The Other Gristmill Trail, 06-02-21

I got up at 5:30 this morning and headed over to the Gristmill Recreation Area, getting there around 6:00 am.  It was 59° when I arrived there, but it warmed up to 70° before I left.

I walked over to where I normally see the Western Screech Owl, and was happy to see her — but she ducked down immediately when a loud Scrub Jay flew down in front of her.

I then walked on the longer trail on the opposite side of the parking lot. I hadn’t been on that one before, so I didn’t know what to expect, really. It was more “wild” than the other trail with lots of trees, plants, and wildflowers (some still surviving in the heat) that are not seen on the shorter trail. It was also flatter with direct access to the river in a few spots.

The little footbridge on the trail

I was surprised to see so many Elegant Clarkia flowers still in bloom. And it looks like there had been several stands of a kind of phacelia (caterpillar flowers) there — which I’ll have to keep an eye out for next year.

Elegant Clarkia, Clarkia unguiculata

There was much of anything on the water, although I did see a Great Egret and the mama Merganser with her red-headed babies. She’s still got her four little ones, so she’s been pretty successful in keeping them alive and safe.

Common Merganser, Mergus merganser

I found quite a few galls on the trees including those of the Black Walnut Pouch Gall Mite and the Willow Rosette Gall Midge.  The rosette galls, this time around, were new ones, still all shiny and green.  New-to-me galls included those of the Smooth Petiole Gall Sawfly and Willow Fold Gall Sawfly. 

As their names suggest, the petiole galls were at the petiole (the point where the leaf attaches to the plant) of the willow leaves, and the fold-galls were, well, folded. In some of the fold-over galls, I found aphids being tended by ants. I think the aphids were secondary dwellers, though, having taken over the folds after the sawfly larvae hatched out.  I’m not sure, though.

Formicine Ants, Subfamily Formicinae, tending to aphids

On one of the cottonwood trees, I saw a collection of about a dozen “things” hanging down from the branches.  They looked like bushtit nests or maybe masses of bees, but I could tell they weren’t. They were made of plant material. But they weren’t like any of the hanging seed pods, and there weren’t any of them on any of the other trees. They were — and still are — a bit of a mystery to me. I think they might be panicles of seedpods that have been taken over by some kind of fungus or insects — like large leafy galls. More research is required…

Among the insects, I found a single specimen of a tiny planthopper, Agalmatium bilobum.  It’s an “adventive” species, which means it’s not native but also not very well established yet.

Issid Planthopper, Agalmatium bilobum

I also found several examples of what I think is a kind of “moth leaf tier” on an Arroyo Willow. They were collections of leaves with a dead leaf in the center surrounded by several live leaves — and I think they hid moth caterpillars of some kind.

I opened up a couple of them, and found that whatever had been inside the leaves was now long gone, leaving just plant material and old webbing behind. I’m still searching for a more specific ID. The construction of the things was really interesting to see, though.

CLICK HERE for the full album of photos.

Although I didn’t get any really good photos of it, the most interesting moment on the trail today was seeing a female Nuttall’s Woodpecker foraging in the bark of a tree, while below her, near the ground, was a female Downy Woodpecker foraging on Mugwort plants.

I’d never seen a woodpecker foraging on plants before, so I had to look it up.  For the Downy Woodpecker, it’s rather unusual (used only about 2% of the time). I assumed the bird was looking for ants more than plant matter itself.

Fun fact according to Cornell: “…Percussion not a means of securing prey, but rather a means of locating prey by rapidly tapping along a branch or trunk, presumably in order to hear resonance produced when tapping is above tunnel of a wood-boring insect…”

I was out on the trail for about 3 hours and then headed back to the car…and it was from the car when I got photos of House Finches and Lesser Goldfinches. Always have to keep my camera at the ready.  This was hike #50 of my #52HikeChallenge.

Species List:

  1. Anna’s Hummingbird, Calypte anna
  2. Aphid, Family: Aphididae
  3. Arroyo Willow, Salix lasiolepis
  4. Bewick’s Wren, Thryomanes bewickii
  5. Black Locust Tree, Robinia pseudoacacia
  6. Black Phoebe, Sayornis nigricans
  7. Black Walnut Pouch Gall Mite, Aceria brachytarsa
  8. Black Walnut, Eastern Black Walnut, Juglans nigra
  9. Black-Tailed Jackrabbit, Lepus californicus
  10. Blue Elderberry, Sambucus nigra cerulea
  11. Boxelder, Box Elder Tree, Acer negundo
  12. Bushtit, American Bushtit, Psaltriparus minimus
  13. California Manroot, Bigroot, Marah fabaceus
  14. California Mugwort, Artemisia douglasiana
  15. California Scrub Jay, Aphelocoma californica
  16. California Wild Grape, Vitis californica
  17. Canada Goose, Branta canadensis
  18. Coast Live Oak, Quercus agrifolia
  19. Common European Greenbottle Fly, Lucilia sericata
  20. Common Merganser, Mergus merganser
  21. Conical Trashline Orbweaver, Cyclosa conica
  22. Dog, Canis lupus familiaris var. Golden Retriever
  23. Downy Woodpecker, Dryobates pubescens
  24. Elegant Clarkia, Clarkia unguiculata
  25. European Earwig, Common Earwig, Forficula auricularia
  26. European Praying Mantis, Mantis religiosa
  27. Exclamation Damselfly, Zoniagrion exclamationis
  28. Fennel, Sweet Fennel, Foeniculum vulgare
  29. Fremont’s Cottonwood, Populus fremontii
  30. Goldwire, Hypericum concinnum
  31. Goodding’s Black Willow, Salix gooddingii
  32. Great Egret, Ardea alba
  33. Green Lacewing, Chrysoperla rufilabris
  34. House Finch, Haemorhous mexicanus
  35. House Wren, Troglodytes aedon
  36. Issid Planthopper, Agalmatium bilobum
  37. Killdeer, Charadrius vociferous
  38. Lesser Goldfinch, Spinus psaltria
  39. Mallard Duck, Anas platyrhynchos
  40. Moth Leaf Tier on Willow, Order: Lepidoptera
  41. Mourning Dove, Zenaida macroura
  42. Narrowleaf Willow, Salix exigua
  43. Northern Catalpa, Indian Bean Tree, Catalpa speciosa
  44. Northern Mockingbird, Mimus polyglottos
  45. Nuttall’s Woodpecker, Picoides nuttallii
  46. Oak Apple, California Gall Wasp, Andricus quercuscalifornicus
  47. Oak Titmouse, Baeolophus inornatus
  48. Phacelia, Caterpillar Scorpionweed, Phacelia cicutaria [white]
  49. Pied-Billed Grebe, Podilymbus podiceps
  50. Red-Shouldered Hawk, Buteo lineatus
  51. Smooth Horsetail, Equisetum laevigatum
  52. Smooth Petiole Gall Sawfly, Euura sp. [willows]
  53. Spotted Towhee, Pipilo maculatus
  54. Stink Bug, Trichopepla sp.
  55. Tree Swallow, Tachycineta bicolor
  56. Turkey Vulture, Cathartes aura
  57. Valley Oak, Quercus lobata
  58. Western Boxelder Bug, Boisea rubrolineata
  59. Western Ragweed, Ambrosia psilostachya
  60. Western Screech Owl, Megascops kennicottii
  61. White Horehound, Marrubium vulgare
  62. Willow Fold-Gall Sawfly, Phyllocolpa sp.
  63. Willow Rosette Gall Midge, Rabdophaga salicisbrassicoides
  64. Wood Duck, Aix sponsa
  65. ?? growth on cottonwood trees
  66. ?? soft blobby “eggs” on oak leaf