I migrated from farming into livestock grazing in large part because of my deep love for land and wildlife, and my desire to address global issues on a practicable scale. Yet a common misconception I often face in my work is the idea that the cows are in the way of wildlife, both directly and by taking their food. If this were true, my work would be highly contradictory and misguided. Note that I work primarily with cattle but much of this applies to other ruminants... and wild species as well.
Livestock eat grass, but you can bet that because we're talking about relationships within a complex trophic web, this is not a zero-sum activity. Most grasses exhibit a response to grazing and animal disturbance that is often overlooked by those who aren't. We talk a bit about how grass benefits from having old, dead material cleared off to allow light to reach new growth points. And we talk about the nutrient-cycling benefits of grazing animals (wild and domestic): animals yield that dead material to the soil, where it can break down biologically in the soil instead of oxidize chemically into the air, and grazing animal disperse fertility across fields and add their own fertilizing urine and biologically active manure to the mix.
But it's critical to also acknowledge that when plants are grazed appropriately during the active growing season (which in coast range California is approximately mid-March thru May, depending on seasonal variation in precipitation and temperature), the plants will not only recover quickly but will actually be stimulated to put on more growth than they otherwise would. Provided they aren't grazed too soon in their development, or grazed down to a nub, even with a significant removal of vegetation the plants will regrow bigger and better than they would with no grazing at all.
What's more, the plants continue photosynthesizing longer than they otherwise would. Below is a photo where I installed a temporary fence in the same place twice this year - in late January and again in late March (a 60 day recovery). The green side was grazed twice during the growing season, and the brown side not at all because there were certain species we wanted to express without animal impact this year. On the left, the grasses have already senesced (set seed and died), whereas the grasses on the right are just beginning to flower.
At left, no grazing from mid-October. At right, two quick grazes with 60 day recovery period during the growing season.
The difference is pretty stark. I should note that the fenceline also approximates a slow change in soil depth, because the flowers we were protecting grow in thinner, rockier soils. But the abrupt change has at least as much to with grazing, and the sharp line in the grass is exactly where I built my fence.
When viewed from above, the grasses grew back denser and more lush on the right side than on the left. And most importantly, they continued to grow for at least a week longer than the ungrazed grasses. This means more energy was created through photosynthesis, and more calories made available to surrounding biota. That green grass is edible sunlight.
The longer a pasture can photosynthesize, the more it's yielding to its environment. With the help of big animals, we can keep grass plants photosynthesizing for longer, literally making more life for all entities above and below ground.