There's a new paper out by political scientists on support for animal rights. It's in line with most of the data I'd seen but bears repeating. High correlations with support for human rights and being female, and not much of a connection with wealth, but if anything wealthy people are less supportive of animal rights.

The abstract:

In this article, we empirically test explanations for variation in support for animal rights at the individual level and across the United States. We draw on a combination of national public opinion surveys and cross-sectional data on animal rights laws from the fifty US states. We find a strong connection between recognition of human rights and animal rights both at the individual attitude level and at the US state policy level. Our results demonstrate that support for animal rights strongly links to support for disadvantaged or marginalized human populations, including LGBT groups, racial minorities, undocumented immigrants, and the poor.