The most important overall conservation goal for the 70-acre Somme Prairie is the restoration of its original prairie community – as large and fully diverse as possible. The birds are just one part of that community, but our main goal today is to focus on the birds part.
The basic bird-conservation objective is a large and unbroken grassland of good structure for breeding prairie birds, especially Henslow’s sparrow, dickcissel, sedge wren, savanna sparrow and possibly meadowlark.
Currently no prairie birds nest in Somme Prairie. But with increasing size and quality of habitat, breeding birds can be expected, in time. Currently, some prairie species breed at Air-Station Prairie (a few miles to the south) and Willow-Sanders preserve (a few miles to the southwest).
Would we be wise also to save shrublands here? No. For a site of this size, a single focus on grassland bird habitat is far superior to a compromise that would attempt to restore both grassland and shrubland. Other sites (including the adjacent Somme Prairie Grove) are successful and superior for shrubland bird conservation. More importantly, shrubs are a main threat to grassland birds – and challenging to manage. The agreed-on best strategy here is for the entire site to be restored as prairie.
But the major first-step threat here is shrubs and trees. When just a foot or two tall, shrubs are not in themselves a detriment to the grassland birds. But, in two or three years, between burns, woody plants with well-developed root systems tend to grow sufficiently to shade out the species of grasses and other conservative plant diversity that make for successful grassland bird nesting habitat. The plan is to treat shrubs, trees, invasive weeds, and seed planting in a step-by-step process. (See Endnote 3.)
Another principal threat is aggressive forbs such as tall goldenrod (Solidago altissima) and saw-tooth sunflower (Helianthus grosseseratus). These and other rank species can create a vegetation structure that blocks or retards the desirable establishment of natural prairie. Such “thug” vegetation is also not nesting habitat for most grassland birds. These areas frequently do not burn under the moderately flammable conditions of most controlled burns, as the fuel quality is low. The rank species are thought to obstruct better quality vegetation by shading it out and possibly by emitting chemicals from their roots that inhibit the growth of other species. One solution to this problem that has been effective in some cases is to seed diverse prairie vegetation and then mow the rank growth when it becomes too dense for the survival of desirable seedlings.
|The new Forest Preserve plan (above) shows Somme Prairie outlined in red, Somme Prairie Grove in orange, Somme Woods in yellow and green, and Chipilly Woods in blue.|
Relative conservation priority of shrubland, savanna, and prairie birds: They’re all important, but the prairie species are a higher priority, especially for Somme Prairie. Birds of shrubland and savanna are second priority.
We were entertained during our walk in Somme Prairie by a merlin (an uncommon mid-size falcon) which was being mobbed by blue jays in between bouts of the feisty merlin harassing a kestrel (a smaller falcon) and a sharp-shinned hawk. Perhaps this performance was a good omen for our bird conservation planning efforts here.
The planning session on bird conservation was assembled by Becky Collings and Laurel Ross. The full roster for that field meeting included:
In case "model of collaboration" sounds Pollyanna to anyone, let me hasten to assure you that "collaboration" does not mean an absence of problems. It means we all pitch in, respect each other, and work problems out, as best we can. Good work goes forward, and we all contribute.
|Step one, as seen from Dundee Road, looking north, with the small brush clearing just completed. The existing prairie is that pale horizontal line behind the trees.|
Photo by Forest Preserve resource project manager Troy Showerman.
Does this post make too much of a fuss over birds, compared to the rest of the ecosystem? Yes, but. Birds often rightly get extra attention because the data for them is especially clear and strong. We know better how big preserves need to be (and what vegetation structure needs to be) for bird conservation than we do for most other species. Part of the reason for that, is that people have done more research on birds, in part because they have more constituency and support. Birds bring more supporters to conservation efforts than do rare walking sticks or snakes.
John McCarter, Wendy Paulson, Arthur Velasquez, and Eric Whitaker: co-chairs of the Next Century Conservation Plan Commission – along with the scores of people who contributed to the planning process. And forest preserve President Toni Preckwinkle who coordinated the adoption of the plan.
Dozens of Forest Preserve staff and contractors as supervised by John McCabe who has much upgraded the professionalism of the Forest Preserve’s Resource Management Division.
Volunteers by the hundreds, including Somme Prairie co-steward Lisa Musgrave and Eileen Sutter who, with many leaders and volunteers, has headed up the seed-gathering crews of the North Branch Restoration Project.
Jeanne Muellner who took the great photos of the Henslow’s sparrow and the dickcissel at the Orland Grassland, where they both thrive in restored habitat.
Thanks for proofing and edits of this post to Becky Collings, Troy Showerman, Lisa Musgrave, Eriko Kojima, and Kathy Garness.
For an introduction to Somme Prairie Nature Preserve, check out captions and photos of Somme Prairie from a walk in late May - and a set of very different photos and comments from July.