Bill Poole

Ducks Unlimited Canada

Compared to conventionally-tilled fields, zero tillage does provide improved opportunities for wildlife. What I'd like to do today is start right from the ground up in looking at why this is so. I'll be using the term "wildlife" in a broad sense to include more than just ducks, although waterfowl will certainly be mentioned in the discussion.

The improved surface cover conditions and slightly altered microclimates found at the soil surface in zero tilled fields provide a more hospitable home for insects. Over time, that should result in an increased insect population that has an appropriate balance between potentially harmful species and species that are beneficial to agriculture.

A larger insect population, in turn, provides an essential part of the habitat base required by higher forms of wildlife. Small mammals like shrews and voles and many bird species depend on insects as a primary food source. As insect populations increase, there may be opportunities for increases in populations of these other types of wildlife. We'll come back to the way those changes might affect ground-nesting birds -including some waterfowl species - in a moment.

Zero tillage can improve conditions for ground-nesting birds both directly and indirectly. Increased surface cover and reduced field disturbance provide direct benefits by increasing the amount of land area which can be used as nesting habitat for some species. A study which Wayne Cowan (1982) did just north of here at Minnedosa in 1977 and 1978 indicated a potential production of 25 broods of waterfowl per section on zero tilled land compared to 7 broods per section on conventional farms. Since spring-seeded crops were used in both years of that study, those results were only possible because the farmers involved actively avoided destroying nests during the seeding operation.

The value of spring-seeded fields as habitat for ground-nesting birds depends largely on the configuration of the seeding implement. Machines with wide row spacing and narrow, on-row packers are the most "wildlife friendly". If they are to be widely used, however, they must also be "farm income friendly" - providing yields at least equal to other seeders, lower draft requirements and so on. DU is currently helping to fund a research project with David Rourke at Ag Quest which is evaluating some of the agronomic aspects of wide row spacings.

Fall-seeded zero till crops can provide even greater benefits to ground-nesting birds. A North Dakota study by Duebbert and Kantrud (1987) 100ked at the use of no-till winter wheat fields by nesting ducks in 1984 and 1985. Although nest densities were low - 8 per 250 acres in 1984 and 6 per 250 acres in 1985 - nest success rates were 26% and 29% respectively. While those success rates may sound low, they were substantially above the 15% required to maintain population numbers and were higher than the rates which have frequently been found in other studies in different habitat types.

Zero till provides some direct benefit to ground-nesting birds for one primary reason; it provides a greater area for them to disperse their nests over. That makes it more difficult for predators to find the nests and increases the chances for a successful hatch.

Now let's go back to the indirect benefits to wildlife that I mentioned a few moments ago. We talked briefly about the fact that zero till can create conditions which may lead to increased populations of small mammals. Although it may not seem obvious at first glance, that can benefit ground-nesting birds. Those small animals are also prey for some of the predators - particularly foxes - that feed on nests. As the numbers of small mammals increase, they can make up a higher proportion of the food source for predators thus reducing the predator pressure on nests. Indirectly, a higher population of voles could result in improved populations of ground-nesting birds.

In addition to the agricultural benefits I'm sure you'll be hearing about from some of the other panel members, zero till can provide opportunities for wildlife by creating improved habitat conditions for a wide range of species.

REFERENCES

Cowan, W.F. 1982. Waterfowl Production on Zero Tillage Farms. Wildlife Society Bulletin. 10:305-308.

Duebbert, H.F. and H.A. Kantrud. 1987. Use of non-till winter wheat by nesting ducks in North Dakota. Journal of Soil and Water Conservation. 42:50-53.