Saturday, January 27, 2007
Here is the weaner of Schnitzel lying next to an immature elephant seal that was probably born last year. You can see that the weaner is much larger, I count at least 4 chins on her.
Weaner Schnitzel is the first completely successful breeding attempt for its young mother.
Although the first wave of weaners has arrived, there are still 85 pups out there with their mothers. We are about 10 pups above the average for this date so it looks like the SEFI elephant seal population is continuing to increase, as it has for the past decade.
As for the males, Don Francisco has taken over the Sand Flat and is the undisputed alpha of SEFI. He is a bit less exclusive than Nero was, allowing Brendan, Salvatore, and DMX to lay among the peripheral cows of his harem. Bedlam Boy is harem master of the Terrace, and Rusty is on Mirounga Beach, but he quickly vacates whenever Don comes down for a cooling swim. Puffy is in Garbage Gulch with 3 cows.
West End Island Bulls are Baraka and BobBond.
Monday, January 22, 2007
75 Gray Whales Today
Saturday, January 20, 2007
A Day in the Life of a Farallones Biologist
During the winter season we primarily study the demography (reproduction, survival, and population change) of the Farallones northern elephant seal population. These parameters can be determined by individually marking the elephant seals to see where they move, how long they live, how often they reproduce and whether their pups survive. We put permanent colored plastic tags with a unique number and letter combination in their hind flipper that we can re-read year after year – and we give each tagged animal a name.
For short-term tracking within the breeding season, we stamp a unique number on each adult elephant seal with blonde hair bleach and black hair dye generously donated by Clairol. The bleach and dye numbers disappear when the animal molts in a few months. But during the breeding season (December through March), these big, clearly stamped numbers allow us to efficiently keep a daily count of seals arriving, defending harems, giving birth, nursing, and departing. We check all the breeding beaches in the morning and again in the afternoon to get the count.
Every pup gets the same stamp number as its mother so we can monitor each female’s reproductive success and pup fate. Also, the number helps us to identify the pup so we can tag it once it is weaned and we’ll know the exact age and who its mother was when we see the animal again in future years. See the picture below of the cow Drip and her pup – they are both stamped “-25,” and Drip's tags are also visible.
At about 110-180 pounds, your average Homo sapiens biologist poses no threat to a 5,000-pound bull male northern elephant seal. These large males are remarkably tolerant of human presence and do not seem to mind if we get close enough to read their tags or stamp a number. But, of course, we still tread very carefully around these animals, as one misstep could yield some painful results!
In addition to intensively studying the elephant seals, we monitor the abundance of
Finally, we post a lookout at the lighthouse to observe and record whales, sharks, dolphins, and any other interesting and notable wildlife that come to the island’s waters to feed or just pass by on their annual migration. For example, the other day we saw a pod of 8 Orca in the waters just off West End Island, and another day 500 Risso's Dolphins swam by. Our one-day high count of grey whales migrating south to calve and breed in Baja California, Mexico is 58.
Saturday, January 13, 2007
Nero Goes from Hero to Zero
Early this morning, biologist Shawn Farry went to check the beach and discovered a phenomenal sight. Nero, the Sand Flat bull, was dead in Log Channel from severe head wounds. From the evidence we found, it appears that Nero and Don Francisco fought an epic battle that ended when Nero’s head was crushed in Don's jaws. We are all still reeling from the shock. Now that we were able to get a very close look at Nero, we were overwhelmed by his size and bulk. He was nearly 5 meters long, and 5 meters around the chest (sadly we didn’t have the equipment to weigh such a massive creature, but he likely weighed thousands of pounds). In the picture below, biologist Derek Lee prepares to take measurements.
The loss of Nero left a power vacuum on the Sand Flat. First, Aubrey (a tough fighter but not quite a bull) rushed onto Sand Flat and promptly and excitedly attempted to mate with numerous females – most of them with young pups and not yet sexually receptive. Not surprisingly, the females snarled their protest. Salvatore, a bull who had been hanging on the periphery of the Sand Flat and previously fled whenever Nero displayed his nose and bellowed, heard the ruckus and looked up from his nap. Realizing that Nero was gone, Salvatore fought Aubrey for 20 minutes across Sand Flat and
With hormones still raging, Salvatore then attempted to challenge Don at
We also had our first weaner today. Cow -27 was nowhere to be seen, and her pup was looking round and healthy after more than 3 weeks of nursing the richest, fattiest milk in the animal kingdom. It is likely that the weaner is the offspring of Nero from last year. While Nero’s life ended brutally after only one full year as alpha bull, he probably sired more than 90 pups.
Thursday, January 11, 2007
The first cow-pup drama of the season was started by the abandonment of pup -46 by its mother. She then caused some mayhem by trying to steal the newly born pups of cows -51 and -57. In the melee, the pup of -57 was killed. Cows -51 and -57 shared the remaining pup for a couple days before -51 claimed sole rights. -57 has been wandering around trying to adopt a pup, but without success. -46 is also roaming about, trying to steal pups, continuing to cause disturbance. Meanwhile, the abandoned pup of -46 has been severely bitten in the head, but was adopted by Schnitzel. Schnitzel hasn't nursed the adoptee much, but it is still alive and alert. Two of the three pups born on Mirounga Beach have died after being crushed or bitten by other seals. The crowded and high traffic area is very tough on the new pups there.
For those readers keeping a score card, the newly-arrived cows that haven't yet been mentioned in this blog include: Grasshopper, Daphna, Arwen, Lynne R., and Galadriel.
Wednesday, January 10, 2007
The Nose Knows
But the inflatable proboscis is without doubt the most exceptional feature of the male elephant seal. Its full size is reached when the male is about eight years old. This peculiar proboscis is an enlargement of the nasal cavity that hangs down about a foot over the mouth when the animal is relaxed (much like the trunk of an elephant, thus the name).
But when that nose inflates…watch out!
A combination of muscle action and blood pressure causes it to form a large cushion on top of the snout, with the tip hanging down so that the nostrils open immediately in front of the mouth. The seal then forces air from his lungs into the nostrils at about 3 to 5 pulses per second. The inflated proboscis acts like as a resonating chamber, projecting the rhythmic, metallic-sounding snorts for nearly a quarter of a mile.
The male elephant seal’s proboscis is a classic example of sexual selection, in which females select males with a certain characteristic that communicates the male’s fitness such that it evolves to extreme proportions. The nose does not appear to perform any particular function for the male other than to attract females and repel males with its enormous size and resulting deep bellow, and is known as a “secondary sexual characteristic.” This is similar to the large showy tail on a peacock or the massive antlers on an elk.
Friday, January 05, 2007
Crowds of Cows (and pups)
The number of cows and pups on SEFI’s main elephant seal beach, Sand Flat, is growing by the day. Once again, First Cow, Giovanna, Schnitzel, and Drip had the first pups of the breeding season – they like to arrive early so they can take advantage of the uncrowded beach to nurse their babies without too much wrangling for precious space. Later in the season Sand Flat will have scores of cows and pups and mayhem often ensues. In fact, it is starting to get a bit crowded already. There are 21 cows and 12 pups, with three or four new cows and pups arriving each day! The beach resonates with the cries of the little seals and the gentle responding “pup sound” that the mother makes to reassure her pup that she is nearby.
The timing of cow arrival at the Farallones each year (known as phenology) has changed over the decades. This could possibly be due to changes in the average age of the cows breeding here. The islands were first colonized in the 1960s by young animals dispersing from colonies at Año Nuevo and the Channel Islands of Southern California. The graph here shows the median arrival date of females to SEFI from 1974 until 2006. The shifting phenology could also be due to changes in the ocean climate causing periods when food was more or less abundant and cows returned to SEFI earlier or later as a result. Our research has found that during the last 15 years, earlier phenology means higher reproductive success.
Below, we profile a few of the cows we’ve been tracking since their birth.
Mercury was born on Sand Flat in 1990, making her a whopping 17 years old this year! She’s given birth 10 times on the very beach where she was born, producing seven healthy weaners. Furthermore, Mercury’s pup from 1999, Princess Superstar, returned to SEFI this year as a pregnant cow. Both of them just gave birth in the past couple of days, resulting in three generations together on the beach. Mercury and Princess Superstar spend a lot of time near each other – perhaps the bonds of kinship reduce antagonistic behavior that decreases nursing time and hinders pup development.
Another relatively old female on Sand Flat is Drip. Drip was born in 1992 at
Queen Latifah was born on Sand Flat in 1999. This is her first year returning to SEFI and she’s now nursing her pup that was born on New Year’s Eve. She is a relatively calm cow who really seems to enjoy her sleep – unlike some of the others who spend lots of time snarling at neighboring cows. Since this is her first year back at SEFI, we’re not sure where and with whom she mated last year, but we’re happy to see her back home.
Maddy also was born on Sand Flat in 1999, first returned in 2003, first pupped in 2004, and has given birth here every year since. Unfortunately, she is only “one for three” so far, with only one successful weaner, but she is young yet. She hasn’t pupped yet this year but we’re checking the beach every day.
Schnitzel is a relatively young cow, born on Sand Flat in 2000. This is Schnitzel’s third year returning to SEFI to pup. Hopefully the third time’s the charm. In 2005, she did not nurse her newborn pup and it died, but we chalked it up to the terrible wounds Schnitzel had on her head and back from an attack by an over-enthusiastic male elephant seal. Last year Schnitzel abandoned her pup as soon as it was born, which often happens with younger, inexperienced cows. Happily that year, First Cow adopted Schnitzel’s abandoned pup and nursed it for several weeks. This year Schnitzel hit her stride and her pup is looking nice and fat. This year, in an interesting karmic twist, Schnitzel herself appears to have adopted an abandoned pup.
Christine is another relatively young cow from the class of 2000. She pupped successfully on Sand Flat in 2004 but she didn’t breed here for the past two years. We’re glad that she is back. She hasn’t given birth yet but it will probably happen any day now.