the brilliant birds and the little monkeys had become accustomed to their new acquaintances , and as they had evidently never seen human beings before they presently , after their first fright had worn off , approached closer and closer , impelled by that strange curiosity which dominates the wild creatures of the forest and the jungle and the plain , so that within the first month several of the birds had gone so far as even to accept morsels of food from the friendly hands of the claytons .