Friday, August 3, 2012

Sparrows of Nelson Lake

One might imagine that the vast prairies of the middle western United States have always been there, but in the geological time scale they are relatively new, the product of global warming.  The last glacial period reached its peak only about 18,000 years ago. Ice covered most of Canada and extended down into what are now the north Atlantic states and south to around the Ohio River in the Midwest.

Studies of the age and species of pollen collected at nearby Nelson Lake provide an interesting picture of the history of the prairie. As the ice receded over the next 2,000 years the area around my second home in Illinois resembled present-day Arctic tundra, covered by low-lying sedges and scattered evergreen trees. Humans crossed over to North America from Asia via the land bridge before the oceans rose to separate the continents.

Spruce forests then proliferated over the next 5000 years. The soil remained moist, favoring hardwoods such as ash and elm that began replacing the evergreens.  About 11,000 years ago, as rainfall diminished, oak and hickory appeared, and the pollen record indicates that grasslands developed in forest openings. Beginning around 6,500 years ago, with the onset of a 3,000 year dry period, lightning-caused fires greatly enlarged the grasslands as they flourished and evolved into the landscape that greeted the first European settlers. Following this, as prairie was tilled and forests were cleared, exotic plant pollens appeared. Native grasses and plants declined.

A view of the old silo and restored tall grass prairie at the east entry of the Nelson Lake Marsh/Dick Young Forest Preserve, Kane County, Illinois. Ahead, a woodland borders the east shore of the lake.

East Entrance Nelson Lake 20090818

There are wetlands along the southern and western edges of the lake, as well as in several potholes.

NelsonLakeOverview 065

Prairies extend to the north and west of the lake. These 800 acres of former crop and grazing lands are actively managed by mowing and controlled burns to restore them as nearly possible to their original condition. In fall the grass turns a golden brown and is a rich source of seeds for overwintering wildlife.

Looking east from sign 20100315

Over the course of the seasons, the diverse habitat attracts a stunning variety of bird species, from the large...

EagleLanding20091001 the small.

Ruby-throated Hummingbird 20090813

 Sandhill Cranes breed in the wetlands.

Sandhill Crane SOOC cropped 20100415

A Cooper's Hawk soars overhead. The prairie suddenly falls silent.

Coopers Hawk 20090917

Sparrows are among my favorite photographic subjects. Catching them out in the open and in good light requires patience (and I must admit that at my age I don't mind the opportunity to rest a bit while I wait). Several species of sparrows breed in the grasslands and marginal savannas. Song Sparrows are most abundant.

Song Sparrow 2-20120529

Savannah Sparrows often forage on the trails.

Savannah Sparrow 2-20110707

Tiny Grasshopper Sparrows are less often seen out in the open. Their numbers seem to depend upon the availability of short grass in areas that had been recently mowed or burned.

Grasshopper Sparow 20080603

A few Henslow's Sparrows breed in the prairie in small clusters.

Henslow's Sparrow SOOC crop 20100630

The habitat requirements of this threatened species are very demanding, as they will not build a nest in a recently cleared area. Henslow's Sparrows select nesting areas that have a couple of  years of dead grass litter accumulated on the ground. They abandon the site after two or three years, when taller weeds and saplings start invading. They also require an expanse of tall grass prairie surrounding their breeding areas, and will not nest in fragmented habitat.

Henslows Sparrow crop 20120620

Henslow's Sparrows are more often heard than seen, as they sneak through the grass like mice. They look as if they are putting great effort into their song, which comes out sounding like little more than a squeak.

Henslow's Sparrow (Ammodramus_ henslowii) 5-20120529

Field Sparrows prefer the woody edges of the prairies.

Field Sparrow 20110707

Swamp Sparrows build their nests in the marshes.

Swamp Sparrow 3-20100420

Chipping Sparrows are most commonly found in the woodlands.

Chipping Sparrow 20100515

Among the non-breeding sparrows, I have seen a few Lincoln's Sparrows.

Lincolns Sparrow 20101029

White-crowned Sparrows invade as winter approaches, and stay until spring. (This photo is my favorite of the species. I took it in Alaska. All the other images are from the Nelson Lake area.)

White-crowned Sparrow 20110617

White-throated Sparrows favor  the shrubby margins of the woodlands.

White-throated Sparrow 20081004

Fox Sparrows can be elusive, rummaging through the ground litter or hiding in the trees.

Fox Sparrow 2-20101017

This [I thought was] is the only Clay-colored Sparrow I have ever seen at Nelson Lake. [See Steve's comment below. The corrected identification is Swamp Sparrow-- sorry about that, but in the field its light breast and dark "mask" led me astray, not to mention the fact that it was in a thicket out on the prairie. Ken]

Clay-colored Sparrow 2-20101007

Now take a good look at this-- will you ever again call sparrows just LBJs*?
White-throated Sparrow SOOC heavy crop 20100419

* "Little Brown Jobs"-- NOT

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  1. Fantastic post. Love the geologic history of the area and the wonderful series of sparrow shots. I have yet to see half of these.

  2. Great history and great photos! Very nice post Ken.

  3. Wonderful post learning the history of the formation of the prairies. I never knew there were so many sparrows, you really are a very patient photographer, sparrows are never still. Loved your shot taken in Alaska, it has beautiful blend of colors. Cheers, Ruby

  4. Great stuff Ken. I love the Sparrows too, and I love your photos! It looks like you've got some prime sparrow sites nearby!

  5. Coincidentally, Henslow's Sparrow has just been named ABA Bird of the Week!

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  7. I should have mentioned that this BirdNote broadcast features Henslow's Sparrow and other birds of the Tallgrass Prairies:

  8. I was fascinated by the history of the prairies and loved seeing all the different sparrows!

  9. Amazing shots of the Henslow's. Ive only seen them once, and would love to make that happen more often. I really like the Lincoln's image as well...they are an underrated bird.

    I hate to be "that guy" but I think the Clay-colored is a young Swamp Sparrow. Clay-colored has a much lighter ear patch, with a dark border all the way around it.

  10. Oh, Steve, you would spoil my fun. I think you are correct. Take a look at the shots I just posted on FLICKR at

    They are all straight out of the camera and are best viewed in the original size. In the field I thought its breast was too clear and its "mask" too distinct for it to be an immature Swamp Sparrow, but as I examine some of the shots I see a suggestion of reddish color in its cap and wings, a bright white throat with some faint streaking on upper breast, so I now think I was wrong. Most likely a Swampie. Not sure it is an immature, as the face is quite light and the streaking is faint. I shot these on October 7, 2010. Well, I'm still waiting to see that first Clay-colored at that location!

  11. Fantastic post, Ken! First of all, thanks for the geological information which I always find fascinating. And then thanks for sharing your superb photos! I had the opportunity to observe a Henslow's Sparrow in a meadow in Mass. It was apparently a lone errant bird and sadly its songs to attract a female went unanswered.

  12. Wonderful post filled with interesting information and stunning photographs! I will have to look into birding at Nelson Lake.