A French couple who died during an afternoon hike across the searing New Mexico desert probably saved their nine-year-old son by giving him two sips of water for each one they took.
The boy was dehydrated but in remarkably good shape when he was found by park rangers alongside his dead father on a trail in the White Sands National Monument, Otero County Sheriff Benny House said.
The father and son were found on Tuesday about an hour after park rangers found the mother dead.
"That may be why he fared so well, is he was a lot smaller and probably had twice as much water," House said.
"He was well hydrated, compared to the other two."
The couple appear to have died of heat-related causes after setting out in 38C degree heat with just two 566 gram water bottles, House said.
There is no vegetation or shade, and the National Park Service warns summertime visitors to hike only in the cool hours and carry at least 3.8 litres of water per person.
The boy's grandmother flew from France to be reunited with him.
US authorities have rescued a nine-year-old French boy in the New Mexico desert after finding photographs of him on his dead mother's camera.
David Steiner, 42, and Ornella Steiner, 51, both from the small town of Bourgogne near Reims, had been hiking in the White Sands National Monument on Tuesday afternoon when they apparently died from heat exhaustion, Otero County Sheriff's Detective David Hunter said on Friday.
"They underestimated the elements," Hunter told AFP, adding that autopsy results were still pending.
Park rangers found the mother first while on a routine patrol. They checked her camera and saw that she had been with two other people, Hunter said.
Authorities followed her tracks and found the body of the father, with their son nearby. He was dehydrated but responsive and was taken to a local hospital for treatment.
The New York Daily News said authorities had contacted the French consulate and the boy's grandmother had flown from France and taken custody of him on Thursday.
Otero County Sheriff Benny House told local media that the family had been travelling across the United States, visiting national parks and monuments.
"The father and mother would take one drink while they made the child take two swallows of water," House told the Alamogordo Daily News.
"It might have been why the child fared so well due to his smaller stature, plus he probably consumed more water than they did," House was quoted as saying.
House said the boy told authorities that his mother had headed back toward the car after becoming ill on the hike. He carried on with his father.
House said temperatures had topped 38C, according to the Alamogordo Daily News.
National Parks spokesman Patrick O'Driscoll told the newspaper there was no shade or water along any of the trails in the dune-filled White Sands National Monument.