Most custodians have husbands who are either away working in a city nearby or busy elsewhere, and their children are left at home for them to look after.
It's a tradition developed for female custodians to bring children to work.
Sonam Kyi, 37, has been working as a custodian for more than 10 years and has two daughters.
Lhamo Tsering, Sonam Kyi's younger daughter, is just 1 year old, and has been growing up on her mother's back for eight months. She often pokes her head out from behind her mother's shoulder and quietly stares at the vibrant world in front of her.
"When it's raining or snowing, I patrol up the mountain driving a pickup truck; and when the weather is fine and pleasing, I ride the motorbike with the child on my back on patrol," Sonam Kyi says shyly.
Sonam Kyi claims that when the child is crying because of the burning sun or the bumpy road, she will shade the baby with an umbrella, comfort her by fondling her head or pick a beautiful Galsang flower to distract her.
"When this naughty little girl is given free access to nature, she can't resist putting flowers and plants into her mouth, trying to taste them. I had to carry her all the time, often for over an hour straight."
Almost every holiday, Sonam Kyi's 16-year-old daughter, Lhakdron, comes to the station to accompany her mother, following her around on patrol as she used to since she turned 4.
"Seeing my mother contributing her force to the protection of the ecological environment in our hometown, I'm also encouraged to protect the plants and animals on Qilian Mountains that I grew up with," says Lhakdron.
Tsering Drolma, 22, joined the station in 2019. Her grandmother used to be a custodian, and she filled the place after the grandmother retired. She feels her colleagues are very united, and the local scenery "massages" her eyes every day.
She's deeply attached to her hometown.
"It was a wonderful and proud feeling to take over the job from my grandmother," she says.
Yudron, 29, who wished to earn more money to cover family expenses, joined the custodian team at the beginning of 2020. It was never expected that she would become pregnant with her second child within a few months after starting the job.
"As I became a custodian, I felt the responsibility on my shoulder, and I didn't want to stop working just because I was pregnant," Yudron says.
Yangmotso specially assigned her to cover the area near her home. She didn't miss one single patrol until the very day before the expected date of pre-birth care, and returned to work one month after giving birth.
Her daughter is now over 1 year old, and won't stop smiling at people when she is in her mother's arms. When Yudron is talking to others, the little girl quietly plays with her phone.
Sitting on the grass, Yudron pulls her shirt up and starts breastfeeding twice in half an hour.
Female custodians, who patrol with their children, carry many items in their backpacks every working day, including milk powder, feeding bottle, diapers, toys and bread. Sometimes, when they go on patrol, custodians take turns to share the sweet burden of climbing the mountain with the children on their backs. "We mothers often help each other out," Yangmotso says happily.
"My mom is doing a very meaningful job," Lhakdron says with a shy smile but firm eyes.