I interviewed Mike Hudak, chair of the Sierra Club's National Grazing Team and author of Western Turf Wars when we spoke at an Earth Day event together. All views expressed are Hudak's own views and do not necessarily represent the views of the Sierra Club.

We all know that animal agriculture is very inefficient and is damaging to the environment. Why is grazing on public lands especially harmful?

The grazing on public lands is especially harmful because the landscape has not adapted to grazing by animals like cattle because these areas are particularly arid and receive low amounts of precipitation or are high elevation areas that have very short growing seasons.

So all of those characteristics make the vegetation particularly vulnerable to intense grazing or "herbivory," as it might be called, by these animals.

Is it just cows? Or is it mostly cows?

It's mostly cows now. A lot of the damage was done a long time ago in the late 19th century. At that time, there were a lot more domestic sheep grazing on these lands than there are now. But since about 1950 or so, we've been getting competition from foreign sources, particularly New Zealand, resulting in a significant downsizing of the sheep industry in the United States. There have been many sheep grazing allotments that have been converted to cattle as a result of that.

During your talk, you mentioned that some animals are killed directly and some are killed indirectly. Why are some animals killed directly, and which species are affected?

The types of species that are killed intentionally or directly are those animals that the livestock industry regards as competitors of livestock or predators of livestock.

Predators would include animals such as mountain lions, wolves, to some extent coyotes. Competitors are those that consume forage that the ranchers would like to have remaining for their cattle, so the competitors would include everything from grasshoppers to prairie dogs.

How are animals killed indirectly, and which species are affected?

The animals that are killed indirectly are those that rely on healthy habitat in these arid regions of low precipitation or high elevation and they are unintentionally harmed as a result of changes in that habitat that results from the either short term or in many cases, long term, grazing of cattle or sheep.

During your talk, you mentioned a bill that people should support.

It's called the Rural Economic Vitalization Act (H.R.3432), or "REVA."( You can look up your U.S. Representative on the House of Representatives website, while your senators can be found on the official Senate website.) This is a bill that would extend the authority of the federal government to the rancher permittees. To direct the government to retire the grazing permits for permittees and to permanently close the associated grazing allotment. The bill does not request any federal funding to compensate ranchers who would be inclined to want their permits retired. Any funding would have to come from private sources. The legislation limits the number of permits that could be retired in a given year to one hundred. We wrote this legislation to kind of get the ball rolling with this kind of approach to lessen grazing pressure. Of course in the long run, if it's going to be successful, ranchers will have to embrace this and call for an expanded bill. We have indication that this might be the case. There was actually a study done by some Canadian researchers done back in 2006. And they surveyed the public lands ranchers in Nevada. From those that responded, and there were quite a few that responded, they found that about half of those ranchers would retire their permits for the right price. The price was a little high, but it wasn't outrageous. It was $255 per animal unit month (Ed. Note: An animal unit month is "the amount of forage needed to sustain one cow and her calf, one horse, or five sheep or goats for a month.") Now, if you consider that the going rate for those permits might be $70, you can see that they might have a pretty good deal. But I just have the feeling that if real money were put in front of these ranchers, a lot of them would take less than $255. This was only basically a theoretical, hypothetical situation.

And those were Canadian dollars?

No, the study was done by a Canadian academic and his grad students, I think there were two grad students, but they surveyed these Nevada ranchers. It was a little strange that a Canadian would do this. It was someone who was interested in agricultural economics, so go figure. Anyway, I'm just saying a study like that gives us some hope that ranchers will embrace an approach like this to solve some of their financial problems, even if they won't come out publicly and say that they would support this legislation before it's enacted. There's a lot of social pressure on ranchers, particularly small ranchers, to not publicly advocate for a buy-out of any sort.