Why do ostriches put their heads in the sand?

Since you were all (there is someone out there, isn't there?) too shy to come up with a Why this past fortnight, I had to think of one myself. 

I did so last night whilst reading my little boy a book called 'Faster, Faster' about a little girl who rides on her daddy's back in the park and imagines he is all sorts of animals. On one page she imagines he is an ostrich, which is seen on the previous page with its head buried in the sand.

So, I thought, why do ostriches do that? And then I asked my husband, approximately three hours later when the kids were actually asleep and we had time to sit down for about five minutes before we went to bed. "They don't," he said, "it's a myth. I think."

Huh.

So this week's Why is: Why do ostriches bury their heads in the sand, or if they don't, why do people think they do?

It feels strange to just go answering it right away, but here goes. My husband is right. Ostriches don't bury their heads in the sand, exactly. However, they do put their heads in the sand to turn the eggs in their nests, which they build in a hole in the sand.

The nesting hole is built by the male and can be quite large, about 1.5 - 2.5 metres wide and 0.5 - 1 metre deep. Despite the size of these holes, the vast expanses of desert landscape ostriches live on mean that from a distance, the nests and eggs are not usually visible. So with their long necks and all that shimmering sand, it does appear that the big bird is sticking its head in the sand.

If an ostrich sees a predator, it will run, abandoning the nest. However, this is really in the best interest of the eggs, as it will lead the predator away. The ostrich can then return when the coast is clear.

Ostriches lay between 40 and 100 eggs in a year. Busy, busy birds.

Oh my Science!

Next week I'm going to document a science experiment that my little boy tried out at Playcentre the other day. It's all about the weight of liquids and the like. It should be fun. Tune in.

Why do trees lose their leaves in Autumn?

Winter Trees

BY William Carlos Williams

All the complicated details
of the attiring and
the disattiring are completed!
A liquid moon
moves gently among
the long branches.
Thus having prepared their buds
against a sure winter
the wise trees
stand sleeping in the cold.

Like some animals, deciduous trees go into a sort of hibernation state in colder weather. Producing and maintaining leaves is an expensive business, requiring a good deal of sunshine and moisture. Leaves contain nutrients that a tree needs to survive. These nutrients are derived through photosynthesis, so the tree can't get them from the soil. 

Trees know their environment well and pre-empt the upcoming winter (or, interestingly, the dry season in warmer climates), absorbing the nutrients from their leaves as the weather starts to get cooler or dryer, but before the leaves can be damaged by the unfavourable weather.

The main nutrient the tree sucks up is Chlorophyll. This is the nutrient that gives a leaf its green colour. Once it's gone, the other nutrients in the leaf become visible, such as caroteins, which are orange and yellow, and phycoerythrins, which are red. Filled up on Chlorophyll, the tree detaches its leaves and goes into a winter slumber. Thus, the golden and amber leaf drop of Autumn!

In a New Zealand winter, there is a lot of rain and the temperature barely drops below zero, unless you're up a mountain. This might explain why our native trees are mostly evergreens. They get enough rain and light to keep their leaves through the cold weather. 

In other climates that have very cold winters, such as North America, some trees have adapted to become evergreen so they can survive through a longer winter. They do this with needle-shaped leaves, which retain water that on a broader leaf would be lost to wind and evaporation from the sun. These trees stay evergreen so they have more chance to carry out photosynthesis all year round, and thus survive.

Clever old trees, so different from us humans. I tend to lose weight in the summer, when it feels too hot for stodgy food, and pack it on when the weather is cold. This makes sense too, since I don't hibernate and have to carry on through the wind and rain. A little extra weight to help me through the colder months? It's only natural. Yeah, I like that excuse. Pass the Tim Tams..

What's my Why?

It's been a busy week, too busy to wonder why, so I thought I would leave this one up to the readers. Can you suggest a Why for my next post in the comments? I need to take a weekend off to work on another project, so the next post will be in two weeks time. Gives you plenty of time for wondering...

Why is a street called a street and a road, a road?

Wanna know what this blog is all about? Click here to read the initial post and learn why we are learning.

How many metres must a road stretch down, before you call it a road? The answer, my friend...is it's not to do with the length. Ahem, sorry Bob.

Well, not exactly anyway, although a road is usually longer than a street. A road used to run between two towns and didn't have any buildings on it. Historically, roads weren't paved and were created for transit purposes only.

A street on the other hand was paved and created for living on, for meeting, for shopping, for walking. Streets made up the towns and roads connected them.

If you look at my hometown, Auckland, you will see this is no longer true, as a lot of the main roads in the city are developed now. However if you think of our fair city just fifty years ago, before urban sprawl attacked it, you can see the main arterials like Great North and Great South Roads were just that, roads leading from the central city to the north and south.

What about the other names? 

• An avenue is supposed to be the label for a straight road lined in greenery. 
• A boulevard was (and in most cases, still is) wide and multi-laned, with a central median and landscaping on either side. 
• A crescent is a crescent shape, often intersecting with the same road at both ends. Saying this, not all crescent shaped roads are called crescents (the 'avenue' I live on included). 
• A lane is often one-way, or at least very narrow.
• A court is a short cul-de-sac.
• A way is a minor street in a town.
• A drive could be one of two types of roads: either a long and windy road, or it could be short for a driveway, or private access road. 

However, most of these definitions don't apply to the modern city, and these days the names of roads are probably determined more by what rolls off the tongue than the actual use and shape of the street.

Next weeks' Why?

In New Zealand with its temperate climate, the majority of native plants are evergreens, and in the North Island at least, our seasons have a tendency to blur together. This means we don't get the dramatic 'falls' of such places as New England in the USA. Saying this, the Queenstown Lakes District does it pretty well. Ah, Arrowtown. 

Anyway, enough dreaming. This week's Why is pretty simple.

Why do (deciduous) trees lose their leaves in Autumn?

Now I must love and leave my computer to help my husband with my two grizzling children. Happy questioning!

Why do we sometimes see the moon in the daytime?

I actually find this one really hard to get my head around, but it's one of those fundamental things everybody who lives on Earth should know. Once upon a time this stuff was cutting edge. Cute little ink-smudged newsboys stood on street corners calling, “Earth spins on its axis! Read all about it!”

Okay, maybe I've been watching too many movies. Still, we live on Earth so we should know how it works, especially if we happen to be parents – our kids' first teachers.

The basics are: The Earth spins on its axis, but it also travels around the sun. The moon spins on its own axis too, but more slowly than the Earth does, and it orbits the Earth. The Earth takes a day to spin on its own axis and a year to travel around the sun.

The moon is basically a rock, so it doesn't shine. We see the moon because light from the sun bounces off it. The moon appears to change size and shape because we see different parts of it as it completes its orbit, depending on where the sun is in relation to it. A full moon happens when the sun and moon are at opposite sides of the Earth, so the light from the sun shines directly onto the moon's surface. A new moon happens when the moon is at its closest point to the sun.

The moon is actually often in the sky at some point during the day, but it isn't visible because the light from the sky washes it out, or it might be behind some cloud cover.

So basically, the moon isn't just a magical globe that comes out at night, it's just that's when we see it best because the dark sky contrasts against it. When we see it during the day, that is probably because it is traveling away from the sun, so is brightly lit at that point and in one of its larger phases, and the sky is blue.

Traveling the streets and the avenues

This week's Why is probably more likely to come from the mouth of a curious eight-year-old than a toddler, but it's one of those things that often crosses my mind when I'm driving, but I've never gotten around to finding out the answer. Which is what this blog is all about...

So, why are some streets called streets, some roads or avenues, etc? Is it to do with the width of the street, or the length or shape? 

Next week, no excuses, I will journey this road of knowledge and impart my newfound wisdom.