The four adult sandhill cranes were lying in a ditch beside a road near Kinuso, Alta.
Their bodies seemed fine, but something had killed them.
All around the bodies lay thousands of dead grasshoppers, victims of a recent pesticide application.
“Aha,” said some local people. “The chemical is the culprit.”
It was a strange situation, so the Alberta government’s fish and wildlife service decided to investigate.
They checked whether the birds had been eating sprayed grasshoppers, even though cranes don’t normally eat grasshoppers. Autopsies showed no grasshoppers in their bellies.
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“That turned out to be a false lead and totally coincidental,” said Margo Pybus, a wildlife disease specialist with the fish and wildlife service.
“But in these cases, you wonder what could possibly have happened here, and like any forensic detective story, you look at all factors.”
The birds had no outward signs of damage. They had no head, leg or wing injuries. But the autopsies revealed the birds had severe internal injuries.
The cranes had many broken bones and extensive hemorrhaging around the heart and other organs.
To the researchers, this was proof the birds had been killed by “blunt trauma.” In other words, they were killed by getting smacked really hard by something, or smacking into something really hard.
They concluded the cranes had crash-landed into the ditch.
“They just hit the ground,” said Pybus.
But why would four adult cranes – all of them veteran flyers – crash into the ground?
“If their navigational system gets fouled up, their perception of where the ground is can be completely thrown off,” said Pybus.
“They were probably coming down, thinking they were still high above the ground, so they hadn’t put the brakes on yet.”
Fish and wildlife officials talked to local people and found that just before the birds were discovered, the area had been cloaked by a thick fog. The fog must have hidden the ground, and the cranes plummeted right into it, unaware that their sense of where the land lay was dreadfully confused.
Pybus said incidents like this sometimes occur during migration. This crane crash occurred in September.
Wildlife often leave researchers with forensic mysteries.
Pybus remembers a strange case in which the fish and wildlife service investigated the discovery of a number of dead pelicans.
Some had broken wings. Most were seriously bruised. One had a bad bruise on the back of its skull that would probably have caused a concussion.
There was nothing around the dead birds to explain what had beaten and killed them.
Then people in a local coffee shop told officials about a severe but localized hailstorm in which golf ball-sized chunks of ice flailed part of the area.
“That flock of pelicans must have been right underneath the eye of the storm,” said Pybus.
“But when we got there, everything had melted. By the time our staff got there, there were just dead pelicans.”
