Apex predator - Wikipedia
Meanwhile, moose – the wolves' chief prey – are eating island greenery down to wilderness area to manipulate a predator-prey relationship. View the Isle Royale Wolf/Moose Study Slide Show this ecological dance in an effort to better understand the predator–prey relationship. Can coyotes fill the ecological gaps left by lost wolf populations? Thus, they must feed on calorie-rich prey, such as moose and large deer. However, improved models of predator-prey relationships and ecological systems, of sharks and other top predators on coral reefs and local fish populations.
Prey dispersal from human-created sources to neighboring areas may not increase prey populations in these sinks, but instead buoy wolf populations. Similarly, wolves may make temporary movements to hunt large prey populations at the edges of developed refugia, leading to increased wolf numbers and declines in the more vulnerable prey outside the refuge.
These potential source-sink dynamics take on particular importance in the context of managing prey refugia, as high ungulate prey density poses threats to economic activity, human health and ecosystem health  An example of this potential source-sink interaction between wolves and prey with a human-induced refuge occurs in Banff National Park BNP. Wolves recolonized BNP through dispersal in the mid 's, but avoided the townsite of Banff, resulting in differential predation by wolves on elk .
In the Bow Valley, adjacent to Banff, wolves prey primarily upon elk whereas the Banff elk population exists with little or no known predation by wolves . Within years, the distribution of elk shifted to where most elk in the valley occupied the predation refuge surrounding the townsite .
This distributional shift may lead to source-sink movements between the refuge and non-refuge areas with the potential to influence the overall predator-prey dynamics of BNP. The townsite of Banff may function as an elk refuge from wolf predation and affect the predator-prey dynamics of the Bow Valley wolf-elk system. This wolf-elk dynamic represents an interesting predator-prey refuge system to examine source-sink interactions in a spatially heterogeneous environment.
The development of a spatial predation refuge in and around the townsite of Banff provides an opportunity to test source-sink movements between Banff and Bow Valley of elk or wolves and the impacts of these movements on predator-prey dynamics of the system.
We hypothesized four ways in which the Banff refuge might influence the Bow Valley predator-prey dynamics through source-sink dynamics in the prey elkpredator wolvesor both. First, since the Banff elk existed at or near carrying capacity for much of the time-series this population likely experienced density-dependent competition for resources, which may have motivated elk dispersal to neighboring areas, such as the Bow Valley.
Thus, the Banff townsite may have served as a source elk population for the adjacent Bow Valley through density-dependent elk dispersal from source to sink. Alternatively, Bow Valley elk may move to Banff to avoid wolf predation, such that the Bow Valley serves as an elk source population, provided emigration rate exceeds mortality rate i.
Third, these two kinds of movements may occur simultaneously, such that elk disperse from Banff to Bow Valley in a density-dependent fashion at the same time as Bow Valley elk move to Banff to escape wolf predation.
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Finally, wolves may make short-term, temporary movements to prey on the Banff elk directly without elk dispersal. This mechanism implies no source-sink phenomenon for prey, but rather source-sink movements for wolves that allow Banff to act as a source of elk for Bow Valley wolves.
These predator source-sink movements occur on a short-term basis. Of course, these mechanisms may occur in parallel, as in the third hypothesis, or other forms of wolf-elk source sink dynamics may occur e.
We assess these potential interactions between the Banff refuge and the Bow Valley with these five predator-prey models. We fit competing continuous-time predator-prey models to time-series counts of wolves and elk in the refuge and non-refuge populations from a year period. The rugged terrain gives rise to a climate characterized by long, cold winters with short, irregular warm periods, and short, dry summers.
The Bow Valley km2 and area surrounding the Banff townsite 41 km2 have been previously partitioned into distinct ecological zones based upon variation in human, wolf and elk densities . Elk populations correspond to these zones, showing strong home range site fidelity and rarely relocating to adjacent zones .
Home range size of elk in Banff was 28 km2 . Neither Banff nor Bow Valley elk migrate to distinct seasonal ranges so seasonal counts appropriately describe the population dynamics of Banff and the Bow Valley. Parks Canada monitored wolf and elk winter populations annually in BNP during the study period over 26 years from — i.
The agency began counting the Bow Valley non-refuge wolf population upon wolf recolonization in the winter of — . Prior to the winter of —, the Bow Valley supported two wolf packs the Castle and Spray packswhich then merged to form a single pack the Bow Valley pack.
We summed the population counts from the Castle and Spray packs to determine the total number of wolves in the Bow Valley during the early years of the study period. Secondary prey species included caribou Rangifer tarandusmule deer Odocoileus hemionuswhite-tailed deer Odocoileus virginanusmoose Alces alces and bighorn sheep Ovis canadensisalthough wolves rarely interacted with these species due to rarity or spatial segregation .
Wolf diet composition justifies a predator-single prey approximation of population dynamics . Parks Canada conducted late-winter aerial surveys to determine elk populations in the town of Banff refuge and the Bow Valley .
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Parks Canada took aggressive management actions to control growing urban elk populations in the Banff townsite Banff hereafter starting in From toParks Canada relocated elk far outside the system equivalent to harvest with no return to mitigate emerging human-elk conflicts .
As a part of this management plan, Parks Canada began an aversive conditioning program to further combat the problems of habituated elk . Outside of this three-year period, Banff elk have not been subjected to any human harvest under the management authority of Parks Canada.
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Similarly, the Bow Valley wolf and elk populations have not experienced any human hunting or culling for the duration of our study, although both were subjected to occasional vehicle caused mortality despite extensive highway mitigation .
Source-Sink Modeling We tested for the various mechanisms of source-sink dynamics described above by fitting five predator-prey models that considered: Both species have cultural meanings that extend beyond their predator-prey relationship. Moose were first sighted on the island around the turn of the 20th century, and scientists have been examining them continuously since at least the late s. Wolves arrived around For decades they could reach the island by crossing over ice from the mainland in winter.
Now climate change is altering ice formation in Lake Superior, leaving wolves on the island isolated. Isle Royale is in the northwest corner of Lake Superior. NPS Isle Royale measures just over square miles and is well suited for ecological research.
Animals exist there in relatively small and thus, countable numbers. The island is easily accessible by boat, ski-plane and seaplane, weather permitting. And it is isolated. More people visit Yellowstone National Park on a single summer day than trek to Isle Royale in an entire season, which runs from May into October.
There are no roads and no motors allowed. The only people present in winter are park employees and scientists. Grey wolves in the Great Lakes region have been moved on and off of the U. Endangered Species List several times in the past 20 years. But they are not as controversial here as they are in the western United States — perhaps because fewer farmers and ranchers are affected by their presence, or because even though their numbers dipped to a few hundred in the s, they never really went away.
Three years later, writer and wolf advocate Lee Smits brought four more wolves from the Detroit Zoo to the island. Over the next several decades the wolf population grew, peaking at 50 in and then declining due to inbreeding, fighting among wolves, disease and starvation. Even with wolf predation, the moose population swelled, shrank and swelled again, peaking in at about 2, Although Murie had hoped these two species would achieve ecological balance, wolf and moose numbers fluctuated between peaks and crashes.
Populations of wolves blue and moose yellow on Isle Royale have fluctuated between peaks and crashes in recent decades.