Biological Mechanisms Of Migration

Migration is the long distance movement of individuals from one place to another. It carries an energy cost but there are energy savings in travelling as a group. Migrations are usually for the purpose of feeding, breeding or overwintering. True migrations involve a return Journey.

Biological mechanism such as an internal biological clock in the Bar-tailed Godwit is the endogenous timing system that the organism uses to synchronise its activities with the environment. These activities are things such as changes to day length and changes to temperature. Biological clocks stay synchronised with the environment because they are regularly reset by an external environmental cue of Zeitgeber. These biological mechanisms are important as they are

Migration is an energy expensive behaviour. The Bar-tailed Godwit prepare for their journey by feeding continuously to store body fat, so before departure, up to 45% of their body weight is fat. Feeding is crucial for the Bar-tailed Godwit as they require enough energy to sustain them throughout the journey to prevent starvation or they could face exhaustion or death due to the long journey. The Bar-tailed Godwit also prepares by changing feather types. For the flight they have very sleek feathers so their body is very streamlined, so when they fly they have lowest resistance and so preserving energy. The journey from New Zealand/Australia to Alaska is longer (13000km) and increases chance of starvation and exhaustion, so the Bar-tailed Godwits have staging sites in South Korea, Japan or China where they can restore some energy by feeding before continuing their journey. Before they migrate, Bar-tailed Godwits congregate so they fly together in a flock in V-formation. This is so that the bird in front is cutting the wind first and the other birds are passing into the wind that has already been sliced to a degree, so the bird at the front is

The Bar-tailed Godwit migrate to Alaska to avoid the cold winter in New Zealand/Australia and migrating to New Zealand/Australia to avoid the Alaska’s harsh winters. Places that are too close to the equator may be too hot for Bar-tailed Godwit. So migration allows the individual to locate to an area with more favourable conditions warm conditions that are in their tolerance zone all year round. Warmer temperature enables them to spend less energy on keeping warm and more energy on breeding, searching for food and rearing young successfully. By spending time in the summer periods by migration, there are constant supplies of essential resources for themselves and offspring so increasing survival chances. If the Bar-Tailed Godwits did not migrate, they are not suited for the cold conditions so it decreases their survival chances. The risks of the Bar-tailed Godwits migration involves getting lost/going away from their natural path, dehydration, exhaustion that could lead failure to reach their destination or death. However, the advantages of migration outweighs the disadvantages so thats why the Bar-tail Godwits migrate