Neighborhood Nature

Our Family's Nature Blog

A Red-tailed Hawk is Hunting the I-290 Median! January 6, 2010

For the past three days a Red-tailed Hawk has been hunting from lamp posts at the end of our block:

Red-tailed Hawk, I-290 median, south Oak Park, Illinois, January 5, 2009.

The Red-tailed Hawk sits on lamp posts at the end of our block. The posts are in the grassy median between the east- and west-bound lanes of Interstate 290 (also called the Eisenhower Express, the Ike, or the Congress).

I first noticed the hawk on Monday while I was walking to Maze Library across the Ridgeland bridge. I saw the hawk flying from post to post, approaching me from the east. Once it got close enough, I recognized it as the pale-bellied Red-tail that I’ve seen in Columbus Park, about a mile east on the expressway:

Red-tailed Hawk, I-290 median, south Oak Park, Illinois, January 5, 2009.

The Red-tailed Hawk's chest and belly look distinctively pale compared with other local Red-tails.

A few weeks ago I watched this hawk hunting Mourning Doves behind the Refectory at Columbus Park — it failed rather miserably. On Monday the Red-tail made a pass at Pigeons roosting on the apartment building at the end of our block — another fail. Then it flew directly at the large Red Cedar in our alley where House Finches and Goldfinches roost — the small birds scattered, and the hawk was not even close to scoring a meal.

Since then, every time I see the hawk it’s sitting on a lamp post:

Red-tailed Hawk, I-290 median, south Oak Park, Illinois, January 5, 2009.

The I-290 Red-tailed Hawk in south Oak Park.

It’s always look down, at least when it’s not looking at me. It’s probably hoping for a glimpse at a potential meal — a mouse, perhaps a rat, maybe a rabbit brave enough to cross three lanes of traffic.

I hope the hawk is more successful with mammals than it is with birds. And I hope it understands the dangers of speeding cars and trucks.

Red-tailed Hawk, I-290 median, south Oak Park, Illinois, January 5, 2009.

The I-290 Red-tailed Hawk on a distant lamp post.

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Red-tailed Hawks often hunt along highway right-of-ways. Here are some links that discuss this aspect of Red-tail natural history:

 

Our Chicago Urban Christmas Bird Count Data 2009 December 20, 2009

The boys and I spent the entire day conducting our part of the Chicago Urban Christmas Bird Count. Nationally, Christmas counts are organized by the National Audubon Society. The Chicago Urban count circle is sponsored by Evanston North Shore Bird Club and Chicago Audubon Society, with Jeff Sanders as the compiler.

Our part of the count covers the following areas in Chicago and Oak Park: Birding on foot in Columbus Park, Douglas Park, and south Oak Park residential areas; feeder watching at our home on South Elmwood in Oak Park; and driving through industrial and residential areas in between these sites.

This year, birding from sunrise to sunset, we found a total of 26 species. The highlights of our day included:

  • Four species of hawks, including a MERLIN at Columbus Park (photo below), 2 AMERICAN KESTRELS, 2 COOPER’S HAWKS, and 2 RED-TAILED HAWKS.
  • A WINTER WREN beside the Columbus Park lagoon (where we saw this species often through the fall — photo below).
  • An AMERICAN PIPIT at Columbus Park, in the same field where we saw a Pipt on December 11 (photo below).
  • A SWAMP SPARROW at Columbus Park (photo of its rump, below), plus 20 AMERICAN TREE SPARROWS (15 at Douglas, 5 at Columbus).

We were also pleased that WHITE-BREASTED NUTHATCHES put in 2 appearances, since we’ve been seeing them much more frequently this year. We also were happy to see a BLUE JAY, because they were common this summer, then mostly disappeared within the last few weeks. We were disappointed that overall sparrow numbers were down at Douglas Park, where the golf-course sanctuary often holds 50 or 60 sparrows this late in the year. And we were very sad that we did NOT see the Great Horned Owl that had been roosting near Austin in late November and early December. (We still hope it returns in time to be registered as a count-week species!)

Here’s our entire list for today, with count numbers:

Canada Goose    280

Cooper’s Hawk     2

Red-tailed Hawk     2

American Kestrel     2

Merlin     1

Herring Gull     1

Ring-billed Gull     5

Rock Pigeon     115

Mourning Dove     45

Downy Woodpecker     4

Hairy Woodpecker     3

Blue Jay     1

American Crow     9

Black-capped Chickadee     9

White-breasted Nuthatch     2

Winter Wren     1

American Robin     55

European Starling    350

American Pipit     1

American Tree Sparrow    20

Swamp Sparrow     1

Dark-eyed Junco     25

Northern Cardinal     21

House Finch     14

American Goldfinch  30

House Sparrow     180

We also have two count-week species so far for our areas:

1 Red-bellied Woodpecker  (seen in Douglas Park 12/17/09)

2 African Collared-Dove and/or African X Eurasian Collared-Dove (seen in south Oak Park 12/18/09).  We are soliciting input on these photos, taken on Dec. 18th — what do you think they are?

Here are some of Aaron’s photos from today:

Merlin, Columbus Park, Chicago, Illinois, December 20, 2009.

The Merlin roosted in several trees around the lagoon, but it was tough to get a good photo because of the distance and overcast skies. Note the back color, streaking on the side of the breast, and minimal patterning on the head (all of which we could see much better through our binoculars). Photo by Aaron Gyllenhaal.

Merlin, Columbus Park, Chicago, Illinois, December 20, 2009.

This shot, from even further away, gives another view of the Merlin's head. Photo by Aaron Gyllenhaal.

Winter Wren, Columbus Park, Chicago, Illinois, December 20, 2009.

Although it was hard to get a clear shot at the Winter Wren, a few times it hopped into the open, possibly to get a better look at us! Photo by Aaron Gyllenhaal.

American Pipit, Columbus Park, Chicago, Illinois, December 20, 2009.

There was a large, if late, migration of American Pipits to inland parts of Chicago earlier in December. We were happy that one stuck around Columbus Park for the Christmas Count! Photo by Aaron Gyllenhaal.

American Pipit, Columbus Park, Chicago, Illinois, December 20, 2009.

Here's a front-on view of the American Pipit. It was hanging out at the north end of the large ball field that fills the southeast corner of Columbus Park, sometimes visiting a seepage area that has some unfrozen water. Photo by Aaron Gyllenhaal.

Swamp Sparrow, Columbus Park, Chicago, Illinois, December 20, 2009.

Although we got good binocular views of the Swamp Sparrow's gray-patterned head, Aaron only got photos of its butt! Photo by Aaron Gyllenhaal.

We’ll post links to Ethan’s photos once he gets them online.

 

First Hard Freeze for Our Jars of Water December 7, 2009

Filed under: Experiments,Fall,Geology,Puzzles and Mysteries,Seasons,Water,Winter — saltthesandbox @ 10:22 pm
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Back on November 29th we started an experiment on our front porch, with four plastic jars filled with water. At the start of the experiment, the jars looked like this:

Water jar experiment, Day 1, November 29, 2009

Here's what the experiment looked like five days ago, before the temperature hit the freezing mark.

Now, here’s what the experiment looked like on Friday, December 4th, after the air temperature went below freezing, hitting 24 degrees Fahrenheit overnight:

Water jar experiment after a hard freeze, December 4, 2009.

Here's what the water jars looked like after a hard freeze. Three of the five jars had frozen overnight: A, B, and D. Also, we had added a fifth jar: In Jar E, the water that had been BOILED first, then cooled, put in the jar, and sealed with a lid that had NO holes in it. (Thanks to J of Science Museum of Minnesota for suggesting this addition to the experiment.)

Three of the jars had frozen water in them, including the jar with SALTY water. No one predicted that! The two jars that did not freeze were both sealed tight — there were no holes in their lids.

Here’s a closer look at Jar A, which started out as cold, fresh tap water, and was covered by a plastic lid with holes drilled in it:

Jar A (fresh water, started cold, holes in top), Decmber 4, 2009, 24 degreees F

A closer look at Jar A shows intersecting sheets of ice, more densely frozen closer to the top of the jar.

Jar B showed a similar pattern, although the sheets of ice were more horizontal than vertical:

Jar B (fresh water, started warm, holes in top), Decmber 4, 2009, 24 degreees F

Jar B also had sheets of ice, more densely frozen towards the top of the jar -- but the ice sheets were more horizontal than vertical.

Jar D was most surprising. I was expecting the salty water wouldn’t freeze, but the top part of the jar was frozen fairly solid. However, the bottom of the jar was not frozen, but had a bunch of bubbles sticking to the side of the jar:

Jar D (SALTY water, started cold, holes in top), December 4, 2009, 24 degreees F

In Jar D, notice the clear division between frozen water above and unfrozen water below.

So, that leaves us with two mysteries to solve:

  • Why did most of the water in the salty jar freeze?
  • Why did the water in the sealed jars not freeze?

I have some ideas, but I won’t tell you about them yet. However, I will give you one hint about the second mystery. Here’s what the lower part of salty Jar D looked like on December 2, 2009 — three days after the experiment started, but before the temperature dropped below freezing:

Jar D (SALTY water, started cold, holes in top), December 2, 2009, 37 degrees F

Here's what Jar D looked like three days after I had mixed in several handfuls of sidewalk salt, but before the first hard freeze. How can this help us understand why the top of the jar froze, but the bottom did not?

Feel free to tell us your ideas in the comments section (below) or on Facebook.

 

An Experiment with Freezing Water November 29, 2009

Filed under: Experiments,Fall,Seasons,Winter — saltthesandbox @ 3:39 pm
Tags: , , , , , , ,

The weather forecast says we’re headed into an extended spell of cold weather, with freezing temperatures predicted for the end of the week. So, it’s time to put some water jars on the front porch to see what happens. This year we’re going to be a bit more organized than usual and set up the jars as an experiment. There are reasons we’re setting it up this way, but we’ll let you try to figure out what those reasons are (with a few hints at the end of this post).

First, here’s our experimental setup: Four PLASTIC jars of water set on our front porch rail this afternoon, here in Oak Park, Illinois:

Water Jar Experiment Day 1, November 29, 2009, Oak Park, Illinois

Here are our four experimental jars of water (all made of plastic). Read the descriptions to see how they differ from one another. We started this experiment on November 29, 2009.

Jar A, on the far left, was filled with cold, fresh tap water. It’s lid has holes in it, so air can get in.

Jar B, just left of center, was filled with warm, fresh tap water. It’s lid also has holes in it, so air can get in.

Jar C, just right of center, also was filled with warm, fresh tap water. It’s lid has NO holes in it, so NO air can get in.

Jar D, on the far right, was filled with cold tap water, then a couple of handfuls of rock salt were added — the same kind of salt you may put on your steps or sidewalk when it snows. It’s lid has holes in it, so air can get in.

So, we are experimenting with the following variables:

  • Does the water start out cold or warm?
  • Is the water exposed to the air or not?
  • Is the water fresh or salty?

Why do we want to experiment with those variables? Maybe you can guess if you check out these blog posts from last winter:

And now, here’s the big challenge:

What do you think will happen to each jar once the weather gets really, really cold?

You will need a separate guess — or “hypothesis” — for each jar, A through D. You can list your hypotheses in the comments section, below, or send them to me by e-mail (eric@saltthesandbox.org) or Facebook.

Think hard, and good luck! (Or should I say, “good skill”?)

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Note: I revised this post later the same day to make it clear that the jars are made of plastic. (Although it might be fun to try it with glass some day. Fun in a Mythbusters kind of way….)

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To find out what happened on December 4th, when the air temperature dropped below freezing, please go here: https://neighborhoodnature.wordpress.com/2009/12/07/first-hard-freeze-for-our-jars-of-water/

 

Seasons of the Tulip Tree: Almost Full Circle November 22, 2009

Filed under: Fall,Plants,Seasons,Trees — saltthesandbox @ 1:25 pm
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We’ve been following a neighborhood Tulip Tree as it cycles through the seasons. The last time we posted photos was way back on June 18, when the seeds were green, but ripening. The seeds remained that way through most the summer, then gradually started turning brown. Once the leaves had turned bright yellow in late October, the seeds looked like this:

Tulip Tree seeds, Oak Park, Illinois, Octber 27, 2009.

The Tulip Tree seeds are framed by yellow leaves. Also note the duck-bill shaped bud to the left of the seeds.

Soon the leaves were swept off the tree by a wind-drive rain, and something — probably squirrels — found the ripened seeds to their liking. Here is one of the last remaining seed clusters, photographed in early November:

Tulip Tree seeds, Oak Park, Illinois, November 9, 2009.

This was one of the last seed clusters remaining on the Tulip Tree.

Once the seeds have all been eaten or fallen to the ground, the tree will be back to where it started last spring.

You can see our first photos of Tulip Tree buds at the bottom of this post from April 8, 2009.

Go here for our most complete post about Tulip Trees, which starts with the flowers and then goes back in time to how the tree looked as the buds were opening.

 

Cooper’s Hawk in the Brush Pile November 18, 2009

Filed under: Animals,Birds,Fall,Mammals,Seasons — saltthesandbox @ 12:41 pm
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For the third day in a row we had a juvenile Cooper’s Hawk trying to pluck House Sparrows from our backyard brush pile. For the third day in a row it came up empty clawed.

Here’s is Monday’s drama. The hawk kept trying to find a route to the very center of the brush pile, where a sparrow cowered on the ground:

Cooper's Hawk in the brush pile, Oak Park, Illinois, November 16, 2009.

Cooper's Hawk in the brush pile, Oak Park, Illinois, November 16, 2009.

Cooper's Hawk in the brush pile, Oak Park, Illinois, November 16, 2009.

Cooper's Hawk in the brush pile, Oak Park, Illinois, November 16, 2009.

Cooper's Hawk in the brush pile, Oak Park, Illinois, November 16, 2009.

As the hawk jumped down to the far south corner of the brush pile, the sparrow scrambled out from the north edge and took off, flying over the fence and through the neighbors’ yards. The Cooper’s Hawk followed as fast as it could, but gave up four backyards north. It flew back to our yard and landed on the fence, were it was greeted by a Gray Squirrel:

Cooper's Hawk facing off with Gray Squirrel, Oak Park, Illinois, November 16, 2009.

Juvenile Cooper's Hawk faces off with a Gray Squirrel. This time the squirrel blinked first, jumping down to forage while the hawk held its perch.

I thought we would be in for another bird-mammal confrontation, which our Cooper’s Hawks always seem to lose. Instead the squirrel calmly jumped into our backyard, where it resumed foraging for stray sunflower seeds.

Since then, we’ve seen the juvenile hawk on our brush pile at least once a day. Each time the sparrows wait until the hawk is on the south edge of the pile, and then they flee to safety.

 

Natural Leaf Prints on a Concrete Canvas November 9, 2009

Filed under: Fall,Plants,Puzzles and Mysteries,Seasons,Trees — saltthesandbox @ 9:20 am
Tags: , , , ,

For the past few weeks our neighbors have been raking and blowing fallen leaves into the streets to be hauled away to someone else’s compost heap. Soon all out trees will be bare, and most our leaves will be gone — only memories of a leafy summer will remain.

Or so I thought. Until I saw this:

Natural leaf prints, Maple, Oak Park, Illinois, November 1, 2009.

Naturally made prints of maple leaves on a concrete sidewalk.

Some leaves remained as ghostly stains on the sidewalks of south Oak Park! I found the first leaf prints after a week of wet weather had given way to the first dry day. Perhaps water-soaked leaves had been plastered to the sidewalk for days, leaching biochemical stains into the sidewalk cement.

The best individual prints were along this stretch of sidewalk:

This stretch of newer sidewalk, with widely spaced young trees, had the best individual leaf prints.

This stretch of newer sidewalk, with widely spaced young trees, had the best individual leaf prints.

The sidewalk here was pretty new, smooth and fairly flat, and the trees were small and evenly spaced. When leaves were scrunched instead of flat, or when sidewalk blocks were tilted, the prints were less than perfect:

Runny leaf print, Oak Park, Illinois, November 1, 2009.

This leaf was scrunched up in the middle, so the print was incomplete. And the sidewalk here was tilted, so the stain left a streak mark as it leaked out from under the leaf and towards the street. (These imperfections provide clues to how the leaf prints formed.)

When trees above were large or closely spaced, the prints were crowded together and often overlapped:

Lots of Maple leaf prints, Oak Park, Illinois, November 1, 2009.

When too many leaves were plastered on the sidewalk, their prints overlapped and blended together.

That must be why concrete street gutters are stained brown this time of year:

Concrete gutter stained brown by water soaked leaves.

Concrete gutter stained brown by mounds of water soaked leaves.

The first prints I saw were maple leaves — I wondered if other leaves could make prints, too. Searching the neighborhood sidewalks, I found some oak leaf prints, but they were on a older stretch of sidewalk, so weren’t as well defined:

Oak leaf print, Oak Park, Illinois, November 1, 2009.

This oak leaf was printed on a stretch of older, rougher sidewalk.

Then I found some clearer oak prints on a newer sidewalk — but they were black instead of brown:

Oak prints of a different sort, Oak Park, Illinois, Nove,ber 1, 2009.

These oak leaf prints were different — they brushed away. They were made of dark, dusty dirt, not brown stain.

I looked closely and saw that these prints were made of dark dirt trapped in tiny rough spots on the sidewalk. They were dust-prints, not stains, because I could brush the prints away. I noticed that dust-prints had only formed in a sheltered spot, by a recessed door:

Site where the oak dust-prints had formed, Oak Park, Illinois, November 1, 2009.

The oak dust-prints had formed in a sheltered spot beside a little-used, recessed door.

So, here’s my guess about how these prints formed: I think a layer of dust accumulated in the sheltered spot beside this little-used door. Then oak leaves blew onto the dusty sidewalk. The previous week’s rains had first plastered the leaves to the sidewalk — protecting the dust below — and then washed away the dust between the leaves. As the weather cleared, the oak leaves dried and blew to one side, exposing the leaf-shaped patches of dusty concrete below.

Now, here’s a question: If humans provide the concrete canvas, but nature does the rest, are these leaf prints art? I think not. But an artist inspired by these prints could make art using nature’s techniques. All that’s needed for stain-prints would be  a stretch of newer sidewalk, leaves, water, and time — at least several days, I’d guess. To make the dust prints, you’d need new sidewalk, dust, leaves, and water. If I’m right about how these prints formed, you could make them in a few hours.

And if you try to do the art, you will also be testing my ideas about how the leaf prints formed. If my hypotheses prove wrong, then your art will fail, too. Hypothesis testing is science — so you’d be doing art and science at the same time!

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Go here to read about the biochemistry of leaf stains. The stains may be made by tannins, or perhaps by pigments called anthocyanins.

Go here to contribute to a debate on “Is there a name for the stains left on sidewalks by fallen leaves?” Here are some of my favorite contributions from that debate (beyond “leaf stains”):

  • Ghost leaves or tannin shadows  (steef’s contributions)
  • Leaftovers  (krippledkonscious’s idea)
  • Foliagraph  (contributed by Terminal Verbosity)

If you don’t like leaf stains and want to make them go away, try here or here. (I can’t personally vouch for either site, though — you’re on your own with this issue!)

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Note added Friday, November 13, 2009: On this morning’s walk I found examples of a third type of leaf print on a concrete sidewalk. Here’s a photo of imprints made when leaves fell onto a concrete sidewalk right after it had been poured — when the cement that would eventually bind it all together was still soft and wet:

Elm leaves imprinted into a concrete sidewalk, Oak Park, Illinois, November 13, 2009.

These prints were made when Elm leaves fell onto concrete when the cement was still soft and wet.

On a 20 foot stretch of sidewalk there were at least 50 prints of two types of leaves (plus a trail of squirrel footprints — more about that in another blog post). In addition to the Elm leaves, there were also a dozen prints that looked like a type of Basswood or Linden:

Elm and Basswood/Linden leaf imprints in concrete, Oak Park, Illinois, November 13, 2009.

These prints include a Basswood or Linden leaf above and two Elm leaves, below.

Although it’s hard to tell from these photos, the leaf prints were a couple of millimeters deep — that’s why I called them imprints. Because many of the prints were so perfect, I imagined that the leaves must have stayed in the concrete until after the cement had set, perhaps rotting in place. However, as shown in the photo above, some prints were not perfect — the leaves were folded or had slipped to one side after they had fallen into the soft cement.

So, I’m wondering if we can tell anything more from these imprints. Because there are so many leaf prints, does that mean the sidewalks were poured during autumn, when leaves were falling? Did strong winds blow the leaves onto the concrete and then fold or slide some once they were embedded in cement? Perhaps the evidence can’t rule our other possibilities, but it’s interesting to speculate.

By the way, other folks have posted photos of similar leaf imprints on the web.  Some folks call them “sidewalk fossils,” and teachers sometimes use them to get students thinking about how fossils form:

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If you’d rather make your leaf prints in a more portable form, here are some web pages to help get you started:

anthocyaninsanthocyanins