More than a thousand dead geese that washed up on the shore near Cambridge Bay, Nunavut, last August appear to have died of natural causes, including toxicity caused by drinking salt water.
Three of the birds were sent to the University of Calgary's faculty of Veterinary Medicine for testing, and the results have come back.
The theory is that the young birds were not fit enough for the harsh weather conditions they encountered while making the crossing from Victoria Island, where Cambridge Bay is located, to the mainland.
They may have become dehydrated thanks to their poor physical condition and likely drank salty sea water, leading to salt poisoning and death, before washing up along more than 20 kilometres of shoreline near Long Point, west of Cambridge Bay.
This probable cause of death has been determined by the Department of Environment and Climate Change Canada.
"They were already in a poor enough condition, probably because they're young birds," said Ray Alisauskas, a research scientist with the department.
"And that compounded with thirst — some of these birds have salt glands but they're not fully developed in young birds — if they consumed too much salt water, which they probably did, it can lead to salt toxicity."
The birds sent in for testing — two cackling geese and one snow goose — all appeared to be in very poor physical health based on diminished pectoral muscles and minimal or absent body fat. Toxic levels of salt were detected in the brain of one bird carcass, the only one that could be tested for it.
In an email to the CBC, a spokesperson for the department described "sustained strong winds and fog during the week" when the birds died, speculating that the birds — already malnourished and probably drinking salt water — weren't strong enough to fly through the conditions, and died.
"Other potential causes of mortality were dismissed based on the extensive testing completed," the spokesperson added.
"Some of the other potential causes of mortality that were tested for but not detected include: avian influenza, botulism, avian cholera, Newcastle disease, duck viral enteritis, lead or other heavy metal intoxication."
Snow geese migrate to the Arctic in massive numbers each summer.