Why Evolution is True is a blog written by Jerry Coyne, centered on evolution and biology but also dealing with diverse topics like politics, culture, and cats.
UC Davis math prof Abby Thompson usually contributes photos of the California intertidal, but today she sends us five mammal videos from her house. Abby’s captions are indented.
In a brief departure from tidepools, I bring the results of our recent trailcam experiment. A few posts ago I mentioned that something had excavated a major tunnel system under our front yard in Northern California, with multiple large entrances. We installed a trailcam to try to discover what it was and spent about six weeks collecting endless short videos of grasses waving in the wind, plus various deer body parts. We decided that probably the tunnels had been abandoned and were losing hope. But in the last few weeks (the grass got mowed, and the settings got adjusted), things picked up on the trailcam.
On 6/17 we captured a striped skunk, Mephitis mephitis, which, though charming, was our least-favorite choice for tunnel builder :
Really exciting, on 6/25 a bobcat, Lynx rufus strolled by:
And you’d have thought that was more than we could’ve hoped for, but on 6/28, we saw this:
Taxidea taxus, the American badger! Although I still feel like I’ve never seen a wild badger in person, this was pretty close. I don’t know if the badger really was responsible for the tunnels, but I’m happy he visited.
Today’s photos and videos come from reader/physicist/origami master Robert Lang in California. Robert’s captions are indented, and you can enlarge the two DUCK photographs by clicking on them.
The creek named Arroyo Seco runs from Red Box Saddle in the San Gabriel mountains down past the Jet Propulsion Laboratory (JPL), through western Altadena and Pasadena, and then on to Los Angeles, joining the Los Angeles river near downtown L.A.; the historic Pasadena Freeway (now State Highway 110) follows its channel much of the way. True to its name, it’s dry much of the year, but above JPL, it runs year-round, providing lush, verdant and shady hiking any time of year. Since the Eaton Fire resulted in the closure of much of the front range of the San Gabriels, the still open Arroyo Seco and its Gabrielino Trail have been my go-to spot for a quick, regular getaway.
It’s also been a regular source of wildlife sightings, some of which have made it to RWP (for example, here, here, and here), but today I have an offering particularly near and dear to our host: ducklings and their momma!
This was at Brown Mountain Dam falls, which is about 3.5 miles up the trail from JPL. The dam was built in the 1940s, and quickly filled up its basin with sediment (there is now a forest of full-grown trees at the level of the top of the dam), but it provides a 40’ waterfall with a deep pool at the base and is a popular destination for bikers, hikers, and runners, especially on a hot day. Today, it had some unusual visitors: a momma mallard (Anas platyrhynchos) and her seven ducklings, who followed her up the creekbed to the pool where they then proceeded to feed, play, and shower under the falls.
Today we have two videos from Tara Tanaka, who has been absent a while due to a drought Florida that dried up much of the wetlands on the family property, creating an absence of wading birds that she used to feature. Fortunately, as she writes below, the drought may be over. In the meantime, we have a kayaking video and a video featuring a BOBCAT.
In 2024 when we had a swamp full of water, we got a sit-on-top kayak that I could use to shoot from and that my husband could use to get out into the swamp to manage exotic plants. I chose this one because it’s incredibly stable, and I wanted an open deck to be able to paddle without having the camera in front of me. This kayak has a seat that swivels 360 degrees, allowing me to mount my tripod with a 500mm lens in the stern, and then just pivot around between paddling and videoing. This was the maiden voyage in our Nucanoe kayak.
I was able to make quite a few trips out during the 2024 nesting season, and after a relatively dry winter and then one good rain, made a few trips out in 2025. I stopped going out not because there wasn’t enough water to float the kayak, but because it was getting so shallow and our alligators that patrol the rookery for raccoons and snakes are so big that I didn’t feel comfortable paddling right over one with just a couple of feet between us. It wasn’t long after that that a couple in a canoe in Lake Kissimmee paddled over an 11’ gator in 2’ of water causing the gator to thrash and overturn the canoe, with a tragic ending.
The swamp has been dry for at least 9 months, with only a few pools of water, and now that it’s really starting to rain I’m hoping that the water level will return to normal and the birds will return to nest next spring.
A 5-minute YouTube video, narrated by Tara, showing the maiden voyage of the canoe (sound up.) You can see there are still birds around. Can you identify them?
And here’s a Vimeo video with an animal encounter. Enlarge this as you can see a lot more detail on full screen.
We had seen one or two coyotes around 9:30 the last two mornings. Hoping they would return for a third day. I got my camera ready in the living room to try to record them. About 9:00 my husband said he saw one, so I made some final adjustments for the lighting and began to search for something moving in the distance. When I finally centered the subject in the viewfinder, I said “I think I’m looking at a bobcat.” Almost immediately the cat stood up and as I panned with it I was shocked when two coyotes ran into the frame, one on each side of the cat. Enjoy the interactions between the two species and between the very bonded pair of coyotes. I believe the female is pregnant.
After I finished filming I just sat in disbelief that I had had the opportunity to record something so unique – and from my living room! I feel like I could have gone to Yellowstone and spent a month in the field and not witnessed an encounter like this. Because of the dramatic temperature difference between the thawing ground and the sun heating the brown grass, the waves of heat shimmer intensified as the sun got higher and you can see them rippling across the screen. Despite the extreme conditions, I was thrilled that I was able to record the interaction so clearly from 1000’ away, and through a double-paned window.
We should have a pond full of water with waders arriving to nest right now, however due to a severe drought that started over a year ago the entire swamp is dry. Without water to allow our large alligators to patrol under the nests and protect them from predators, I’m afraid that our hundreds of waders that nest here every year will not feel safe and will likely nest elsewhere.
Filmed with a Panasonic GH6 + Nikon 500mm f2.8 lens. Since I filmed it from inside the house, I used the audio from a video I shot from the yard last year.
I forgot to post part 2 of Abby Thompson‘s latest batch of California intertidal photos, so here they are (the first batch is here). Abby’s captions and IDs are indented, and, as always, you can enlarge the photos by clicking on them.
The stars of this set, improbably enough, are two flatworms. The first two pictures are of the elegant Eurylepta californica, which I think of as the “art-deco flatworm”. It’s rare up here; I’ve found it once before. The next flatworm (Family Euryleptidae) is an undescribed species. It’s been recorded several times, almost all in the Monterey Bay area. This is its third sighting (as recorded on inaturalist) this far north. There isn’t agreement on the genus. It’s a beauty, and it’s unusual to have such a striking animal remain undescribed. Both worms are about ¾” long.
Eurylepta californica (striped polyclad flatworm) Art deco flatworm:
The starfish plague of several years ago was devastating along the coast, and several species (like the incredible sunflower stars) have not recovered, but the ochre stars are back with a vengeance. I see many more of them than of the bat stars, but the next picture is one of each buddying up on a rock above the low tide line.
The next three pictures are a slightly deceptive series. I’m not sure that the first two pictures really are otter tracks, but the alternative is probably raccoon tracks, and otter is a better match. They did not, in fact, end on the beach right next to the where I saw the otter in the third picture. But at least the third picture below is definitely an otter. This almost surely is a river otter, not a sea otter, as are most seen around here.
Leucism, the absence of pigment in all or parts of the body in animals, is a genetic condition often mistaken for albinism (leucistic animals havenormally pigmented eyes). It’s found in all sorts of animals, from reptiles to mammals, and Scott Ritchie has spotted it in Australian ducks. Scott sent some pictures, which you can enlarge by clicking on them, and his captions are indented:
The leucistic Plumed Whistling Duck (Dendrocygna eytoni), is back at Hasties Swamp, Queensland, the white one in in middle. We have seen it for at least 2 years running. And “he/she” appears to have busy, with at least one (several white light feathers head and breast), and perhaps 3 (2 based on “forehead” feathers) individuals showing leucicism traits. It’s interesting that they were hanging together at the log to the left of the hide.
We have a short RWP today as there are more posts to come. First we hear from Robert Lang, who sees a surprising amount of wildlife near his home in the eastern LA “suburb” of Altadena. Robert’s intro is indented, and you can enlarge the photo by clicking on it.
Although every day sees another few housing starts in post-fire Altadena, it’s still mostly empty of people, but after a year that included plenty of rain, the vacant lots are lush with plants—a mix of native coastal sage scrub, invasive weeds, and landscaping gone wild. This temporary rewilding provides plenty of cover for the local wildlife to come down out of the hills and hang out. Yesterday the workers at our site reported that a bear had stopped by and done a walk-through of the framed house (fortunately, just lookie-looing, no damage). Today I did a short hike on the Gabrielino Trail above my old stomping ground of JPL and saw a different (younger) California black bear (Ursus americanus californiensis) just off the trail, and I shot the photo below. . .
. . . also this video.
This isn’t the bear species on the California state flag, which is the California grizzly bear (Ursus arctos californicus); that was native to this area but was hunted to extinction in the early 20th century. In the 1930s, 28 “problem bears”, California black bears, were taken from Yosemite and released in the San Gabriel and San Bernardino Mountains of Southern California. The black bear species is highly variable in coloration, ranging from black through brown, blond, and even white (the so-called “spirit bears” of British Columbia). Most of the bears we see in Altadena are brown, like this youngster, all descended from the original Problematic Twenty-Eight.
JAC: Here’s the California state flag sporting a grizzly:
Original: Donald Graeme Kelley. Vectorization: Devin Cook, Public domain, via Wikimedia Commons
I’m starting to get some new batches of wildlife photos, and I encourage readers to submit their good photos for consideration.
Today’s installment features the photos of UC Davis ecologist Susan Harrison, who recently went birding not too far from Chicago:
Birding in the Upper Midwest
Minnesota and Wisconsin may not be at the top of everyone’s list of nature travel destinations, but do they have darned nice birding? You betcha! On a late May work trip to Minneapolis, it was my good fortune to visit some of the Upper Midwest’s riparian forests, wetlands, and restored prairies during spring migration. Friendly people and well-tended parks and nature reserves helped make it delightful.
Rarer small birds that were new (a.k.a. “lifers”) for me….
Kirtland’s Warbler (Setophaga kirtlandii), a specialized inhabitant of young Jack Pine (Pinus banksiana) forests, only recently removed from the endangered species list:
Louisiana Waterthrush (Parkesia motacilla), a warbler that lives on the banks of crystal-clear headwater streams in forests:
LeConte’s Sparrow (Ammospiza leconteii), a secretive marsh dweller that sings in the dark and scurries around on the ground:
Henslow’s Sparrow (Centronyx henslowii), a stealthy bird of the region’s much-diminished grasslands (historical note: it was named by John James Audubon in honor of Darwin’s mentor John Stevens Henslow):
