The nation's largest animal protection organization just got bigger. The 9.5 million-member Humane Society of the United States has joined forces with Doris Day Animal League, which claims more than 180,000 members and supporters.

A stated aim of the merger, announced in September, is to increase public policy activity and coordination on animal welfare issues and further streamline operations among national animal advocacy groups.

The union follows the HSUS merger with the Fund for Animals in 2005.

The DDAL has partnered successfully with the HSUS on many issues, including aid for animal victims of Hurricane Katrina, opposition to greyhound racing and animal testing of household products and cosmetics, and legislation mandating the addition of bittering agents to antifreeze to protect children and animals.

The merger also paves the way for increased public policy activity by the HSUS' affiliate, the Humane Society Legislative Fund, by combining the existing organization's membership and donor support with the DDAL.

"Our visions are in lockstep now," said Wayne Pacelle, HSUS president and CEO. "We both want to strengthen the capacity of the humane movement, and we recognize that we can achieve that by combining our operations, in order to eliminate duplicative programs and to create a more powerful force for animal protection."