Tag Archives: Water Tiger

My First Trip to the Mather Field Vernal Pools, 03-27-19

Around 8:00 am, my naturalist class graduate Roxanne M. and I went to the vernal pools at the end of Zinfandel Blvd. in Mather Field.  Rain was threatening, and it was about 51° outside, but the rain held off until after we’d left – about 2 hours later.

I’d never been there before, but Roxanne had so she showed me some of the highlights out there – like the white pipes used for hydrology studies, and the somewhat lumpy landscape dotted with “mima mounds” around the pools.

“…One theory on the origin of Mima mounds is that they were created by small burrowing rodents such as pocket gophers (Thomomys talpoides) of the endemic North American family Geomyidae. Researchers in the 1940s found that Mima mounds tend to form in areas with poorly draining soils, so the “Fossorial Rodent Hypothesis” proposed that gophers build mounds as an evolutionary response to low water tables… It could be argued that gophers live in the mounds opportunistically but did not build them.  Consequently, gophers in mima mound fields seem to be aware of randomly distributed topographic highs and orient their burrowing accordingly in early mound creation stages. However, the mounds were already fully formed and the gophers may have just been maintaining them. Nevertheless, the fact that the surface area of a typical Mima mound is similar to the size of an individual gopher’s home range is consistent with the theory they were constructed by the rodents…”

Roxanne and I were hoping the wildflowers would be out, but there were only a few species showing. In another week or so, if we get some sunshine, the place should be covered in flowers.  We could see large swaths of Frying Pan poppies around some of the pools, but they were all closed up because it was overcast outside. Along with the poppies, among the flowers we did see were things like Butter ‘n’ Eggs, Blue Dicks, Showy Fringe Pod, Popcorn Flowers, and Jointed Charlock.

CLICK HERE for the album of photos.

We also saw some Canada Geese, Western Meadowlarks, and some Western Kingbirds. One of the Kingbirds was eating a large sphinx moth, but it was too far away for me to get a clear photo of it.  Along the road we saw a Mourning Dove, a pair of dark morph Swainson’s Hawks, and some wild turkeys.

Both Roxanne and I had brought little bowls to collect some of the pond water in so we could look for little critters in it.  We lucked out and were able to find a lot of tiny swimmers in the water including the larvae of Predaceous Diving Beetles, called “Water Tigers”, Damselfly larvae, and California Clam Shrimp.  So cool!  I need a portable microscope to take with on trips like this – and I need a book on vernal pool creatures. I don’t know very much about this kind of habitat; it’s all kind of new to me.

We both enjoyed the walk and vowed to go back to the pools in another week or so.

Species List:

1. Blue Dicks, Dichelostemma capitatum
2. Butter ‘n’ Eggs, Triphysaria eriantha
3. California Clam Shrimp, Cyzicus californicus
4. Canada Goose, Branta canadensis
5. Copepods, Copepoda
6. Damselfly Larvae, Class: Odonata, Order: Zygoptera
7. Dock, Curly Dock, Rumex crispus
8. Filaree, Stork’s Bill, Big Heron Bill, Erodium botrys
9. Flatworm, Dugesia gonocephala
10. Frying Pan Poppy, Eschscholzia lobbii
11. Jointed Charlock, Raphanus raphanistrum
12. Mourning Dove, Zenaida macroura
13. Painted Lady Butterfly, Vanessa cardui
14. Popcorn Flower, Slender Popcorn Flower, Plagiobothrys tenellus
15. Predaceous Diving Beetles, Water Tiger, Cybister fimbriolatus
16. Rio Grand Wild Turkey, Meleagris gallopavo intermedia
17. Showy Fringe Pod, Spokewheel, Thysanocarpus radians
18. Slug, Reticulate Taildropper, Prophysaon andersoni
19. Swainson’s Hawk, Buteo swainsoni
20. Tadpole, Western Tree Frog, Chorus Frog, Polypedates occidentalis
21. Western Kingbird, Tyrannus verticalis
22. Western Meadowlark, Sturnella neglecta
23. White-Lined Sphinx Moth, Hyles lineata