The birthday party was at a nature center where friends and family petted animals and hiked on an unseasonably warm February day.

Five-year-old birthday girls Jemima and Helen Snyder also asked their guests to donate money to Philabundance and the Philadelphia Animal Welfare Society (PAWS) - and went without gifts. The family put the charities' links in the invitations.

"The girls have lots and lots of toys," said their dad, Mark Snyder of Abington. "Feeding a family is something they can comprehend. We frame it as, people are giving food to someone instead of giving you another toy, but they're doing it for you."

For years, people have used milestones - bar and bat mitzvahs, graduations, weddings - as a way to support favorite causes. Now, that kind of philanthropy is trickling down to young kids' birthday parties, fueled by parents who want to combine empathy lessons with a deemphasising of material goods. Most parents would agree that the presents classmates typically give aren't the stuff of keepsakes, just things that add to the clutter of the house.

"It's a reflection of crowdsourcing or crowdfunding, using technology at its best to facilitate supporting good causes," said Robert Evans, president of the Evans Consulting Group in Willow Grove, which helps nonprofit companies with fund-raising and strategic planning. Online giving has increased "spectacularly" over the last five years, Evans said, to the point where 10 percent of all giving in 2016 was a result of donating online. The increase in donations from birthday parties follows the same trend.

PAWS started marketing this option when it opened its Old City adoption center in 2008, and it now gets more than a dozen birthday-related donations annually.

"PAWS is completely donor funded, so we are constantly seeking support of high-level gifts and major funders," said Melissa Levy, executive director of PAWS. "The dollar amount may be smaller [with birthday donations] but the meaning is probably greater than any other support we receive."

Kids who choose to steer donations to a cause are often incorporating the theme into their parties, sometimes even holding the gatherings at the charity. For instance, parties at Cradles to Crayons - which provides everyday items, including clothing, books, toys, diapers, and school supplies to kids younger than 12 through gently used product collection - put the kids to work, sorting and packing customized packages.

About half a dozen kids' parties each year are held in the local Cradles to Crayons facility; each month, one or two parties held elsewhere donate goods in honor of a birthday child.

When Jennifer Grey of Collegeville stumbled across the Cradles to Crayons website, she was intrigued enough to give her daughter, Maddie, a philanthropic sixth birthday party in September. She told Maddie her friends would donate presents to the nine-year-old charity - and Maddie was excited about it.

Grey contributed what she would have spent at a typical party venue (generally $250 to $500) to cover the costs of staffing the event and providing paper goods and party favors, and she donated new baby-related items that Maddie helped pick out.

The staff explained their mission in a kid-friendly way, and, after a warehouse tour, the seven children were assigned the task of cleaning and sorting donated shoes.

"They sprayed the shoes with Simple Green and had toothbrushes and scrub brushes," she said. "They were getting their hands dirty, but they could see the results of what they were doing and had a lot of pride."

The girls then got crafty, decorating cards to accompany the donations. Next came cake and snacks, completing the two-hour party.

"It's a very impactful way for the kids to participate in tangible philanthropy," said Michal Smith, executive director of Cradles to Crayons in Conshohocken.

Judith Martin, the woman otherwise known as Miss Manners, questions whether those good intentions leave out critical lessons and teach unintended ones.

Birthday parties offer important messages about the host/guest relationship and the custom of exchanging presents, she said: The guests learn to think about the other child and to shop for something that child would like, and the host learns to receive presents graciously.

"These are very hard lessons to learn, and to add to it the also-important lesson - but a much more abstract one - of caring for other people whom you don't know, leads to the idea that any occasion of your own, you can take control of other people's resources and tell them how to spend it."

Advocates think it's a simple concept that kids can digest.

The Mazelis EauClaire family supports the Student-Run Emergency Housing Unit of Philadelphia by regularly volunteering to cook and eat with about 20 homeless men.

"There are stereotypes about people who are homeless and struggling, and I want my kids to know that they are people just like anybody else. They're just struggling more than we are," said Joanie Mazelis of Queen Village. "Eating a meal with them demystifies that in a lot of ways."

So for Amelia and Sam's seventh birthday in June, the email invitation for the party at a local park announced "no gifts necessary" but listed the family's favorite nonprofit. The party raised about $200.

Some family members and friends still gave the twins presents, Mazelis said, "so they were actually able to focus on those and appreciate them more instead of having a giant stack where they didn't even know what they had gotten."