WASHINGTON - When Jody Richards saw a homeless man begging outside a McDonald's here recently, he bought the man a cheeseburger. There's nothing unusual about that, except that Richards is homeless, too, and the 99-cent cheeseburger was a good chunk of the $9.50 he'd earned that day from panhandling.

The generosity of poor people, however, isn't so much rare as rarely noticed. In fact, America's poor donate more, in percentage terms, than higher-income groups do, surveys of charitable giving show. What's more, their generosity declines less in hard times than the generosity of richer givers does.

"The lowest-income fifth [of the population] always give at more than their capacity," said Virginia Hodgkinson, former vice president for research at Independent Sector, a Washington association of major nonprofit agencies. "The next two-fifths give at capacity, and those above that are capable of giving two or three times more than they give."

Supporting her point, the U.S. Bureau of Labor Statistics' latest survey of consumer expenditure found that the poorest fifth of America's households contributed an average of 4.3 percent of their incomes to charities in 2007. The richest fifth gave at less than half that rate, 2.1 percent.

None of the middle fifths of America's households, in contrast, gave away as much as 3 percent of their incomes.

"As a rule, people who have money don't know people in need," said Tanya Davis, 40, a laid-off security guard and single mother.

Certainly, better-off people are not asked by friends and kin as often as Davis said she was asked, having earned a reputation for generosity while she was working.

Now getting by on $110 a week in unemployment insurance and $314 a month in welfare, Davis still fields two or three appeals a week and lays out $5 or $10 weekly, she said.

To explain her giving, Davis offered the two reasons most commonly heard in three days of conversations with low-income donors:

"I believe that the more I give, the more I receive, and that God loves a cheerful giver," she said. "Plus, I've been in their position, and someday I might be again."

In terms of income, the poorest fifth seem unlikely benefactors. Their pretax household incomes averaged $10,531 in 2007, according to the BLS survey, compared with $158,388 for the top fifth.

In addition, its members are the least-educated fifth of the U.S. population, the oldest, the most religious, and the likeliest to rent their homes, according to demographers. They are also the most likely fifth to be on welfare, to drive used cars or rely on public transportation, to be students, minorities, women, and recent immigrants.

But many of these characteristics predict generosity. Women are more generous than men, studies have shown. Older people give more than younger donors with equal incomes. The working poor, disproportionate numbers of which are recent immigrants, are America's most generous group, according to Arthur Brooks, the author of the book Who Really Cares, an analysis of U.S. generosity.

Faith probably matters most, Brooks - who is the president of the American Enterprise Institute, a conservative Washington policy-research organization - said in an interview. That is partly because above-average numbers of poor people go to church, and those who attend church give more money than non-attenders to secular and religious charities, Brooks found.