We thought interesting to share this video recorded by Damjan Juznic:
Monitoring of Scavenger Activity in Slovenia
Carnivores and Scavengers are not well accepted in rural comunities although they play an important role in the ecosystem and their presence benefits humans through ecosystem services. This video shows the variety of animals that can feed on carrion. Enjoy it and share!
For more than 100 years, the US government has conducted lethal control of native wildlife, to benefit livestock producers and to enhance game populations, especially in the western states. Since 2000, Wildlife Services (WS), an agency of the US Department of Agriculture, has killed 2 million native mammals, predominantly 20 species of carnivores, beavers, and several species of ground-dwelling squirrels, but also many nontarget species. Many are important species in their native ecosystems (e.g., ecosystem engineers such as prairie dogs and beavers, and apex predators such as gray wolves). Reducing their populations, locally or globally, risks cascading negative consequences including impoverishment of biodiversity, loss of resilience to biotic invasions, destabilization of populations at lower trophic levels, and loss of many ecosystem services that benefit human society directly and indirectly.
The rapid loss of top predators such as dingoes, leopards and lions is causing an environmental threat comparable to climate change, an international group of scientists has warned.
A study by researchers from Australia, the US and Europe found that removing large carnivores, which has happened worldwide in the past 200 years, causes a raft of harmful reactions to cascade through food chains and landscapes.
Small animals are picked off by feral pests, land is denuded of vegetation as herbivore numbers increase and streams and rivers are even diverted as a result of this loss of carnivores, the ecologists found.
“There is now a substantial body of research demonstrating that, alongside climate change, eliminating large carnivores is one of the most significant anthropogenic impacts on nature,” the study states.
The research looked at the ecological impact of the world’s 31 largest mammalian carnivores, with the largest body of information gathered on seven key species – the dingo, grey wolf, lion, leopard, sea otter, lynx and puma.
In Australia the downfall of the dingo, which has been largely pushed out of the country’s eastern and southern states, has had a number of detrimental effects. Dingoes have been culled to prevent them preying on sheep, while inter-breeding with dogs has also had an impact.
Dr Mike Letnic, the report’s co-author and research fellow at the University of NSW, told Guardian Australia that his studies either side of the vast dingo-proof fence showed the consequences of their absence.
“We found there were more small native animals such as poteroos and bilbies where the dingoes were,” he said. “That’s because they [dingoes] suppress foxes, which have given small mammals a really hard time since they were introduced.
“Dingoes also kill kangaroos, so losing them means more kangaroos. That means areas are overgrazed, nutrients are lost from the soil and you risk desertification of areas. More dingoes aren’t ideal for kangaroos, but they are a net benefit to the ecosystem.”
This increase in kangaroo numbers in parts of Australia has had other unintended consequences, with the marsupials targeted by farmers for competing with livestock for prime grazing land. Letnic said they may even be to blame for outbreaks of Ross River fever.
Further afield, researchers found that the reintroduction of wolves to Yellowstone national park in the US caused a reduction in deer numbers, in turn benefiting the park’s trees and plants.
The spread of Lyme disease in the US was partially attributed to booming deer numbers, which host the ticks that carry the disease, while an increase in the number of herbivores grazing is thought to change the flow of local rivers, making them straighter and threatening creatures that dwell in slow-moving waters. Loss of vegetation also removes key carbon storage from the environment.
Letnic said: “A good example is in west Africa, where people removed lions and leopards. They then suffered an outbreak of baboons, which give small animals a hard time but also give people a hard time. They raid crops, which mean that kids don’t go to school because they have to guard the crops all day.
“Overall, we’ve got to find better ways to live with carnivores. They aren’t always easy to live with, but they are an important part of the ecosystem.
“In terms of dingoes, we need to find landscapes where they are left alone or actively promoted. In livestock grazing areas we need to work out what impact they are having and work out a system, perhaps with guard dogs, that we can use to avoid killing them off.”
“Consider the subtleness of the sea; how its most dreaded creatures glide under water, unapparent for the most part,” wrote Herman Melville in Moby Dick. Today, we no longer dread whales, but their subtlety remains. “For a long time, whales have been considered too rare to make much of a difference in the oceans,” notes University of Vermont conservation biologist Joe Roman. That was a mistake.
Huge blue whales plunge to 500 feet or deeper and feed on tiny krill. Then they return to the surface—and poop. This ‘whale pump’ provides many nutrients, in the form of feces, to support plankton growth. It’s one of many examples of how whales maintain the health of oceans described in a new scientific paper by the University of Vermont’s Joe Roman and nine other whale biologists from around the globe. Credit: Frontiers in Ecology and the Environment.
In a new paper, Roman and a team of biologists have tallied several decades of research on whales from around the world; it shows that whales, in fact, make a huge difference—they have a powerful and positive influence on the function of oceans, global carbon storage, and the health of commercial fisheries. “The decline in great whale numbers, estimated to be at least 66% and perhaps as high as 90%, has likely altered the structure and function of the oceans,” Roman and his colleagues write in the July 3, 2014, online edition of Frontiers in Ecology and the Environment, ” but recovery is possible and in many cases is already underway.”
“The continued recovery of great whales may help to buffer marine ecosystems from destabilizing stresses,” the team of scientists writes. This recovered role may be especially important as climate change threatens ocean ecosystems with rising temperatures and acidification. “As long-lived species, they enhance the predictability and stability of marine ecosystems,” Roman said.
Baleen and sperm whales, known collectively as the “great whales,” include the largest animals to have ever lived on Earth. With huge metabolic demands—and large populations before humans started hunting them—great whales are the ocean’s ecosystem engineers: they eat many fish and invertebrates, are themselves prey to other predators like killer whales, and distribute nutrients through the water. Even their carcasses, dropping to the seafloor, provide habitat for many species that only exist on these “whale falls.” Commercial whaling dramatically reduced the biomass and abundance of great whales.
“As humpbacks, gray whales, sperm whales and other cetaceans recover from centuries of overhunting, we are beginning to see that they also play an important role in the ocean,” Roman said. “Among their many ecological roles, whales recycle nutrients and enhance primary productivity in areas where they feed.” They do this by feeding at depth and releasing fecal plumes near the surface—which supports plankton growth—a remarkable process described as a “whale pump.” Whales also move nutrients thousands of miles from productive feeding areas at high latitudes to calving areas at lower latitudes.
Sometimes, commercial fishermen have seen whales as competition. But this new paper summarizes a strong body of evidence that indicates the opposite can be true: whale recovery “could lead to higher rates of productivity in locations where whales aggregate to feed and give birth,” supporting more robust fisheries.
As whales recover, there may be increased whale predation on aquaculture stocks and increased competition—real or perceived—with some commercial fisheries. But the new paper notes ” a recent investigation of four coastal ecosystems has demonstrated the potential for large increases in whale abundance without major changes to existing food-web structures or substantial impacts on fishery production.”
In death, whale carcasses store a remarkable amount of carbon in the deep sea and provide habitat and food for an amazing assortment of creatures that only live on these carcasses. “Dozens, possibly hundreds, of species depend on these whale falls in the deep sea,” Roman notes.
“Our models show that the earliest human-caused extinctions in the sea may have been whale fall invertebrates, species that evolved and adapted to whale falls,” Roman said, “These species would have disappeared before we had a chance to discover them.”
Until recently, ocean scientists have lacked the ability to study and observe directly the functional roles of whales in marine ecosystems. Now with radio tagging and other technologies they can better understand these roles. “The focus of much marine ecological research has been on smaller organisms, such as algae and planktonic animals. These small organisms are essential to life in the sea, but they are not the whole story,” Roman said.
New observations of whales will provide a more accurate understanding of historical population dynamics and “are likely to provide evidence of undervalued whale ecosystem services,” note the ten scientists who co-authored this new paper, “this area of research will improve estimates of the benefits—some of which, no doubt, remain to be discovered—of an ocean repopulated by the great whales.”
The Gardeners of the Forest: Ian Redmond at TEDx Southampton University
Drawing on four decades of research with gorillas, starting as an assisstant to Dian Fossey, Ian Redmond OBE passionately argues why we must protect these and other species such as elephants because of their important impacts on ecosystem processes that we, even in the industrialised countries of the north, depend on.
Mark D. Bertness, an ecologist at Brown University, began studying the salt marshes of New England in 1981. Twenty-six years later, in 2007, he started to watch them die. In one marsh after another, lush stretches of cordgrass disappeared, replaced by bare ground. The die-offs were wiping out salt marshes in just a few years.
“It’s unbelievable how quickly it’s moved in,” Dr. Bertness said.
Scientists have been witnessing a similar transformation in a number of plant species along coastlines in the United States and in other countries. And in many cases, it’s been hard to pinpoint the cause of the die-off, with fungal outbreaks, pollution, choking sediments stirred up by boats, and rising sea levels proposed as killers.
There is much at stake in the hunt for the culprit, because salt marshes are hugely important. They shield coasts from flooding, pull pollutants from water and are nurseries for many fish species.
In the journal Ecology Letters, Dr. Bertness and his colleagues have nowpublished an experiment that may help solve the mystery. The evidence, they say, points to recreational fishing and crabbing. A fisherman idly dangling a line off a dock may not appear to be an agent of ecological collapse. But fishing removes the top predators from salt marshes, and the effects may be devastating.
Once New England salt marshes started dying off, Dr. Bertness and his colleagues embarked on a broad survey. Quickly they noticed a difference between healthy marshes and sick ones. The dying marshes tended to be near docks, marinas or buoys where boats could anchor, or where there were other signs of fishing.
“It wasn’t a brilliant thing we thought of sitting around the lab,” Dr. Bertness said. “By the time we got to 10 marshes, we realized there was this huge disparity.”
Dr. Bertness and his colleagues wondered how fishing and crabbing were affecting the food webs of the salt marshes. If people pull out striped bass and blue crabs and other predators from a salt marsh, the animals’ prey species — including those that feed on plants, like marsh crabs — are left to thrive. A growing population of marsh crabs might wipe out the cordgrass in a marsh. Without the roots of the cordgrass to anchor the soil, the marsh would erode, making it harder for new plants to grow.
To test this idea, Dr. Bertness and his colleagues surveyed salt marshes in Narragansett Bay in Rhode Island, comparing marshes that were healthy with ones that were almost entirely dead. The scientists found that in dying marshes, the plants had more signs of being fed on by crabs. And when they looked for other proposed causes of marsh die-off, such as pollution, they didn’t find a correlation. They published their results in March in the journal PLOS One.
Next, the scientists took a step beyond simply observing the die-offs: They tried to cause them. If the predator hypothesis was right, then creating a predator-free salt marsh habitat should lead to the disappearance of cordgrass.
In May 2013, the scientists installed cages in a healthy salt marsh on Cape Cod. Each cage was three feet on a side, with mesh walls and an open bottom. Marsh crabs could feed on the cordgrass inside the cages by burrowing up through the mud, and the wire mesh walls protected them from predators like fish and blue crabs.
The experiment quickly yielded results. In a matter of weeks, the cages were crowded with marsh crabs, and much of the cordgrass inside the cages was dying off. “We were planning on it being a two- or three-year experiment,” Dr. Bertness said. “But by the beginning of July, I thought, ‘My God, this is really going fast.’”
William J. Ripple, an ecologist at Oregon State University who was not involved in the research, said, “This is an important new scientific discovery for salt-marsh systems, and more generally for ecology.” Scientists like Dr. Ripple have argued that predators are important to the ecological health of other ecosystems. But it’s been difficult to test the hypothesis directly the way Dr. Bertness has.
Merryl Alber of the University of Georgia agreed that the experiment showed that removing predators could decrease salt marsh grass. But she was reluctant to draw big lessons from the study. “It is still a leap to connect dieback to recreational overfishing,” she said.
Wade Elmer, a plant pathologist at the Connecticut Agricultural Experiment Station in New Haven, thinks that the full story of the salt marshes’ decline is more complex than just fishing. Dr. Elmer has identified a new species of fungus that attacks cordgrass in New England salt marshes. He has suggested that the fungus may weaken the plants in a way that prevents them from making chemical defenses to ward off the marsh crabs.
“I think we all have our pet theories that explain what we see in our backyard,” said Dr. Elmer, “but these theories often fail as soon as we look elsewhere.”
Dr. Bertness doesn’t rule out the possibility that other factors are at play in the die-off of marshes. But he argues that fishing is having an enormous impact.
“The implications of these findings for the conservation of salt marshes are huge,” he said. “We need to maintain healthy predator populations.”
Social species, such as the African wild dog, require strict participation from group members to be successful. This strategy can enhance fitness benefits for the group, but also a higher critical threshold for extinction. Awareness of life history needs to guide management strategy. “Failure to consider the impacts of group dynamics may result in underestimation of critical threshold population sizes or densities required for population persistence,” the researchers write.
Carnivore management is not just a numbers game, Virginia Tech wildlife scientists assert in response to an article in the Jan. 10 issue of the journal Science that urged “minimum population densities be maintained for persistence of large carnivores, biodiversity, and ecosystem structure.”
“This type of approach may fail in social carnivore species,” said Kathleen Alexander, an associate professor of fisheries and wildlife conservation in the College of Natural Resources and Environment. “Predator management is incredibly complex and we need to be extremely cautious in applying blanket approaches which rely on securing some target number or density of individuals in an ecosystem.”
The research-based argument appears in a letter in the March 14 issue of Science and an article abstract in the October 2013 issue of the journal Population Ecology.
“Life history strategy, including number of offspring, lifespan, diet, and behavior that evolves from ecological pressures of the species in question should also guide management approaches,” wrote Alexander and Claire E. Sanderson, a postdoctoral associate in fisheries and wildlife conservation, in the Science letter.
The research published in Population Ecology evaluated 45 solitary and social medium and large carnivore species and their key life history attributes, population trends, and identified the presence of factors that increase the potential for extinction.
Disturbingly, 73 percent of carnivore species — both social and solitary — were declining, observed Sanderson, Sarah Jobbins, also a postdoctoral associate, and Alexander.
“Social carnivores appeared to be particularly vulnerable with 45 percent threatened by infectious disease but only 3 percent of solitary carnivores similarly impacted,” they report. “In this, increased contact between individuals, disease-related mortality, and loss of individuals below some critical threshold seems to be the issue, pushing social carnivores closer to the brink of extinction.”
Reporting on their research on social carnivores, Sanderson, Jobbins, and Alexander said in the article, “Highly cohesive social species, like African wild dog, require strict participation from all group members … in all areas of life, including predator avoidance, reproductive success, hunting, and survivorship. This life-history strategy can result in enhanced fitness benefits for the group, but also a higher critical threshold for extinction.”
“The number of individuals in the group then becomes the critical factor influencing population persistence,” said Sanderson.
For example, rabies and distemper have caused local extinction of African wild dog in regions of Africa. Even in a large population, transmission of an infectious disease from only a few infected individuals can result in sufficient mortality to push groups below a critical threshold, ultimately threatening population persistence, the researchers report.
It has been found in certain ecosystems that when wild dog packs are reduced to less than four individuals, they may be unable to rear pups because of trade-offs between specialized roles, such as pup guarding and hunting.
“While aggregation of conspecifics may be beneficial for reproduction, hunting, and vigilance, social living is a disadvantage when it comes to transmission of disease,” according to Alexander’s research.
Also a wildlife veterinarian, she cofounded the Centre for Conservation of African Resources: Animals, Communities and Land Use, in Kasane, Botswana and has been conducting research in Africa since the late 1980s.
“Failure to consider the impacts of group dynamics may result in underestimation of critical threshold population sizes or densities required for population persistence,” Sanderson, Jobbins, and Alexander write.
Alexander and Sanderson conclude in their letter in Science, “We urge consideration of life-history strategy and social behavior in the development of carnivore management strategy.”
W. J. Ripple, J. A. Estes, R. L. Beschta, C. C. Wilmers, E. G. Ritchie, M. Hebblewhite, J. Berger, B. Elmhagen, M. Letnic, M. P. Nelson, O. J. Schmitz, D. W. Smith, A. D. Wallach, A. J. Wirsing. Status and Ecological Effects of the World’s Largest Carnivores. Science, 2014; 343 (6167): 1241484 DOI:10.1126/science.1241484
Claire Elizabeth Sanderson, Sarah Elizabeth Jobbins, Kathleen Ann Alexander.With Allee effects, life for the social carnivore is complicated. Population Ecology, 2013; DOI: 10.1007/s10144-013-0410-5
Virginia Tech (Virginia Polytechnic Institute and State University). “Preserving large carnivores in ecosystem requires multifaceted approach.” ScienceDaily. ScienceDaily, 13 March 2014. <www.sciencedaily.com/releases/2014/03/140313142447.htm>.