News This Week
Tag! You’re…..a Seal
- Total elephant seal numbers continue to decline as females leave the beaches.
- Mating and aggressive male interactions are ramping up.
- Researchers begin tagging seals.
- Drakes beach, parking lot, and access road remains closed. On weekends from 9 am - 5 pm the road will open, and visitors can access the parking lot and visitor center only.
This year researchers at Point Reyes will try to tag as many weaned pups as possible at Drakes, Chimney Rock, and South Beach, as well as adult females at the harem in front of the visitor center. Tagging is an important tool in tracking the movement and life history of individual seals, and is especially helpful at Point Reyes with all the movement we have seen in the past few years. The tags are meant for tagging the ears of cattle, but we apply the tag in the inter-digital webbing of the seal’s rear flipper. The tagging causes some discomfort to the animal, probably a similar experience to a human getting an ear pierced, but they recover quickly. Many seals have been observed falling right back to sleep post tagging! At the Año Nuevo colony, researchers from the University of California Santa Cruz apply scientific instruments to seals using a special glue. These instruments can record the animal’s movements such as dive depth and duration, feeding strategies, and general ocean conditions. One of their animals, an adult female, was spotted at the Point Reyes Headlands colony this week! The Año researchers hope to retrieve the tag from the hard to access beach, weather permitting. If you spot a seal with scientific instruments please contact park staff.
With the peak of breeding activity upon us, there will be a lot of movement, fighting and mating taking place on Point Reyes beaches. Many males will start to congregate around groups of breeding females, and the alpha male will be busy fending them off. The alpha male can usually be spotted in the center of the harem, although he will frequently change position to mate and chase off other males. Alphas typically are very large, with an impressive proboscis and chest shield. Some harems, especially very large ones, will also have a beta male. The beta is usually closer to the perimeter of the bulk of females, and the alpha will allow the beta to be part of the harem and will even allow him to mate. Having a beta to help defend a large harem can actually be beneficial to the alpha, allowing him to conserve energy needed for mating. As more females come into estrus, more males will approach the harems and try their luck at mating. These peripheral males can successfully mate while the alpha is distracted or sleeping, or when females attempt to depart the beach after weaning their pup. A male who successfully mates even just once has beaten incredible odds. Approximately 5% of male seals survive to breeding age (7-8 years), and less than 1% of males successfully mate!
A Time to Mate
As mating activity increases it is common to see female elephant seals vigorously protesting when a male attempts to mate. Protesting mating, such as vocalizations and swinging the rear end, are normal behaviors for female seals. Female seals are in estrus for about three days at the end of the nursing period. Females will be much more receptive to mating near the end of their estrus period, and also typically more receptive to an alpha male over an interloper. Researchers believe that when a female selects a harem she is not selecting a particular mate, but looking for safety in numbers with her fellow female seals. However, since alphas have the health and stamina to beat the odds and make it to alpha status, the genes he is passing on are probably of superior quality.