This nest building behavior is instinctual for male bettas and it is not necessary to have a female present to observe your betta building his nest. Most males will blow bubbles but the rate and size of the nest seems to depend on the individual male and possibly, other factors like age, health and water parameters.
Berlin was always the centerpiece of the Cold War and, more often than many remember, very nearly the front line of real combat. At the end of World War II, the city was divided into four sectors, each occupied by one of the four allied armiesâU.S., Soviet, British, and French.
The Cold War began after World War II. It was between the United States and the Soviet Union. It was called the Cold War because both nations were afraid to fight one another directly, so they they did it indirectly.