By Fatos Bytyci PRESEVO, Serbia (Reuters) - Thousands of migrants, many of them refugees from Syria, surged through the Balkans on Monday en route to western Europe, riding by boat and bus in an organised effort by cash-strapped governments to move them on as swiftly as possible. Eight thousand poured into Serbia in the space of 24 hours, trekking five kilometres (3 miles) from the border to a reception centre in the town of Presevo, where a Reuters reporter counted 25 buses waiting to carry them north. Extra trains and buses ran regularly too from Macedonia’s southern border, which has been inundated since Greece began ferrying migrants from islands to the mainland at a rate of 2,500 per day.