In 1944, the US Coast Guard released 29 reindeer on an Alaskan island as a food supply; 19 years later, scientists found them to be 6000, and next winter, only 42 were alive

In August 1944, the U.S. Coast Guard did something that made perfect sense at the time. They trucked 29 reindeer (24 females and 5 males) from Nunivak Island to St. Matthew Island, a remote 128-square-mile patch of tundra in Alaska's Bering Sea. The idea was to give the station's 19-man crew a dependable backup food source. And then the Second World War ended, and the station was abandoned, and the reindeer were left on their own.

In the next two decades, what followed became one of the most cited cautionary tales in all of ecology. According to the landmark study ‘The Introduction, Increase, and Crash of Reindeer on St. Matthew Island,’ published in the Journal of Wildlife Management by wildlife biologist David R. Klein, the reindeer population grew from 29 animals to 6,000 by the summer of 1963 before crashing to fewer than 50 in one winter. The last female reindeer on the island died in 1981, leaving the island completely empty, according to the U.S. Geological Survey.

No hunting. No predators. No significant illness. Only reindeer, open tundra, and a food supply, they had no reason to ration.


Paradise, at first
When Klein first visited St. Matthew in 1957, the herd had grown to 1,350 animals and was thriving. Klein's research showed that St. Matthew reindeer were 24 to 53 percent heavier than domestic herds in females and 46 to 61 percent in males. The lichens were deep and untouched, the rate of birth was high, and that of mortality was low. This was a population living under optimal conditions by any standard.

But that abundance was quietly masking a crisis in the making. There were no natural checks on their numbers, and reindeer were steadily eating away the island’s most critical resource, lichen, the slow-growing organism that was their primary winter food. According to research, ‘Monitoring Recovery of Overgrazed Lichen Communities on Hagemeister Island, Southwestern Alaska’ published by the Canadian Conservation and Land Management Knowledge Network, after reindeer overgrazing on Hagemeister Island, it was estimated that it might take 34 to 41 years to recover only grazeable lichen biomass, and full recovery could be as long as 400 years. The reindeer were eating up a resource that would not bounce back quickly.

The numbers tell a different story
When Klein came back in 1963, there were signs everywhere of a looming collapse. By 1963, the density of reindeer on the island had reached 46.9 per square mile, average body weights had fallen by 38 percent for adult females and 43 percent for adult males compared with 1957. The ratio of fawns to adult females had dropped from 75 per 100 in 1957 to 60 per 100 in 1963, while yearling ratios fell even further, from 45 to just 26 per 100 adult females.

The lichen that had covered the windswept ridges, the only usable winter grazing ground, was nearly all gone. Sedges and grasses were moving in, but neither had the same nutritional kick during the brutal Bering Sea winters. The animals were crowded, starving, facing the coldest season on record, and with almost nothing in reserve.

A winter that ended everything
The Bering Sea region experienced one of its coldest winters on record in 1963-64. Snow accumulations at monitoring stations in the vicinity were the highest in 20 years. The die-off was caused by a mix of factors: overgrazing had eliminated lichen as a major component of the winter diet; too many animals were competing for what remained; the reindeer entered the winter in poor physical condition following a summer of fierce competition for food; and extreme snow accumulations buried the already-depleted winter forage even deeper. Skeletal remains confirmed starvation. The marrow cavities of the long bones were completely hollow, meaning the animals had used up every last fat reserve.

The study indicates that of the 42 surviving reindeer counted in 1966, all but one were females. The sole male survivor seemed reproductively compromised, and no fawns or yearlings were counted among the survivors. The herd never recovered.

This pattern was familiar
St. Matthews Island was not unique. According to a U.S. government fish and wildlife resource inventory citing Scheffer's research, the St. Paul Island reindeer herd grew to a peak of more than 2,000 animals in 1938, before crashing to just 8 by 1950, due to overgrazing of lichen combined with the stress of harsh winters. In both cases, there were no predators, and the geographic limitations of an island meant there was no release valve for the population.

Klein’s study found that more ecologically complex environments, where multiple species interact, compete, and prey on one another, tend to slow population booms more gradually. Islands take that complexity away. If the food supply is the sole limiting factor, the result can be a near-total collapse.

Why this still matters
The St. Matthew Island story appears in ecology textbooks and conservation policy discussions for a reason. This was a well-documented example of what happens when a population grows beyond the resources that support it, what ecologists call an overshoot. There weren’t any bad guys. The reindeer simply used the resources available to it, like any population would, until that resource was exhausted.

To anyone paying attention to how humans manage land, fisheries, or freshwater systems, the math has the same uncomfortable logic: unchecked growth in a finite space tends to end the same way every time.