We are hardly in the wilderness, but there is plenty of danger if you are small enough.
Fly on daisy. The flower is about 2 cm across, and the fly seems to be upside-down. 8/25/26
Wandering around the garden this morning, I saw a tiny fly sitting on a blackfoot daisy flower. It stayed put, so I took some photos for identification.
Looking more closely, it became clear that the fly was remaining on the flower because a crab spider had grabbed it.
Closer view, showing spider holding fly more clearly.
As is often the case, the spider matched the color of the flower closely, which both allowed it to capture the fly and to avoid detection by the many potential predators that would like to eat it.
Another view of the spider holding the fly.
A few more photos showing the drama happening at the millimeter to centimeter scale.
Side view of spider holding fly.
On a larger scale, I have been trying to figure out who is eating the local beetles, by tethering a few and setting up a trail camera. So far, nobody has tried to eat the beetles, but I did get a nice view of another resident walking through.
It went through the meadow at about 7:20, which is when we often see bunnies back there. Interesting to think that the cats are probably watching us many of the nights we are walking around behind the yard.
Two new draft pages have been added to the Wildlife descriptions. Mammals showcases the carnivores, rodents, and even bats that are found in the neighborhood. Reptiles and Amphibians provides some information about lizards and snakes, along with our favorite toad.
As always, the pages are works in progress, with more details and photos to be added as time and resources allow.
We still have a lot to learn about the local wildlife, even the species that live near the lab. For example, bats have been partying on the property for years without us knowing.
Let’s start with a few observations.
First, we have seen streaks of uric acid on the walls of some of the portals (the local name for covered patios).
Uric acid stain on wall. 7/31/26
At first we thought these were from some sort of bird, maybe swallows. The marks made more sense when we learned they were from bats.
We realized they were still active roosts when we had another epiphany: the poop under the roosts was from bats rather than rodents. It seems obvious in hindsight, but there are so many deermice, woodrats, etc., that it took a while to make the bat connection.
Bat scat below a roost. 7/31/26.
The bats’ diet provides another piece in a beetle ecology puzzle. Local Tenebrionid beetles seem to respond differently to predators compared to the same species found elsewhere. For example, undefended beetles do not seem to closely mimic chemically defended beetles. This might make more sense if we knew who was eating them. We have found plenty of carnivore scat, presumably from skunks and/or raccoons, that contains beetle parts and shows that nocturnal omnivores are eating Tenebrionids.
Enter the bats. Unlike other bat species, pallid bats (Antrozous pallidus) feed on ground-dwelling insects, and others have shown that pallid bats readily eat Tenebrionid beetles. Rather than using echolocation to find the insects, they hunt using noises generated by the insects’ movements, and reserve echolocation to avoid obstacles (Bell, 1982). At the portal, discarded jaws and legs of Jerusalem crickets indicate that the insects (about the same size as large Tenebrionids) are popular menu items.
Jerusalem cricket jaws. 7/31/26
Among Tenebrionid prey, they have been identified feeding on Stenomorpha based on bits of exoskeleton found near roosts (O’Shea and Vaughan, 1977) and tracks in the soil next to bowls in which beetles had been left as bait (Slobodchikoff et al., 1987).
As it turned out, the roosts in our portal were sites where pallid bats eat and socialize at night. We were lucky that one decided to spend a day in the portal, so we could make a positive identification.
Pallid bat trying to ignore the photographer . 7/27/26
To get a better idea of their activity patterns, I set out a couple of trail cameras to catch them at night. After a few nights working on the sensitivity and finding the right locations, we were surprised to discover that it was quite the little group.
Coming in for a landing. 7/30/26Bat group greeting next arrival. 8/1/26
The size of the group was surprising. In the photo above, there are at least five bats on the walls and one more arriving. That explains the relatively large nightly deposits of poop and insect parts.
The video below gives a better idea of how much activity there is on a given night. The file is a bit large and may load slowly.
The biology of pallid bats is quite interesting. Your classic insectivorous bat uses echolocation to hunt flying insects and dodge obstacles. In practice, they basically scream and then wait for echoes to return from potential prey.
Pallid bats are considered “gleaners” or “whispering bats.” They listen for rustling to find prey on the ground. They still use echolocation to avoid running into things, but can be much quieter about it. Because some insects have evolved to hear and avoid bat calls, being quiet may improve the hunting success of the gleaning bats.
Pallid bats make use of two roosts at different times of day. During daylight hours, they roost in out of the way locations to stay cool and avoid disturbance while they sleep. At night, they make use of roosts to rest and to eat larger insects that they have caught. Our bats are using the portal as a night roost, and their daytime roost remains a mystery.
Leg of a Tenebrionid beetle under bat roost. 7/31/26
One of them left a hindleg of a Tenebrionid, possibly Philolithus, after a meal, so we can say with some confidence that pallid bats are confirmed beetle predators.
References
Bell, G. P. “Behavioral and Ecological Aspects of Gleaning by a Desert Insectivorous Bat Antrozous Pallidus (Chiroptera: Vespertilionidae).” Behavioral Ecology and Sociobiology 10, no. 3 (1982): 217–23. https://doi.org/10.1007/BF00299688.
Harris, J. “Pallid Bat.” In California’s Wildlife., 3 vols. California Department of Fish and Game, 1990.
O’Shea, T. J., and T. A. Vaughan. “Nocturnal and Seasonal Activities of the Pallid Bat, Antrozous Pallidus.” Journal of Mammalogy 58, no. 3 (1977): 269–84. https://doi.org/10.2307/1379326.
Slobodchikoff, C. N., T. A. Vaughan, and R. M. Warner. “How Prey Defenses Affect a Predator’s Net Energetic Profit.” Journal of Mammalogy 68, no. 3 (1987): 668–71. https://doi.org/10.2307/1381600.
It was a successful year for science and wildlife.
Peninsular landscape on the trip down. 6/17/26
Once again, I joined Dr. Drew Talley and Dra. Dr Natalia Rodriguez Revelo for a summer survey of the islands in Bahia de los Angeles, Baja California.
Natalia and Drew on Jorobado. 6/19/26
The work on the islands went well, and we got data regarding beetle populations from twelve islands. It is also a highlight of my year to spend the time with my best friend and our wonderful colleague.
Although work on the islands can be challenging, we are usually done by late morning, and there is time for other activities. This year, I thought it would be interesting to test the thermal resilience of some of the beetle species. The specific idea is that beetles that produce defensive chemicals (like Eleodes does) would be more sensitive to extreme conditions such as high temperature when compared with undefended beetles (such as Philolithus in Santa Fe or Cryptoglossa in Bahia). This has been assumed to be the case, but has not been tested rigorously.
My idea was simple: collect beetles from two species, one defended and one undefended, and test their survival at temperatures ranging from benign to lethal. My prediction would be that the undefended beetles would survive at higher temperatures than those that invest energy and water in defensive scent glands.
We decided it was better to collect the experimental beetles on the mainland. The project was added to the permit application along with the other, ongoing projects. However, the permit only allowed us to survey the beetles on the mainland, not collect or test them. Nonetheless, sampling would allow us to determine where it would be best to find enough beetles for experiments in the future.
Bahia de los Angeles dump. 6/18/26
For our first sampling location, we set traps at the local dump. We reasoned that we could avoid protected areas and private property by sampling at the dump.
We set nine pitfall traps, baited with oatmeal along an arroyo. After checking back every afternoon for three days, we had caught six Cryptoglossa muricata. It was good to find beetles that would be appropriate for experiments, but we needed at least two species, and about 40 of each. We thought it best to look elsewhere.
One can see why beetles in the Cryptoglossini are called “death feigning beetles.” This C. muricata is quite alive, but waiting for me to go away. 6/20/26
We thought that the Glendale Community College field station might be a better location, so we asked Jared Ocampo, an old friend and the station manager, for permission to set traps around the station. He agreed, and even helped us set the traps.
Arroyo on the southern approach to the Glendale Station. 6/24/26
We set a total of 24 traps in three sets of eight. One group was set in an arroyo to the south of the station, one set was placed in desert to the west, and the last was placed near the beach to the north. Rather than checking every day, we left the traps for two nights.
The results were pleasing. We trapped more than sixty C. muricata, and ten Eleodes loretensis, along with a number of Stibia. This is an almost ideal result, in that E. loretensis is chemically defended, whereas C. muricata is not, and they are well-matched n terms of size and mass.
Eleodes loretensis from a trap at Glendale station. 6/26/26. Click to enlarge.
Cryptoglossa muricata from a trap in the arroyo at Glendale station. 6/26/26
The traps in the arroyo were the most productive, and those in the desert also caught a good number of beetles. Interestingly, those by the beach only trapped a few Cryptoglossa.
Assuming that all goes equally well next year and we have the proper permit, we should be able to compare the temperature sensitivities of these two species that are highly similar except for the presence of chemical defense.
