Don't put much ( better yet, any) faith in these "studies".
I know from 2 people directly who have been part of these"studies" (one in YNP, the other was MT fish and game -decades ago ) where the official conclusions were in complete contradiction to the actual study results. I have no reason to believe the conclusions fed to the public nowadays is any more unbiased or the conclusions less pre-determined.
Years ago I worked on a YNP Beaver-elk-willow dynamic study with CSU researchers. The key finding was that
in small streams, the beaver won't come back unless the willow comes back, and the willow won't come back unless the beaver come back. This is because small streams incised so deeply over the decades in the absence of beaver & their dams that the groundwater table declined so much that willow roots can no longer reach it. This process got triggered by the explosion of the elk population overgrazing willow, which corresponded to no wolves and no hunting in YNP. Some researchers at Oregon State made some sweeping conclusions on how the YNP beavers would rebound following the reintroduction of wolves. While rebounding beaver may be possible for larger rivers, these CSU researchers demonstrated that there are exceptions for smaller streams. You can read all about it in this good article written for the general public audience here:
https://www.hcn.org/issues/46.21/have-returning-wolves-really-saved-yellowstone
Ecology is the study of messy, complicated systems. There's nuance to every dataset and conclusion. For the average person hearing about scientific studies without getting into the details, of course skeptics will arise if a finding doesn't jive with their own mental model of how things work. Science follows a rigorous peer review process (at least in the respected journals, aka not some low-grade journal mill from China) and never claims to have all the answers. Generally we're talking a gradual improvement in understanding how things work. Science will always need the important job of journalists judiciously translating work and findings into something digestable for a broader audience.
What really grinds my gears is when folks use broad generalizations and claim to use scientific studies to back up their assertions. We see this on both sides of any argument, and misunderstandings can amplify in the age of social media. For example - watching this video one would conclude that beaver are restored in Yellowstone thanks to wolf reintroduction:
. These broad statements ignore the nuance of a system, and then you end up with an organization on one side of an issue oversimplifying things for their agenda. See:
https://wolf.org/headlines/leave-it-to-beavers-not-if-youre-a-wolf/ They posted the following summary here, and one may presume the typical reader will connect the dots on this, thinking wolf reintroduction will change how stream flows.
"
Beavers are influential. By cutting trees and damming streams, these rodents change the world around them, raising water levels and creating habitats for diverse plants, insects, fish and more. They are some of the world’s best-known ecosystem engineers, a term for species that produce outsize effects on their environments.
Wolves are powerful. As apex predators, their facility at killing reverberates down the food web, and their direct effect on prey species may affect vegetation, other animals and even how streams flow."
To reiterate, there is nuance to every issue. Be mindful of that, and be curious rather than interpret things as black or white. I am of the opinion that what's done is done, and now we need to start thinking about strategies to move forward. Reductionist thinking can make it tough for opposing views to move forward on anything.