On the Heron Rookery Trail

On our trip to the Indiana Dunes National Lakeshore on Mothers’ Day weekend, we walked on the Heron Rookery Trail.  This trail runs along the east arm of the Little Calumet River, some distance inland from the large sand dunes by the lake.  On the north side of the river is the rookery, home to the nesting sites of about 100 pairs of great blue herons, which have come to this area for 60 years.  On the other side of the river is a trail, from which visitors can look for the herons, and enjoy a lovely stand of bottomland forests.  The trail runs through a fragment of forest that is about a mile long and half a mile wide, situated in the middle of agricultural land a couple of miles away from the main body of the National Lakeshore. The Indiana Dunes area has been conserved by purchasing patches of habitat that have been knitted together into one administrative unit, and there are a few other outlying patches of the park like this (another one is Pinhook Bog, a quaking bog that we have also visited).

We’d been on this trail last year in the summer and found it had a number of interesting wildflowers.  It also has a reputation as a good place for spring wildflowers. We started out at the east end of the trail, as we had last summer, where there are numerous large sycamores, and some savanna-like patches quite near the river.  We didn’t manage to see any herons (I think you need a ranger along to point them out).  There were a lot of wildflowers to look at, though – 3 species of violets, purple deadnettle, spring beauty, lots of bedstraws, woodland phlox, cow parsnip starting to come up but not blooming yet.  But the weather was a little dicey, and there wasn’t quite the profusion of wildflowers that we’d been expecting.  So we walked back to the parking lot, by which time the weather cleared up a little.  On the spur of the moment, we decided to try starting at the west end of the trail, where we’d never been before.

Purple Deadnettle (Lamium purpureum) and Common Blue Violet (Viola sororia)

After a short drive, we came to the west end parking lot and got out the camera gear. Right away it was obvious we were in a very different environment.  There was an absolute riot of typical Midwestern spring wildflowers all over the forest floor.  Three Trillium species, rue anemone and false rue anemone, mayapple, dwarf ginseng, blue cohosh, wild ginger, more spring beauty, wild ginger, and jack-in-the-pulpit were in bloom.  We found leaves of Hepatica, though the early-blooming flowers of this species were already gone. Bloodroot fruits were in evidence, but the plant was no longer in bloom. The contrast with the west end of the trail was striking.  We also noted that the tree species had changed. Instead of sycamores, there were beeches and maples, as well as tulip trees.  Beeches and maples are characteristic of the final stage in succession in this area, which suggests this area has been undisturbed for a long period. 

Declined Trillium (Trillium flexipes), Red Trillium or Prairie Trillium (Trillium recurvatum)

and False Rue-anemone (Isopyrum biternatum)

Dwarf Ginseng (Panax trifolium)

The soils along the Little Calumet River are all poorly drained and flat.  Different soil types appear in different parts of the area, which may account for the contrasting forest types at the different ends of the trail.  We had noticed last summer how wet it was at the east end of the trail, although the west end also had some large areas of standing water on this trip.  These wet soils are likely what has saved this patch of forest, and others along the Little Calumet River.  They are simply too damp for farming, so they have not been cut down, which has been the fate of most of the native forest.  Because the forests were relatively undisturbed, this rich spring wildflower community has been allowed to grow into its present diverse and highly developed state. The lovely scenes in this habitat fragment are a reminder of what can happen when we leave natural areas undisturbed.  It stands as an inspiration for all our conservation and preservation efforts.

Wild Ginger (Asarum canadense)

Charlotte