Tuesday, December 23, 2014

Winter Wonderland—for Squirrels!

Squirrels don’t migrate. And they don’t hibernate. Which means that here in New York City, you see squirrels scampering up trees and into garbage cans no matter the weather: wet, snowy, sub-freezing. How do squirrels survive the cold months?  By building nests called “dreys.” You can see four of them in this photo, taken here in Brooklyn just a few days ago:

Squirrels—we have eastern gray squirrels in New York—start to build their dreys in the summer. While they look like big sloppy piles of leaves, they’re actually pretty strong and stable. Unless they were made by young squirrels—their dreys sometimes are just big sloppy piles of leaves, because they haven’t perfected their architect skills yet.

Dreys start with a solid base layer of branches. Squirrels weave the branches to a tree, usually near the trunk, or where two branches come together, or sometimes, further out on a strong limb. These are the sturdiest places on the tree. On top of the woven branches, builder squirrels add wet leaves and moss. This makes a nice, cozy dry floor for the drey. Then they start building the skeleton of a sphere on top of the base. This is made up of more branches and also, vines. Then the squirrels cover the whole structure with moss, leaves, bark, pine needles, grass, paper—whatever a city squirrel can scrounge that will help keep his drey water-tight and warm.

Squirrels usually live by themselves, or with their newborn babies for a few weeks (just the moms, though, and just in summer and winter, when new broods are born). So why would any squirrel need four nests, as is shown in our picture? One or two nests might be old and rickety—maybe left over from last winter. One nest is the squirrel’s preferred new nest. And one is an extra, in case the favorite nest is invaded by a predator, or becomes infested with lice and fleas. Always nice to have a backup!

Monday, December 15, 2014

Turning Winter to Spring

Here at City Science Kids, we've been performing a little science experiment. We wanted to see if we could make it spring in our Brooklyn apartment—in the month of December! It turns out, we can. By "forcing" bulbs.
Back in November, we bought 4 paperwhite bulbs and 1 hyacinth bulb at our local nursery. Paperwhites are related to daffodils and they look a lot like them, only they're smaller and all-white. Hyacinths are amazingly fragrant purple-blue flowers. Both kinds of flowers bloom in early spring. Instead of growing from seeds, like lots of plants and flowers do, these grow from bulbs.

The International Bulb Society calls a bulb "an underground storehouse and flower factory" that contains everything a plant needs to sprout then flower when the time is right. In the case of paperwhites and hyacinths, that's when the frost first begins to melt. In the middle of the bulb are leaves surrounding the bud itself. And scales that provide all the nutrients the bud will need to grow. Also the roots, which will start to emerge before the bud does. All held together by an outer layer called a "tunic."
Normally to get a flower from a bulb, you stick the bulb in the ground in the fall. It spends the winter underground in cold temperatures. When the ground start to warm, the bulb knows it's time to grow! To get bulbs to grow off-season, you just need to trick them into thinking it's spring. Our nursery kept the bulbs in a refrigerator for a few weeks. Then we brought them home and "planted" them. Really what we did was layer some stones in the bottom of glass pitchers, then we stuck the bulbs on top of them, sprout-side up. Then we added a little water, so the bottoms of the bulbs were wet. After about a week, the roots began to emerge:
And the sprouts got taller and taller and longer and longer. Finally, buds appeared between the leaves.  
After about 5 weeks, the first of them opened up, revealing 6 beautiful white flowers (you can see another bud that will soon open on the bottom right of this plant):
The hyacinth will take several weeks longer to flower. We hope to have purple blossoms festooning our windowsill sometime in January!

Have you got any flowers blooming in your house this month? Write in with pictures!

Monday, December 1, 2014

Presenting November's Most Popular Episode!

Ever since it posted, City Science Kids' most popular episode has been the one on Pickle Science. It featured Brooklyn's own Brooklyn Brine Pickle Factory and its genius, pickle-making owner, Shamus Jones. But in November, our episode on Manahatta—that's what Manhattan's original residents, the Lenape, called the island—suddenly took off like hotcakes! If you missed this episode on what NYC looked like when Henry Hudson sailed up to its shores 400 years ago, you can catch up on it here! If you're a teacher and can't access videos supported by YouTube, watch with your students on SchoolTube.

Also, some of you may be celebrating Christmas and getting ready to buy Christmas trees with your families. Find out how a cut Christmas tree stays green all throughout the holidays, here on CSK or on SchoolTube.

Hope you all had a very happy Thanksgiving!