Mesopredator Release Hypothesis

Luckily, humans have put in efforts to understand and sometimes reverse the damage done. Wilcove describes ecosystem restoration, where usually humans put concentrated effort into recreating original habitats to restore indigenous populations. This is, unless “a very different assemblage of species has taken hold of the land and cannot be dislodged,” also known as a new “steady state” (Wilcove, 2000, p. 12). Wilcove himself joined the effort by studying the impacts humans have caused on woodland critters. He surveyed an area in Maryland to detect predators by setting cardboard coated in masonry powder to record footprints. He concluded that there were “six predators: opossum, raccoon, striped skunk, dog, cat, and blue jay. All are animals that benefit mightily from their association with people”(Wilcove, 2000, p. 42). He also mentions how extensive data can only be collected when looking at the observations of many people over the generations. He talks about “generational blindness,” which means how observers of a current generation cannot make conclusions on populations without the help of data collected from the past (Wilcove, 2000, p. 13).

Thought to have been first introduced into the wild via pet owners (Dorcas & Wilson, 20011) have caused significant declines in mammal populations. An observational study conducted by Dorcas et al (2012), found a 90% reduction in encounter rates of a number of species including racoon, opossums, bob cats and white tailed deer over the period 2003-2011 in which Burmese python populations have increased. The introduction of the Burmese python has also caused a significant decline in bird species. A study conducted by Dove et al (2011) found remains of 25 different species of birds in the digestive tracts of 85 Burmese pythons collected from 2003-2008, 4 of which are of special concern in Florida and 1 the ‘Wood Stork’ is listed as endangered. Preying on native wildlife and competing with native predators has impacted the food web and trophic level dynamics of the ecological

of the food chain. This would cause their numbers to rise, which would lead to irreparable damage to the ever-fragile ecosystem.

Conservationists have been particularly interested in the restoration of carnivore populations because they have a big impact on the rest of that ecosystem. One example of how carnivore population can cause issues is the decrease of the wolf population in Yellowstone Park. They killed the wolf population thinking it would help, but little did they know they were actually destroying the rest of the ecosystem. Certain ecosystem are like a car; if you remove one piece, then the entire car won’t function correctly. A decrease in carnivore populations means an increase in herbivore populations and then those organisms will use up all the possible resources in that area. That can cause many problems. It shows that the carnivores keep everything together

The scale and pace of change is dramatic; for example, the extinction of species is occurring at around 100-fold pre-human rates4. The population sizes of vertebrate species have, on average, declined by half over the last 45 years5. More than 2.3 million km2 of primary forest has been felled since 20006. About

“Restoring an ecologically complete ecosystem in Yellowstone requires the return of willows--and with them, beavers. There's a clear threshold for ecosystem recovery. Willow stands must be more than 6 feet tall, the scientists found. That height is important, says Marshall. Then willows are beyond the reach of browsing elk, and can serve as seed sources for new young willows. Once willows have returned, beavers will gnaw down a certain number of them to build dams. The dams will further slow stream flow, allowing yet more willows to grow. The results offer new insights on the role of wolf-driven trophic cascades in the Yellowstone ecosystem, says Hobbs. Trophic cascades like that in Yellowstone occur when predators--or the lack thereof--in an ecosystem change the abundance or alter traits of their prey, in turn affecting the next lower trophic level.” ("National Science Foundation", 2013)

Say a frog eats a caterpillar, then a snake eats the frog, then finally a owl eats the snake. This is just a simple food chain but something called biodiversity, which means that’s there is a variety of things a that one animal can eat. An owl cant only eat a snake it could eat the frog or something smaller like a worm. This keeps form one species dying out completely, which would cause multiple species to die out. When someone releases a pet into the wild they are causing a disturbance into the wild habitat. When a python is released into a place full of crocodiles these two will start competing for food which would cause all of the lower species to start lowing in numbers faster until they become extinct which would then make the snakes and the crocodile die off too. If this keeps on happening the eventually every animal would die off!

Herbivores make up the second trophic level. Predators that eat herbivores comprise the third trophic level; if larger predators are present they are then represent a higher trophic level. Organisms that feed at several trophic levels are classified at the highest of trophic levels at which they feed. Decomposers breakdown wastes and dead organisms and return nutrients back to the soil. (Future Direction International,

-Reintroduction of a top predator lowered the number of over grazing herbivores, leaving a more stable amount of food for many species of herbivores.

In this article, authors William Ripple and Robert Beschta focus on the issue of predation and the way it affects biodiversity and otherwise alters ecosystems. While many other studies have stressed the lethal effects of predation by carnivores, the authors of this study have chosen to focus on how nonlethal outcomes of predation affect the structure and function of ecosystems. The authors give two main objectives to their study: first to provide a short synthesis of the potential ecosystem responses to predation risk in a three-level trophic cascade involving large carnivores, hoofed animals, and vegetation; and secondly to present research that centers on wolves, elk, and woody browse species in the northern area of Yellowstone National

Predators and prey are organisms that interrelate, and they can influence on another’s success in reproduction. Predators are organisms that consume other organisms-their prey. These two organisms evolve together. They live in an environment where they must develop certain adaptations to survive. When an adaptation is developed, it gives an organism certain physical characteristics that create an advantage for survival and can come to dominate in a population. An adaptation aids survival by either decreasing a prey's chance of being eaten, or by increasing a predator's chance of obtaining food to survive and reproduce. Predators must fight for food. They face density-independent

Sea otters (Enhydra lutris) are marine mammals capable of spending their entire lives in water. Being carnivorous in nature, they feed on sea urchins, crabs, fishes, mussels and clams. They are referred to as keystone species due to their profound impact on marine ecology. The interaction between sea otters, sea urchins and kelp forests has been studied as a model of the impact of predator-prey interaction on community ecology. Sea otters are keystone predators, whose presence has a far-reaching influence on the marine food web by affecting the population of sea urchins in particular, and kelp forests & other marine organisms in general. There has been a steep decline in sea otter populations due to water pollution and exploitation for

The exact scenario changes in each example, but the central idea remains that through a chain of interactions, a non-abundant species has an outsized impact on ecosystem functions.

According to Van Driesche, nonnative species are more likely to establish if they invade habitats with lowered biotic resistance, encounter prey with poorly developed mechanisms of self-defense, or invade habitats unaccompanied by their specialized natural enemies or when their invasion is facilitated by earlier invaders (2000).  Damage to these communities, then, can be seen both in cumulative effects and in a cycle of self-reinforcement.  Although pristine environments are still at risk from invasion, this positive feedback loop makes habitats already with a disturbance by exotics even more vulnerable to other invasions.

Since the beginning of life itself, some species have lived and prospered while other species have gone extinct never to be seen again by mankind. Because of this, some would claim that extinction is natural and not significantly problematic to the world that we live in. Others, however, understand that due to climate change, habitat loss, and poaching, more and more species are becoming endangered which leads to a chain reaction that can be devastating to ecosystems. Species such as the Chinook salmon, gorillas, tropical sharks, and polar bears are all directly affected by climate change, species such as northern spotted owls, Sumatran tigers, and lemurs are greatly harmed due to habitat loss, and species such as the sea turtle, Javan rhinoceros, African elephant, and the Red-Fronted Macaw are all affected by poaching driving them all closer and closer to becoming extinct.