Sven,
I will spell it out for you in simple terms....
ICAO, Boeing, and other studies show the probability of Bird Strikes increases as the frontal area of the aircraft increases, the closer one is to an airport, the lower one flies.
The most dangerous phase of flight is landing and taking off.
Cruise flight generates the fewest bird strikes.
80 percent of all bird strikes occur below 1000 feet AGL.
95 percent of all bird strikes occur below 2500 feet AGL.
80 percent of all bird strikes go unreported.
Highest recorded bird strike is 37,000 feet.
So Sven....if you can hit them at 37,000 feet.....there is no guarantee you can evade a bird strike altogether by flying "high". That being said....flying at 5,000 feet or higher does mitigate your chances of whacking a Bird.
Shawn is right....flying with a landing light on helps deter birds....the flashing light system is better than a single steady light.
Avoiding thermals is another way of decreasing your chances of smacking a soaring bird....Hawks, Buzzards, Eagles. (If that sounds silly....talk to a glider pilot who will be able to explain both thermals and soaring birds to you.)