Thursday, October 2, 2014

Can Humming Birds Sit Down?

I've heard them all! Hummingbirds can't sit down because ... they can't sit still; they have to eat constantly; and my favorite, they don't have feet. All of these, however, are false. Hummingbirds can sit down.


Do hummingbirds sing?

Hummingbirds make chirps and peeps that have been
described as 'creaky hinges' and 'squeaky wheels'. Listen
to this  recording of a Black-chinned Hummingbird
and see what you think. Thanks to the Cornell
Lab of Ornithology, Macaulay Library
Now I ask you, if a hummingbird couldn't sit down, how would they lay an egg? It would be quite a feat of skill, aiming an egg coming from their posterior into such a tiny nest on the fly. I'd be even more impressed with these little birds than I already am.

Hummingbirds have very high metabolisms thus requiring them to search for food during most of their waking hours. During this daily activity they take short breaks to sit on tiny branches and preen. Often hummingbirds will sing from these perches as well. To me, their song sounds remarkably like a squeaky wagon wheel.

When it comes to being still, sleeping does pose a challenge. A hummingbird's high metabolism may cause them to starve over the short duration of a single night. To avoid this, hummingbirds go into a torpor when asleep. Similar to dormancy, torpor is a deep sleep during which the animal's metabolism slows down, thus requiring less energy. The difference between this and dormancy is that, when in torpor, a hummingbird can be roused by outside stimuli whereas an animal that is dormant cannot.

If Hummingbirds Can't Sit Still for Long, How Do They Sit on Their Eggs?

By Kevin Bondelli

Hummingbirds spend very little time sitting on their eggs. The mother hummingbird used quite of bit of her body's resources to produce two eggs and therefore, she needs to build up her energy by eating even more than she typically would. And, she will soon have two more mouths to feed.
Female hummingbirds are single parents and therefore, planning ahead is a must! Because she will spend little time sitting on her eggs, she needs day care. This comes in the form of a cleverly designed nest that holds the eggs securely until they hatch and then stretches with the hatchlings as they grow. Cleverly, she builds her nest out of spider webs. The nest keeps the eggs snug, safe and provides insulation. After hatching, the nest flexes and grows along with the chicks.
Watch 2 Hummingbirds from Hatching to Fledging
By the Numbers
Number of species: 325

State with the most resident species:   
Texas - 20 species                               
Arizona - 18 species
New Mexico - 17 species                   
California - 14 species
Louisiana - 13 species                         
Colorado - 12 species

Country with most native species:
Columbia (160)

Lifespan: 5 to 8 years                      
Heart rate: Over 1,000 beats/min.
Average adult weight: ~3g                
Smallest species: 5cm (Bee hummingbird)
Typical wing beats per second: ~60  

(c) Magnus Manske

Bug or Bird?

There is a large family of moths, the hawk moths (Sphingidae), that can easily be mistaken for hummingbirds. While these moths are slightly smaller than hummingbirds, they also hover and fly forwards or backwards. As hawk moths hover in front of flowers they sip nectar with their long proboscises and are important pollinators. 
by Sarah Striech
Have you ever wondered how a hummingbird drinks nectar? Even though their beaks are long and narrow, they don't work like straws. Without lips or cheeks they can't create suction to draw up the nectar. So how do they do it? They use their long, thin tongues. Really! Their long beaks reach into the flower and then they stick their tongues into the nectar to draw it into their mouths. Check out the hummingbird's tongue sticking out of its beak in the photo to the right.

Often, if you see something that you think is a hummingbird flying about your flowers at dusk, it is likely to be a hawk moth. Like hummingbirds, the hawk moths' wing beat so quickly that they make a buzzing sound. Unlike hummingbirds, hawk moths have antennae - a dead give away that they are insects and not birds!

Glint of green and blue.
A flash, a buzz, here, now gone.
    Happiness a-wing.
                    — R. Copeman
  Creative Commons License
Nature Snacks, Brain Food for the Nature Curious by Ruth Copeman Carll is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.
Based on a work at (excludes photographs and video/audio links)

Wednesday, October 1, 2014

Why do Leaves Change Color in the Fall?

Source: Fall Season Free Wallpaper
While some Governors in the Northern United States swear that the leaves change color in the fall to support their tourism industry and some artists swear it is Mother Nature painting, reality is more complex than the economy or color theory. In order to answer what seems like a simple question, we need to explore the role of leaves and how they work. Don't worry! This is going to be a lot more interesting than you may expect.

Working Two Full-time Jobs

While leaves serve many secondary purposes for plants, they have two primary jobs: Short order cook and traffic cop. Let's explore both of these in order to understand what leaves do for plants and what this has to do with leaves changing colors in fall.
Short order cooks work in fast paced restaurants preparing simple foods for people on the go. They collect ingredients and prepare meals as quickly as possible. The more ingredients they get, the more they can cook. Just like hungry people eat a lot a food, growing plants need sugar, which they break down to make the energy required to live. Luckily, leaves are excellent short order cooks.
Leaves take basic ingredients, sunlight and carbon dioxide, and make them into cake. Well, sugar really. In order to make as much sugar as possible, they collect every bit of sunlight that they can. Sunlight is not a single a type of light but is rather mixture of different color lights. Out of these colors (red, orange, yellow, green, blue, indigo and violet), plants use blue, green and red light to make the cake... I mean sugar. Each color of light moves at its own speed and therefore, you need a different "nets" to catch them. The nets in leaves are pigments and leaves have three kinds.
The first type of pigment, is called carotenoids because they are orangey-yellow colored, but don't be fooled. Even though they are this color, their job is to catch blue light. The second type of pigment in leaves, anthocyanins, look pinkish-red while they catch blue and green light.
Carotenoids and anthocyanins aren't the star player of the team though. That is chlorophyll, the "Hulk" of pigments. Like the Hulk, it is big, green, strong and needs a lot of energy to collect red light. Because chlorophyll is so big and plentiful it covers the other pigments so all you see when you look at leaves is green - until fall that is.
While the short order cook is slaving away in the kitchen, the traffic cop is keeping the trucks moving. Trucks? Yup. Chemicals inside plants act like trucks carrying supplies from the roots to the leaves and carrying the sugar made in the leaves to the rest of the plant. A traffic jam could be deadly! If the trucks get backed up, they can't bring the other ingredient needed to make sugar, carbon dioxide, to the short order cook. Without both ingredients, the leaves can't make sugar. No sugar equals no food for the plant. No food equals no energy. No energy means death.
So how do leaves act like traffic cops, keeping plant chemicals moving? Leaves have windows on their surfaces called stoma. Opening and closing the stoma is like putting up and down a bridge. When stomas are open, traffic flows and when they are closed, traffic backs up. Controlling the stoma so that the chemicals in the plant move at just the right speed is vital. Therefore, the leaves act like traffic cops by controlling the speed that chemicals move through plants.
Now you know that leaves already have green, orange, yellow, pink and red colors inside them and why. You also understand that, without functioning leaves, the plant can't move chemicals and energy to where it needs them. Read on to learn why both of these roles of leaves influence the changing color of fall leaves.

Changing to Fall Colors

In the fall, plants that loose their leaves, called deciduous plants, get ready to go to sleep for the winter. Since they'll be sleeping, they can survive using just the energy they stored over the summer. Therefore, the cook can take a vacation. Chemicals won't be moving around much either so the traffic cop also isn't needed. In other words, leaves aren't needed in winter. The plant will make new leaves in the spring so the current leaves won't be needed again and are dropped. Changing colors is part of the process of dropping leaves.
Notice the colors in these maple leaves. At first, the green
overshadows the other colors. As the green recedes, yellow
is the dominant color. As the yellow receded the red remains.
Finally the red gives way to brown and the leaf dries up.
The first step to dropping leaves is to close the road into the leaf, cutting off its supplies. When the supplies are cut off and the cook stops cooking, high energy users such as chlorophyll die off. Caroteniods and anthocyanins are smaller and use less energy so they can survive a little longer. With chlorophyll gone, the leaves are no longer green.
You can imagine what happens now. Without the green color hiding the orange, yellow, pink and red of the other pigments, the leaves look like they have "changed colors". In reality, these fall colors were always there waiting for their chance to shine! These pigments won't last much longer without energy. Soon the leaves die, turn brown and fall. The plant sleeps as we look forward to the green of spring.
Source: Free Fall Leaves Wallpaper

Almost the end now
Yet growing beautiful still.
Fall leaves turn to gold.
— R.Copeman

Creative Commons License
Nature Snacks, Brain Food for the Nature Curious by Ruth Copeman Carll is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.
Based on a work at (excludes photographs)