Memberships and loyal volunteers might be described as the lifeblood that motivates participation in Balboa Park’s 15 museums. Representatives of some of the major museums weighed in about their programs that encourage thousands of people to become active at San Diego’s history-packed gem. From the big facilities in the Prado to the Japanese Friendship Garden and international colony, there are plenty of reasons to be a supporter. Reuben H. Fleet Science Center’s membership has grown to 14,430, with 300 working volunteers, according to Michael Conley, who has headed the membership campaigns for 20 years. Across the patio, Eowyn Bates, in charge of development and membership, said the Natural History Museum reaches 8,700 households. Devon Foster, manager of marketing and communications at the Museum of Art, reports they have 11,000 members, and about 500 active volunteers. “All membership levels receive a subscription to the Member Magazine, an exclusive preview day for major exhibitions, free admission to Art Alive and event and store discounts,” she said.  “Members provide the critical support the museum needs to acquire, conserve and exhibit the finest works of art created throughout time,” said Museum of Art executive director Roxana Velasquez. “Thanks to the support of our members, we are able to share exhibitions — both special traveling exhibitions like El Greco to Dalí, and those created with works from our permanent collection like Toulouse-Lautrec’s Paris and Dreams and Diversions — with the public. We are also able to continue our outreach into schools and the community.” Located beneath the ornate 200-foot California Tower, the Museum of Man is the city’s only museum devoted to anthropology. One of the oldest in the park, it lists 1,100 members and over 50 docents and volunteers.  Beyond President’s Way and next to the Starlight Bowl, the Air and Space Museum reports 3,525 member supporters, along with 264 volunteers. “Even though the economy has been down, our membership has climbed at the Science Center,” said Conley, who has seen it grow from 4,000 in 1998. “We took an aggressive stance in recruiting volunteers about two years ago and started using them in more areas than before. “I’d say 62 to 64 percent of our memberships come in with our family package. Next largest are the seniors. The categories can range from $150 to $2,500.” “Several years ago, museums began to understand that memberships meant the bottom line,” Conley continued. “That became a steady source of revenue. And, too, they are likely to donate at the annual fundraisers.” Generally, the benefits of membership at most museums include unlimited admissions, discounts at gift shops and for special tours, preferential enrollment in educational programs and newsletters. “It’s a longtime family tradition to bring kids and grandkids to explore,” said Bates. “Family days and kids programs are important. Bates added that, in order to continue offering exhibits that visitors find interesting, each new member receives a survey to provide feedback and suggestions. “Our museum is constantly changing and there is always something to come back and see. We’ve recently added Balboa Park’s only 3D/4D movie theater, new simulators and a special kid zone,” said Jessica Packard, publicist for the Air and Space Museum. “We encourage people to become members so they can have unlimited access to the museum for an entire year.”