Pacific Walrus at Cape Peirce

There are many natural causes of mortality for Pacific walruses.  However, sometimes these natural causes may in fact seem very unnatural.  In mid-October, residents from the village of Togiak, Alaska, observed a unique cause of natural mortality: a walrus falling off a 120-foot cliff at Cape Peirce within Togiak National Wildlife Refuge.  Villagers assumed more animals had fallen over the cliffs as 29 walrus carcasses were seen in the immediate vicinity.

Odd as it seems, this type of mortality has occurred at Cape Peirce before.  Between 1994 and 1996, Togiak Refuge staff stationed at Cape Peirce observed a total of 159 walruses fall to their death from the same cliff area.

More than a behavioral phenomenon, this activity seems to be a result of naturally-occurring landscape changes.  Prior to 1994, high grass covered dunes confined walrus activity to a traditional haul-out site on the beach.  But over time, wind and walrus activity eroded those dunes which opened a pathway that allowed access higher up the beach and ultimately, about 200 yards to the cliff edges. 

Preventing a herd of 3,000 pound walruses from going wherever they want to go presents a challenge.  A solution that proved quite successful a decade ago took advantage of the walruses’ strong aversion to disturbance as Refuge staff hung tarps between fence posts along the upper edge of the sand dunes.  In a location with no shortage of wind, the flapping tarps proved an effective deterrent to prevent walrus from climbing through the dunes to reach the cliff.

In response to the recent walrus deaths, Togiak Refuge staff herded some 50 walruses down from a precarious position above the sand dunes to another group of about 1,200 animals resting safely on the beach below.  We then installed a tarp fence along the open slope to prevent further access to the cliffs and monitored the walrus haul-out for six days to mitigate any further access to the cliff.

This year's event occurred a month-and-a-half after the Refuge field camp was closed and was only observed because Togiak residents were visiting the area.  The 4,009 walruses hauled-out on Cape Peirce beaches was a surprise to everyone after a season where the high count for the year was just 61 animals.  Increased monitoring last year documented more winter use of Refuge haul-outs than was thought to occur, and this latest event justifies continued off-season observations.