- Written by Nadia O'Carroll
The winters and summers of each hemisphere are opposite. This is because the Earth is tilted on an axis of 23.5 degrees, and when its lower half tilts towards the Sun, the angle of the Sun’s rays striking the Earth’s surface concentrate heat in the Southern Hemisphere, and spread the heat in the Northern Hemisphere. However other factors can effect local weather, and ironically on Christmas Day in 2006 snow fell on Mt Buller, Thredbo and Mt Wellington, while according to the UK Met Office, the last “official” white Christmas in Britain was in 2004.
The typical White Christmas scenes may be picturesque, but to survive, plants and animals must overcome low temperatures, food shortages and lack of available water.
To avoid drying out over winter, deciduous plants shed their leaves, shut down and live off stored nutrition in their roots. Evergreen plants retain their leaves through winter; this includes conifers, which have thin, tough, waxy needle like leaves with recessed stomata to reduce moisture loss.
Many animals improve their insulation by growing fatter and furrier to prepare for the cold, lean times of winter. Some even change the colour of their fur or feathers to white, in order to blend in with the snowy environment.
Birds and animals may escape the harsh extremes by migrating to warmer areas. The reindeer (called caribou in North America) migrates farther than any other land mammal, they can travel up to 55 kms per day, have a top speed of 80 kph and are competent swimmers.
The creatures, which remain in their territory during winter, cope with the conditions in a number of ways. They may conserve energy by suspending growth, development and physical activity in a state of dormancy, such as hibernation or torpor. They may hide or retreat to somewhere safe and warm such as network of underground burrows or flock together in large numbers for warmth and protection.
To cope with food shortages, some creatures harvest and hoard food in autumn, which is then retrieved throughout winter. Food hoarders either use a larder where food is stored in one location, or they scatter and store their food in many locations. Some scatter hoarders have amazing spatial memories and can remember the exact location of several thousand storage points.
The robin redbreast, a favourite tame garden visitor in Britain, is featured in many Christmas stories. We have our own red robin on Tamborine Mountain – the rose robin. Technically it is not closely related to European Robins, but it is a spectacular little bird, and if you have some dense understorey planted, it may visit your garden and remind y