The single predator single predator relationship between wolves and deer on Isle Royale on Lake Superior is unique, and has been the subject of detailed study for over 55 years. Isle Royale, the main island of Isle Royale National Park in Michigan in the United States, is a remote island with little animal migration in and out of the island and as a human interaction of national parks and impacts on two species is also limited. Both wolves and deer first became established populations on Isle Royale in the 1900s. During fifty years of research, deer and wolf populations have shown repeated spikes and declines and have not achieved a balanced relationship. The deer population ranges from 500 to 2500 while the number of wolves ranges from almost 50 to now down to one.
The relationship between wolves and deer on the Isle Royale has been the subject of the longest research study of its kind, beginning in 1958. Wolves have been subjected to inbreeding and carrying the deformity of the spine. By 2014, there are only 9 wolves on the island, with 2015-2017 numbering only 2. A review completed in 2014 stipulates that new wolves will not be introduced into the park to attempt genetic rescue, but by December 2016, the National Park Service decided to introduce 20 to 30 wolves to the island.
Isle Royale National Park consists of about 400 islands, and is located in the northwestern part of Lake Superior. It is about 50 miles (80 km) from the coast of Michigan, and 12 miles (19 km) from the Canadian coast. The main island is about 45 miles (72 km) long, and nine miles (14 km) wide at its widest point, with an area of ​​205 square miles (530 km 2 ). There is no road, and no motor vehicles are allowed on the island. The park is closed from September to May where werewolf study personnel are the only human inhabitants on the island.
Video Wolves and moose on Isle Royale
Interaksi dinamika serigala-rusa
As a remote island, Isle Royale initially had neither wolves nor deer. The deer are believed to have swum in Lake Superior from Minnesota in the early 1900s or were stocked on the island by humans for recreational hunting purposes. In 1949 a pair of wolves crossed the icy bridge from Ontario to the island during a harsh winter. But since only a pair of wolves are migrating to the island, they have suffered severe blood marriages. According to Rolf Peterson, a professor at Michigan Technological University and a leading werewolf researcher, "Moose was isolated here 100 years ago, most of the genes are still here, but they have a sufficient population (to compensate.) There are so few wolves that they have lost genetic variability.The scientific dogma shows that they will not succeed. "In fact, all the DNA of wolves on Isle Royale can be traced back to an ancestor. Inbreeding causes inbreeding depression and fitness problems, often accompanied by harsh social rejection by other wolves.
When the study began in 1958, many researchers believe that two species would eventually reach a population balance of about 25 wolves and 1,500 deer; but there have been no signs of this, with the population fluctuating unexpectedly. The largest number of deer observed since the arrival of the wolf was 2,450 in 1995. The highest number of wolves observed was 50 in 1980 followed by the population falling to 14 in 1982. In 2005, there were 540 deer, the lowest recorded, and the relatively high population of 30 wolves. In 2008, there were 700 deer and 23 wolves.
The density of both species depends heavily on the forage density. Moose prefers birch and aspen trees, which once flourished on the island, but over a century of sighting the deer have been replaced by the less nutritious balsam sprouts, which now account for 59% of the deer diet. In fact this has declined dramatically: in 2002, the understory growth of fir balsam was 5%, down 40% from the observations of the 19th century. This plant is more on the east side of the island, which results in higher deer concentrations. Because firs balsam does not provide enough moisture, the deer have recently been seen eating snow, a very rare occurrence. They have also been seen eating moss, which researcher Rolf Peterson has compared to eating dust. When deer populations grow too high, the pine buncham population falls, causing accidents in deer populations, in a population that is constantly "sight-seeing". Deer mostly die from the consequences of malnutrition: they become emaciated and slowed by arthritis, until they become easy prey for wolf herds. In addition, calves suffer from malnutrition when they are born during the winter with too deep snow to find food easily.
Moose makes nine-tenths of Isle Royale's wolf diet (the rest being snowshoe hare and beaver). Deer in their early years generally run faster than wolves in the hunt, especially in soft snow: the deer can cross the deep two foot deep at 20 mph (32 km/h). Even if wolves can chase a deer, they can not always lower it; Researchers often find wolves with hunting bruises and scars. To increase their chances, the wolf selects the deer that is calf, old, diseased, or injured. The commonly killed deer are about 12 years old and suffer from arthritis, osteoporosis, and/or periodontitis. Eighty to ninety percent of deer are brought down by wolves instead of directly by disease, and each wolf kills an average of between 0.44 and 1.69 deer per month.
Maps Wolves and moose on Isle Royale
A series of wolf population dynamics
The wolves on the island, historically, have been separated into three or four packs, with each pack usually having between three and eight members, including two or three puppies. The number of wolves in the pack depends largely on the amount of snow that fell in the previous winter. In winter with mild snow, puppies tend to leave their backpacks in search of a mate, so the pack runs with four or five members; in the snowy winter, the puppies live with the pack, which can reach ten to twelve members. If many members of the pack die, packets are broken up and new ones are formed within a year. One pack will dissolve about once every thirty years.
In 2006, the wolf population, with the exception of 10 loners and separate couples, formed three packages; east pack , middle pack , and Chippewa Port package . Packages of wolves on the island have been known to struggle to try to expand their territory and, thus, the supply of deer. In 2006, the eastern package killed the Alpha men of the Chippewa package, as witnessed by John Vucetich, a professor at Michigan Technological University and one of the island's main researchers, who believe the Chippewa Harbor package may die without their leader.
Old Gray Guy
During the winter of 1997 a very manly wolf (later called "Old Gray Guy" and wolf No. 93) crossed a 15-mile-long ice pass to Isle Royale. Old Gray Guy is bigger and more territorial than the other Isle Royale wolves. His own pockets grew into 10 huge wolves, and fled and went to the extinction of one of the other four packages. It is so named because as it ages, its feathers become very pale, an unusual phenomenon. It was determined that in 2009, 56% of wolves on Isle Royale had descended from Old Gray Guy.
"We do not know any other example - except when they first came - wolves across the ice," said John A. Vucetich, lead author of the study of wolves published online in The Proceedings of the Royal Society B in 2011. "The whole population is descendants of a single woman. "
The population of wolves on Isle Royale is small, on average only about 23 wolves. At the end of his eight-year breeding period, he produced 34 children, producing 45 children.
Such genetic implications are evidence of an even greater Old Gray uniformity compared to other inbred wolves on the island. Scientists hope that such recognition will create a "genetic rescue" population explosion, but that does not happen. "A co-author of the study, Rolf O. Peterson, a research professor at Michigan Technological University, said that the Isle Royale population depended on a thread, as it did for decades.Average reproduction after Old Gray Guy arrived was no different from before But this does not mean that he has no effect. "
"The simple interpretation is that genetic saving is not working," said Dr. Vucetich, assistant professor of animal ecology at Michigan Technological University. "But what happened here is when immigrants came in 1997, in the next decade, deer population dropped dramatically, it makes sense that we do not see the effect because wolves suffer from other problems disguising its benefits.What if wolf No. 93 never arrived? Vucetich said it was impossible to know for sure, but the Isle Royale wolf may have vanished completely, maybe Old Gray Guy arrives just in time. "
Other species
After the deer is brought down and killed, the wolf must compete with the vultures. Crows are ductile scavengers who can easily avoid wolf attacks and are not bothered by them. Crows can eat and store up to two pounds (0.91 kg) in a few days, which is very small compared to the storage capacity of a wolf, which is up to eighteen pounds (8.2 kg) in just a few hours.
Other anti-social species have an even, rather small, effect on the relationship between wolves and deer on the Isle Royale. Before the wolves hunt them down to extinction, the coyote is used to inhabit the island. Beavers and snowshoe rabbits also have an effect on both populations, since beavers and snowshoe rabbits are the only two animals that prey wolves do not include deer, representing one-tenth of the Isle Royale wolf diet. The beaver population has declined sharply since the arrival of wolves, but they still exist, and although they are not the primary food source for regular wolves, they are the second for deer as the animals most consumed by wolves on the island. Beavers benefit both species. They are easy prey for wolves and they create aquatic macrophytes, plants that are highly nutritious for deer, although macrophytes are also consumed by beavers. Although wolves are thought to be contributing to the decline of beavers, researchers believe that the decline in aspen, the main source of the main beavers, once abundant, can cause a decline. Beavers have been exposed to predation by having to travel long distances to find only parts of the island where aspen remains.
Snowshoe hares, the third animal most consumed by wolves on the Isle Royale is a very small part of the wolf diet, because snowshoe hares are very hard to catch. Researchers have found that wolves show no great interest in prey on rabbits, and only eat them by chance. Hare Snowshoe has a negative effect on deer when they eat some of the same vegetation that feeds deer, which only contribute to the proper decrease of feed for deer. Red fox is another animal in the Isle Royale; Red foxes mainly eat snowshoe hares and occasionally scavenge deer, or other flesh left by wolves. Wolves usually do not hunt foxes, although wolves have been observed killing foxes as they try to feed animal carcasses.
Climate effects
Climate plays a major role in the relation of wildebeest as well. Since El Nià ± o was hit in 1998, the climate has warmed up, which significantly affects deer populations throughout North America. The warm climate in recent years has resulted in more winter moose fleas, which consume animal blood, make them more susceptible to anemia, and encourage deer to scratch their hair, so they are exposed to hypothermia in cold weather. A deer can have tens of thousands of lice that eat its blood at a time, each sucking in a milliliter of blood. Bite ticks cause a lot of discomfort for deer, so they try to get fleas from their bodies by biting their hair, and rubbing against the trees. It keeps the deer busy, and keeps them from searching for food, which can lead to malnutrition. Compensated with blood loss, deer are attenuated by warts more easily killed by wolves. Fleas are more prominent in the years when spring arrives earlier than usual, because when they fall on the ground that is not covered with snow, they can reproduce. If not, they die. Then, if summer is hot, ticks can reproduce at a higher rate. Hot summers also cause deer to rest in the shade, or in the water to keep calm, making them easier to prey on wolves. Also, hot summers make it harder to feed deer that make them less prepared and more vulnerable to winter. Not only does the recent warming up on the Isle Royale hurt the deer, but the really opposite issues also hurt them. The harsh winter creates significant problems for deer, since deer have problems finding food when there is too much snow on the ground. The less snow there, the more free deer can move around the island. When there is a large amount of snow, deer live in coniferous swamps, making them easier to prey on wolves, because they are more limited, and can not move due to snow. Thick or deep snow decreases the speed and agility of deer needed to avoid wolf attacks, and calves born during the winter with deep snow are more prone to fall prey to the wolves later in their lives due to the problem of feeding that occurs when deep snow. The strong survival instinct of the deer has been clearly seen from studying their actions on Isle Royale. The female deer (called "cows") have been found on adjacent small islands, around the main Isle Royale island, as they swim across to give birth. This allows them to give birth and raise their child without the threat of wolves prey on their children when they are vulnerable. This also causes problems for deer born in winter, because they can no longer swim across the water to other islands, and must raise new calves in the snow. Once the calves mature physically, they can swim back, and then can better protect themselves from wolves, because they are in the prime ages.
Trends
Initially, it is estimated that the wolves and deer population will achieve a stable balance, but this is not possible anymore. For nearly sixty years of research, populations of both species fluctuated up and down with the number of deer ranging from nearly 2500 to 500 and the number of wolves ranged from 50 to one in 2017/18.
During 2016, the wolf population is now almost extinct with only two very inbred wolves. The deer population is about 2/3 of its historical maximum with many forages and grows rapidly. There is no new migratory wolf infusion, or human intervention, the original situation of high deer population only limited by starvation is a prospect.
However, in December 2016, the National Park Service (NPS) submitted a plan in which they would add 20 to 30 wolves to the island to prevent the packet completely disappear.
In December 2017, Sarah Hoy et al. Michigan Technological University published a 40-year study that showed a decrease in deer size and lifespan. The moose skull analysis documented a 16% shrinkage possibly consistent with winter warming that correlated with smaller brain size in a one-year-old deer. The deer population has tripled in the last decade, reaching about 1,600 in the 2017 survey, but as the wolves die approaching, competition for food due to overpopulation will become more pressing on deer.
In March 2018, with the enactment of a final Environmental Impact Statement, the NPS formally proposed to move 20 to 30 wolves to the island for a period of three years, to begin immediately. A Record of Decision was officially released on June 7, 2018 by selecting this preferred alternative from several others including non-action, introducing wolves for a longer period of 20 years, and delaying immediate action but allowing for possible future action after ongoing monitoring of deer population metrics. As of June 2018, NPS is actively developing specific implementation strategies.
References
External links
- Wolves and Deer Island Royale
- Isle Royale National Park website
Bibliography
- "Food Fight: Wandering Outside Ravens." Ascribe Higher Education News Service (August 19, 2004): NA.
- Moose of Isle Royale, (1934). Adolph Murie. Ann Arbor: University of Michigan, Zoological Museum, Misc. Publication No. 25. Study of deer population before the wolf arrives.
Source of the article : Wikipedia
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