Property owners mow their fields for different reasons. Some do it simply for aesthetics. Farmers often mow to keep trees from taking over fields that may one day be used for crops. Others mow to prevent invasive weeds such as autumn olive from spreading through pastures. Whatever the reason, mowing can have both positive and negative effects on wildlife. By mimicking the natural successional growth that happens after wildfires, you can create habitat that is ideal for many birds and other animals. But if you mow too often or at the wrong time, you can end up hurting these species more than helping them.
We asked Marc Puckett, a certified wildlife biologist with the Virginia Department of Game and Inland Fisheries, for advice on mowing. Here are some basic considerations.
Is Mowing Necessary?
Think about why you are mowing and whether it’s needed every year, or even at all. If you are trying to keep your fields clear of trees, then mowing on a two- or three-year rotation may be all that’s needed. It varies based on where in the state you live, as things grow faster in the coastal plain than they do in the mountains.
If you need to mow more regularly but still want to promote good wildlife habitat on your property, learn to differentiate between good wildlife shrubs, thicket-forming cover, and beneficial trees, and other things that you do not want. Leave the good and cut or spot spray the bad. Good things for wildlife include plum, sumac, blackberry, persimmon, greenbrier, grape, blueberry, azalea, dogwood, slower growing oaks, and hickory. Bad things, at least in terms of being invasive and quickly taking over fields, are sweetgum, red maple, poplar, Tree of Heaven, and locust. It takes time to become good at selective management, but most folks can at least learn to identify several good plants to avoid mowing or spraying.
Finally, if you are mowing simply to have your land be more accessible, consider mowing paths rather than whole fields. Not only will you still be able to walk around and enjoy your land, but you’ll also be able to appreciate all of the cover and wildlife that you spared.
If you can find other ways to keep your fields clear, such as controlled burning (only in safe, well-planned situations) or disking (only where erosion is not a concern), then do that instead. These management practices should also be done in rotation, working half or a third of the land each year, usually during late winter or early spring. You can even use spot herbicide treatments to control encroaching trees and further lengthen the time between mowings. Properly applied, non-persistent herbicides can help, not hurt, wildlife.
No mowing should occur between early April and early September if possible, as many birds are nesting during this time. Quail will nest well into early fall, for example. Many folks like to bush-hog during fall, as it somehow makes sense to them to “clean” things up before winter. Or, others will say they like to bush-hog during summer before the weeds set their seeds, thinking they are preventing weedy growth. Again, landowners need to understand the value of so-called weeds for wildlife. Unless they are really farming and concerned about weeds, weeds are great.
Ideally, mowing is best done during early to late March because cover quickly regrows during spring. Within two to four weeks, lots of new herbaceous growth will come back and provide nesting and brood-rearing areas for a variety of birds and other animals. When you mow in late fall, the area is essentially barren of cover all winter long, when escape cover is sorely needed. So, ideally, you would mow on a 1/2 to 1/3 annual rotation during March.
Mow from the Inside Out
Many people instinctively start mowing the perimeter of their fields and work their way in. This can often send wildlife into the centering of the field, where they will ultimately be killed. To prevent this, start mowing in the middle of the field and work your way out. That gives wildlife a chance to seek refuge in surrounding unmowed fields or tree stands. But remember that this will still destroy any nests or young that can’t escape, so it’s still important to avoid mowing during the nesting season.
Avoid Mowing to the Water’s Edge
Landowners with streams or rivers running through or adjacent to fields should leave an unmowed buffer strip as much as possible. The vegetation helps to filter pollution from runoff and prevent erosion. It also helps to mitigate flooding.