Breeding Bird Revival– After Habitat Restoration

On two June mornings, I recorded birds along a transect in the gloomy oak woods of Somme East, in 2002 and 2006. Birds were few. Similar monitoring in 2016 and 2017 told a different story. The results, before and after restoration, (combining two years of data in each case) are shown below: 

	Year	# of birds	# of species
Before restoration	2002/2006	15	8
After restoration	2016/2017	112	26

Many years earlier, before we’d done much restoration in Somme Woods, I approached excellent birder Jeff Sanders and asked if he might be willing to monitor the breeding birds there. Jeff is highly-respected and dedicated, though not always an optimist. He checked out the place and, understandably, turned me down. “What’s the point of monitoring birds where there are no birds?” he asked. 

I had confidence in the future. As it turned out, however, the habitat improvements came slowly. More than a decade passed before even a few acres were well under way. But there were clues. When initial stewards Drew Ullberg and Tom Murphy cut the first Somme Woods brush, in an area of beautiful old oaks, our first pair of blue-gray gnatcatchers moved in and wove their charming little nest. A year or two later, in the middle of another small area where Drew and Tom cut over-dense pole trees, their work was honored again, this time by our first Cooper’s hawk nest. The gnatcatchers and Cooper’s seemed to vote for restoration. Indeed, most birds don’t try to raise a family in an invasives-clogged oak woods, degraded by lack of fire. (See Endnote 1 for a description of this woods – before and after  restoration.) 

Blue-gray gnatcatcher gathering nest material.
Breeding gnatcatchers were our first indication that we were on the right track.
Photo by Jerry Goldner.

In the western part of Somme Woods, where Drew and Tom began in 1989, the vegetation had been gradually recovering, and more and more species of breeding birds were returning. But we had no “before data.” My records show that it took me until 2002 to finally get up off my own duff and sample a transect through the eastern part of the woods (see Figure 1). There had been no habitat restoration then, but we hoped we’d get to it. 

Beginning at 6:00 AM on June 29, 2002, I hiked a loop as marked on the map, clipboard in hand, watching and listing. The basic principle is that you go slowly and quietly, write down all the birds you see, and, more importantly, all the birds you hear. You identify many more birds by sound than by sight. So, to do a breeding bird sampling transect, you have to be able to identify birds by their songs and chirps. (This takes some practice, but I highly recommend learning bird calls as a one component of appreciating the ecosystem. So much more is around you than you usually see!)

The six species I recorded are shown below (numbers of individuals in parentheses): 

Red eyed vireo (3) 

Great crested flycatcher (1) 

Black-capped chickadee (1)

Hairy woodpecker (1) 

Blue jay (1) 

Wood pewee (1) 

It then wasn’t until 2006 that I managed to sample this transect again. That time I recorded five birds of four species:

Downy woodpecker (1) 

Red-bellied woodpecker (1) 

Red eyed vireo (2)  

Blue jay (1)

None of the 2006 species were birds of conservation concern (see End Note 2). Jeff Sanders' question was still haunting me on that day. 

The map below has acronyms to indicate where I saw or heard a bird of a given species. For example, REV shows where I saw or heard the red-eyed vireo.

Breeding bird monitoring map from 2002

Compare the map above with the map from 2016:

 

Figure 2. Breeding bird monitoring map from 2016.

This change is a triumph of conservation. 43 birds of 24 species sing and eat bugs (mostly) in the June woods because hundreds of trained volunteers (mostly) and staff people have been doing successful and beautiful work. The many birds of conservation concern that have returned to raise families at Somme include American woodcock, northern flicker, red-headed woodpecker, and scarlet tanager. For the full list of birds and acronyms and a repeat of this map, see Endnote 3.

The restoration in the eastern two thirds of Somme Woods (the area mapped and discussed here) had begun when Forest Preserve contract staff in the early 2000s cut the buckthorn out of the southwestern 15 or 20% of the area mapped. Some of this limited work had been done by the time of my 2006 monitoring, but the canopy was still dark from maples and basswoods. A second round of funding and contractors cut some pole trees from this same area, but the ground beneath remained dark and bare in summer, and, though I have no data, my impression was that little natural vegetation or birds revived or returned.

Beginning in 1997, under the leadership of steward Linda Masters, more ambitious restoration had been slowly working its way east. By 2010, stewards reached this "Somme East" area – cutting over-dense pole trees and planting the herb layer (grasses and wildflowers) that are essential to a healthy oak woodland. (More detail on this in Endnote 4.) It would take more careful research than we have resources for to determine the relationship between a rich herb layer and oak woodland birds. But it is my impression that many bird species increase as the richness of the herb layer recovers. Among the species that spend a lot of time among the herbs are indigo bunting, yellowthroat, eastern bluebird, goldfinch, and blue-gray gnatcatcher. Also many woodpeckers, flycatchers, hawks, and owls seem to get a lot of food from the herbs and the species that eat them. Although most people think of scarlet tanagers as treetop birds, in Somme Woods I have also seen them hunting food among rich grasses and flowers.

Long ago, as it seems to me, in the early days of restoration, we focused on the vanishing prairies. We cut the trees and shrubs that were shading out the prairie plants. By doing so, we saved a lot of rare plants and animals (especially invertebrates). But we also destroyed the habitat of others. Judy Pollock (of the Bird Conservation Network) and Alan Anderson (of Chicago Audubon Society) deserve credit for encouraging us to notice the loss of rare shrubland bird habitat in some areas. At Somme Prairie Grove today (immediately west of Somme Woods), some of our most beloved (and bird-filled) areas are our increasingly-natural shrub thicket areas. They support such species as the orchard oriole, brown thrasher, field sparrow, cedar waxwing, black-billed cuckoo (in some years), yellow warbler, willow flycatcher, and many more. 

The great crested flycatcher nested in Somme Woods before restoration began.
We wondered: would it still be there after all the habitat changes?
Photo by Jerry Goldner. 

It seemed like the next logical step was a focus on oak woodland birds. Since the natural prairies, savannas, and woodlands of the tallgrass region were all at death’s door when restoration began; and since most animal species require more acreage than the early “test plots” that were successful for plant restoration; and since good quality restoration may take decades – we are only just beginning to learn what natural richness these ecosystems are capable of recovering. As our techniques improve and our resources increase (see Endnote 4), we’d like to hypothesize that we might reach the sort of richness documented for Somme Woods by Frank Woodruff in 1908 (see http://woodsandprairie.blogspot.com/2017/12/the-unexpected-discovery-of-somme-woods.html). The northeastern 75% of the area covered by this report saw no restoration at all before 2014. The increased avian richness here in just three years is inspiring to many.

Will we soon be seeing nesting screech owls, cerulean warblers, chats, redstarts, and thrashers? Or will we see them decades hence as the community of plants, invertebrates, herptiles, and birds continues (we hope) to improve? Or will we see current nesting birds drop out? Time will tell us. (At least it will if we keep studying the biota.)

We badly need more and better studies to compare a variety of approaches – to help us make better conservation and habitat management decisions. We need more generous leaders and volunteers of all kinds. Conservation also needs more resources, understanding, and spreading of the word. (See opportunities at https://sommepreserve.org). Everyone’s invited. Thanks for your interest.

PS: Since this post is already too long, many additional details will be relegated to a subsequent post that may be entitled something like “Qualifications, Justifications, and Fun Details.”

Endnotes

Endnote 1

At Somme Woods, invasive species had darkened the habitat into nearly a “bird desert” in most areas. There were few grasses, wildflowers (except brief spring ephemerals), and few young oaks. The ground in summer was mostly bare dirt or seedlings of buckthorn or maple. Sadly, this state was common in this region’s oak woods. 

A natural maple woods can be a fine habitat, but we have only small pockets of that in Illinois. It’s typical to our east (including southeast and northeast). Maple forest birds include wood thrush, ovenbird, and hooded warbler. 

The scarlet tanager nests in mature woods, whether oak or maple.
It feeds its young on insects, like this one is gobbling, that would otherwise degrade the forest.
Woodlands without birds are not healthy woodlands.
Photo by Jerry Goldner. 

Most of the Chicago region was naturally prairie, oak savanna, or oak woodland. Sunny, grassy, flowery (and sometimes shrubby) – oak woodlands depended on frequent fire. The birds that ate the kinds of insects, seeds, and fruits growing in those sunny woods are in many cases declining and have few other places to go. These birds include the American woodcock, red-headed woodpecker,  northern flicker, and ruby-throated hummingbird – all of which have returned to the areas of Somme Woods that are under restoration, sometimes only after many years. Also returning or increasing are some species that might be found in both maple and oak woods, including the great crested flycatcher, wood pewee, yellow-throated vireo, and scarlet tanager. 

For some "before and after" photos of Somme Woods restoration, skip the first (prairie) photo, and check out the next few at: Six Minute Talk (on conservation success).

Endnote 2

Bird conservationists have a variety of lists that help habitat managers focus on the species that need help. Robins and downy woodpeckers are fine birds, but they don’t seem to need special conservation help. American woodcocks, northern flickers, red-headed woodpeckers, and scarlet tanagers need higher-quality habitats. We are especially happy when our habitat restoration attracts such species.  

The great crested flycatcher, hairy woodpecker, and wood pewee – recorded in the 2002 sample – depend to some degree on specialized quality habitats. One concern we have about restoration is whether existing birds of conservation concern will thrive in the changed habitat as it is being restored. 

Endnote 3

On June 3, 2016, 43 birds representing 24 species were recorded along the Somme east footpath. They are listed below – alphabetically by acronyms – to make it easier for you to check what was where (with a repeat of the map, below), if you wanted. (In parentheses is the number observed.) 

BCC     Black-capped Chickadee (1)

BJ        Blue Jay (4)

BGG    Blue-gray Gnatcatcher (1)

BO       Baltimore Oriole (1)

Cow     Cowbird (1)

DW      Downy Woodpecker (1)

HWo    Hairy Woodpecker (2)

GCF     Great Crested Flycatcher (2)

GF       Goldfinch (1)

GHO    Great-horned Owl  (1)

GK       Grackle (1)

IB         Indigo Bunting (5) 

NF       Northern Flicker (1)

R          Robin (3) 

RBW    Red-bellied Woodpecker (1) 

REV     Red-eyed Vireo  (3)

RHW   Red-headed Woodpecker ()

RTHk   Red-tailed Hawk (1)

ST        Scarlet Tanager (3)

SS        Song Sparrow  (2)

WD      Wood Duck  (1)

WP      Wood Pewee (3)

WBN   White-breasted Nuthatch (2)

YTV     Yellow-throated Vireo (1)

Birds recorded on June 2, 2017 that were not recorded on June 3, 2016:

EB        Eastern Bluebird

CY        Common Yellowthroat

Other birds that we saw commonly through the nesting season, but were not recorded on these two transects:

CH       Cooper’s hawk

AW      American Woodcock (males performing courtship flights; unfledged chicks observed in multiple areas)

Hum    Ruby-throated Hummingbird (commonly seen wherever red flowers were blooming; seen performing courtship flights)

Thus, according to this data, no breeding species were lost from the oak woods – and twenty species were gained. 

Endnote 4

This report covers the area within and surrounding the Somme East footpath – a loop trail covering 2.1 km or 1.3 miles. It does not cover the "Little Skokie" area, east of the narrow, easternmost edge of this trail. This area had not been under restoration and was distinctly different from the oak woods that this study covered. It was dense brush under dead elm and ash trees in the North Branch floodplain. 

It did not exist until 2014, but my memory (and the maps I made) suggest that those two earlier bird transects generally followed the same route as the current footpath. (Its course follows the way a person would walk, to avoid crossing wetlands more than needed.) 

We continue to monitor this transect. An update of the table that began this opost is shown below:

The people who constructed the Somme East path and did most of the restoration in this area are the intrepid volunteers of the Somme Woods Community, which started with a recruiting “kick-off” in 2014 (credits below). Since that time, ten new “Zone Stewards” have been leading group “workdays” most every weekend, and special projects are under way on many other days. 

Somme Woods restoration by volunteer stewards typically starts with cutting and herbiciding the stumps of buckthorn, oriental bittersweet, box elder, maple, basswood, and other species that are unnatural to (or now overabundant in) the oak woods. The “native trees” we cut are typically “pole trees” – tall, mostly leafless trunks with narrow tops that are fighting to reach the light. Maples and basswoods usually win this race. Many dead young oaks, which don’t survive in this little light, stand among them. We also cut many red oaks and hickories (sometimes herbiciding the stumps and sometimes leaving them to re-sprout like shrubs) when they’re too dense for reproduction of the oldest trees, which are generally white and bur oak (and swamp white oak in wetlands). Our goal is to increase light levels sufficiently for oak reproduction, at least as the older oaks die.

Our thinning of pole trees was probably more extensive than most woodland restorations but was less ambitious than some interesting efforts underway by the Lake County Forest Preserves. (It would be interesting for these efforts to be compared scientifically – with each other and also with the good work being done at Busse Woods, Deer Grove, and elsewhere by the Cook County Forest Preserve staff, partnering with Openlands at Deer Grove.) 

Our brush and tree cutting is mostly done in late fall and winter. We spend much of the summer and early fall gathering seeds of hundreds of species of grasses, sedges, wildflowers, and shrubs, which we broadcast in the areas thinned to reduce shade. We try, especially in the initial stages, to burn most areas at least every second year. This burning kills the seedlings of invasive trees and encourages a thriving herb (grass and wildflower) layer. It rarely damages the old oaks.

Indigo buntings are not thought of as forest birds, but they're one of the most common species
of our newly restored oak woods, even in areas with few shrubs. We have much to learn (and appreciate).
Photo by Lisa Culp Musgrave. 

What is the best way to manage the shrub component of oak woodlands? This is a question that should not get a one-size-fits-all answer. Some natural woodlands were largely free of shrubs, and these were important habitat for many bird (and other) species. Other woodlands (or areas of woodlands) had plentiful shrubs, on which other species depended. At Somme, one of our ponds is bordered by a thriving thicket of willow and silky dogwood, but when we started most shrubs had been lost from most areas (as was documented for woodlands generally by Marlin Bowles of the Morton Arboretum in a study for Chicago Wilderness). I remember hazel in Somme Woods from long ago, but we found none to protect during the restoration process. The only upland shrubs we found in any numbers were black haw (Viburnum prunifolium). These were mostly pitiful, light-starved survivors just a few inches tall (although often spreading over areas ten to fifty feet in diameter). To allow these thickets to recover, we have remedially raked around them to protect them from fires and caged some to protect them from the deer. 

Credit for the ambitious work of the expanded Somme Team (starting in 2014) goes initially to Friends of the Forest Preserves, Audubon Chicago Region, Friends of the Chicago River, and to the Forest Preserve District which helped train the new stewards and to fund organizer Josh Coles. The Woods and Prairie Foundation funded organizer Cecil Hynds-Riddle. 

The speed and quality of the restoration has continued to benefit mightily from Forest Preserve staff and contractors who conduct the prescribed burns and hire contractors (who spray large areas of buckthorn re-sprouts after areas are first burned, to ready them for the next conservation steps. 

But the real credit goes to the volunteers, especially the Zone Stewards: Eriko Kojima, Jim Hensel, Karen Glennemeier, Linda Masters, Matt Evans, Paul Swanson, Sai Ramakrishna, and Stephanie Place.

If you’d like to learn more about the work of the stewards, check out other posts in this blog and the two Facebook pages and other resources at https://sommepreserve.org

 

Gnatcatcher on nest - beautifully woven of spider silk and camouflaged with lichens.
Neither the gnatcatcher nor this hawthorn tree can survive in the dense shade of unburned woodlands.
They depend on more light - like so many oak woods plants and animals.
Photo by Carol Freeman.

First published April 15, 2018
Additional info added to Endnote 4 on May 9, 2022