By Andrew Walker
Economics reporter, BBC World Service
The report says 140 million Chinese have left rural areas in search of work
The global recession has had a marked effect on international migration according to a special report commissioned by the BBC World Service.
Fewer people are moving abroad for work but those who are already abroad are, for the most part, staying put.
And in general, money sent by migrants to their families in their home country, has declined.
The research was done for the BBC by the Migration Policy Institute, an independent agency in Washington.
And you can see the report
explained in graphics
The story is varied, but the general pattern is that fewer people are moving abroad for work.
The number of Mexicans moving to the United States, for example, has fallen sharply - down 40% since 2006.
The drop is even greater in the case of Romanians and Bulgarians moving to Spain. Their numbers have fallen by 60%.
Migrant workers are more at risk of losing their jobs than native workers as they often work in industries especially exposed to the recession - notably construction and hospitality.
Hence, for the most part, they are also sending less cash home to support their families.
The number of Mexicans moving to the US has fallen sharply
In the case of Turkey, the decline in these remittances was 43% from 2008, the report says.
The impact of Moldova's 37% fall is especially severe, because remittances are equivalent to a third of the country's national income.
Although the general trend is downwards, a few countries including Pakistan and Bangladesh, have enjoyed an increase in the amount of money sent home by its citizens working abroad.
But despite the loss of income many face, in most cases there has not been a large-scale return home.
This may reflect the fact that, for many migrants, economic conditions are even worse at home and it would be difficult and costly if they wanted to return to their host country later.
That's especially true for people who have moved illegally.
There are some striking exceptions to these patterns, however.
Many migrants to the UK and Ireland from Central and Eastern Europe have returned home, where economic conditions have not deteriorated as much.
And as nationals of European Union countries, they can legally go back to their host country later.
Country on the move
The main focus of the research was international migration, but it did look at one example of migration within national borders, namely China.
The numbers are extraordinary.
Migrant workers are sending less money home to their families
The report says that 140 million have left rural areas in search of work in industrial cities near the coast.
That's the equivalent of the world's tenth largest population.
Every year millions return home for the Chinese New Year. This year, as China's economy weakened, record numbers went back and fewer returned to the cities afterwards.
Protecting their own
A recession often pushes international migration up the political agenda, and governments frequently take action intended to protect employment opportunities for their own nationals.
Several have cut the numbers of work permits for foreigners, including Malaysia, Australia and Russia.
Some, including Spain and Japan, are offering incentives for migrants to return including one-way tickets and lump-sum payments.
The picture the research paints is rich and diverse in detail, but a few things stand out.
Migrant workers have been especially vulnerable to the global economic storms that were created by the financial crisis.
They are more likely to lose their jobs, and their families at home have paid the price in the shape of less financial support.
Many have pulled down the shutters while the storm rages and decided to wait for better times - either at home or, if they have already moved abroad, in their host country.
It is also very plain from the report that migration is an increasingly important part of the global economic landscape.
Investment moves across borders fairly freely in search of the best opportunities. Increasingly, people want to do this as well.
The pattern depends on where the opportunities are. But when the economy recovers, people will be on the move once again.