Sketching Mayslake’s Trophic Structure

by Carl Strang



As I familiarize myself with an area, there are several big conceptual nets with which I try to comprehend that place. These lack fine detail, but provide first approximations that can be filled in as I learn more. One conceptual frame for an area is its general topography and drainage pattern. Another is the general human history and influence on the land. A third is the mosaic of vegetation communities. A fourth is the geology. Today I want to focus on yet another frame, the trophic structure. This is a broad-brush first stage in constructing a food web. The trophic levels of an ecosystem are the steps through which energy “flows” (the quotes are a field ecologist’s recognition that abstract food pyramid diagrams, and the arrows that connect food web elements on the page, cover up a certain amount of desperate flight-and-chase, crunching, and screaming. All our lives continue at a cost, but I digress).


In earlier posts I have documented some of Mayslake’s animal life. The top predators mentioned already include coyotes and mink. A day seldom goes by without me seeing a red-tailed hawk or two. I also have seen tracks of great horned owls, and the Mayslake staff have observed these birds at that preserve for years.


Great horned owl tracks, Mayslake

Great horned owl tracks, Mayslake



Note that in this photo, the great horned owl tracks are farther apart than in the photo I took on the Christmas bird count. This is the more typical spacing, but again there is that odd asymmetry in the toes.



Mayslake’s part-time predators include raccoons and skunks, among others.


Skunk tracks (far right), Mayslake

Skunk tracks (far right), Mayslake


On a smaller scale, I have seen tracks of short-tailed and masked shrews, which are predators of small animals including invertebrates but also mice.


Common plant-eating animals at Mayslake include deer, mice, voles, squirrels, chipmunks and cottontail rabbits. There are also the wandering winter birds eating seeds (as in the paper birch account).


Rabbit trail, Mayslake

Rabbit trail, Mayslake



Over 50 kinds of trees, shrubs and vines, along with uncounted herbaceous plants, are the preserve’s primary producers, solar energy harvesters that form the foundation for the whole trophic shebang. In the warm months, each kind of plant hosts several insect consumers that in turn are food for predators including an influx of migrant nesting birds.


And let’s not forget the scavengers. Some of the animals listed already, the coyote and skunk for instance, along with opossums such as the young one whose tracks I saw in the southern part of the preserve recently, are happy to clean up the odd dead carcass they encounter.


Mayslake is not a huge property as forest preserves go, but it’s big enough and diverse enough in vegetative structure to support a complex community for which I have here provided only the broadest of introductory sketches. More detail to come.

1 Comment

  1. January 25, 2009 at 2:12 pm

    […] an earlier post  I mentioned that I think food chains are abstractions. While that is true, sometimes you find one […]

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