Heermann’s Gull

Larus heermanni

The Heermann’s Gull’s story, along with the Elegant Tern’s, is closely linked to a small, 142 acre island in the Gulf of California, called Isla Raza. Studies show nearly 95% of all Heermann’s Gulls are born there.

Humans have been the biggest threat to survival for the Heermann’s Gull. Population declines reached their low point in 1975, when their numbers fell to 55,000 pairs. Pesticide levels in their flesh reached high levels. Mexican fishermen poached eggs in large quantities, introduced mammals such as Black Rats (Rattus rattus) and House Mice (Mus mus) wreaked havoc on the remote islands they nested on, commercial fishing of sardines, anchovies, and other prey fish affected the nesting success for these gulls.

Things turned for the better in 1964 when the Mexican government established Isla Rasa as a seabird sanctuary. The rat and mouse invaders were eradicated in 1975. Pesticide levels in their tissue have been reduced in more recent years, and the current population is estimated at 350,00 individuals. Recently, nesting colonies have spread north, some even off the California coast.

Taxonomists regard the Heermann’s Gull as monotypic (i.e. there are no subspecies).

Most of my encounters with these gulls have come from the rocky cliff shoreline near La Jolla (California), my father’s birthplace. He was born in 1927, when La Jolla was a sleepy village with cobblestone streets. Life then was simpler, and little pressure from humans was put on wildlife. I worry today, as the wealthy upper-class continue building larger homes, and creeping ever closer to the shore.

Areas like the La Jolla Cove can attract seasonal congregations of bird and mammal sea life, and the aroma can become quite strong. Eventually storms wash all the decaying organic material out to sea, and clear the air. But during those pungent periods, I have heard locals bitching and moaning, claiming ‘someone should do something‘ to get rid of the birds. But California Sea Lions are likely the worst offenders leaving obnoxious organic deposits. But Brandt’s Cormorants nest on these cliffs. And Brown Pelicans, multiple gull species (including our Heermann’s), terns, and shorebirds frequently rest on cliff ledges.