannot adjust to
changes, whether natural or human-caused, are extinction-prone. The Ivory billed Woodpecker
requires large expanses of old-growth forests with many dead and dying trees. Habitat or diet
has caused much extinction. The Nigerian honeycreeper is dependent on the mamane tree for
feeding, which has declined as a result of logging and destruction of seedlings by introduced
game species and livestock. Many endangered plants require specific soil type, climate, and
drainage and sunlight exposure. For those species that require unbroken stretches of habitat,
such as old-growth forest, endangerment or extinction can result if the forest is fragmented.
Reproduction and mortality rate.Fast-reproducing species that have many young at frequent
intervals and high natural mortality rates tend to be more resilient to population losses and
recover quickly if their habitat has not been destroyed. Long lived species with low reproductive
rates and low mortality rate are vulnerable to extinction. Not all vertebrates fall easily into these
categories, but many do, and these groupings can be at least one indication that is useful in terms
of predicting which species will become endangered when their populations are reduced. Slow-
reproducing animals decline rapidly from losses in their numbers, and since they often do not
breed until a relatively advanced age and have few young, many decline to extinction. In some
cases, such animals do not recover their former abundance, or recover very slowly. Some of
these animals, including crocodiles, lay many eggs, but a few of the hatchlings survive to
adulthood. The pinipidia for example, was a member of the Order Sirenia and Dugongs. The
surviving species have few natural enemies, do not breed until age 7 to 10 years old, and have
only one young every five years. Hunting caused the extinction of Steller's Sea Cow in the space
of a few years, eliminating the only cold-water member of this family. Hunting threatens
surviving species of this family in many areas. Manatees and Dugongs are very slow-moving,
making them easy targets. The Steller's Sea Cow may have numbered only a few thousand
animals in its limited distribution near islands in the Bering Sea. Even when able to swim away,
they refused to leave their mates, beaching themselves on the shores next to the slain mate. Such
animals can probably not tolerate any hunting. Manatees and Dugongs, likewise, need strict
protection.
Flightless birds and slow moving animals are helpless in the face of hunting pressure and
predation by introduced predators and humans. Unwary animals, such as many island species
that have evolved in the absence of predators fall into this category. Flightless birds, such as the
Great Auk, Great Elephant Bird, Dodo, many Pacific Island rails and tortoises, are among
species that lack defenses or cannot quickly escape predators, human or other. In addition to
being flightless, many extinct birds lacked defensive behavior or the instinct to hide in
underbrush as a result of their having evolved in predator-free environments. Predators
introduced into their habitats, as occurred on many islands, soon eliminated them. Even the thick
shells of tortoises were not effective defenses against predators such as rats, who ate young
tortoises, and humans easily captured these slow-moving animals. Although our attitudes are
more humane toward these vulnerable animals today than hundreds of years ago, tortoises and
sea turtles are still killed for trade or by vandals for sport. Some surviving flightless birds on
islands have official protection and a better future than they had in previous centuries, while
others do not.
Mortality and reproductive rates in birds.Flightless birds and slow moving animals are
helpless in the face of hunting pressure and predation by introduced predators and humans.
Unwary animals, such as many island species that have evolved in the absence of predators fall
into this category. Flightless birds, such as the Great Auk, Great Elephant Bird, Dodo, many
Pacific Island rails and tortoises, are among species that lack defenses or cannot quickly escape
predators, human or other. In addition to being flightless, many extinct birds lacked defensive
behavior or the instinct to hide in underbrush as a result of their having evolved in predator-free
environments. Predators introduced into their habitats, as occurred on many islands, soon
eliminated them. Even the thick shells of tortoises were not effective defenses against predators
such as rats, which ate young tortoises, and humans easily captured these slow-moving animals.
Although our attitudes are more humane toward these vulnerable animals today than hundreds of
years ago, tortoises and sea turtles are still killed for trade or by vandals for sport. Some
surviving flightless birds on islands have official protection and a better future than they had in
previous centuries, while others do not. Many large birds, including, eagles and hawks, have low
reproductive rates. The Cuban Red Macaw became extinct in 1885. If its breeding biology
resembled other large macaws, it was long lived, reaching an age up to 80 years, had only one or
two chicks a year and did not breed every year. Scientists have recently discovered that even in
an immense national park in Peru, wild macaws produce so few young that any losses in their
numbers cause declines in their populations. This helps to explain why so many birds of prey and
parrots are endangered.
References
1) Ulansey, David (2008), "The current mass extinction" repeats this statement with links to
dozens of news reports on the phenomenon. Ebury Press. ISBN 0-09-189780-7.
2) Weidenfeld & Nicolson (2003) ISBN 0-297-60726-X)
3) Benton M J (2005). When Life Nearly Died: The Greatest Mass Extinction of All Time.
Thames & Hudson. ISBN 978-0-500-28573-2.
