KEY WEST -- Inside the bus, Jim Grosby of San Diego strummed a Jimmy Buffett-inspired tune on his guitar to a captive audience with needles stuck in their arms.

“It’s like in the Irish bar — it’s one pint at a time,” Grosby said.

For the 14th consecutive year, Parrot Heads from around the country have taken 45 minutes out of their busy party schedules in Key West to donate to the Community Blood Centers of South Florida. It’s one of the many community service activities Jimmy Buffett fans perform during their annual Meeting of the Minds convention, taking place this weekend in Margaritaville.

“We party with a purpose; that’s what we do,” Brenda Jackson of Surfside Beach, N.C., said as she gave the “gift of life” with party beads hanging around her neck. “And, we have a good time doing it.”

On Thursday and Friday, 143 Parrot Heads — hard to miss in their tropical shirts and festive hats — donated blood in three buses staged around the Casa Marina beach resort, the convention’s headquarters. They also will collect blood on Saturday.

“It is our largest blood drive in the Keys,” said Nancy Brundage, who heads up the Keys operation for Community Blood Centers of South Florida.

That has been the case for the past six years. Jeff Hoffman, the Parrot Head who has organized the blood drive all 14 years, said: “We hope this year to make it seven in a row. Other groups have tried to beat us, but they haven’t.”

Last year, during the 20th anniversary of the Meetings of the Mind, Buffett made a rare appearance. The blood drive set the Keys’ single day record with 116 donated pints. They collected 175 overall, with 200 people attempting to donate. (Many people can’t donate for a variety of reasons, including having lived in a country when it had an outbreak of mad cow disease).

But as many Parrot Heads have found out, having just downed a couple of cocktails does not disqualify a potential donor.

“No, you can go right in,” Brundage told one man who was still holding his adult beverage. “The alcohol will evaporate.”

All the blood that is collected in Key West stays in Monroe County, supplying its three hospitals. “The recipient of that blood probably will never be able to thank you personally,” Brundage said. “Maybe you will save somebody’s mom or grandmother or child. It’s so far reaching, and a lot of people don’t get it. Your donation will make the difference in three lives.”

Parrot Head Michael Acuff, who retired from the Coast Guard and now lives in Jacksonville, said: “In the military, they say: ‘Give blood or we’ll take it from you.’ It’s something I’ve been doing for years and years.”

But most people do not. Figures vary, but most estimates say that fewer than 5 percent of eligible donors ever donate even one pint.

“That’s just a shame,” said Grosby, a member of the 10-gallon club. That means he has donated 80 times — one pint at a time. By federal law, a person is allowed to donate whole blood once every 56 days. Grosby has been donating since the 1970s.

“Some day I may need help,” he said. “And they are always low on blood.”