Eclipse Plumage

Common Mergansers female & juvenile  - Mergus merganser

Inset: 2 females & 2 males in breeding plumage

After breeding, most ducks molt into "eclipse plumage" in which males acquire a female-like plumage. That's why in the summer, it seems as if all the male ducks have left! 

This plumage change also coincides with the molt of all flight feathers in the male ducks.  The male ducks are quite vulnerable without their flight feathers, so the female-like plumage provides better camouflage than their breeding plumage.  It takes about a month for the flight feathers to grow back!  The males will molt again this fall, back into their breeding plumage.  The females molt their flight feathers later than the males, usually after their young have fledged.  The females molting process does not noticeably change their appearance.  All juveniles look like females. 

Common Mergansers (males or females) - Mergus merganser

Earlier this year I photographed a female Merganser with 9 downy ducklings.  I kept seeing her and her brood throughout the summer, but unfortunately the number of ducklings kept diminishing.  Lots of critters eat ducklings, including herons, river otters, and even foxes.   A few weeks ago I saw her with 2 almost full-sized juveniles.  Then this week I saw what I thought was two female Mergansers and 1 juvenile!  It was probably her and a male, in eclipse plumage, with their 1 remaining juvenile!  

Osprey - Pandion haliaetus

Osprey!

I saw the Osprey several more times this week!  I also heard it several mornings without seeing it!  There appears to only be one Osprey on our stretch of the river, probably because they aren't a lot of fish.  Lots of critters eat fish besides Ospreys.  River Otters, Kingfishers, Herons, Mergansers, Aquatic Garter Snakes, and even Dragonfly larva eat fish!  The competition is tough!  Right now the river is really low.  Does that make it easier or more difficult for wildlife to catch fish?  

 Osprey - Pandion haliaetus

I was down on my usual section of the North Yuba River one morning this week, when this Osprey landed in a tree on the opposite shore just like he did last week!!!  This week he stuck around, and I was able to get lots of photos!  So beautiful!

 Columbian Black-tailed Deer - Odocoileus hemionus columbianus

Mammal Update

I looked it up and fawns lose their spots 90-120 days after their birth.  These fawns were probably born sometime in June or July.  So, in another month or so these fawns will start changing into their winter coats.

        Black Bear - Ursus americanus     Blackfruit Dogwood - Cornus sessilis - Bear Poop

The Black Bears are definitely around.  I see their poop everywhere, mostly composed of apples!  Every year at this time, I see bear poop (right) with large seeds in it.  I have never been able to figure out what kind of seeds they were, until this week.  In my wanderings I happened to come across a Blackfruit Dogwood that was "in berry".  I squished one of the berries and the seed inside was the same as the ones in the poop!  Aha!  Another mystery solved!

Yellow-billed Magpie - Pica nuttalli

Yellow-billed Magpie Update

The Yellow-billed Magpie is still living in our neighborhood all by itself!  I continue to see it in the mornings near our bird feeders.  We have even seen it on the ground with the Steller's Jays eating birdseed!   Apparently the jays have accepted it into their neighborhood!  Originally they made a lot of noise whenever the magpie showed up.  Now they don't seem to be bothered by it at all!  I'm glad it's sticking around!  It is such an unusual, strikingly colored, large, fun bird to watch! 

Yellow-billed Magpie - Pica nuttalli

 European Mantis - Mantis religiosa

Down in the Garden

I found several different kinds of insects in my garden this week.  The Praying Mantis above was a big surprise!  I submitted an ID request, with photos, on the bugguide.net website, and they identified it as an invasive European Mantis.  There is a Praying Mantis that is native to California that looks quite similar, except that it doesn't have markings that look like an "eye" on its inner arm.  In all mantises the prominent front legs are bent and held together at an angle that suggest the position of prayer, hence their name.  I think a more appropriate name would be "aliens".  Their head and eyes look especially like a typical alien, with their tiny pinpoint pupils!  

They use camouflage to ambush their prey.  The one above was in a bunch of dry grasses, and was pretty difficult to distinguish!  Their arms are their main weapons, and can move with lightning speed.  They use the spikes on their arms to skewer and hold prey.  They eat only live prey, including crickets, grasshoppers, small lizards, and other mantises!  Females will occasionally eat the head of the male they are mating with!  Apparently they need the extra protein to create their egg mass!  How weird! 

  Sand Wasp - Steniolia scolopacea    Goldenrod Crab Spider (female) - Misumena vatia

The Sand Wasp above left feeds on nectar, but will also prey on insects, mainly flies, to feed its larva.  It digs a short, simple, underground burrow with a single enlarged chamber at the end.  Unlike most other wasps, their stings generally kill (and not just paralyze) the prey.  Instead of stocking the cell first, sand wasps commonly lay the egg first and then supply fresh food to their larvae as they grow. Once the larvae have gotten large enough, they pupate and emerge the following year as adults.

The Goldenrod Crab Spider uses camouflage and ambush to catch its prey, instead of weaving a web.  It can slowly change color from white to yellow, orange, or green, to match its environment.  Once it catches its prey, it paralyzes it, and then injects it with digestive fluids, like most spiders.  The one above right has been hanging around in my marigolds for a week or more, and is getting fat off of the bees and butterflies it has been catching!

Katydid (adult) - Scudderia sp. - Katydid (nymph)

I've been seeing several Katydids in our garden lately.  They look like grasshoppers except that their antennae are as long as their bright green bodies. They are so camouflaged!  They look just like leaves, and that's what they eat!  They make their distinctive sound by rubbing the scraper on one forewing against the toothed edge of the other forewing as part of their mating ritual.  Katydids hear each other with ears on their front legs!  Right now is the time that Katydids are mating.

After they mate, the female will lay her eggs in a plant stem or in the ground.  The eggs will over-winter and hatch into nymphs in the spring.  Nymphs look like tiny, colorfully marked grasshoppers, but they have no wings.  They will go through several molts over a period of 60-90 days, until they have matured to adults.  I never knew Katydids and Grasshoppers had nymphs!  I thought the nymph I found in our garden was some kind of fancy adult grasshopper!

What kind of ducks are these?  What are they doing?

What lovely Fall-colored plant is this?

What other birds have begun their migration south?

No one has seen any crayfish in the river this year.  How come?

I haven't yet found out why squirrels don't get coated with sap, but I will!

Where are the foxes?

Check back next week for the answers to these questions and more!

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Please email me at northyubanaturalist@gmail.com