"I am not getting anything," he says.
We are standing together on a railway line on the edge of Hwange National Park in western Zimbabwe. On one side of the tracks, the animals are protected. On the other, they can be shot. Jericho has moved to the other side.
"When we look at our satellite images or listen to the signals and see that the lions have moved across, there is definitely a knot in our stomach," says Stapelkamp.
For nine years Stapelkamp, a field researcher with an Oxford University-funded project, has been tracking the lions of Hwange. He knows more than 200 by sight and by name.
But one lion was always his favorite: a black-maned male called Cecil who, in death, has perhaps become the world's most famous lion.
In early July, the 13-year-old lion was lured out of the park with food
, shot with a crossbow, tracked for 40 more hours, then finished off with a gun, authorities say.
Cecil was skinned, his head reportedly cut off as a trophy.
It was a tragic end for the much-loved lion, if not an altogether surprising one for those who knew him best.
"A big lion like Cecil, if you ask us, we probably knew that is how he was going to die," Stapelkamp says.
After years of working in near anonymity, Stapelkamp has been at the center of a story that has touched a nerve around the world. The killing of Cecil, a protected animal, sparked international outrage that quickly reached the doorstep of hunter Walter Palmer, who has gone into hiding.
Palmer, an American dentist, allegedly paid around $50,000 to kill Cecil
. Park officials claim the hunt was illegal, but Palmer says he did nothing wrong.
Stapelkamp isn't so sure.
"I am quite sure that he knew what he was doing," he tells CNN. "He came for the biggest lion he could find and that had been organized for him. Cecil was delivered to him like a pizza."
Journalists have descended into this corner of Zimbabwe, searching for the cubs that Cecil left behind.
Experts feared the cubs would be killed as part of a power struggle over the pride but Jericho, who ran the pride with Cecil, appears to have taken them in.
Last week several of the cubs were reportedly spotted
, alive and well, with the lionesses of the pride by a safari tour in the park.
No love lost for lions here
While Cecil's killing has infuriated many around the world, that feeling is not shared by everyone in Zimbabwe.
We find a woman named Margaret Sibanda washing clothes on the side of a highway. Sibanda means lion in Sindebele, but there is no love lost here for Cecil or any other lion.
"If a lion is killed, I really don't care, because it destroys our cattle," she says. "The children in this part of Zimbabwe walk long distances to get to school. Lions and other animals are a threat."
Sibanda's granddaughter Tamaka walks two miles each way to get to class. Tamaka's mother says, "I hope she can walk to school and come back safely because of the wild animals."
The Sibandas say they get no money from the tourists or hunters that drive past their homestead on the way to the park. And Zimbabweans we've talked to say there are other things the world needs to focus on, like corruption and the cost of living.
"Here in Zimbabwe we are starving, the life we are living here now is difficult. You can't live," says Charles Nkomo, who we meet at a bus stop.
He says the world should care more about Zimbabwe's people, not its lions.
But Stapelkamp believes there is space for both. He hopes the killing of Cecil will raise enough awareness to help the country create sustainable conservation that can help local communities.
And he has gotten a signal for Jericho. It's a faint "tuk tuk tuk" on the receiver.
Stapelkamp hopes it too won't fade away.