Blog | Sheldrake Environmental Center

Baby, it’s cold outside

Thursday, February 23, 2017

Last week the winds howled and temperatures fell below freezing. Trees and branches cracked and sprawled across the ground. Leaving my house, I pulled my coat tight, drew my hat over my face, and in my fuzzy boots scuttled the 15 feet to my car. I blew a gust of frozen breath in the safety of the front seat. Then I looked out and saw a dark eyed junco, a tiny songbird pictured above, sitting on a branch, calm as can be.

How can a wee bird weighing no more than three pennies spend 24/7 in such cold temperatures without freezing to death?

Down, down, down

That jacket or blanket that you may have for extra cold days is stuffed with down for a reason. Unlike the long flight feathers on a bird’s wings and tail, the down feathers are short and can be fluffed up. This fluff creates air pockets that trap the warmth escaping from the bird’s body. The specialized down feathers can keep a bird’s body temperature at 104 degrees even in freezing weather!

Birds also undergo a fall molt in which they grow up to fifty percent the number of feathers on their body for greater insulation. That fluff is what makes these tiny birds look round as tennis balls in winter.

Have you ever seen birds poking their beak into the base of their tail, then rubbing their beak all over their bodies? They are collecting oil from the uropygial gland and spreading the oil over their feathers. Not only does the oil keep feathers preened and clean, but it also adds a weatherproofing layer that keeps them from getting wet. Can you even imagine the misery of having wet feathers in winter?

Wait, what about my feet?

No matter how warmly I dress, my feet and hands are usually the first thing to freeze in winter. So how do those featherless, little reptilian bird feet stay warm in winter?

For one thing, those sinewy feet have very few nerves, which reduces the cold that the birds feel through their feet. The scales are specialized to minimize heat loss. Birds also take turns lifting one foot and tucking it into their feathers to warm it up, or crouching down over their feet to warm them.

But they have another brilliant adaptation as well: rete mirabile, which is Latin for “wonderful net.” In the rete mirabile, arteries that carry warm blood away from the heart intersect with veins that carry cold blood from the feet. A heat exchange occurs, and the blood from the feet warms before reaching the bird’s heart.

And then there is shivering

Birds are warm blooded creatures and, through a high metabolism, maintain a body temperature at about 105 degrees Fahrenheit. How challenging it must be to keep such a high body temperature in extremely cold weather! When all else fails, birds will start shivering their powerful chest muscles. The pumping of their strong flight muscles sends blood and heat surging through the body. But this relief comes at a cost. Half the calories that a bird needs to survive a wintry day could be depleted in the act of shivering. A chickadee, for example, requires the equivalent of 65 sunflower seeds to survive a cold winter day. Food to replace those lost calories is scarce in winter. Most insects and trees are dormant.

Birds are highly resourceful creatures, and they have adapted to find sustenance in seemingly barren environments. They have exceptional eyesight, and can tease out tiny cracks in tree bark serving as insect hideaways. As gardeners, we can help them by not removing our dead plantings in the fall. Those browned flower heads can contain seeds and insects that sustain birds through the winter (see Hidden Provisions blog entry). And if you are feeling extra generous, you can fill a feeder with sunflower seeds or suet, and enjoy the feeding frenzy that ensues.

cardinal — Cardinal waiting for his turn at bird feeder

cardinal1 — “What are you waiting for?,” this female cardinal must be thinking.

cardinal2 — Joining the junco and sparrow for a sunflower seed snack.

Jelly Fungus Among Us

Sunday, January 8, 2017

They looked like a group of butterflies resting on a branch. But as I approached, the purplish wings morphed into something gelatinous, fleshy, and etched with veins. I touched them. There was something human and macabre about them, like severed decaying ears. I had mistakenly thought that winter was not a great time for mushrooms, but the rain of the previous day had launched an abundance of them.

ears-4 — Photo credit: Svetlana Wasserman

What I was seeing was a member of an entire subgroup of mushroom–the jelly fungus, or for you Latin speakers, Basidiomycota. These particular ones are an example of Auricularia auricula, otherwise known as the Jelly Ear fungus. Perhaps not so pretty to look at, they perform a vital public service by decomposing dead wood. When weather is dry, they shrivel and harden, like an old cork. But once the rain returns, they quickly reabsorb water and recover their shape, size and color, and can begin to produce spores. This ability to dry, rehydrate, and revive with a small amount of moisture is a remarkable adaptation, allowing these fungi to endure.

Not ten paces from the first jelly fungus, I came across another oddity. Creamy yellow layers folded in and out of themselves, like buttercream roses. This was also a jelly fungus, growing right amid the turkey tail mushrooms that had already colonized this decomposing log (Some speculate that this fungus actually feeds on the turkey tails).

witch-butter — Photo credit: Svetlana Wasserman

This particular fungus is called witch’s butter. Legend originating in Eastern Europe holds that this mushroom was hung on doorposts by people to rid themselves of a witch’s curse. Piercing the fungus was said to banish the curse.

Like other jelly fungi, witch’s butter is very absorbent, and after a rain it can soak up so much water that it looks more like a slime. Once the water evaporates, the fungus shrinks back and the fruiting body remains dormant until the next rain.

witch-butter1 — Photo credit: Svetlana Wasserman

Two sunny side up eggs? No, this is also witch’s butter fungus, but with more water absorbed than the one above. In case it is making you hungry, witch’s butter is edible, although allegedly tasteless. Its gelatinous consistency makes it a good soup thickener and if you are an adventurous eater, you can find these for sale at Asian groceries.

The next time it rains don’t miss the opportunity to seek out the jelly fungus among us, at Sheldrake or another woods near you.

The Hidden Lives of Leaves

Sunday, November 20, 2016

Svetlana Wasserman

During the warmer months, tree leaves inhabit the world above our heads, giving us shade and a pleasant rustle as they soak up sunlight and convert it to food. But as they swirl to the ground on these November days, the leaves reveal their hidden lives, if we care to look.

Pick up a leaf. If the surface has started to wear away, you’ll discover a jumble of tiny veins twisting and merging that may remind you of a map of lower Manhattan. This is the inner skeleton of the leaf. It provides both structural support for the leaf and is also part of the hydraulic system that transports water and nutrients from the tree roots to the leaves, and sugars from the leaves back down to the rest of the tree.

These gossamer remains of the leaf are the handiwork of myriad decomposers, large and small. For example, while photographing these leaves, a tiny transparent worm smaller than one letter on my newspaper crawled out, and I could see the contents of the leaf it had been chewing inside its body.

decomposition-3 — Do you know how tiny this worm is? The bar under it is part of one letter in a newspaper.

This little worm, along with slugs, snails, millipedes and miles of fungal roots are the workhorses that clear our forest floors of fallen leaves, and recycle the nutrients from the leaves back into the soil. That is one reason gardeners should consider mulching their leaves instead of relying on gas blowers to take them away. The mulched leaves provide premium free fertilizer! Instead of having your tax money used to pay composters to process the leaves, and then sell them back to you as mulch, you can ask your gardener to mulch mow your leaves, and make your own for free. Extra leaves can be blown or raked into a compost pile for the future.

The fallen leaves reveal not only their beautiful inner structure, but also how important they are to sustaining forest life. Pick up a leaf and you are bound to see signs of it having provided room and board.

Oak leaves, such as the one pictured above, support more life forms than any other native trees. They host hundreds of species of insect, supplying many birds with an important food source.

The bumps on these leaves are galls made by the eggs of a small midge which lives inside. When the insects hatch, the leaf that hosted them becomes their food and in turn, they become food for birds and their squalling babies. These galls cause no harm to the tree, and are quite beautiful in spring when they are plump and pink.

oak-leaf-gall — Oak leaf gall in summer. Photo credit: Randy Rosenberger

Next time you are outside take a moment to pick up a few leaves. Look for signs that they have nurtured insects. Admire the remaining latticework, not only highly functional but hauntingly beautiful as well.