Snowshoe Hare Ecology and Population Dynamics

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Questions and Answers

What is one of the ecological factors that contribute to the cycle of snowshoe hares?

Overgrazing (correct)

Sunspot activity

Climate change

Pollution levels

What specific method was used to study the snowshoe hares in the mentioned studies?

Live trapping and radiocollaring (correct)

Genetic sampling

Field observation and photography

Population modeling

Which factor was dismissed as a potential agent affecting the snowshoe hare cycle?

Food shortage

Sunspots (correct)

Parasites

Predation mortality

Who initially proposed the concept of 'shock disease' as a cause for declines in hare populations?

Green and Larson Signup and view all the answers

What is the primary diet of snowshoe hares, as indicated in the content?

Herbaceous plants Signup and view all the answers

During which season do snowshoe hares primarily breed?

Summer Signup and view all the answers

What color do snowshoe hares turn in winter?

Pure white Signup and view all the answers

What did William Rowan describe the 10-year hare cycle as?

An outstanding problem of Canadian conservation Signup and view all the answers

What was the purpose of surrounding one of the trap grids with a 2-m-high electrified fence?

To keep mammalian predators out Signup and view all the answers

Which hypothesis was being tested regarding hare population dynamics?

Both food quality and predator presence Signup and view all the answers

What impact did feeding hares have on their population density?

It tripled the population density Signup and view all the answers

What type of fertilizer was used in the bottom-up regulation model experiments?

NPK fertilizer Signup and view all the answers

What was a key finding regarding the increase in hare population density?

It was mainly due to immigration from other areas Signup and view all the answers

What was the limitation in the predator reduction experiment's design?

Inability to keep mammalian and avian predators out Signup and view all the answers

Which species of tree was mentioned in relation to browsing and toxic compounds?

Deciduous trees Signup and view all the answers

What does the 10-year experiment's synopsis reveal about hare survival rates?

It remained constant despite feeding Signup and view all the answers

What factor is suggested to contribute to the low phase in hare populations?

Stress-induced maternal programming Signup and view all the answers

What did Sheriff et al. find regarding the low phase length in hare populations?

It varies with the severity of the decline phase. Signup and view all the answers

What was the outcome when nematode prevalence was reduced in hares?

Increased predation risk Signup and view all the answers

According to the hypotheses, what might explain the persistence of epigenetic changes in hare populations?

Time required to dilute the changes from the population Signup and view all the answers

Which predator's role is suggested to impact the low phase duration in hares?

Great horned owl Signup and view all the answers

What did the research by Keith et al. on snowshoe hares focus on?

Helminth parasites and their prevalence Signup and view all the answers

What has been found regarding mortality in snowshoe hares from diseases or parasitism?

No evidence of high mortality exists in the Kluane area. Signup and view all the answers

What interaction is suggested between parasitism and predation in snowshoe hares?

Predation enhances the effects of parasitism. Signup and view all the answers

Which animal is a primary predator in the Kluane ecosystem?

Red-tailed hawk Signup and view all the answers

Which herbivore is included in the Kluane food web?

Snowshoe hare Signup and view all the answers

What type of animal is a goshawk?

Carnivore Signup and view all the answers

What role do insects play in the Kluane food web?

Herbivores Signup and view all the answers

Which of the following animals is a top predator in the Kluane ecosystem?

Wolf Signup and view all the answers

Which of the following animals primarily preys on small rodents?

Great-horned eagle Signup and view all the answers

Which species could be considered a competitor to snowshoe hares?

Coyote Signup and view all the answers

What ecological role does the ground squirrel serve in the Kluane ecosystem?

Herbivore Signup and view all the answers

What primary factor was attributed to the mortality of the radiocollared hares?

Predation Signup and view all the answers

What was the main objective of the experiment conducted on winter food plants?

To evaluate the impact of food on hare population cycles Signup and view all the answers

Which of the following trees was not mentioned as a food source for hares in the study?

Pine Signup and view all the answers

What did the results suggest about the role of winter food in hare populations?

Winter food is important but not the limiting factor Signup and view all the answers

In the context of the study, what were the two main factors manipulated during the next hare cycle?

Food and predation Signup and view all the answers

What trend was observed concerning the levels of secondary compounds in hare food?

They showed a decline during the peak phase Signup and view all the answers

Which of the following hypotheses was contradicted by the experimental results?

Hare population cycles are solely determined by food supply Signup and view all the answers

What did the findings from the hare crash in Rochester, Alberta support?

Predation as a significant factor in hare mortality Signup and view all the answers

Study Notes

Snowshoe Hare Cycle Drivers

Overgrazing, food shortage, predation, parasites, and diseases are all potential drivers of the ten-year snowshoe hare population cycle.
Sunspots were quickly dismissed as a potential factor due to their fluctuating timeline mismatch with the snowshoe hare cycle.
Early research concluded that "shock disease" was a potential cause of cyclic declines but this has been dismissed as an artifact of laboratory studies.
Snowshoe hares experience chronic stress which may contribute their cyclical dips, further supporting this hypothesis.
In the Kluane area, predation has been identified as the primary cause of mortality, which aligns with studies conducted in Alberta.

Snowshoe Hare Natural History

Snowshoe hares are the primary herbivores in the boreal forest ecosystem, possessing significant ecological significance because of their biomass.
They have distinct winter (white) and summer (brown) fur colours.
Snowshoe hares experience a peak in breeding during the summer, with a maximum of four litters being produced.

Food Quality as a Driver

Research has debunked the hypothesis that food quality could be a driving factor in the hare cycle.
Plant secondary compounds were expected to increase over the cycle, but instead, they decreased, negating the hypothesis.
This result however is not a universal truth and should be further investigated in different regions of the boreal forest.

Food Addition & Predator Reduction

Experiments manipulating both food and predation during the 1986–1996 cycle resulted in increased hare populations.
Food addition dramatically tripled the hare population density but did not prevent the cycle's decline.

The Low Phase

The "low phase" of the cycle is characterized by low hare populations and is associated with a high level of stress in individual hares.
Offspring of stressed hares may experience epigenetic alterations (heritable changes in gene expression) that contribute to their reduced fecundity.
The low phase lasts for a variable amount of time, potentially due to the gradual removal of these epigenetic changes from the population.
The severity of the decline seems to impact the duration of the low phase, suggesting that the higher the predation risk, the longer it takes for the population to recover.
The role of great horned owls as predators during the low phase could also contribute to the prolonged low phase.
The Kluane area lacks evidence of high mortality in snowshoe hares due to diseases or parasitism.

Predation

Experiments have shown that predator removal, especially mammalian predators, can have a significant impact on snowshoe hare population dynamics.
The combined impact of reducing predation and increasing food resources can lead to a significant increase in hare numbers.
Although the exact mechanism is still under investigation, predation is a key factor in driving the snowshoe hare population cycle.

Snowshoe Hare Food Web:

Species such as owls, lynx, coyotes, hawks, foxes, martens, wolves, humans, grizzly bears, and black bears prey upon hares, highlighting their significance to the food web.
Hares consume a wide variety of plants, including white spruce, aspen, ground squirrels, red squirrels, insects, bark beetles, and small rodents.
This complex food web highlights the intricate relationships that structure and maintain the health of the boreal forest ecosystem.

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Description

Explore the fascinating life cycle of snowshoe hares, including the factors that drive their ten-year population cycles. This quiz covers topics such as overgrazing, predation, and the ecological significance of these animals in boreal forests. Test your understanding of their natural history and the impact of environmental stressors.