When is Best to Migrate
Travelling by night will help some species elude their predators. Those birds that do not fly non-stop, will usually land in the very early morning hours, find a safe place to rest and will be able to find food during the daylight hours. Night migrators include warblers, cuckoos, thrushes, a number of waterfowl and flycatchers. Those who prefer a daytime trip include hawks, eagles, pelicans, storks, swifts, swallows, shrikes and some finches.

The most important factor to consider is prevailing winds. Flying With the wind will greatly aid the Migration whereas flying into Wind could easily be the difference between making the trip and not making it. In the Northern Hemisphere, many species wait for the Passage of Cold Fronts that sweep through the North American and European continents regularly. Ahead of these Cold Fronts, wind currents flow from North to South making it beneficial Migrate South just ahead of them, whereas behind the Cold Fronts, Wind directions are generally South to North. This means that returning Migration from the South back to the North will be greatly aided by flying just behind the Fronts.

The Influence of Global Warming on Migration
In recent years Global Warming has created some severe problems with Migration. This has occured in 2 main ways
a) Longer, warmer Summers can mean some Species leave later and later each year for their alternate homes as Winter takes longer and longer to arrive. Arriving in the new home may mean food resources have changed and are not in the same state as usual
b) The main problem however, is that some Species are arriving only to find that their usual insect prey has hatched, lived and died earlier than usual meaning that their food resources weren't there when they arrived back from migration