Read the following text to answer questions number 42 to 45

    Ostrich is a large flightless bird native to Africa. It is distinctive in its appearance with a long neck and legs. It has the ability to run at maximum speed of about 70 km/h, the top land speed of any bird. The Ostrich is the largest living species of bird and lays the largest egg of any hying bird. The diet of the Ostrich mainly consist of plant, though it also eats insects. It lives in nomadic groups which consist of five to fifty birds. When threatened, the Ostrich will either hide itself by lying flat against the ground or run away. Moreover, it can attack the enemy with a kick from its Powerful legs.

    Ostriches become sexually mature when they are 2 to 4 years old. Females mature about six months earlier than males. The mating begins in March or April and ends before September.

"It lives in nomadic groups ... " The underlined word is closest in meaning ....