Squirrels are running rampant in the rafters of a synagogue. Desperate to find a way to deal with the pests, the rabbi decides to bar mitzvah them. The day after, the squirrels leave the synagogue and never come back.

This old joke tells the sad truth about the many b’nai mitzvah kids who disappear from synagogue life after the ceremony. To bring those teens back into the fold, a group of philanthropists created Birthright Israel nine years ago, offering Jewish young adults free trips to Israel to ignite their passion for Judaism.

The program has had enormous success in sending more than 100,000 Jews to the holy land. Many participants get more involved in Jewish life on their respective campuses after the trip, but new research points to a staggering 44 percent of Birthright alumni who stop attending Jewish events after college. (See related story, Beyond Birthright — Report: Communities must do more to attract alums.)

That figure is representative of a larger problem in the Jewish community, said Rabbi Ely Allen, director of Hillel at UJA Federation of Northern New Jersey, which operates on four area college campuses.

UJA-NNJ will sponsor its third Birthright trip this summer, which will bring the number of participants on its trips to 120. Some participants are from the local colleges, while others are area residents who go to schools elsewhere. On campus, about 80 percent of Birthright alumni stay active in Jewish life, Allen said, but Hillel can only offer so much. The larger Jewish community is not focused on what happens to Jews after they leave college, which makes the Birthright experience more of an isolated event, he said.

Follow-up “has to be an important part of the federation world and the Jewish education scene,” he said. “You can’t just expect people to have a 10-day trip and no follow-up … to carry them through their Jewish lives.”

An editorial in this newspaper last month lamented the lack of Jewish social opportunities for young adults outside of New York City. Allen agreed, adding that the Jewish community largely has been ignoring the population.

“There need to be organizations for young adults,” he said. “That’s the time we’re most likely going to lose them.”

Allen praised organizations such as Birthright Next that offer opportunities for alumni, but chastised the larger Jewish communal world for not following suit.

“If all these Jewish organizations want to have a next generation, there needs to be programming,” he said. “There needs to be a concerted effort and teamwork among all the organizations. We have to have the same [effort] for after they graduate from college.”

While most students stay active in Jewish life on campus after Birthright, Allen has noticed the falling away of about 15 percent to 20 percent of Birthright participants on his campuses. He had no answer as to why.

In addition to his work with Hillel, the rabbi runs classes and Shabbatons out of his home, open to students and young adults in the community. He sees many young adults who are out of college and have few other groups reaching out to them in the area.

Natalia Kadish attends events at Allen’s with her husband, Aaron. They both went on Birthright through Ma’ayanot, although on different trips. Kadish praised the trip but said that now that she and her spouse are out of college and living in Teaneck, they need more support. Both are in their mid-20s and feel that only Allen and another Teaneck family that hosts Shabbatons have consistently reached out to their age group, she said.

“I’m very blessed to have Ely and the Shulman family, and all our chevra,” she said, “but if it weren’t for Ely’s family and the Shulmans, my heart would not be as close to HaShem.”

To highlight the need for more outreach, Kadish paraphrased a quote from the band Tool: “If no one was here to see us through the tedious path we have chosen, we might have walked away by now.”

Debra Segal, who works for The Cornerstone Group in New York, has lived in Teaneck with her family since seventh grade and says there has never been any programming for her generation. She is active in her synagogue but says that it mostly reaches out only to young children. Now 20, Segal remains involved, but laments that the larger community still hasn’t extended itself to her demographic.

“People recognize that this is something we have to work on,” Allen said. “There are plans and things happening. At this time when we’re going through all these cuts, I hope there will be an increase in investment in young adults and who’s going to the future leadership of the Jewish community.”

The full impact of Birthright won’t be seen for a few more years, said Amy Winn-Dworkin, UJA-NNJ’s director of Birthright Israel Support. Those among the 18-26 age group that Birthright targets are either still in college or, in the case of the organization’s oldest alumni, still in the early stages of their careers and adult lives.

Winn-Dworkin argued that enough time has not passed to determine the full impact of Birthright on its participants. The years between ages 18 and 26 can be filled with critical decisions and Birthright could later affect whom alumni marry, how they raise their children, and how active they are in Jewish life.

“It’s going to be a constant research experiment to see what happens,” she said. “The people we are sending to Israel today, in this generation, are future shul presidents, federation presidents, mayors, heads of states, CEOs.”

Since going on Birthright in 2006 with Hillel at Penn State University, Perry Bindelglass, 22, has remained active in Jewish life. He has volunteered with UJA-NNJ for Super Sunday and other fund-raising events, and is an active booster of Birthright.

“I was always involved but because of my parents. I grew up with it,” he said. His parents, Gale and David of Franklin Lakes, are active in organizing and fund-raising for UJA-NNJ events.

After Birthright, Bindelglass would continue to run into other participants around campus. Some graduated soon after they got back, some he would see only at High Holiday services, but they always had a bond, he said.

“Any time I meet somebody who’s gone on the trip, we’ve connected,” he said.

Now Bindelglass lives in Washington and, while he has met with the president of the local federation, he has not yet gotten involved with the organization.

“It’s a little harder now,” he said. “But I’m still involved as much as I can be.”

UJA-NNJ does not offer formal Birthright alumni programming. Such organizations exist in New York, but for local Birthright alumni still in college those programs can be difficult to attend.

“We have tried a couple of times to try to engage alumni into other federation activities but it doesn’t work as well because most of our alumni are going to college out of the area,” Winn-Dworkin said.

Within the next seven to 10 years, Winn-Dworkin expects to see those numbers begin to change, and hopes the federation will be able to attract more alumni to its events. Many recent college graduates head to the city rather than the suburbs, but as they eventually marry and have children, northern New Jersey becomes more popular. That shared Birthright experience from college might be the foundation to build upon later.

“Trying to still maintain that Birthright connection might be something important for us to look at,” Winn-Dworkin said. “The value of this program is it creates connections where other things have not. This is going to be the future of our community.”