Lots of Cavity Nesting Birds, 05-19-18

I got up around 6:00 am and was out the door by 6:30 to go over to the American River Bend Park. I was sure the Great Horned Owl owlets were fully fledged by now and off hunting, so I didn’t expect to see them. I wanted to go out there, though, to see if the Pipevine Swallowtail Butterfly caterpillars were mature enough yet to start making their chrysalises. It’s apparently still too early for that around here, but I still got to see a lot birds and bugs and other things.

A lot of the usual suspects were out – Wild Turkeys, Starlings, Tree Swallows, Mourning Doves, House Wrens – and I was able to get photos of some of the cavity nesting birds in and around their nests. One pair of wrens was just starting to work on their nest, bringing sticks and soft stuff to line it with; another pair of wrens had babies and were flying food to them every few minutes. Standing nest tot heir tree, I was able to hear the bay birds inside cheeping away. I need to get a camera with a stretchy arm that can reach up and look down into the cavities…

The neat find of the day – even though I didn’t get many good photos because of the lighting and where the birds were – was a Western Bluebird nesting cavity. Both the male and female were feeding their nestlings (which, like the wren babies, I could hear from inside of the tree). Western Bluebirds are shy, though, and move really quickly, especially if they think you’re looking at them. (As brightly colored as the males are, it always surprises me how easily they can disappear into the shadows.) Still, I managed to get some photos of both the mom and the dad and they flew back and forth and brought bugs for their babies. At one point, the papa Bluebird figured I was getting too close to the nesting cavity, and he flew right at me, beak open. I got a few shaky photos of that before I backed off from the tree. I’m there to observe, not interfere…

CLICK HERE for the album of photos.

I also found a male hummingbird high up in a tree, and tried to get photos of him, but I couldn’t tell if he was an Anna’s or a Black-Chinned.

I saw some Scarab Hunter Wasps hovering close to the ground, looking for grubs to infest, and some other wasp-like insects that I haven’t been able to identify yet. There are sooooooo many insects with superfamilies, families, and tribes to go through before you ever get down to the genus and species level… They’re really difficult for me to identify properly. I really admire entomologists and their bug and insect proficiency.

One of the odd-ball insects I found was a small wasp-like thing with an iridescent blue thorax, red-orange abdomen, and somewhat clear wings. I was thinking maybe it was a kind of “Digger Wasp”, but I couldn’t find one on Bugguide.net with the right color legs. Maybe a “sawfly”?  I also found a golden fly-like thing with red eyes and an iridescent green thing I think is some kind of cuckoo wasp. I’m not sure. I’ll have to continue the search for the IDs.

I also came across quite a few Tussock Moth caterpillar cocoons. Most of them were already spent (with an opening at one end through which the mature moth emerged), but one was completely intact and had a layer of hard white “fluff” over the top of it. I’d never seen one like that, so I took photos and then did some more research when I got home.

I knew that the female moths (which are wingless) laid their eggs on their old cocoons and then covered the eggs with a layer of hair and foamy secretions from their bodies (which hardens to protect the eggs as they overwinter), and that could have been the case with the cocoon I found, but it seemed at first glance that the pupal casing was still inside the cocoon, which meant the moth hadn’t emerged yet.  A puzzle.

My research indicated that sometimes parasitic wasps will lay their eggs on top of the cocoons and as the larvae emerge they build a tight white webbing around them to protect themselves while they feast on the moth pupa inside the cocoon. I wasn’t sure which scenario I was looking at, so, I opened up the cocoon to see if there was anything inside of it.  Although the cocoon itself was intact (no emergence hole in the end of it), the pupal casing inside of it was empty.  I’m still not absolutely positive about what I was seeing, but I’m assuming the white fluff was made by a wasp, not by the female moth, and the pupa was devoured before the moth had a chance to develop. Nature is so fascinating.

The buckeye trees are all in bloom right now; so pretty. And some of the black walnut trees are already sporting new walnuts. I was surprised to see that many of the Hop Trees around had already lost most of their seeds. Lots of hungry birds out there, I guess.  Along the river, I found a lot of Elegant Clarkia in bloom as well as Bush Monkey Flowers. I would have gone further along that part of the trail but by that time I had already been on m feet for over three hours, and I needed to get back to the car.

All in all, I ended up walking for about 4 hours.

Posted by

Mary K. Hanson is a breast cancer survivor who, at age 61, took coursework to become a Certified California Naturalist. The author of “The Chubby Woman’s Walkabout”™ blog, Ms. Hanson has also written nature-based feature articles published in regional newspapers, authored over ten books, including her "Cool Stuff Along the American" series of guide books, and has had her photographs featured in books, articles, calendars, on the American River Parkway Foundation’s Instagram stream, and even the White House blog. This year Ms. Hanson is helping to launch and teach a new Certified California Naturalist course through Tuleyome, in partnership with the University of California and the Woodland Library, so members of the public can themselves become certified as naturalists in the state. All of the photos seen on her website were taken by Ms. Hanson herself (unless noted otherwise) with moderate- to low-end photographic equipment more easily affordable to the everyday nature enthusiast. She also occasionally leads photo-walks through the American River Bend Park for the public and is sometimes available for public speaking.