I go to Natural Bridges quite often, to play in and study the rocky intertidal. But at this time of year, before the low tides really get useful, there is another reason to visit Natural Bridges—to see the monarch butterflies (Danaus plexippus). Natural Bridges State Park is a butterfly sanctuary, providing a safe overwintering spot for migrating monarchs.
Yesterday morning, while it was still cool enough for the butterflies to be hanging in clusters, I went out and photographed them. Last year's count was only 550 for the winter, but I'd heard that there were more butterflies this year and it was definitely worthwhile going out and looking for them.
The butterflies rest with their wings up, so when they are hanging like this you see the duller underside of the wings. A few of them were starting to warm up their flight muscles and showing off the more brilliant orange of the dorsal wing surface.
I am really not good at counting things like this, but my guess is that there were hundreds of butterflies, all told. Based on the 2020 season, when I didn't see any monarchs at all at my house and only a few scattered individuals at Natural Bridges, this year's population seems to be doing much better. 2020 was an awful year in California in general, and in the Santa Cruz region in particular. The CZU August Lightning Complex fire put air quality into the unhealthy-for-everybody range for several weeks. Much of the rest of the western U.S. also burned, with much habitat loss for nature. Maybe that's part of why there were so few monarchs last winter in Santa Cruz. Of course, the monarchs' populations have been declining for years, so last year's population crash may be only a dip in the grand scheme of things.
Whatever the cause, it really was good to see even this many butterflies at Natural Bridges.
Oh, and before starting my butterfly hunt in earnest, I spent about an hour watching and listening for birds. I wanted to get the birdwatching in before human activity drowned out the birdsong. Unfortunately, most of what there was to hear was the cawing of crows.
Next time I'm at Natural Bridges, I'll try to remember to check in with the visitor center to see what the official count for monarchs is. Fingers crossed the number is a lot higher than 550!
Over the past couple of weeks I've rented two super telephoto lenses, to see what all the hype was about. I mean, do I really need 500 or 600mm of reach? I had read up on the specs of such lenses, and one major drawback is the weight—1900 grams or more. Would I be willing to lug a beast like this around, and would I be able to use it effectively? You never know until you try, so I rented them. And, of course, it was foggy both weeks so I didn't have much opportunity to take decent photos. But since the entire point of renting the lenses was to see if I could use them at all, that was fine.
As part of the test-drive for the second lens, I went up to Waddell Beach to see if there would be any birds to photograph. It is migration season, and our winter residents will be arriving soon. Some of them, such as the red-necked phalarope, have shown up at Younger Lagoon over the past four weeks or so. It was really foggy at Waddell, remember, and I didn't have much hope of seeing anything remarkable. There were some gulls and whimbrels off in the distance. But it turned out that the stars of the show were blackbirds!
They were hard to miss, because there were 50-60 of them and they were hopping up and down like jumping beans.
This is a mixed flock of Brewer's blackbirds (Euphagus cyanocephalus) and red-winged blackbirds (Agelaius phoenicius). The glossy greenish-black birds are the male Brewer's blackbirds, and most of the brownish birds are female Brewer's blackbirds. Since both sexes were doing the hopping, I didn't think this behavior had to do with courtship or mating.
So yes, while most of the birds seemed to be Brewer's blackbirds, I did hear the liquid gurgling of the red-winged blackbird's song coming from somewhere in the flock. When I got home and looked at the photos on the big monitor, I did see some red-winged blackbirds. Here's a male, surrounded by other males red-wingeds and both female and male Brewer's blackbirds.
In this photo above the black birds are male Brewer's blackbirds. The brown birds without faint wing bars are female Brewer's blackbirds, and the brown birds with the wing bars are male red-wingeds. There were no female red-winged blackbirds in any of my photos. According to an article from Cornell's Bird Academy, the males spend the weeks leading up to springtime competing for territories, and when the females return from their winter migration they will choose mates based partly on the quality of the territory. Mid-September is too early for this kind of competition, though. We are just about up to the autumn equinox, but not near winter quite yet.
Back to the hopping. There's a clue in this photo about what I think was going on:
See that little fly? There were many such flies, most of which were lower on the beach gathering around the kelps and other wet detritus that had washed up. There were fewer flies up where the driftwood accumulates, though. Once again, it wasn't until I saw the pictures on my big monitor that I could figure out what those blackbirds were doing. They were hopping up to eat flies!
Here's a series of shots showing one of the male red-wingeds in mid-hop.
Looking up, just before the hop:
Up he goes! See the very edge of the red epaulette on his right wing? And all those flies?
Is he going to catch something?
After all that, I'm not at all sure if he actually got anything!
I don't have any hard evidence that the blackbirds (both Brewer's and red-wingeds) are catching flies. And while I was at the beach watching them hopping up and down I had no idea what they were doing. However, now that I've seen the flies in the photos, it makes sense that the birds would be hopping up to catch and eat them, especially since both sexes of the Brewer's blackbirds were doing the same thing.
A utility pole across the street and one house down has, for years, been an object of interest for a variety of birds. The hairy and downy woodpeckers drum on it in the spring, and various songbirds hang out and rest on the top. About a month ago now I saw a raptor up there, eating something. It was a female merlin (Falco columbarius). According to Cornell's All About Birds, merlins are in our area during the nonbreeding season, but I've never been certain about having seen one.
On the morning of Saturday 13 March I went outside to look around, and saw a bird on the pole. It appeared to be either eating or cleaning its beak. I ran inside to grab the camera, which fortunately had my longest lens and the 1.4x teleconverter attached, and snapped off a bunch of shots. The sun was rising, but I was able to get some decent photos of the bird even though from the best vantage point it was backlit.
Clearly, he's eating something:
But what is it eating? Rodent bits?
No, look at that foot. It's a bird!
Yep. Definitely a bird.
And here he is, taking a break between courses:
Merlins are members of the falcon family. Smaller birds make up the majority of a merlin's prey, but they also eat large insects such as grasshoppers. As with peregrine falcons, merlin populations were severely reduced in the years when DDT was widely used to keep insect populations down, but they have since recovered. Truly, the recovery of birds of prey after DDT was banned is one of the great successes of conservation biology.
There were feathers in the street below the pole. I assume they are from the merlin's prey, as when I looked at the top of the pole through binoculars I could see the same sort of feathers up there. I compared the feathers with photos on a few ID sites, but it's no easy identifying feathers without any additional context. Someone suggested that they might be from a male house finch. We have lots of those around all the time, so that's probably the best guess possible.
So there you have it: Saturday brunch with songbird on the menu!
We have all heard about hummingbirds and their ability to hover and fly backwards. These tiny feathered jewels are a delight to observe. They are birds of the New World, and I feel sorry for people living in parts of the world that don't have hummingbirds. Where I live, on the coast of Northern California, the resident hummers are Anna's hummingbirds (Calypte anna). We get the occasional Rufous and Allen's hummers (Selasphorus rufus and S. sasin, respectively) passing through on their migrations, but the Anna's are here year-round. We have front-row seats to watch their mating displays, and I know they must be nesting nearby even though I've never managed to locate a nest.
The other day, while sheltering in place at home, I went outside to photograph birds. The Anna's hummers were putting on quite a show. The males have been displaying since February, flying straight up-up-up and then plunging into a J-shaped dive near an observant female. At the bottom of the dive the male uses his tail feathers to create a sharp and very loud chirp. When this occurs about a meter from your head, it sounds like a pistol shot. Trust me on this.
Anyhow, that day I was lucky and captured some shots of a male Anna's hummingbird hovering in place. These aren't National Geographic quality photos, but then again I'm not a National Geographic-caliber photographer. For anyone who is interested in such details, here are the EXIF data:
300mm f/4 lens
1/2500 sec at f/4
At a shutter speed of 1/2500 sec, you can freeze even the movement of a hummingbird's wings. You can see very clearly that although the bird's wings are moving, his head remains perfectly skill and his position doesn't change at all.
A hovering hummingbird moves its wings in a figure-8, similar to the sculling motion of a skilled rower. If you use your imagination a bit you can see the rotation of the wings in this set of photos.
Given the mandate to shelter in place at home, I don't know how many of the upcoming morning low tides I'll be able to explore. On the one hand, I'd be by myself, not risking exposing anyone to any germs I might be carrying. On the other hand, staying home means, well, staying home. The tidepools are calling to me, but this year I might not be allowed to accept the invitation. All for the greater good, right?
We Californians are all under a state-wide mandate to stay at home, to minimize the spread of COVID-19 this spring. School hasn't been cancelled, but all classes have converted to distance learning. I had four days to figure out how to deal with that. Fortunately we are in spring break this week, which gives us all a little bit of a breather. I'm going to use the time to catch up on grading and plan for the second half of the semester.
The marine lab is also closed for business. Only essential personnel are allowed to be there. The term 'essential personnel' includes people whose responsibilities are animal husbandry. Since animals will die if I'm not there to feed them, I have met that criterion for essentiality. That's not a word, but you know what I mean. With so many fewer than usual people at the marine lab, there's a lot more wildlife activity. A few days ago I saw a long-tailed weasel (Mustela frenata) chase down and capture a young brush rabbit. I just barely had time to catch a quick shot with my phone.
The most noticeable thing, though, is the increased birdsong. The sparrows, finches, red-winged blackbirds, mallards, doves, towhees, and hawks are all making a lot of noise. The barn swallows (Hirundo rustica) returned to the lab on the 21st, right on time! Maybe this year they'll have a more successful nesting season than they did last year.
Yesterday I witnessed something I'd never seen before: a territorial dispute between a black phoebe (Sayornis nigricans) and a barn swallow. The fact that I had never seen it before in no way implies that it happens only rarely; maybe I've just never paid that much attention to these things before, or they've never happened while I've been around to watch.
Here's the story, in a series of snapshots.
Prologue. The barn swallow (H. rustica) is perched on one of the outdoor light fixtures. The phoebe (S. nigricans) swoops up from below.
The swallow takes to the air, only to be divebombed by the phoebe.
The swallow retreats. . .
. . . and the phoebe perches, triumphant, on the rain gutter.
The entire altercation lasted maybe as long as four seconds. I didn't see where the swallow flew. The phoebe remained on the rain gutter for about a minute or so, then took off over the meadow. Perhaps it has a nest somewhere nearby and was defending it. Both species build mud nests on cliffs and buildings, so these birds could be competing for nest sites. Or maybe phoebes just don't like swallows. Either way, this was the sort of interaction that I don't notice when there is a lot more human activity at the marine lab. Nature has a way of re-asserting herself when humans are removed from the scene for even a short period of time.
It's no secret that I love pelicans. I love watching them soar low over the waves, where they are truly in their element. I love watching them plunge from the air into the water and then bob right back to the surface, because unlike their cormorant relatives, pelicans can't fly underwater. And I love watching them plunk around on land, where they are dumpy and awkward but still somehow elegant.
The other day I ventured out between storms to photograph birds. As per usual I ended up down at Natural Bridges, where pelicans were hanging out on the last remaining rock arch. They were well within the reach of my long lens, so I took a lot of photos.
The best photos I got were of a subadult pelican coming in for a landing.
Landing gear down!
Decreasing air speed:
And. . . touchdown!
A job well done!
The youngster managed a safe landing without knocking one of its compadres into the water. That isn't always the case--those wings can do a lot of damage. But the three adult birds on the left hardly seemed to notice, which means the youngster has learned how to stick the landing without disturbing everyone else in the vicinity. I'm sure that's a lot easier said than done!
Autumn is migration season in California. We all know that, in the northern hemisphere, birds fly south for the winter and return north for the summer. And indeed, this is a very good time to go bird watching along the Pacific Flyway, as migrating birds stop to rest and feed at places such as Elkhorn Slough. Here in Santa Cruz, autumn is punctuated by the return of monarch butterflies (Danaus plexippus), roosting in eucalyptus trees at Natural Bridges State Beach and Lighthouse Field.
Since 1997 the Xerces Society for Invertebrate Conservation has been tracking monarch sightings on their migrations between the western U.S. and Mexico. They conduct a volunteer butterfly count every Thanksgiving. More recently, community science data sources such as iNaturalist provide much of the information.
This morning, before it got warm, I went to Natural Bridges to see how the monarchs were doing. I wanted to photograph clumps of butterflies dripping from tree branches. It seemed, however, that there aren't as many butterflies as I remember from previous years. The clusters were not nearly as large or as dense as they should be. And the data shown in the figure below do demonstrate a precipitous decline in monarch since 2017. We're still a couple of weeks away from this year's Thanksgiving count, and there is still a chance that the butterflies might arrive in larger numbers.
Trained observers know how to estimate the number of butterflies in a cluster like this. The numbers of butterflies at various roosting sites are aggregated to assess overall population sizes.
This morning I did see one butterfly that had a tagged wing. It was wearing a green Avery round sticker, with some writing in what looks like black Sharpie. The color of the sticker was very close to the green of the surrounding foliage, so I wasn't even able to see the sticker until I downloaded the pictures from the camera.
At first I thought the tag resulted from an official scientific project or undertaking, but it turns out that anyone can tag a monarch. The tags are used to track migration of the butterflies. There doesn't seem to be a central depository of tags and their origins, so knowing the color of the tag doesn't tell me where this particular butterfly came from.
Once the sun hits the butterflies and they begin to warm up, the clusters start breaking apart. Butterflies open and close their wings, exposing the darker dorsal surfaces to the sun and warming up their flight muscles. Sometimes they dislodge one another.
On a cool morning like this, many of the butterflies that fell out of the clump couldn't fly yet, and landed on the ground. The boardwalk is perhaps not the safest place for a butterfly to wind up, but at least in a monarch sanctuary such as Natural Bridges the visitors are knowledgeable and look out for the butterflies' safety.
As I wrote before, the butterflies we see at Natural Bridges this year were not born here. This means that their survival to this point has depended on healthy conditions in the Pacific Northwest and the western slopes of the Rocky Mountains, where they lived as caterpillars and emerged from their chrysalises. This also means that planting milkweed for monarch caterpillars in California won't help the butterflies that we see here, although it would help butterflies that are destined to overwinter elsewhere. What will help local butterflies--monarchs and otherwise, and all nectar-feeding insects, in fact--is planting California native plants, to provide them with the nutrition they have evolved to survive on.
People call them air rats or trash birds, but I really like gulls. Especially the western gull (Larus occidentalis), known colloquially among birders as the WEGU. Yes, gulls eat garbage, but that's only because humans are so good at making garbage and leaving it all over the place. Other gulls may travel quite far inland--in fact, the state bird of Utah is the California gull (Larus californicus)--but the WEGU is a California Current endemic species. This means that its natural food sources are the fishes and invertebrates of the California Current, which flows southwards along the west coast of North America. As a result, it lives in only a very narrow strip of coastline, nesting on cliffs and restaurant roofs.
Case in point. Yesterday afternoon I was at Moss Landing with my marine biology students. We had hiked along the road, over the dune to the beach, down the beach a ways, and returned over the dune to circle back to our starting point. The last item of note that we all watched was a western gull hunting along the shoreline of the Moss Landing harbor.
It had grabbed a crab. It looked like a rock crab, but I couldn't tell what species.
The crab wasn't dead, and was thrashing around enough to make it difficult for the gull to get a good grip on it.
The crab gets a reprieve!
But the gull didn't give up. It reached down, came back with the crab in its beak, and then flew off.
Joshua Tree National Park gained a certain notoriety this past winter, when idiots went there during the federal government shutdown and trashed the place. The vandals chopped down the iconic Joshua trees (Yucca brevifolia), let their dogs run around unleashed, left litter scattered over the landscape, and carved new roads through the desert. I'd like to give most people the benefit of the doubt and assume that they didn't realize the damage they were doing to the park. However, it takes only a few bad apples to destroy a public resource for everybody, as we've all experienced at some point.
The very first thing I learned about Joshua Tree is that it has two distinct desert habitats. Hey, I'm a marine biologist, and the desert--any desert--is new territory for me. None of this landscape has been anywhere near the ocean for millions of years! Anyway, the eastern half of the park is Colorado Desert, which is similar to what we had seen at Anza-Borrego State Park. Many of the plants in this region were also familiar to us because we had seen them in Anza-Borrego, but for the most part were more abundant here in Joshua Tree.
For example, we saw many more bluebells (Phacelia campanularia) at Joshua Tree than in Anza-Borrego. The P. campanularia at Joshua Tree also looked healthier (more robust and vigorous, less spindly) than they did in Anza-Borrego. Perhaps the higher elevation of the Colorado Desert in Joshua Tree (approximately 914 meters, or 3000 feet) compared to Anza-Borrego (182 meters, or 597 feet) accounts for this observation.
I really liked the Colorado Desert in Joshua Tree. Even though it was the same ecosystem as what we saw in Anza-Borrego, here the flowers seemed more colorful and striking. The yellows were a little brighter, and the pinks and blues a little deeper. The scenery was breathtaking everywhere I looked. I wish my photos could do justice to the beauty of the landscape.
Aside from the desert bluebells, other flowers that we had seen at Anza-Borrego included the brittlebush (Encelia farinosa), which seems to be ubiquitous in the Colorado Desert. The Arizona lupine (Lupinus arizonicus) was also common in Joshua Tree; like the bluebells, these appeared to be more robust here than in Anza-Borrego.
There were new flowers, too. My favorite, which I didn't see a lot of, was this desert globemallow, Sphaeralcea ambigua:
Here's a close-up of the same plant. Look at that gorgeous orange color!
Against the prevailing palette of yellows and purples, this orange really stood out and caught the eye. This plant is also called the apricot mallow, for obvious reasons.
Some other flowers that we saw:
Among all the colorful flowers in the overall landscape, there was this very subtle plant, easily overlooked by eyes accustomed to more brilliant blossoms.
Something that tickled my funny bone was the little chia plant, Salvia columbariae. It looks like a prickly purple pom-pom. Two days in the desert had taught me not to touch things if I didn't know what they were, but I had to know if these blossoms were as pokey as they looked. They weren't!
There are parasitic plants in the desert, too. The red branches in this bush are the desert mistletoe (Phoradendron californicum), a hemiparasite. It drains water and nutrients from its host plant but performs its own photosynthesis.
In Joshua Tree National Park there's an area called the Cholla Cactus Garden. Chollas are cactuses with cylindrical stems, rather than the flat stems of the beavertail or prickly pear cactuses. The most common one in the Colorado Desert (that we saw, at least) was the teddybear cholla, Cylindropuntia bigelovii. As the name implies, it's a cute, fluffy cactus, but it's definitely still a cactus.
The teddybear cactus blooms in May and June, so we didn't see any flowers. In addition to having the normal plant sex using flowers, these cactuses also reproduce clonally by dropping branches. The dropped pieces roll around and find a new place to attach and grow. Interestingly, this type of clonal replication, called budding, is common in many marine invertebrates!
Here's a newly detached bud from a teddybear cholla:
And here's a recently established, young plant:
Cute little cactus, isn't it?
The trees that give Joshua Tree National Park its name live in the higher and cooler western region of the park, known as the Mojave Desert. The Joshua trees (Yucca brevifolia) live singly or in clusters. In some ways, Y. brevifolia is the symbol of the Mojave Desert. They are also abundant in the higher elevations of the Tehachapi Mountains along Highway 58 between Bakersfield and the town of Mojave.
In Joshua Tree National Park, said trees were blooming in late March.
I'll have more to say about reproduction in Joshua trees and some other desert plants in another post. This one is getting long, and we had more desert adventures to come.