Guest Post: We’re pleased to present the research of Cassandra Wilcoxen. Over the course of the past 3 years, Cassandra, a University of Illinois graduate student in the department of Natural Resources and Environmental Science, has been conducting research on PrairiErth Farm in Atlanta, IL. Her research has primarily focused on the effects of various farming practices on surrounding wildlife. The findings suggest a positive relationship between cover crops and bird populations. Read on below to learn more!
In my experience researching the effect farming practices have on wildlife, I have noticed a common trend among comments from farmers. They often note witnessing a decline in wildlife from their younger days; most notably game birds, such as Ring-necked Pheasant and Northern Bobwhite Quail. However, a whole suite of grassland birds that used to utilize the vast grasslands that once existed in Illinois have experienced population declines as well. Land conversion to agricultural production has nearly wiped out native habitat for grassland birds and tillage and herbicide practices have also rendered farm fields less suitable for birds to forage or nest in due to the lack of necessary vegetation structure. With the recent push to adopt cover crops to improve water quality and manage nutrients, researchers and farmers alike have wondered if cover crops are beneficial for wildlife.
Cover crops introduce more vegetation structure back onto the landscape during times of the year when the landscape is fairly barren. Spring bird migration coincides with the growing period of cover crops which gives rise to the possibility that those cover crop fields may be beneficial for birds during their migration. We know that birds are most stressed during their spring migration and that little habitat remains in the Midwest along their migration routes. If cover crop fields can serve as temporary habitat for birds to rest and refuel during their migration, it is possible to slow their population declines or at best to hold them steady.
After surveying birds in cover crop and non-cover crop fields for 3 years, I have observed the importance of additional habitat in an agricultural landscape. More birds were found in cover crop fields and cover crop fields hosted more diverse assemblages of species. With that in mind, we need to realize that not all birds are “equal” in the eyes of conservation; grassland birds are of higher conservation concern than habitat generalists due to their large population declines and their lack of natural habitat. As an example, the Eastern Meadowlark (grassland species) is of high conservation concern, but the American Robin (generalist species) is not. As far as game species, pheasants were found primarily in cover crop fields, but very few were detected during the surveys partly due to their cryptic behavior making them difficult to detect.
With my study, cereal rye was the most common cover crop, but there were a handful of fields with “cocktail mixes” that included various legumes and non-legume broadleaves. Evidence from my research suggests more species had greater abundances in cereal rye than cocktail mixes, but further research needs to be done on the type of cover crop or mix focusing on the vegetation structure created by each. In my study, the time of cover crop termination varied greatly due to farmer preference. Several farmers terminated at the first chance in the spring, but others waited until late May to allow more growth of the cover crops. Further research on the effect of cover crop termination and timing of termination on bird nesting will determine if cover crops are acting as an ecological trap or not.
Before my arrival at graduate school, I was not well acquainted with cover crops. I grew up surrounded by agriculture in central Illinois, but no one ever used cover crops; even now there are only a handful of fields that are green after harvest when I drive to visit my parents. The 2012 Agricultural Census reported 1 million acres of cover crops were planted across Illinois and the research arm of the USDA has shown an increased adoption of cover crops since then. With the increased acreage, the potential impact on the bird community has also increased; 1 million or more acres is nothing to sneeze at. The use of cover crops possess as an important opportunity for wildlife conservation and agriculture to work together for a win-win situation.