The girls went door to door in their Glendale and La Crescenta neighborhoods and opened the donation pool to the local Scout council.
They also posted fliers about the towel drive in local businesses, and they assisted with the humane society's mobile outreach program by signing up for two separate days of adoption-outreach duty.
The girls gathered on Sunday in front of the humane society's RV, converted into a pet transporter, with kitties, dogs and a bunny up for adoption.
Sierra held a rat terrier named Jade in her lap as she talked about the Scouts' roles in the adoption effort.
"We're just helping the animals and like, taking them for walks," she said.
All of the girls are animal lovers, said Susie Zadravecz, Amber's mother and the troop leader. Deliberation on what they should do to earn their scouting honors was short.
The girls decided there was no better way they would like to spend 15 hours of community service, which each girl must complete for the award.
"It's a lot of fun to know that you're helping the animals on the adoption days," said Amber, 11, of Glendale.
Each of the girls has at least one pet at home and Sierra and Amber both have golden retrievers in their family.
"It's worth the work and the time," said Jillian, 11, of La Crescenta. "I was able to reach out to my community in this way in the Montrose area. We have a big heart for animals so it was a perfect match for our personalities."
Kevin McManus, mobile outreach coordinator for the Pasadena Humane Society, said the RV adoption days have a 90% success rate.
The girls will continue their towel drive until Nov. 19 when they participate in their last mobile pet adoption day in front of the La Cañada Flintridge Petco.
