By Laura Paine, Portage, Wisconsin — One of the small pleasures of grass farming is watching and listening to the songbirds that share our farms in spring and summer. Grassland songbirds don’t do anything for the bottom line, but they can be indicators of environmental health. If our farms are capable of sustaining not only our families and livestock, but also a complex community of plants and animals, we know that we are part of a healthy, resilient, and fundamentally sustainable system.
And perhaps there is more of a distinct bottom line to this idea. For instance, Minnesota grazier Art Thicke has found that some of the same practices that are good for birds also improve forage utilization and contribute to the long-term productivity of his pastures. There are ways to improve songbird-nesting habitat that can work within a profitable grazing operation. But first, let’s think about the landscape from a bird’s perspective.
As he flies back in March and April for the breeding season, a meadowlark is greeted by mile after inhospitable mile of barren farm fields. The green islands of pasture on grass-based farms must look pretty appealing.
Upon choosing a suitable grassy area, males set up housekeeping and start looking for a mate. Where he is, there’ll be a nest nearby. The size of the pair’s territory varies with species. The meadowlark stakes out a territory of about 10 acres, but you can find two or three savanna sparrow pairs in a five-acre paddock. Red-winged blackbirds often nest in colonies, with several nests clustered closely, and several pairs of adults working together to raise all the young.
The meadowlark breeding cycle takes about five weeks from nest building to fledging. Nesting is timed to take advantage of critical food sources. In Wisconsin the peak of nesting is in May and June, when there is an ample supply of high protein insects to feed young birds. Later in the season, as the babies fledge and the plants around them mature, the diet shifts over to seeds. Some species lay several clutches of eggs in a season, but the first one has the best chance of success.
Even under ideal conditions, only about 60% of nesting pairs successfully fledge each year. Predators, bad weather, and other factors conspire to cause nest failure. In a pasture situation, disturbance by cattle is an added risk.
I looked into this risk several years ago. In the mid-1990s I coordinated a research project sponsored by the University of Wisconsin College of Agricultural and Life Sciences and the Wisconsin Department of Natural Resources that looked at the habitat quality of farmland for grassland birds. The research suggested that grass-based farms do provide high quality habitat that meets many of the birds’ needs. We found as many nesting pairs in rotationally grazed pastures as are found in Conservation Reserve Program (CRP) fields, and more than twice as many as are found in an average alfalfa field.
Determining the impacts of various factors upon nest survival is challenging. For our study, we located as many natural nests as we could find for each pasture type. We checked each nest every few days until an outcome was determined (successfully fledged or failed). We found that nest survival varied from 5-22% in intensively grazed paddocks (an average of 24 head/acre rotated through two or three times during six weeks, with occupation periods of one day per grazing event), to 31-40% in paddocks that were set aside during the peak nesting period. Continuously grazed pastures had a 25% nest survival rate. The continuously grazed paddocks tended to be lightly stocked, with large “waste” areas that provided relatively undisturbed nesting. However, overall poor habitat limited the number of nesting pairs/acre to about two-thirds of what we found on the managed grass farms.
These data must be used with caution since there are a variety of factors that can limit the accuracy of such estimates. The extreme variability we saw between the two years of the study suggests that a few more years would have improved the confidence with the data. Unfortunately, lack of funding and researcher interest halted the project.
Having said that, what did we learn about grassland birds’ habitat needs, and what management practices can help provide for them?
First, simply converting your farmland to pasture is the single most important change you can make in terms of improving habitat. We estimate that a conventional farm with 100 acres of alfalfa and 100 acres of corn attracts only about 125 nesting pairs, while the same 200 acres of grass pasture will provide a home for over 600 nesting pairs.
The highest quality habitat on your farm is a pasture area in a large bloc (more than 20 acres -the bigger the better) and away from trees, buildings and other sources of disturbance. Although hedgerows are promoted as increasing wildlife diversity, research has shown that these provide corridors for predators, and actually reduce nest survival for grassland birds. Grassland birds are going to select nest sites that are in the middle of large, open expanses of grass.
Our research also showed that we can dramatically increase both the total number of nesting pairs and nest survival in a paddock if we’re able to defer grazing between May 15 and July 1, when the highest number of nests are active. For our study, each cooperating farmer simply avoided grazing a cluster of paddocks totaling about 20 acres between mid-May and early July. These paddocks were rank and headed out by the time July 1 rolled around. Quality testing showed that they averaged 10-12% protein with relative feed values around 110 – dry cow hay at best. On the positive side, the re-growth in these paddocks had the best forage quality on the farm when they were grazed in August.
If grazing does occur during this period, disturbance of nesting birds can be minimized in grazed paddocks by moving the herd frequently and leaving more residual (4-inch minimum). Another tactic is to graze alternate rather than adjacent paddocks. This allows a pair whose nest is trampled to move over into the next, undisturbed paddock within their territory and build a new nest.
Yet another approach would be to seed down a few paddocks to native prairie grasses. These warm season species grow slowly in spring and are not ready to graze until early July, providing an undisturbed period in May and June for meadowlarks. Warm seasons have a number of challenges, including high-priced seed, a long establishment period and relatively low forage quality. But if you planted 20 or 30 acres to warm seasons, you’d not only meet the needs of ground nesting birds, but you’d have a reserve of forage ready for the next dry spell.
Probably the most promising solution is Art Thicke’s pasture fallow approach, because it combines bird benefits with pasture improvement. Each year Art outwinters his dairy heifers on a different group of paddocks that he feels are in need of some improvement. Large round bales are set out in rows in the fall, and the cattle are given access to them a few at a time by moving polywire.
By the end of winter, these paddocks are pretty beat up, heavily manured, and covered with waste hay. Instead of reseeding these areas, Art simply lets them rest. They re-grow through the early summer, giving the birds a place to nest undisturbed. By mid-summer the grass has gone to seed. Art mows it, and allows the heifers back in to graze what they will while trampling the rest.
Many people would look at this as a waste, but in Art’s experience it’s like putting money in the bank. The next year these are the most productive paddocks on his farm, with increased diversity of legume and grass species. The improved grass vigor and productivity from the fallowing, along with the fertility and organic matter added by the outwintering, can be observed for several years following the outwintering/fallowing period. And the meadowlarks are happy.
So, contrary to popular opinion, there’s no such thing as wasted pasture. Allowing a pasture to “get away from you” not only provides a place for grassland birds to nest, but gives your grasses and legumes a valuable rest. Even a short, four to six-week rest can translate into pasture benefits that include healthier root systems, increased soil organic matter, seed production, thickened swards and staggered growth across paddocks that results in improved forage utilization.
The results of our study suggest that an acre of pasture set aside for four to six weeks in May and June produces twice as many successful nests as one grazed under a normal, “intense” rotation. Any number of paddocks can be set aside, but the more you set aside, the greater the impact. Other guidelines include:
• create a single large refuge rather than multiple small refuges;
• position set-aside paddocks in the center of the pasture area, away from buildings and woods;
• select a pasture with high legume content to retain quality of late-harvested forage;
• set-aside areas can be grazed lightly before May 15;
• defer grazing between May 15 and July 1, although July 15 is better.
Like any other business, grass farming needs to be profitable. Yet most of us can afford to look at the bigger picture and consider some changes that improve our quality of life, as well as that of the wildlife that share our land – especially when the changes can yield long-term production benefits for your pasture. Over the long term, sustaining the environment and securing the productivity of the land are one and the same.
Laura Paine is the Grazing and Organic Agriculture Specialist at the Wisconsin Department of Agriculture, Trade and Consumer Protection. She can be reached at 608-224-5120.