Happy New Year, let’s talk about E-Seals! By Seth Bartusek
February 20, 2022
Hello everyone and Happy 2022! It’s already been an exciting Northern Elephant Seal breeding season on SEFI, and I’m excited to update you all on the Colony. But first let’s back up and go over some background context: Elephant Seals have been recolonizing SEFI since the 1960s, and we now have a modestly sized breeding population between Sand Flat on SEFI and West End Island (WEI). Northern Elephant Seals spend most of the year out to sea foraging before returning in mid-winter/early spring to their breeding grounds, remote beaches and offshore islands on the Pacific coast from Baja to Northern California.
Here on SEFI, we’ve been watching this firsthand through December and January. When the winter E-seal team arrived early in December, two large males and a handful of immatures were already here (Males tend to arrive first and vie for prime real estate). We immediately set to work identifying the individuals we could, based on their tag color and number. Tags from SEFI or Point Reyes are pink, those from the Año Nuevo colony north of Santa Cruz, CA are green, the Piedras Blancas colony near san Simeon, CA are white, and the Marine Mammal Center in Sausalito, CA are orange. Without doing any tag lookups, the assortment of tags present so early in the season already clued me in to how transient these animals are. The cool thing about working with a historic data set, is that you can go back through the data and track individuals. Amongst the E-seals on SEFI at the beginning of our crews’ winter season were two large males, both of which already had pink flipper tags, indicating that they were returners to SEFI. Big males are clearly distinguishable on account of their size—ours are probably somewhere around 2000lbs—and because of their large nose or “proboscis” which can grow so big it hangs down into their mouth when vocalizing. The larger of the two males had a tag in each back flipper, B141 in the left square bar position and U518 in the right round position (the ‘position’ is correlated to a specific place on the flipper where the tag is, it would be like saying between your pinky and ring finger on a human hand). When you look up PKU518RR in our database you learn that this male is actually named Martin, and was first tagged back in January 2017 when he was a lowly SA2 (subadult male 2). The historic data shows that Martin has been rising in position amongst the breeding population since the 2019 breeding season, and received his second flipper tag in March 2020. Martin has returned to SEFI each year since and was poised to be harem master on Sand Flat at the beginning of the season, but more on that later…
Resighting tags and keeping an eye on individuals’ movements is largely the protocol for males and juveniles. Mature females, or Cows however, get the lionshare of our attention as the season goes on as they are the breeders that are most directly impacting the birthrate of the population, which is what conservationists really care about. Cows tend to arrive a little later to the breeding grounds, many of them pregnant from the previous season (gestation lasts around 11 months). While on SEFI they’ll give birth, nurse and later wean their pups, before mating and heading back out to sea. We had our first cow of the season arrive two days after our crew. Looking up PKT855RR in the tag database, I learned that this was Dahlia and that she is rather prolific. Dahlia was first tagged at the Sand Flat colony back in February 2013 and she’s returned every year since, in fact her tag is so old the number has rubbed off and only the drill hole pattern on the tag remains to be read! Dahlia has pupped in each year (9!) and we know at least seven of those pups were weaned successfully, that’s a pretty impressive resume she’s building.
This is all very cool, but we’ve come a long way from the first week of December and there is a lot more that’s happened down at the Sand Flat E-seal colony. Martin was ousted from his throne by Gryffindor a few weeks ago, and they have now switched spots with Gryffindor the harem master on Sand Flat (about 30 cows), and Martin presiding over Mirounga Beach (about 15 cows). We also have about ten sub-adult males that are hanging around the outskirts of the colony, careful to stay away from the harem masters. These are younger males who are basically looking for an opportunity when a harem master is distracted to opportunistically mate with a female, they seem to bounce around each day as they don’t really have a home. We now have close to 50 cows on SEFI including, Tequila Sunrise, Ursa, Sparkleface, Betty White, Tarantula, Breadcrumbs, and Radish to name a few. We had our first pup of the year on Christmas morning, and now have 29 pups on SEFI. Some of them are only a few days old, but our first pup of the season has become our first wean pup! For a month after birth pups gorge on their mothers’ milk, until they are sufficiently fattened up and the cow abandons her pup. These ‘weaners’ are usually quite rotund at this stage (some too round to move) and they need to lose weight in the next six weeks until they are mobile enough to get out there as a juvenile E-seal. After all the cows have left, we go around and put two flipper tags in each weaner so we can track them as they grow! The weaner may be the cutest stage of an E-seal’s life (see picture).
Though most of our focus is on the Sand Flat colony, every two weeks we try to get over to West End Island (WEI) to do tag resights for all the species that live on the sheltered beaches over there. When we headed over last week we found 32 cows, 14 pups, and four large male Elephant Seals scattered around the island. One of those males was PKB172RR, or Lonestar, who is the harem master of the colony at Shell Beach, and may well be the largest male E-seal we have on the island. Something interesting about Lonestar is that he has a blank green tag on each of his flippers in addition to the pink tag that he was given more recently. Given that green tags originate from Año Nuevo, he may have been born and was a weaner there when he was double tagged with green. In addition to E-seals, we also saw close to 2000 California Sea Lions and several hundred Northern Fur Seals. It was my first time seeing Fur Seals in the wild and they very well give Elephant Seals strong competition for my favorite pinniped on the island. Seeing them in such great numbers on WEI, but having never seen them on SEFI also made me wonder why they shy away so much from our island. Maybe they are even more skittish than California Sea Lions around humans, or maybe there’s just something all the better about West End. I don’t know, but I’ll keep trying to invent crazy theories until one seems to stick.
Looking ahead we are expecting things to keep getting busier down at Sand Flat. We have passed the midpoint of the season now, so we are expecting cows to start to depart en masse and weaners to multiply. We are still trying to tag any of the larger seals around as they are most important to be able to identify over time, but big females especially get pretty defensive and can be quite tough to sneak up on. To help us be able to identify animals from afar we also stamp them with a number that correlated to their arrival date. To do this we have a long pole with Velcro on the end and we attach numbers to the base of the pole and dip it in hair dye. Don’t worry though, these stamps will disappear when the E-seals molt in the spring.
Anyway, that’s the New Year update from the 2022 SEFI E-seal crew. We wish you all a happy 2022 and hope you’ll send your love to those hard working cows down at Sand Flat and West End trying to raise their pups in this crazy world we live in. Be sure to check back for more updates on our E-seals and other animals on the island! Lastly, before I go I wanted to give a shoutout to Stella, the Burrowing Owl intern who stayed on SEFI when we arrived to help settle us in. She wrote a little blog, but it never got to be published so I figured I’d tack in onto the end of mine (see below). Thanks for helping us get acquainted to the island, Stella!
Is that an Owl or a Rock? By Stella Solasz
It’s like finding a needle in a haystack…. This is the job of the fall Burrowing owl research assistant. Every day the burrowing owl research assistant walks the entire island, from Shubrick up to the light house behind corm blind and to North Landing. The goal of this survey is examine all known and possible roosts in order to locate Burrowing owls. The majority of the survey goes like this-looking into many empty crevices for a long period of time until… OH there is definitely an owl in that roost! You take your camera out trying to capture the burrowing owl in its roost. Success! Now time to zoom in on the photo and see if the owl is banded or unbanded. You start zooming in and very quickly your excitement turns into slight embarrassment…you realize you have just taken a picture of a rock. There was no owl in that roost just a cleverly placed and well shaded rock. So the search around the island continues. It is hard not to get discouraged when all the photos on your camera are of rocks in crevices but the possibility of finding a burrowing owl outweighs all the empty roosts. The agony doesn’t last long because soon after you lock eyes with something sticking out of the ground. The piercing yellow eyes are hard to mistake for just another rock. You quickly take a picture and start zooming in. You exclaim “Finally! A burrowing owl.” The rest of the survey continues just like this, rock, rock, rock, rock, and then maybe a Burrowing owl. Some days many owls are seen while other days only 1.
Gotcha, it’s a rock! Burrowing owls are small, long-legged owls that weigh ~150g and have a wingspan of ~55cm. They roost in open landscapes such as grasslands and prairies found throughout the Midwest, Canada, Mexico, and Southeast Farallon Island. SEFI is not the typical habitat for burrowing owls, but they arrive in late September and overwinter on the island. Every fall season a research assistant is hired to monitor the owls, this consists of daily surveys and late-night banding efforts. This is done in efforts to track where they’re roosting and monitor how many and how long they overwinter at SEFI.
If seeing them is a struggle some days, finding a night with the right conditions and actually catching an owl can be just as rare. First you need a calm night, with wind below 10 knots, in order to have a shot at luring an owl in. Second, ensure the moon is out. Cassin’s Auklets breed in burrows on the island and when the nights are darkest around the new moon, they tend come onto land to prospect and dig new burrows. To make sure you won’t be catching auklets, it’s also best to wait for a moonlit evening. If you are lucky enough to have the conditions happen to line up, you have to set the nets up that night, because you might not have another shot. To catch Burrowing Owls I use a mist-net, stake it into the ground around sundown, and wait until after dinner to open the net. You use a speaker playing a contact call to lure them in and then check the net frequently in hopes that you’ll have one. Then it’s a process of carefully extracting the owl from the net and bringing it into the banding lab for measurements including wing chord length, fat, weight, and feather molt. We then give them an identifiable color band with an individually specific letter number combination and a federal issued aluminum band; this season I’ve been able to band 8 owls. My work banding these owls is covered by the USGS Bird Banding Lab Research permit.