After reading the actual study, I have no qualms with the information presented. For the purposes of this study, there was no sizable bias. Their whole purpose taken straight from the abstract was merely, "To better understand the implications of predator management on elk populations..." They did the study and they now know that mountain lions are killing a few more elk than they thought.
Now what the news articles and people in this thread are trying to do is to compare the effects of mountain lions and wolves on elk mortality using this study. This study was not intended to do that and so there is large amounts of bias in this comparison. Some examples off the top of my head are that the elk were not evenly distributed between the 29 populations chosen and the wolf and mountain lion populations were not taken into consideration or accounted for.
It is impossible to do a broad study like this without bias, especially when you have findings that you didn't expect or when people try to make conclusions from the data that weren't intended by the study. Completely unexpected results introduce elements that you didn't even know you should have been controlling to prevent bias.
A few interesting things that I think can add perspective to the findings of this study:
1. Population of wolves and mountain lions in Idaho - There are no real accurate estimates of populations of either wolves or mountain lions in the state of Idaho. "Current unofficial estimates put Idaho's wolf population over 1000 animals" according to the Idaho Governors office. The Idaho Fish and Game has never tried to estimate mountain lion populations. Predators are notoriously hard to estimate populations for. Some population estimates can be made through harvest statistics though. In 2016 (the most recent year with both wolf and lion harvest statistics available) there were 267 wolves killed by hunters compared to 629 mountain lions killed by hunters. I will let you guys decide where that puts population levels. (I believe the wolf harvest statistics include trapping, but don't quote me on that as I can't find a for sure yes or no.)
2. Predator dispersal throughout the state of Idaho - There are 99 different game management units in Idaho. In 2016 wolves were killed in 46 of these units. Mountain lions were killed in 80 of these units. 12 units had no predators of either species killed in them. While this obviously doesn't show either animals entire range, it does show that mountain lions are found and killed in many more areas of the state than wolves.
3. The #2 factor for predicting elk mortality in an area (#1 for calves was body size, #1 for adult cow elk was age), was the average size of the wolfpack in the area. This was before snow depths which was #3. This is taken straight from the abstract of the study itself. It wasn't the the lion population in the area, it was the wolf population in the area that had the greatest impact as far as predators on an elk's chance for survival.
Make your own conclusions from that added data, but in my opinion, it shows a couple things. One is that Idaho can't be lumped into one sum. Wolves are not distributed throughout all the places elk live in Idaho, but mountain lions are. The second is that even with this biased comparison (which is completely one way bias I might add), elk mortality by lion and wolf was very similar. Even though mountain lions are found in more places than wolves and arguably have a much larger population than wolves, they still only killed a similar amount of elk as wolves did in this study. I think that tells us that wolves can and will be more detrimental to an elk population than cats.
Not a wolf hater. I kill elk in units with decent wolf populations in Idaho. I'm not here to say "kill them all", but to say they have little to no effect on an elk population as some here all to often try to say (ESPECIALLY in areas with large populations of wolves) is just stupid and plain wrong.