public void birthHerbivore(int n){
		if (animalMax < n){
			n = animalMax;
		}

		for(int i=0; i<n; i++){
			herbivores[i] = new Herbivore();
			herbivores[i].setSize((int)((Math.random()+3) * 10));
			int tx, ty;
			do{
				tx = rand.nextInt(WIDTH);
				ty = rand.nextInt(HEIGHT);
			}while(tx-herbivores[i].getSize()<0||WIDTH<tx+herbivores[i].getSize()||ty-herbivores[i].getSize()<0||HEIGHT<ty+herbivores[i].getSize());
			herbivores[i].setPosition(tx, ty);
			herbivores[i].setVelocity((float)((Math.random()) * 10));
			herbivoresNum ++;
		}

	}