What Have We Learned?
Once widely distributed along the California and Baja California coasts, northern elephant seals were hunted to the brink of extinction in the mid-1800s for their oil-rich blubber. Some researchers believe that as few as 100 seals may have remained before hunting was banned by the Mexican and United States governments in the early 20th century. The population has since been recovering, with added support from the U.S. Marine Mammal Protection Act of 1972 and they are recolonizing areas where they had been previously documented such as the Channel Islands and Point Reyes.
At Point Reyes, northern elephant seal colonies were absent for more than 150 years until a colony formed in the winter of 1981. The new colony grew exponentially until 1997-98. Growth continues at Point Reyes, though at a much slower pace. In 2012, preliminary results indicate that 723 pups were counted, a new high. Based on previous research establishing the typical ratio of pups to other elephant seal age groups, numbers of births can be multiplied by 3.5 to obtain a rough total population estimate. Using this calculation puts the Point Reyes population estimate for 2012 at more than 2,500 seals. Other research indicates that immigration is also contributing to population growth at Point Reyes.
Above: The maximum number of northern elephant seal pups at Point Reyes is calculated as the sum of the maximum number of pups (live and dead) and weaned pups counted on a single census at each colony site. Data from 2010-2012 are preliminary and have not been analyzed.
The maximum counts were lower in 2010 because storms coinciding with extreme high tides resulted in many young pups being washed away, especially at Point Reyes Headlands sites. Overall, though, the number of pups born at Point Reyes continues to increase.
Above: A map of the four main beach areas within Point Reyes where elephant seals congregate to pup, breed, and molt. A beach along Point Reyes Headlands was the first site to be colonized in 1981. As the population grew, seals began to use Drakes Beach, South Beach and beaches below the Chimney Rock Loop trail. Click on the circled beach areas to see a photo of each site.
While Point Reyes Headlands pocket beaches were the most dominant breeding sites for a long time, more seals now give birth at Drakes Beach near the Chimney Rock parking lot. This is likely due to overcrowding and the fact that Point Reyes Headlands beaches face the open ocean and offer little protection from winter storms that can wash away and drown young pups. Females at Point Reyes Headlands sites may move to the more protected Drakes Beach when there is a stormy start to the pupping season. For example, during 1998 and 2010, turbulent El Niño years, more than half of the pups born at the Point Reyes Headlands were washed away, and several pregnant females moved to Drakes Beach to give birth.
Surveys of tagged elephant seals at Point Reyes indicate that most of the seals coming ashore over the past several breeding seasons were originally born and tagged at Point Reyes. However, many elephant seals tagged at other colonies such as Año Nuevo, the Farallones, Piedras Blancas and the Channel Islands have also been recorded on Point Reyes beaches.
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