Tuesday, April 18, 2017

Only two Isle Royale wolves

According to Rolf Peterson, a research professor at Michigan Tech and co-author of the report, the Isle Royale wolves are no longer serving their ecological function as the island's apex predator--the creature at the top of the food chain. With only two wolves left on the island, the moose population has grown to an estimated 1,600. 
Wolf Genetics
Where have all the island wolves gone? The answer lies in genetics. The population crash on Isle Royale is the result of inbreeding--the remaining wolves are not only father and daughter, they are also half siblings who share the same mother.
The remaining wolves are not expected to successfully reproduce in the future, either. Both animals are approaching old age--the female is seven years old and the male is nine--and no one can predict how much longer either wolf will live. Further complicating matters, the female wolf has been observed aggressively rejecting the male as a mate.
More Moose 
"Everything we're seeing on Isle Royale is consistent with our past understanding of the ecosystem's dynamics," says Vucetich. "We have every reason to expect the moose population will continue to grow and increasingly impact the forest."
Moose aren't the only Isle Royale residents experiencing a population boom with a dwindling number of wolves. The report notes that the number of beaver colonies has increased dramatically over the past six years, from approximately 100 to nearly 300. 

Thursday, April 6, 2017

Wolves often rely on human foods

On landscapes around the world, environmental change is bringing people and large carnivores together--but the union is not without its problems. Human-wildlife conflict is on the rise as development continues unabated and apex predators begin to reoccupy their former ranges. Further complicating matters, many of these species are now reliant on anthropogenic, or human, foods, including livestock, livestock and other ungulate carcasses, and garbage.

Writing in BioScience, Thomas Newsome, of Deakin University and the University of Sydney, and his colleagues use gray wolves and other large predators as case studies to explore the effects of anthropogenic foods. They find numerous instances of species' changing their social structures, movements, and behavior to acquire human-provisioned resources. For instance, in central Iran, gray wolves' diets consist almost entirely of farmed chickens, domestic goats, and trash.

Other instances of these phenomena abound. In a similar case in Australia, dingoes gained access to anthropogenic foods from a waste facility. The result, according to the authors, was "decreased home-range areas and movements, larger group sizes, and altered dietary preferences to the extent that they filled a similar dietary niche to domestic dogs." Moreover, wrote the authors, "the population of subsidized dingoes was a genetically distinct cluster," which may portend future speciation events. Hybridization among similar predator species may also contribute to evolutionary divergence: "Anthropogenic resources in human-modified environments could increase the probability of non-aggressive contact" between species. According to the authors, "If extant wolves continue to increase their reliance on anthropogenic foods, we should expect to observe evidence of dietary niche differentiation and, over time, the development of genetic structure that could signal incipient speciation."

Wolves' use of anthropogenic food could have serious implications for wider conservation efforts, as well. In particular, Newsome and his colleagues raise concerns about whether wolf reintroduction and recolonisation programs will meet ecosystem-restoration goals in human-modified systems. Managers will need to consider "how broadly insights into the role played by wolves gleaned from protected areas such as Yellowstone can be applied in areas that have been greatly modified by humans," say the authors.

Newsome and his colleagues call for further research--in particular, "studies showing the niche characteristics and population structure of wolves in areas where human influence is pervasive and heavy reliance on human foods has been documented." Through such studies, they argue that "we might be able to ask whether heavy reliance of anthropogenic subsidies can act as a driver of evolutionary divergence and, potentially, provide the makings of a new dog."

Thursday, March 23, 2017

Coyotes can't match wolves' hunting prowess

Eastern wolves once roamed forests along the Atlantic coast, preying on moose, white-tailed deer and other hooved mammals collectively known as ungulates. As the wolf population plummeted via the rifle and the trap, however, the eastern coyote inherited the status of apex predator in those habitats.
The eastern wolf weighs between 50 and 65 pounds; the eastern coyote typically hits 40 to 50. Though the extra weight gives eastern wolves a greater chance of killing a moose - or at least surviving the encounter - it also demands the greater caloric intake that moose and other meaty prey can provide.

Monday, February 13, 2017

Snow leopard and Himalayan wolf diets are about one-quarter livestock




Wednesday, February 8, 2017

Brown bears reduce wolf kill rates says USU ecologist

Contrary to popular assumptions, researchers on two continents find wolves kill less often in the presence of brown bears
LOGAN, UTAH USA - If you've ever been elbowed out of the way at the dinner table by older, stronger siblings, you'll identify with wolves competing with larger bears for food. A study by Utah State University ecologist Aimee Tallian and colleagues reveals wolves might be at more of a disadvantage than previously thought.
Tallian is lead author of a paper examining competition between wolves and brown bears on two continents published Feb. 8, 2017, in Proceedings of the Royal Society B[DOI: 10.1098/rspb.2016.2368]. 
"Wolves and brown bears coexist across most of their range," says Tallian, who completed a doctoral degree from USU in 2017. "Although competition between predators such as these is widespread in nature, we know little about how brown bears affect wolf predation."
With colleagues in Scandinavia and North America, Tallian examined how brown bears affected wolf kill rates at study sites in northern Europe and Yellowstone National Park.
"We found an unexpected pattern," she says. "Wolves killed less often in the presence of brown bears, which is contrary to the common assumption that wolves kill prey more often to compensate for loss of food to bears."
Tallian says the consistency in results between the systems on different continents suggests brown bear presence actually reduces wolf kill rate, but the researchers aren't sure why.
They surmise wolves, unlike lynx and mountain lion, may not be quickly abandoning their kills, as bears move in take advantage of the spoils.
"The wolves may be hanging around longer, waiting their turn to gain access to food," Tallian says.
She and her colleagues also wonder if wolves kill less frequently because it takes them longer to find prey.
"We think this may be the case, in the spring, when newborn ungulates make easy pickings for bears," Tallian says. "It may simply take more time for wolves to find calves, when there are fewer of them."
Interactions between apex predators can either relax or strengthen their effect on prey and predator populations, she says.
"The team's results suggest that ignoring such interactions may underestimate the effect competition between predators can have on predator populations," Tallian says. "In addition, it's possible to overestimate the impact of multiple predators on prey populations."

Saturday, January 28, 2017

Machu Picchu in Peru is home to a biologically important species: the Andean bear


The Eurasian grey wolf, Canis lupus lupus, has spread across Germany

Since the year 2000, the Eurasian grey wolf, Canis lupus lupus, has spread across Germany. For Ines Lesniak, doctoral student at the Leibniz Institute for Zoo and Wildlife Research (Leibniz-IZW), and her colleagues, a good reason to have a closer look at the small "occupants" of this returnee and to ask the question whether the number and species of parasites change with an increasing wolf population. This was the case, because the number of parasite species per individual wolf increased as the wolf population expanded. Furthermore, cubs had a higher diversity of parasite species than older animals. The good news: wolf parasites do not pose a threat to human health. The results of this study were published in the scientific online journal "Scientific Reports" of the Nature Publishing Group.
In the course of a long-term study of wolf health in Germany, the internal organs of 53 wolf carcasses were studied in detail. They came from wolves which had died in traffic accidents or were illegally killed between 2007 and 2014.
"Whereas tapeworms are recognisable with the naked eye, the identification of single-celled Sarcocystis parasites was a real challenge, since the species of this genus do not differ morphologically," explains Lesniak.
According to their developmental cycle, endoparasites can be grouped into two types: Some, such as many tapeworms, infect their hosts directly. Others, such as Sarcocystis parasites, first live in an intermediate host, the prey animal of the wolf, and reach their final host, the wolf, only if the intermediate host has been consumed by the final host. With the faeces of the final host, these parasites are released back into the environment. Potential prey animals of the wolf feed then on vegetation that was previously contaminated with the parasites. The parasites thereby invade the intermediate host and settle in the muscle flesh. Roe deer, red deer and wild boar are such intermediate hosts in central Europe. When these are eaten by a wolf, the parasites infect the final host -- the wolf -- and reproduce in its intestines.
By applying sophisticated molecular genetic analyses, the scientists identified 12 Sarcocystis species in the wolf carcasses. They also found four tapeworm species (cestodes), eight roundworm species (nematodes) as well as one fluke species (trematode). In order to examine parasite infections also in the wolf's large prey species, the team collected internal organs of shot prey animals from hunting parties.
In Germany, wolves mainly feed on roe deer, but also red deer and wild boars. Small mammals, such as hares, voles or mice, are very seldom "on the menu." The identified parasites provide indirect evidence for this insight, since fox tapeworms were found in only one of the 53 wolves. Fox tapeworms are transmitted by mice and can occur in all canids, but particularly frequently in foxes. "Good news," Lesniak says, because the larvae of fox tapeworms can cause severe diseases in humans.
The scientists found that the infestation of wolves with parasites varied during their lifetime. "Cubs carry many more parasite species than yearlings or adults." According to Ines Lesniak, such variation in parasite species prevalence can be explained by the more robust immune system of older wolves. Wolves, just like any other wild canid -- other than domestic dogs -- are never dewormed, after all.
Wolves that died at the beginning of the study period had a lower parasite diversity than those who died later. "The bigger the population, the more often wolves are in contact with each other and their prey, and the more often they became infected with different parasites," Lesniak summarises the results.
Currently, there are 46 wolf packs settled within Germany. A pack consists of the parents as well as the cubs of the current and the previous year and can comprise up to ten individuals. "Genetic analyses conducted by our cooperation partners for this study show that the ancestors of the Central European lowland population, which nowadays ranges from Germany to Poland, originated from Lusatia in eastern Germany," Lesniak says. This population was probably initiated by individuals who migrated from the Baltic region at the beginning of the millennium and settled between southern Brandenburg and northern Saxony. From there, they began to spread across northeastern Germany and southwestern Poland, a process which continues to this day.
"Wolves are shy, wild animals. Thus, contact between people and wolves is rare," Lesniak emphasises. "Nevertheless, hunters should boil the leftovers of shot game thoroughly before feeding this to their hunting dogs, in order to avoid possible parasite infections," warns Lesniak. It is also essential to regularly deworm hunting dogs in regions occupied by wolves.
Occasionally, it has been reported that wolves come closer to residential areas; sheep farmers are complaining about losses. "It may well be that today's wolves have learnt that it is easier to find food closer to humans -- those, who once eradicated their wolf forefathers" presumes Lesniak. Of course, it is more convenient for a wolf to break into a sheep enclosure than to chase roe deer in the forest. Therefore, the implementation of appropriate protective measures of domestic animals is very important and now also financially supported by the government in Germany.