Neighborhood Nature

Our Family's Nature Blog

And now they are eating…caterpillars! May 18, 2011

Filed under: Animals,Birds,Bugs,Experiments,Plants,Puzzles and Mysteries,Seasons,Spring,Trees — saltthesandbox @ 8:20 pm

Almost two weeks ago we solved the mystery of what warblers were eating in the streets of south Oak Park: Beetle larvae!

Well, the beetle larvae are not longer tumbling from our elm trees, but the warblers and thrushes and Indigo Buntings keep coming, along with tanagers and orioles and more! So, to find out what the birds are eating now, I grabbed a white plastic box lid, held it under some low elm branches, and started shaking:

I shook the elm branches and caught whatever fell off them with a white plastic lid.

Here’s what I found: Little green caterpillars! (I put the dime there. Money doesn’t grow on trees in our neighborhood.)

Little green caterpillars that have been feeding on newly opened elm leaves.

Just in case someone out there can identify what type of moths or butterflies these become, here are some closer views:

Little green caterpillar number 1.

Little green caterpillar number 2.

I can’t identify the caterpillars, but I do know they taste good to birds. During the past week, we’ve seen 23 kinds of warblers feeding in and under our elm trees:

Golden-winged Warbler

Tennessee Warbler

Orange-crowned Warbler

Nashville Warbler

Northern Parula

Yellow Warbler

Chestnut-sided Warbler

Magnolia Warbler

Cape May Warbler

Yellow-rumped Warbler

Black-throated Green Warbler

Blackburnian Warbler

Palm Warbler

Bay-breasted Warbler

Blackpoll Warbler

Black-and-white Warbler

American Redstart

Ovenbird

Northern Waterthrush

Mourning Warbler

Hooded Warbler

Wilson’s Warbler

Canada Warbler

Feeding along with the warblers we’ve seen:

Yellow-throated Vireo, Warbling Vireo, and Red-eyed Vireo

Veery, Gray-cheeked Thrush, and Swainson’s Thrush

Gray Catbird

Summer Tanager and Scarlet Tanager

Rose-breasted Grosbeak

Indigo Bunting

and Baltimore Oriole

These birds are all spring migrants. The Catbird is the only one who’s likely to stay and nest in our neighborhood. The caterpillars in our elm trees have helped them survive and refuel before the next night with southerly winds to speed them on their journey north.

Did I mention that last week we found thousands of tiny caterpillar poops on our cars each morning? The polite term for caterpillar poop is frass. This morning our cars were almost frass-free, although there was lots of bird poop on our windshields.

We’ll finally get some southerly winds later this week, so we expect most migrant birds to continue north. In their wake we expect our elms to enjoy an almost caterpillar-free summer.

Now if we could just find a biological control for the bark beetles that spread Dutch Elm Disease….

 

Look What’s Falling from Our Elm Trees! May 4, 2011

Filed under: Animals,Birds,Plants,Puzzles and Mysteries,Seasons,Spring,Trees — saltthesandbox @ 7:59 am

Every spring there are a few days in late April and early May when we see warblers in the streets, feeding on something. Two years ago it happened in late April, as seen in these photos of Yellow-rumped Warblers on our south Oak Park  block:

Yellow-rumped Warblers feeding on South Elmwood Street, April 27, 2009

Yellow-rumped Warbler on South Elmwood Street, April 27, 2009

Well, it’s been happening again the past few days. It’s like a block party for the birds, and it got me wondering–what’s for breakfast, lunch, and dinner? What tasty things are the warblers feeding on?

My best guess was that there was some sort of insect feeding on the opening leaves of the American Elms that tower over many sections of our block. Every spring there are also warblers feeding on something in the treetops, and every year there are tiny holes chewed in the leaves:

American Elm leaves - note the insect-chewed holes.

So, I was thinking that maybe whatever was feeding on the leaves somehow fell to the ground, where sharp-eyed warblers could spot them on the asphalt and continue their meals.

To test my hypothesis, I placed a white plastic lid where it could catch whatever was falling. I left it there from late afternoon yesterday until early this morning:

White plastic lid set up to catch whatever fell from the elms. May 4, 2011

Then, this morning, I brought the lid inside to see what I could find. It was covered with tiny, pale yellow grub-like insect larvae!

Tiny, pale yellow grub-like insect larvae that fell onto the lid

Closer view of grub-like insect larvae

So, one question answered: That’s what’s falling from the trees, and probably what the warblers are eating. But many questions remain:

  • What are these things? Hatchling caterpillars, or some other kind of insect?
  • Why are so many falling from the trees? Shouldn’t they be better adapted to hang onto the leaves? Or do they “jump” whenever a bird is picking at their leaf?
  • Once they hit the ground, they are still alive–you can see them moving. Can they somehow continue to live on the ground, perhaps feeding on fallen elm leaves and elm seeds? If so, when they are larger and stronger, would they climb back up into the trees?

So, I guess our next challenge is to try to raise a bunch of the larvae until they are large enough to identify. And once they are bigger we can put some of them at the base of an elm tree and see what happens.

I’ll let you know what happens!

—–

A few hours I posted this, a Facebook friend and garden designer made this comment (Thanks, René!):

“I’m no entomologist, but after some research, my best guess is Elm Leaf Beetle. These guys feed on elms and drop to the ground in large numbers as little yellow guys to pupate. Sounds like the yellow-rumped Warblers are doing a good job of natural pest control.”

Here’s a photo of Elm Leaf Beetle damage: http://www.ipm.ucdavis.edu/PMG/X/I-CO-XLUT-CD.004.html
Here’s a drawing of the Elm Leaf Beetle life cycle: http://www.ipm.ucdavis.edu/PMG/PESTNOTES/pni7403-2.html
Here’s a photo of some Elm Leaf Beetle pupae: http://www.ipm.ucdavis.edu/PMG/X/I-CO-XLUT-EA.001.html

We’ve put some of our fallen larvae (or whatever) into a plastic box with newly opened leaves–now we’ll see what happens!

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Here are links to our earlier blog posts about birds in our streets:

 

A January Walk through Columbus Park January 17, 2010

As I monitored birds this morning in Columbus Park, I did an experiment. I took photos with my iPhone and uploaded them live to Facebook. It was kind of like a virtual nature walk!

Here the link to the public Facebook album with this morning’s photos:  A January Walk through Columbus Park.

Please let me know what you think!

 

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.

 

Last of the Fall Wildflowers at Columbus Park? November 20, 2009

Earlier this year Neighborhood Nature showed the earliest examples of spring flowers we could find. Now that November’s two-thirds gone, I guess it’s time to show the last wildflowers still blooming in Columbus Park. (I’ll do my best to give their names, but bear with me — I’m not a botanist!)

It was sunny and almost warm during this morning’s bird monitoring in Columbus Park. However, some parts of the Park were devoid of birds, so I had time to look down as I listened hard for any birdlike sounds. These nickle-sized flowers caught my eye — I’m pretty sure they’re Daisy Fleabane. (You can see a photo of the entire plant here.)

I'm guessing Daisy Fleabane, Columbus Park, Chicago, November 20, 2009.

Although these look like daisies, the flowers are much too small. So I think it's Daisy Fleabane.

The small patch of prairie habitat beside the lagoon held two plants in flower. The first one looked like a very small example of Queen Anne’s Lace (aslo called Wild Carrot) — the flower head was less than two inches across. (You can see a photo that shows the leaves here. Please use the comments, below, to correct me if I’m wrong.)

I think this one is Queen Anne's Lace, Columbus Park, Chicago, November 20, 2009.

This one looked like a very small example of Queen Anne's Lace (also known as Wild Carrot).

I’m also uncertain what this plant is called. I’m guessing this might be False Dragonhead, a kind of mint. Another name for this species is Obedient Plant, since if you push the flowers to one side, they stay there until you push them back. However, I forgot the try that test today, so my identification has not been physically confirmed. Also, this flower looked more pinkish in the field — I’m not sure why the photos don’t do justice to the color. (You can see a photo of the entire plant here.)

I'm guessing this is False Dragonhead, Columbus Park, Chicago, Illinois, November 20, 2009.

I'm guessing this is False Dragonhead, a kind of mint. (Again, use the comments, below, to help me out!)

My final flowers were just hanging on — most of the others on this plant had gone to seed. It was a kind of thistle, found in Austin woods — but don’t ask me what kind of thistle, I wouldn’t have a clue. (Again, these looked more pinkish in the field. You can see a photo that shows some leaves here.):

Thistle flowers, Columbus Park, Chicago, Illinois, November 20, 2009.

A few thistle flowers remained, but the rest had gone to seed.

“Gone to seed” is where all these flowers are bound. Food for birds, and sometimes a feast for the eyes despite the lack of color. Check out these goldenrod seeds, which may be Showy Goldenrod, one of the most beautiful of its kind. (You can see a photo that shows more of the plant here.)

Gone-to-seed goldenrod, Columbus Park, Chicago, Illinois, November 20, 2009.

Even gone to seed, goldenrods are beautiful.

So, are these the last wildflowers I’ll see this year in Columbus Park? I’ll keep looking for more on future visits. (And I’ll also try to tame that possible Obedient Plant.)

 

Natural Leaf Prints on a Concrete Canvas November 9, 2009

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

—–

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!)

—–

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
 

We Found Tiny Insects Inside Hackberry Nipple Galls October 20, 2009

Filed under: Animals,Bugs,Fall,Plants,Seasons,Trees — saltthesandbox @ 4:50 pm
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Way back on June 18 we did a Neighborhood Nature blog post about Hackberry Nipple Galls, which you can read here. On this morning’s walk I found two Hackberry trees with half a dozen or more Yellow-rumped Warblers in them, hunting for bugs to eat. That got me thinking that maybe some of the bugs they were eating had grown up inside Nipple Galls. The warblers wouldn’t let me get close enough to see what they were eating, so instead I found some Hackberry leaves with lots of galls on them and took them home to dissect.

Before I picked them, the leaves looked like this — covered with nipple-shaped growths, called galls, that grew when insects called Psyllids (SILL-lids) laid their eggs on the leaves:

These Hackberry leaves are covered with Nipple Galls. These galls formed when insects lay their eggs on leaves or stems. The gall becomes a nursery for the baby bugs, which feed on the insides  -- the gall is shelter and food at the same time.

These Hackberry leaves are covered with Nipple Galls. The galls formed when insects, called Psyllids, laid their eggs on the leaves. The gall became a nursery for the baby Psyllids, which fed on the insides of the gall. The gall provided shelter and food at the same time.

After I cut open one of the galls on our kitchen table, it looked like this:

The cut-open nipple gall had a tiny Psyllid insect inside a hollowed-out cavity.

The cut-open nipple gall had a tiny Psyllid insect inside a hollowed-out cavity.

I cut open a few more galls, and more tiny Psyllids crawled out. They were about as big as the head of a straight pin:

The lower left Psyllid was walking around, but the Psyllid on the upper right was upside down.

The pinhead-sized Psyllid on the lower left was walking around, but the Psyllid on the upper right was upside down. You can tell these Psyllids are not yet fully grown, because they don't have wings. They just have "wing buds" behind the head, which will become wings after they shed their skins another time or two.

So, maybe the warblers were eating adult Psyllids that had emerged from galls on the Hackberry trees, or maybe they were eating something else. But what I really want to know is if any birds peck open Nipple Galls to catch the not-yet-fully grown Psyllids. (I’ve seen Downy Woodpeckers break into Goldenrod Galls, but those galls are somewhat larger.) I guess I’ll have to keep a close eye on any birds I see in Hackberry trees this fall. I’ll also search through Hackberry leaves for galls dissected by bird beaks instead of knives.

—–

Update added two days later (October 22, 2009):  Rather than throw the gall-covered Hackberry leaves outside, we put them in a container with a lid and waited to see if adult Psyllids would emerge. When we opened the container this morning, this is what we found:

There were at least for of these winged adult Psyllids in the container with the gally Hackberry leaves.

There were at least four of these winged adult Psyllids in the container with the gall-covered Hackberry leaves. (Because of the wings, they were twice as long as a pinhead is wide.)

Now, doesn’t that look like a good snack for a warbler?

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You can read more about Psyllids and Nipple Galls here and here and here.