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I like to venture out of my comfort zone every once in a while, as that's the only way to keep learning. Even though my particular area of interest is the marine invertebrates, there are a lot of other aspects of marine biology that are almost as interesting. And if I'm going to call myself a naturalist I should extend my knowledge in as many directions as I can, right? Besides, going out and learning new stuff is a lot of fun!

Shortly after the new year I went up to Año Nuevo State Park to see the northern elephant seals (Mirounga angustirostris) at their winter breeding rookery. Of course, I've known about the rookery ever since I came to Santa Cruz and have had friends in the Ph.D. program doing their dissertation out there, yet for whatever reason I never managed to get out there during the breeding season. The park is open all year, but while seals are on the beach for breeding the trail out to the rookery is accessible only via docent-led tour. This year I remembered to buy tickets ahead of time, to ensure that we'd be able to see the seals on a day we had time to do so.

The day we went, a Thursday, was threatening to be stormy, so we took our rain jackets just in case. We met up with our docent, a woman named Trevlyn, and hiked out to the beaches. Before we got there, though, we saw a mother bobcat (Lynx rufus) and her two kittens. This particular mom is well known to the folks at the park, who see her frequently. Because of the overcast skies, these normally crepuscular wild cats were active in the middle of the day.

Adult female bobcat (Lynx rufus) at Año Nuevo State Park
4 January 2018
© Allison J. Gong

And here is one of her kittens. There were two, but they were much shyer than their mom and hesitated to come out of the bushes.

Bobcat (Lynx rufus) kitten at Año Nuevo State Park
4 January 2018
© Allison J. Gong

Both of the kittens looked healthy, alert, and well fed. It looks like the heavy rains of the 2016-2017 season resulted in an abundance of prey--everything from insects to rodents to rabbits to birds--for carnivores, including bobcats. Given the bobcat's variable and adaptable diet, the future looks bright for these kittens who were lucky enough to be born in a state park. They (and their prey) will not be poisoned by pesticides or herbicides or hunted by humans, although it is likely that mountain lions (Felis concolor) prowl these trails as well.

Our guide, Trevlyn, giving us the lowdown on elephant seal biology
4 January 2018
© Allison J. Gong

Before arriving at the rookery we stopped so that Trevlyn could go over some elephant seal biology and give us the rules for visiting the beaches. The rules were: (1) stay behind Trevlyn at all times; and (2) do whatever she says without question. These animals are BIG and can move surprisingly fast over short distances. We were there at the early part of the season and there were only a few hundred animals at the rookery. But later, after all the adult animals have returned to land and the pups are born, it gets very crowded and stinky.

Elephant seal biology

The northern elephant seal is a highly pelagic animal, coming to land for two purposes at different times of the year: to breed in the winter and to molt. While they are hauled out for either purpose they do not feed, and survive on blubber reserves accumulated during the months foraging at sea. The different demographic groups (pups, juveniles, adult females, and adult males) haul out at different times of year.

The breeding season begins in mid-November, with the adult males arriving first. As they are staking out beach territory the females start arriving about three weeks later. They are pregnant and usually give birth a few or several days after their arrival.

Newborn elephant seal (Mirounga angustirostris) with its mother at Año Nuevo State Park
4 January 2018
© Allison J. Gong

A female who has given birth spends all of her time resting and nursing her pup. See how the pup in the photo above is sort of skinny, with wrinkled skin? This tells us that it is only a couple of days old. As it continues to nurse that loose skin gets filled out and the pup gets nice and fat. In the meantime, its mother is fasting while she nurses, and loses a significant portion of her bodyweight.

Sometimes the juvenile males, who have not yet proven their worth against an established bull male, get a little overexcited and try to mate with a female who has just given birth. These females are not receptive because, well, they've just given birth and have not yet gone into estrus. Watch this female above rebuff the attention of a juvenile male. Trevlyn told us that females try to rest near the larger bull males, whose presence will keep the juvenile males in line. Oh, and those markings on the young male? Those are made with ordinary hair dye, to identify the animals being studied.

Pups nurse for 28 days, then are abruptly weaned when their mothers mate and return to the sea. At this point the pups are called weaners. Weaners can't follow their mothers to the sea until they molt their pup fur and learn how to swim. They usually head out around early May, when they become fodder for white sharks lurking just offshore. The sharks ain't stupid.

The spectacular showdowns between adult male seals fighting for mating rights should be starting up about now.

Adult male elephant seal (Mirounga angustirostris) on the beach at Año Nuevo State Park
4 January 2018
© Allison J. Gong

Adult males are by far the largest animals on the beach. They also have a much larger proboscis. And see that pinkish stuff on the neck? That is thickened, callused skin that forms when the animals are fighting. As two bull males charge into each other they rear back and then slam forward, trying to gouge each other's neck with their teeth. The fights are not deadly but can become quite bloody before the loser decides to give in to the dominant male. While they aren't fighting or mating the males are resting to conserve their energy. This early in the season there is plenty of space on the beach and things are pretty serene, although as animals continue to arrive and pups are born, the fighting and mating will begin in earnest and there will be a lot more activity.

Elephant seal rookery (Mirounga angustirostris) at Año Nuevo State Park
4 January 2018
© Allison J. Gong
Elephant seal rookery (Mirounga angustirostris) at Año Nuevo State Park
4 January 2018
© Allison J. Gong

But at least as of early January, youngsters like these yearlings can relax on the beach without having to worry about being run over by males weighing up to 2500 kg.

Yearling northern elephant seals (Mirounga angustirostris) at Año Nuevo State Park
4 January 2018
© Allison J. Gong

Año Nuevo Island lies just offshore. When northern elephant seals began to return to this part of California they established their first breeding colony on the Island. Many pinnipeds, as well as seabirds, breed on islands because they are protected from land predators. In the case of the northern elephant seal, the major land predator was the grizzly bear.

Año Nuevo Island
4 January 2018
© Allison J. Gong

Problem is, Año Nuevo Island has limited beach real estate. Elephant seals can't climb up even short cliffs, so can come ashore only on sandy beaches. The last wild grizzly bear in California was spotted in 1924, and since then the elephant seals have began taking over the coastal beaches near the island. All told, some couple thousand elephant seals will be on the beach at Año Nuevo this winter. This is a small rookery; the rookery south at Piedras Blancas is much larger. The northern elephant seal population in California seems pretty robust, with the animals having recovered nicely after being hunted to near extinction at the end of the 19th century. In these days when all news about the environment seems to be doom and gloom, it's nice to hear of a wildlife species doing so well.

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Back in mid-December I collected some urchins at Davenport Landing. Some of these urchins are the parents of the larvae that I'm culturing and observing now. Towards the end of the trip I flipped over some surfgrass (Phyllospadix torreyi) and saw two fish, obviously sculpins, huddled together; they had been hiding in the Phyllospadix and waiting to be submerged when the water returned with the high tide. I have a probably inordinate fondness for intertidal fishes, and love catching sculpins. These were too big to be fluffies (Oligocottus snyderi) but I couldn't pin down an ID any closer than that. I brought them back so I could take a closer look at them in the lab.

Trying to key out the intertidal sculpins in California is an activity fraught with danger. There are about a dozen species that are likely, plus more that are occasionally encountered in the intertidal. When identifying fishes ichthyologists use meristics, or counts of things such as scales along the lateral line or hard spines in the dorsal fin, to differentiate species. Since you can't very easily count the number of spines in the dorsal fin while observing a fish thrashing around in a ziploc bag, I needed to get them under the dissecting scope.

Here is a picture that I took of the fish this morning. This is the same posture they had when I first saw them in the field. I think the male (paler fish on the right) is guarding the darker female. Oh, and while I'm at it, I should say that skin color is an unreliable characteristic to use when IDing sculpins. Their skin color can and does change very rapidly, depending on the surroundings and the fish's emotional state.

3 February 2017
© Allison J. Gong

See those little tufts on the top of the head of the fish on the left? Those are called cirri. When I was keying out these guys I narrowed down the options to either bald sculpin or mosshead sculpin, and the distribution of the cephalic cirri was the final determining factor. Mosshead sculpins (Clinocottus globiceps) have cirri densely scattered over the entire head, while in balds (Clinocottus recalvus) the cirri extend forward only to just behind the eyes; in other words, bald sculpins have no cirri between the eyes or anywhere anterior to the eyes. In my fish the cirri clearly do not extend forward of the eyes, making these bald sculpins.

Bald sculpin (Clinocottus recalvus) peering at the camera with justifiable suspicion.
3 February 2017
© Allison J. Gong
Bald sculpin egg mass
3 February 2017
© Allison J. Gong

It usually takes animals a week or two to settle in after being collected from the field. After a couple of weeks the fish were eating regularly and hungrily. Sculpins don't have an air bladder, which helps keep them from getting washed out of their home pools as the tide moves in and out, and tend to sink if they aren't swimming. They can, however, swim very well. Once they got used to the idea of food coming at them from above they would start looking up when I removed the lid to their tank. When they're really hungry they will swim up and attack the food, ripping it from my forceps. Otherwise I dangle food in front of their faces and they take it a little more gently. Now they are both eating well.

One of the sculpins went off its feed last week and then surprised me by producing a mass of pink eggs. She had deposited the eggs on the underside of the cover instead of on the surfgrass I have in the tank. No wonder she hadn't been eating; with all those eggs inside her there would be no room for food! I decided to keep the eggs and see what, if anything, would happen with them.

Eggs of the bald sculpin (Clinocottus recalvus)
3 February 2017
© Allison J. Gong

Each of the eggs is about 1mm in diameter, and they are indeed pink. They are stuck together in a pretty firm mass. I peeled it off the cover of the tank and the whole mass remained intact. I can easily pick up the mass and put it into a bowl for viewing under the dissecting microscope. At first I could see that the eggs contained a large yolk and some smaller oil droplets but I couldn't tell whether or not they were alive. I cleaned them off to remove any dirt or scuzz, then returned them to the tank, hoping the parents wouldn't eat them. Over the first several days I couldn't see any change in the eggs except some of them became opaque and white, obviously dead. And it looked like maybe the stuff inside the eggs was shifting around a bit, but I wasn't sure if that was something good going on or the beginning of decomposition. The egg mass continued to stick together, though, which I took as a positive sign.

Then yesterday when I looked at the eggs I was able to convince myself that, yes, something is happening inside them. I saw tiny little fish bodies, complete with bulbous rudimentary heads, developing on the yolks!

Developing bald sculpin (C. recalvus) embryos
3 February 2017
© Allison J. Gong

Each egg is a pale pink sphere containing a darker pink yolk. At this early stage of development the yolk takes up most of the interior space of the egg. Lying across the yolk, with a swelling at one end, is the developing fish embryo. The swelling is the head. Even at this stage the three body axes (anterior-posterior, dorsal-ventral, and left-right) have been established for quite a while. The yolk will shrink as the energy stores within it are consumed by the developing embryo. I don't know if sculpins hatch as larvae (i.e., with a yolk sac still attached) or as juveniles (after the yolk sac has been completely consumed). I hope I get to watch these eggs and see!

Yesterday I went over to the Seymour Center to talk to the person at the front desk about arranging a field trip visit for a class I'll be co-teaching this summer. When I walked through the exhibit hall into the office wing there were a couple of staff members coming the other way down the hall, gesticulating excitedly towards the door that leads to the garden area on the coastal bluff. My first thought was "Whale!" but when I looked out at the water I couldn't see anything of particular interest in the water.

"No! Look on the wall!" they said.

"What? The barn swallows?" I asked. There were two swallows flying around under the patio. Why are they getting all excited about barn swallows? I asked myself. They kept pointing so I went over to the window for a closer look and saw this creature hanging on one of the light fixtures:

Little furry creature at Seymour Marine Discovery Center. 20 April 2016 © Allison J. Gong
Little furry creature at Seymour Marine Discovery Center.
20 April 2016
© Allison J. Gong

It's a bat! A very small one, about the length of my thumb and about twice as wide due to the fur. It had chosen the light fixture for its daytime roost and was sleeping. Here's a picture of its little face:

Bat on light fixture at the Seymour Marine Discovery Center. 20 April 2016 © Allison J. Gong
Bat on light fixture at the Seymour Marine Discovery Center.
20 April 2016
© Allison J. Gong

I know very little about the bat species in California. However, I did some poking around and now am fairly certain that this bat is in the genus Myotis, possibly M. californicus. There are many other species of Myotis, collectively referred to as mouse-eared bats because of their long ears.

Yesterday I couldn't stick around long enough to see if the bat would fly at dusk. I think that quite often daytime roosts are temporary, so there's no reason to expect the bat to return. Tomorrow I'll be at the lab most of the day and will be able to see for myself.

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