When Patrick Kilonzo Mwalua pulls his huge truck up to its destination in Kenya, dozens of elated four-legged customers are already waiting for him and others come racing when they hear the rumble of his engine.

Mwalua is making the rounds in drought-stricken Tsavo West National Park, and he's carrying 3,170 gallons of water to fill dried-out watering holes. His "clients" are elephants and zebras, African water buffaloes, antelopes, and even the occasional donkey.

About four times a week, Mwalua climbs into a water truck where he makes a 55-mile round trip to fill up watering holes in the park. A long-time conservation activist, Mwalua began renting a truck in September 2016 when he noticed the area had become incredibly parched and there was no rain expected for many months. He estimates that each truckload of water costs about $250 and he delivers about two or three in one day.

Patrick Kilonzo Mwalua with a water truck Mwalua delivers more than 12,000 gallons each week to animals in drought-stricken Kenya. (Photo: Patrick Kilonzo Mwalua/Facebook)

"This has got us all very worried of losing many animals from antelopes to elephants if nothing is done very urgently," he wrote on the GoFundMe page a U.S. supporter started to help him pay for the water delivery.

"Some years back we lost many animals including elephants due to a prolonged drought. Elephants are becoming endangered from poaching and we need to save the ones we have left by providing water for them until the drought peril is over. We have many elephants concentrating in very few water holes fighting to drink water and this has made the smaller elephants lacking water. They become very thirsty and they end up spending a lot of time and energy walking very far distances with young ones searching for water."

Mwalua shares photos of the animals on his Facebook page, showing how many of them come to drink and how so many different species gather together peacefully at the watering holes.

"This was how it was in our saving waterhole that collects different types of animals just for a common rare commodity and that is Water for life!" he writes. "I found no Water at all and animals were right resting at the waterhole waiting for my truck and quench their thirst. It is unbelievable how they have known the truck and they just wait patiently for water and surrounding the truck as we deliver. They don't harm us because they know we are helping and now i'm a great fan of fierce buffaloes."

water buffaloes at a watering hole in tsavo African water buffaloes (also known as cape buffaloes) watch as Mwalua fills up the watering hole. (Photo: Patrick Kilonzo Mwalua/Facebook)

When he's not helping thirsty animals, Mwalua is a pea farmer and the founder of the wildlife and conservation nonprofit Tsavo Volunteers. As part of that group, he visits schools to talk to kids about wildlife conservation.

As Mwalua writes, "I choose to stand for animals and please do stand with me to save these wonderful creatures."

Mary Jo DiLonardo writes about everything from health to parenting — and anything that helps explain why her dog does what he does.