Week 5: Olé! Invertebrates!

Date: Sunday, May 5, 2013 (Happy Cinco de Mayo!)

Weather: Sunny

Temperature: 62ºF

Time: 9:30-10:30 AM

Location: Union Bay Natural Area

So much seems to have happened over the past two weeks! I’m back at the Union Bay Natural Area and spring is in full swing. Green is in! Here’s a look:

Green has swept through the area. So lush!

Everything seems to have doubled in size. The Giant Horsetails are at hip height and almost all sterile stems. The grasses have also grown to about upper thigh height. The Pacific Willow I had mentioned two weeks ago has doubled in size and become a perch for a Lincoln’s Sparrow (Melospiza lincolnii). Meanwhile, American Crows and American Robins were zooming by.

A Lincoln’s sparrow enjoying its perch on a Pacific Willow.

One of the Black Cottonwood trees in my observation site now has many orange and dark brown leaf buds on its twig. Emerging from the leaf buds are small green leaves in a whorled pattern. The leaves of the tree in general have increased in size. In addition, there were some dried Red Alder catkins hanging on the branches of the Black Cottonwood indicating yet another plant I had missed earlier! Unfortunately, I also noticed the English Ivy growing along the ground has also crept up the trunk of the Black Cottonwood.

A new leaf emerging on the Black Cottonwood tree.

Nearby is also a Bitter Cherry (Prunu emarginata) tree, which seems to be growing its fruit. Protruding from among its sepals is a round green body. Maybe in a week or two when the fruit has matured, I can confirm this.

Fruit from a Bitter Cherry?

Underneath the Bittery Cherry is a new shrub. Its leaves are very lobed, serrate, alternate, and the underside is pubescent. The twigs are also hairy as well. This one will have to await identification!

The greatest changes have occurred in the marsh area – it is covered in green. Yellow Iris (Iris pseudacorus) has infiltrated the area, growing among the Broadleaf Cattails. It’s green leaves are an obvious contrast compared to the yellow dried leaves of the Broadleaf Cattails. A Red-Winged Blackbird was also perched on the cattails. The grasses growing in the marsh are flourishing and Himalaya Blackberry is prolific in the shallow areas of the marsh. On a log, I also saw a row of Eastern Painted Turtles sunbathing. Each occasionally shifting in position and letting themselves drop right into the water.

Eastern Painted Turtles all enjoying the sunshine.

A Scouler’s Willow (Salix scouleriana) has also grown large enough for me to see and there are many Yellow Pond Lilies beginning to grow in the marsh.

But, the focus of the day is invertebrates, so let me describe what I found.

First, I dug around in some leaf litter and found a few Western Thatching Ants (Formica obscuripes). They were incredibly tiny (not more than 1 mm in length), but were easily identified by their red head and thorax and black abdomen and legs. Despite being tiny, they were very nimble when it came to maneuvering around in the leaf litter. I’m not sure if they were following pheromones left by a previous ant or some other scent, but each ant had very directed movement.

A small area, but many surprises found here!

Also in the leaf litter was a ½ inch long European Earwig (Forficula auricularia), which continued to burrow into the ground every time I tried to unearth it. On a nearby sedge was a Western Yellow Jacket (Vespula pensylvanica) crawling about. There was also a Common House Fly (Musca domestica) on a nearby leaf. It had red eyes with four light gray stripes on the top of the thorax. It had iridescent wings that were held in a triangular shape when at rest. My guess is that it was a female fly because her body was a light yellow color, perhaps filled with eggs waiting to be laid. Her movement was also slow and when she was flying away from me she moved in a serpentine shape.

At the center is a Common House Fly with a pale yellow body instead of the usual gray body.

Next was the marsh area. Here, I saw a rolled up Common Pillbug (Armadilldium vulgare). It was gray and had many plates. It was out in the open sun and despite my rustling of the nearby soil, it remained rolled up in a ball. This was either in defense or because it was dead.

Near the center of the photo is a rolled up Common Pillbug.

There were also Giant Crane Flies (Holorusia rubiginosa) flying around from one blade of grass to another. On the water were some Common Water Striders (Gerris). They had slender bodies and extremely long hindlegs. Due to the surface tension of water, they could stay on the water’s surface. Their movement was very jerky. The water strider would position itself, then hop to its next location on the water. I imagine they were feeding on small insects in the water because there were many of them in the area.

The final insect seen was a beautiful Mourning Cloak (Nymphalis antiopa). The four wings were mostly brown with a white border along the edge. Prior to the white border was a border of blue spots and towards the top of the wing were two white spots. With two antennae subtly moving, the butterfly was sitting on the trail, briefly spreading its wings, but more often folding its wings upright. After a while, it flew off in a swooping motion, which occurred every time it flapped its wings.

A Mourning Cloak showing off its charismatic wing pattern.

What a surprise to find so many invertebrate in one small space! All it takes is a closer look.