Lecture 6 Gray Wolf Trophic Cascade and an Endangered Status

Was there actually a reversal of a trophic cascade following wolf reintroduction?

Some studies indicate very large affects for the recovery of willow, but such studies have been criticized for methodological flaws. Most studies conclude a modest or spatial variable reversal of trophic cascade or none at all.

What were the given confounding factors in the ‘reversal of a trophic cascade’? Hint: 5

1. Spotty pattern of plant recovery

2. Cougar recovery (they kill more elk than wolves)

3. Slow beaver recovery (ecological engineers - they alternate a stable state)

4. Changes in fire regime (seedling establishment)

5. Lack of strong evidence for the operating mechanism

What is the argument regarding the evidence of a reversal of a trophic cascade from wolf reintroduction?

Is it the wolves themselves causing these changes alone as a keystone species or were those other confounding factors taking significant part in the plant recovery?

U.S. Endangered Species Act (ESA)

(1973) Legislation that affords federal legal protections to threatened and endangered species. Regulations implemented by the US Fish and Wildlife Services

Define: endangered

Species that are “in danger of extinction within the foreseeable future throughout all or a significant portion of its range”

Define: threatened

“Those animals and plants likely to become endangered within the foreseeable future throughout all or a significant portion of their ranges”

What are distinct population segments?

A vertebrate population or group of populations that is discrete from other populations of the species and significant in relation to the entire species.

How are distinct population segments described? Give a real life example and what does it mean.

Geographically, rather than biologically. An example being that wolves are considered endangered in the lower 48 states, but are well populated in other countries outside the US.

What does ‘geographically, rather than biologically’ mean in terms of distinct population segments?

There are protections under the ESA that can be applied to a population(s) in a particular area rather than to the entire species.

What year were wolves reintroduced?

1995

Approximately how many wolves were there in the lower 48 states in 1995?

2,450

How many wolves were there in Alaska in 1995?

5,000-7,000

How many wolves were there in Canada in 1995?

50k-60k

How many wolves were there worldwide in 1995?

200k-250k

Where was there already a wolf pack in 1995?

Montana

Under what Act are distinct population segments protected by and what year?

Under the Environmental Protection Act of 1973

Stakeholders

Representatives of conflicting human interests who must agree on a management plant for species survival in the specific context of Endangered Species Act recovery teams and working groups.

More specifically what are stakeholders?

Legal authority federal biologists who write and enforce rules, state wildlife managers, and tribal sovereigns

What is the current status of wolves as of 2021?

4,200 wolves in Michigan, Wisconsin, and Minnesota and 1,900 in the Northern Rocky Mountains states