Western Pearlshell Mussel

I want to introduce you to the Western Pearlshell mussel (Margaritifera falcata). It is a bivalved, freshwater mollusk that can be found in the Willamette River.

Besides being a beautiful creature, they are important part of the ecology of a stream. They are filter feeders which helps improve water quality and clarity. Their shells store nitrogen, calcium, and phosphorus that are slowly released back into the ecosystem when they die. Beds of mussels provide habitat for invertebrates, and the empty shells are safe havens for developing fish.

The breeding cycle of the western pearlshell mussel is fascinating. For fertilization to occur, the male will release sperm and the female will filter it out of the water. The embryos develop into larvae called glochidia and are released into the water where they must encounter and attach to the gill filaments of a host fish. The glochidia are parasites on the fish and remain on them for several weeks or months as they develop into tiny juvenile mussels. When they are ready, they release and fall back to the stream bottom where they to continue to grow and mature. Most freshwater mussels need a host fish to complete their lifecycle. The known host fish for the western pearlshell are salmonids, such as Chinook salmon, coho salmon, cutthroat trout, redband trout, and steelhead. Not only are these fish part of the lifecycle, they are important for distributing the mussels as they move and migrate through the river system.

Amazingly, these mussels have been recorded to live to over a hundred years old, so they are important indicators of the health of the ecosystem. Alarmingly, over seventy percent of North America’s species of freshwater mussels are listed as endangered, threatened or of special concern. This is due to factors like pollution, habitat loss, and decline in host fish populations.

This is another reminder of the crisis we are facing on this planet with the continual degradation of biodiversity and vitality of our ecosystems in nature. We know that we need to be better stewards of the earth. I hope there is a local place in nature that you visit often, have become connected to, and are inspired to help make it a better place.

Nature is an inexhaustible source of wonder. I look forward to seeing you out there.

Sources
“Native Freshwater Mussels in the Pacific Northwest | Xerces Society.” Xerces.org, 2025, xerces.org/publications/guidelines/native-freshwater-mussels-in-pacific-northwest. Accessed 28 July 2025.

Western Pearlshell (Margaritifera Falcata) | U.S. Fish & Wildlife Service. https://www.fws.gov/species/western-pearlshell-margaritifera-falcata. Accessed 28 Jul. 2025.

Western Pearlshell Mussel | Washington Department of Fish & Wildlife. https://wdfw.wa.gov/species-habitats/species/margaritifera-falcata. Accessed 28 Jul. 2025.

Williams, James D., et al. “Conservation Status of Freshwater Mussels of the United States and Canada.” Fisheries, vol. 18, no. 9, Sep. 1993, pp. 6–22. DOI.org (Crossref), https://doi.org/10.1577/1548-8446(1993)018<0006:CSOFMO>2.0.CO;2.

Trailing Blackberry Fruit

Here are the fruits of the native trailing blackberry. It ripens to form a black, delicious berry just like you would imagine. Although, they don’t form the abundant clusters of fruit like the Himalayan blackberries that most people are used to picking around here.

It is fairly easy to identify the native blackberry. The vines are fairly thin and trail along the ground. They do have thorns that will grab on to you and snag a thread in your clothes or lightly scratch your skin. That said, they don’t form dense, impenetrable thickets of stout canes with sturdy thorns like the Himalayan blackberry that will easily shred you and your clothing. The trailing blackberry usually forms leaves that consist of three, ovate, toothed leaflets but they can form five leaflets too. The Himalayan blackberry generally has five leaflets but can also have three leaflets that are also toothed but have a more round, oval-shape.

The last photo below shows the Himalayan blackberry in the top of the photo and the trailing blackberry in the bottom of the photo for comparison.

Trailing Blackberry Flowers

I took these photos at the end of April and wanted to write about them in the spring. I imagine that in the busyness of work the time slipped away from me and the photos got a little buried as I continued to wander around looking at nature taking more photos.

Anyway, meet the our native trailing blackberry that is fairly prevalent out at the arboretum. Here’s a small patch that’s blooming along the river. It can form a dense thicket as it spreads and its vines trail across the ground. I few years ago I wondered why I wasn’t seeing a more abundant crop of berries like the non-native Himalayan Blackberry produces. I discovered that the trailing blackberry is diecious, the male and female flowers are on separate plants. Therefore, as the blackberries “trail” along the landscape and spread, it is not uncommon to encounter fairly large patches of blackberries vines that are only male and don’t bear any fruit.

Western Wood Pewee Sunning & Preening

In the early warmth of the morning sun, I watched this Western Wood Pewee sunning and preening. It spent most of the time with its back to the sun with its tail feathers spread out and its wings slightly open and away from its body. After a five minutes or so of sunning, it would have a session of preening that lasted approximately five minutes. Sometimes when it preened, it would flip around and have its other side exposed to the sun.

Occasionally an irresistible insect would fly by and it would swoop out, catch it, return to the perch, and continue preening. To my surprise, this lasted for around an hour.

I wrote about this sunning and preening last year, observing it in Robins and Steller’s Jays (Sunning, Feb. 28, 2024): This maintenance behavior isn’t completely understood but seems to be largely associated with removing parasites, such as lice, living on their skin and feathers. Studies have shown that exposing the feathers to direct sunlight can allow them to heat up enough to kill some of the lice. In addition, lice might move to escape the heat possibly making it easier to clear them away during preening, which often follows a session of basking in the sun.

Happy Birding!

Caterpillars Descending From Oaks - Update

I’m finally getting around to updating you on the caterpillars that repel down from the oak trees during the middle of May.

I put some soil, old oak leaves, and other debris from the ground in a screened terrarium and captured a bunch of the caterpillars as they descended down from the trees. At the end of the day, I checked in on the caterpillars and some of them had already started spinning small webbed cocoons in the leaf litter and even under the lid of the terrarium. A month later there were small moths fluttering around inside. They were beautifully camouflaged on the old oak leaves. They held their bodies in a diagonal position with their front legs propping up the front of their bodies. They have long stripped antennae that are the length of their bodies. They reminded me of the delicate tip of a watercolor brush.

iNaturalist identifies them as a moth in the genus Caloptilia. The larvae begin as leaf-mining sap-feeders. The latter instars usually exit the leaf and feed within a folded roll at the tip of a leaf lobe. You can see the tissue being eaten away leaving a brown spot on the leaf with the leaf veins exposed. When I unrolled some of the leaf tips, I found caterpillars inside some of them. They were either still crawling around or starting to spin a cocoon. With the leaf tips that were empty, I guessed they were the ones where the caterpillars decided to descend from the trees and spin their cocoons in the leaf litter on the ground. That certainly seems like a good strategy for avoiding chickadees.

Now I am wondering where things go from here. The caterpillars spun their cocoons and hatched out into moths. Do the moths overwinter and lay their eggs in the spring? Or do they mate and lay eggs that overwinter and hatch out in the spring? Also, I don’t remember seeing the caterpillars again later in the summer the same way I see them in the spring. So my guess at this point is that there isn’t a second generation this year. I’ll just keep trying to stay aware, be curious, observe, and research them.

Nature is an inexhaustible source of wonder. I hope to see you out there!

Correspondent from the Blue Beyond

A translucent, powdery blue crawdad speckled with stardust from hitchhiking on comets around the universe has come to visit planet earth on his travels. Ziggy writes poetry for the magazine Cosmic Jones and has generously shared a poem he has been working on:

Even Crawdads Get The Blues

Vibe.

Strive
to be
always be
striving.

Live.

Be kindling
for kindness.

Cleave.

Stay tuned
to the current.

Marvel.

Love all
the creatures
features.

Visualize.

There’s no
such thing as
time.

Elevate.

Lift up
your mind.

Believe.

Find the wealth
inside yourself.

Arrive.

It’s the
moment.

Sweet Dreams

I was out walking around the arboretum the other evening enjoying the cool air and a slight breeze as the day was coming to a close. I was walking along the incense cedar trail and could hear the ethereal notes of brown creepers flowing through the forest. I stopped to listen and saw one swoop down to the base of a tree. I watched it for a little while as it sang and moved around on the furrowed trunks of old incense cedars looking for food. I lost sight of it in the waning light, but I could still hear it singing in the canopy. Suddenly it swept down to the base of an incense cedar in front of me. It went up the tree and came to a small cavity in the bark where a tree limb used to be. It hopped into the entrance and perched there. I watched as it sat there looking around. After about five minutes or so, I saw it nestle a little more into the old knot hole. I occasionally saw it gently close its eyes for a moment and then reopen them. I began to wonder if this was where this brown creeper was going to spend the night. I decided to sit down, wait for night to fall, and see if it stayed. I watched it over the next forty-five minutes or so, occasionally glancing up to see if it was still there. The last time I looked up there I saw that it had tucked its head inside, and I imagined that it had nodded off to sleep. So I said goodnight, quietly stood up, and walked on to go home and do the same.

Great Horned Owl - Thermoregulation

In the later part of spring, there was a hot weekend where the temperature got up to around 90 degrees Fahrenheit. It was the first day of the year where it had become that hot and it felt like summer had suddenly arrived in a blast of heat. I felt a bit drained from the surge in temperature and was staying in the shade as I walked around the arboretum. I was at the beginning of the zigzag trail when I heard a robin alarming on the hillside and went to check it out. I found two great horned owls—a parent and a juvenile. They were briefly on the same branch together and then the parent flew a little ways down the hillside. The juvenile stayed behind and I could see that it was eating a northern flicker. As it sat on the branch, it was occasionally making a screeching call that seemed to be a begging communication to the parent and to me, a possible signal that it was uncomfortable in the heat.

To remedy the stress from the heat It was perched in the deep shade of the hillside where it was coolest. It was also cooling itself by holding its wings open to allow the air to circulate over its body. I could also see that it was holding its mouth open and vibrating its neck. Some birds will perform a version of avian panting called gular fluttering where they open their mouths and vibrate their neck muscles to try and remove excess heat. Basically, opening their mouth and fluttering their neck muscles (in the throat or “gular” region) increases blood flow and moves air across the moist membranes in their mouth and esophagus, resulting in evaporative cooling.

As the daytime highs are consistently rising into the 90’s, I recommend fluttering your feet around in the river. Stay cool everybody. I hope to see you out there!

Resources
How Birds Keep Their Cool | Audubon. 1 Aug. 2012, https://www.audubon.org/news/how-birds-keep-their-cool.

How Do Birds Keep Cool in the Summer? | U.S. Fish & Wildlife Service. 11 Jun. 2021, https://www.fws.gov/story/how-do-birds-keep-cool-summer.

Western Wood-Pewee Nest

The nest of the Western Wood-Pewee is so elegant. It is tightly woven out of fine plant fibers and held together by spider webs. It is a work of art. I love watching the parent sitting on the nest as the branch gently sways in the breeze.

As I sit and watch this nest, it all seems unbelievable. This little bird flies all the way from South America to nest here at the arboretum! The range maps have them breeding in Western Canada and up into Alaska. The migration of birds is truly miraculous. I can’t even imagine all of the landscapes and obstacles this bird had to navigate to get here. And by the end of the summer, they will be on their way back along with the new hatchlings! That is a long way from here. This blows my mind!

Brood Patch

I found a pair of violet-green swallows nesting in a natural cavity of an Oregon ash tree. There were small, dead branches right outside of the entrance that made the perfect perch. As the female landed and began to preen her feathers, I could see that she had developed a brood patch.

For an egg to develop normally and hatch, a certain temperature range must be maintained. One of the ways birds achieve this is by sitting on the eggs and incubating them. To help facilitate the transfer of heat from the parent to the egg, birds temporarily develop a bare patch of skin on their belly called a brood patch. Certain hormones are produced that cause the feathers to fall out in this spot and to create additional blood vessels in the bald area to help transfer warmth to the eggs. Some birds, such as ducks and geese, may pluck their feathers to create a brood patch. The feathers that are shed can also be used to insulate the nest to help with temperature regulation. The time spent incubating eggs varies based on the insulating properties of the nest and the temperature of the environment. The bird can sense the temperature of the eggs through its brood patch and will adjust its time spent incubating the eggs accordingly. Birds will also periodically turn the eggs to warm them evenly and prevent the embryo from sticking to the shell.

Nature is an inexhaustible source of wonder. I hope to see you out there.

Resource
Ehrlich, Paul R., et al. The Birder’s Handbook: A Field Guide to the Natural History of North American Birds Including All Species That Regulary Breed North of Mexico. Simon & Schuster, 1988.

In the cosmic stream swirling about my feet, there is a messenger carrying a spiraling incunabula of time where no words have ever been uttered. To decipher its contents I must forget everything that I have ever learned. I have to wash away every memory, every thought. Then I will be able to feel the silk of its foot grabbing on to mine. Slowly, I enter the stillness of the stream. Me, with my wrinkled snout pushing through the viscosity of the elements. My striped antennae swaying back and forth reading the ebbing and flowing concentric rings. That is all.

Blue-gray Gnatcatcher

The blue-gray gnatcatcher is a beautiful, little bird. The male is blue-gray above and white below. He has a white eye-ring and a black line that starts above one eye and curls around the forehead to above the other eye. The females are gray above and white below with the same striking eye-ring. They both have dark tails with white outer tail feathers.

This is a fun bird to watch flitting around through the landscape. When it perches, it has a noticeable behavior of cocking its tail, slightly fanning out the feathers, and swaying or wagging it back and forth.

Its nest is an open cup that is woven with small fibers and decorated with bits of lichen or bark. It looks similar to a hummingbird nest. Peterson has the length of the blue-gray gnatcatcher at 4.5 inches and Cornell lists it as 3.9 - 4.3. So they aren’t much bigger than a hummingbird.

The range map on All About Birds by the Cornell Lab doesn’t have them this far north, but lots of birds are expanding their range northward. This bird’s breeding range covers a lot of the United States from coast to coast. There is a small band across the lower part of the country where it can be seen throughout the year. Check out the range map at Cornell.

This bird is small and can be challenging to spot, so it’s helpful to also stay tuned into its vocalizations to find it. I love checking out how Roger Tory Peterson describes its voice in his Field Guide to Birds of Western North America. Here’s what he says: “Call a thin, peevish zpee; often doubled, zpee-zee. Song a thin, squeaky, wheezy series of notes.”

Happy birding! I hope to see you out there.

Western Kingbird Nesting

For reasons I don’t understand, kingbirds have chosen to nest on one of the high voltage towers out at the arboretum. The sound of the electricity crackling across the wires is audible from a fair distance. Never mind that the sound of sizzling is loud up there where they are nesting, being that close to high voltage electricity I imagine is not good for their health and the health of their babies. On top of that, I feel like those metal beams would heat up pretty hot in the noon day, summer sun. Again, I can’t believe that this would be an attractive site for them to nest. Trying to put a positive spin on it, I thought that they certainly won’t have to worry about ground predators like snakes and squirrels. Also the view is probably nice from up there and that will come in handy to detect and chase off predatory birds such as owls, ravens, crows and hawks that are in the area. It also looks fun as they dive off the tower and glide down to the hillside to forage.

They have a light gray head and a white breast that fades into a yellow wash on their bellies. They have a stout bill and a black tail with outer tail feathers.

They are a beautiful bird to observe and they love the open landscape of the east side of Mount Pisgah. I see them perching on top of brush piles and on dead limbs of shrubs like buckbrush. They are mainly insectivores and they will use these perches to forage by hawking insects out of the air or flying down to the ground.

Listen for their vocalizations. Peterson describes their voice as “shrill, bickering calls; a sharp kip or whit-ker-whit; dawn song pit-PEE-tu-whee.” I feel like Peterson always has interesting descriptions of a bird’s songs and calls. Check it out and see what you think.

I hope that you are getting in some birding time this spring. Nature is an inexhaustible source of wonder. I hope to see you out there.

Sources
Peterson, Roger Tory. Peterson Field Guide to Birds of Western North America, Fourth Edition. Houghton Mifflin Harcourt (HMH), 2010.

Western Kingbird Overview, All About Birds, Cornell Lab of Ornithology. https://www.allaboutbirds.org/guide/Western_Kingbird/overview. Accessed 30 May 2025.

Woolly Aphids

These little tufts of wool (actually a thick flocculent wax) are aphids and are called, you guessed it, woolly aphids. They are on the underside of the leaves sucking out the juice flowing through the leaf and the leaf will start to curl under as a result. The juice that they can’t digest is excreted as a little sugary droplet known as honeydew. Their sugary droplets create a sticky coating on the ground and leaves below them. Chickadees, bushtits, Bullock’s orioles, black-headed grosbeaks love to eat them. Ants are attracted to the honeydew. Squirrels are also in on the scene, either eating the aphids, licking the honey off the leaves or both probably. I looked at a few of the snipped off leaves that they discarded while foraging and they don’t have any aphids left on them.

They seem especially abundant this year and I doubt there is a single ash tree in the arboretum that doesn’t have them. The interesting thing about woolly aphids is that the first ones to hatch out in the spring are wingless females which reproduce without mating (parthenogenesis). This allows them to produce offspring quickly, which is why you can see them throughout the arboretum at the moment.

I read that woolly aphids typically have two host plants. After a couple of generations in the spring, they will produce winged females that will fly off to another host to feed during the summer. I captured a photo of one below that appears bluish. I am not sure what their second host for the summer is here at the arboretum. As fall approaches the winged females will return to the first host, which appears to be the Oregon Ash. (I remember seeing tons of these flying around in the fall. I posted about it in Woolly Aphids - October 2021.) From here they will produce another generation of both males and females that will mate. The female will then lay her eggs in the bark to over winter.

“If the day and the night are such that you greet them with joy, and life emits a fragrance like flowers and sweet-scented herbs, is more elastic, more starry, more immortal — that is your success. All nature is your congratulation, and you have cause momentarily to bless yourself. The greatest gains and values are farthest from being appreciated. We easily come to doubt if they exist. We soon forget them. They are the highest reality. Perhaps the facts most astounding and most real are never communicated by man to man. The true harvest of my daily life is somewhat as intangible and indescribable as the tints of morning or evening. It is a little star-dust caught, a segment of the rainbow which I have clutched.”
Walden, Henry David Thoreau

Baby Chipmunk

This baby chipmunk was resting on the ground outside of its burrow. Thankfully it sits very still and has beautifully camouflaged fur. It appeared to have just ventured out for the first time and it was exhausted taking in all of the sights, sounds, and smells of its new world. It was just below its burrow and right above it a Bewick’s wren was at the entrance making a clicking noise in protest. There was another baby chipmunk just inside. If it approached the entrance, the wren would try to poke it with its bill, and the chipmunk would retreat back inside. I’m not sure why this wren was so bothered or concerned by these two baby chipmunks. The wren would only briefly leave the entrance to sing nearby. It would soon return and intently look inside the entrance and make this clicking noise. Maybe the wren had a nest nearby, found these chipmunks, and felt that they could be potential predators soon. The one chipmunk soon woke up from its short nap and started exploring nearby. It seemed so small and fragile! Good luck little chipmunks and welcome to the arboretum.

Caterpillars Descending From Oaks

If you walked along any path under the Oregon White Oaks out at the arboretum over the past couple of weeks, you likely found yourself eye to eye with a caterpillar descending down a thread of silk. I also find them lowering them selves down off the brim of my hat quite frequently. Your friends will probably be pointing them out on you somewhere. I let them land on me in hopes that a chickadee or bushtit will come over to forage on me. You can see birds like red-breasted sapsuckers swooping through the air between trees plucking them out of the air. Or you can see robins busily scurrying around gleaning them off the ground. Honestly, it seems like most of the birds out at the arboretum can be seen eating them. They are an important food source during this time of year when birds are expending huge amounts of energy parenting, feeding themselves and their offspring. I’m sure they help attract lots of birds to nest here.

I am still researching which caterpillar this is. Of course, I see lots of these caterpillars dropping down to continue their lifecycle somewhere on the ground, but I also see the ends of oak leaves being folded or rolled over with caterpillars in them. I’ll just keep watching, doing a little research, and I’ll let you know when I figure something out.

Sitting By The River

I was sitting by the river this evening listening to the breeze rustling through the cottonwoods. Fluffy, white parachutes carrying the cottonwood seeds swirled around through the sky like falling snow. It was like the swaying trees were brushing across the bottom of the clouds pulling fibers off their undersides. Some of them were landing on the river and they looked like small clouds floating by on the water. They were so light that they didn’t appear to break the surface tension of the water. Actually, some of them would tumble and skip across the surface of the water and then fly back up into the air. Nature is an inexhaustible source of wonder. I hope to see you out there.

Gopher Snake Beginning to Shed

We found this gopher snake under a rock on the reptiles and amphibians walk at the arboretum. Besides its beautiful body pattern, it had a strikingly milky blue eye. The eye becomes cloudy like this when the snake is starting to shed its skin, a process called ecdysis. The snake has a transparent, disc-shaped scale that covers the eye called a brille, also known as an eye-cap or spectacle. This immovable disc helps protect the eye and keeps it moist like our eyelids which snakes don’t have. During the act of shedding, snakes produce a fluid to help remove the old outer skin. The fluid can be seen clouding the transparent eye-cap which is essentially a modified scale that is part of the epidermal layer of skin being shed. During this time the snake’s vision is obscured, so they are usually hiding under rocks or logs for safety.

Shedding allows the snake to replace old, worn skin, grow, and help remove parasites. The species of snake, its age, gender, size, reproductive state, diet, and the season determine how often a snake will shed its skin. In general, younger snakes shed their skin often because they are growing more. Older snakes tend to shed their skin two to four times a year.

Ring-necked Snake

There was a reptile and amphibian walk out at the arboretum last weekend. The weather the previous week leading up to the walk had been warm and sunny. So naturally it seemed a tad disappointing that the day of the walk it was a little cool and a small amount of rain had fallen that morning. As it turns out, that is a pretty good scenario for observing reptiles. The warm weather has got them active, so they are out and about. The cooler morning slows them down a little, so that when you find one under a rock or other debris, it doesn’t go shooting off before you can see it or perhaps catch it.

There were a couple of kids on the walk that were enthusiastic about flipping over rocks and catching snakes. It wasn’t long when one of them caught this beautiful ring-necked snake. They are a small snake, that usually grows to be around 1 - 1.5 feet long. The upper side of its body is a slate to greenish gray in color with a striking orange ring around its neck. The underside is bright orange speckled with black spots. The orange becomes reddish in color under the tail. When it is disturbed or feels threatened, It will expose its bright orange underside and coil its tail.

This is a secretive snake that likes to stay in moist environments under rocks, logs, other debris on the surface of the ground. I have only seen it out in the late evening in the summertime. Its diet consists of earthworms, small salamanders, lizards, frogs, juvenile snakes, and insects.

I love this little snake. Thanks to Tom who led the walk and everyone who came, the ring-necked snake was the highlight for me.