Sierra Valley Again!

View of Sierra Valley from the Steel Bridge - 4/30/25

For my birthday last month, we went back to Sierra Valley twice! What a gift it was to be there again! We lucked out and had gorgeous clouds one day, as well as an abundance of birds, and even a few flowers! I was able to finally get several photos, and even videos, of two of my favorite birds, Marsh Wrens and Soras! We enjoyed it so much we're going back again this week to see if more wildflowers have blossomed and what new birds have arrived! Can't wait!

The Sierra Valley floor is a grassland/sagebrush ecosystem, and the site of extensive freshwater wetlands. These wetlands provide migratory and breeding habitat for more than 17 rare or threatened species of birds. It is also a critical migratory stop for 230 species.

Black-necked Stilts - Himantopus mexicanus

We saw several Black-necked Stilts on Harriet Lane. It's one of the best areas in Sierra Valley to see shorebirds. The following information about Stilts is from the Cornell website at https://birdsoftheworld.org

"Stilts hold the avian record for the longest legs relative to body size. From on high, the Black-necked Stilt uses its excellent vision to scan mudflats for small invertebrate prey. Stilts also feel for prey by sweeping their sensitive bills through the water. In the presence of predators, stilts quickly flock together as one intimidating black-and-white mass. This defense strategy is so effective that birds of other species often try to join the flock."

American Avocet - Recurvirostra americana

American Avocets spend their winters in California's Central Valley, Baja California, or Mexico. In Spring most migrate to north-central United States and Canada to breed, but some will nest in Sierra Valley. When breeding, the feathers on the head and neck, of both the male and female, turn a rich rusty color, and the legs turn blue! Beautiful! I love their sky-blue legs, and their long, curved bills. They are SO elegant! They are ground-nesters and build a nest scrape in the soft substrate of wetlands, dikes/levees, or islands. Nests are often near the water's edge, and usually on unvegetated ground or in areas with short, sparse vegetation. Avocets nest on islands when available, which provides partial protection from predators.

Killdeer - Charadrius vociferus

Killdeers forage for earthworms, insect larvae, snails, crayfish, minnows, tree frogs, grasshoppers, beetles and small seeds in damp or wet soil. They nest on the ground in shallow "scrapes" or depressions out in the open, which they often "decorate" with white objects (bones, pebbles, feathers...) which may help to camouflage their eggs! To avoid predation of eggs and nestlings they have evolved several unique techniques. "False brooding" is when an adult acts like they are sitting on a nest, but are actually just sitting on the ground. "Broken wing display" is when an uninjured bird acts injured and runs away from the nest area dragging its wing and crying piteously. Both of these techniques are intended to lure predators away from the nest site! 

Sora - Porzana carolina

We saw this Sora two days in a row in the exact same area! Usually secretive, this one stayed out in the open while we watched it for 10 minutes!  We also saw another one briefly emerge from the tules briefly and then quickly disappear in them, which is more typical of their behavior!

Rather than probe in the mud for invertebrates, Soras prefer to peck insects and seeds off the surface of the water. In the winter, they primarily eat seeds. They are secretive and more commonly heard than seen. They live in shallow fresh water wetlands with emergent vegetation, such as cattails. The also prefer to run rather than fly! They migrate down to Mexico, or even as far as the north end of South America, for the winter. 

Video of Sora feeding on the marsh mud

Soras build their open bowl-like nests using dried tules and other marsh vegetation. The following information about their nests is from the Cornell website at https://birdsoftheworld.org.

"Nest-building begins with crude pile of vegetation onto which first egg is laid. Male gathers pieces of surrounding vegetation and gives them to mate, which works them into nest as egg-laying proceeds.

Loosely woven basket of available emergent vegetation; suspended above water from stems of emergent vegetation, or in clumps of vegetation with base of nest at or slightly below surface of water. Constructed of surrounding plants, usually coarser emergents on exterior, with lining of finer sedges or grasses. Usually built with ramp or runway leading up to lip of nest. Often built with overhead canopy made by bending over surrounding vegetation and tucking it into rim on opposite side."

Marsh Wren (adult) - Cistothorus palustris

I have seen and heard Marsh Wrens many times in the past, but was never able to get a photo of one, as they flit about so erratically. One of the days in Sierra Valley, they were out in the open singing and calling, and I finally got several photos! Yay!  We even saw one with a blade of grass in its beak, that it used in its nest building!  Wow! Their nests are initially made by lashing upright tules together with sedges and grasses, and then constructing a basket shaped nest "hanging" between them, with a short tunnel-like entrance on top.

Video of Marsh Wren singing/calling

Their calls and songs are quite loud for such little birds (5" long including the tail)! The following information about their vocalizations and mating behavior is from the Cornell website at https://birdsoftheworld.org. 

"Although the Marsh Wren's harsh, broad-band songs contain few pure musical tones that resonate with our ears, careful analysis of this wren's vocal behavior has now shown a rich array of behaviors that rank it among the most impressive of all North American songsters. During their early sensitive phase, for example, males learn 50–200 song types. As adults, neighboring males engage in complex countersinging duels and seemingly sing almost continuously, day and night, in their bid for success.

The Marsh Wren's abundant singing and complex vocal behaviors are undoubtedly an evolutionary consequence of its polygynous mating system. About 50% of the males in some populations mate simultaneously with 2 or more females, and study of these populations was pivotal in understanding the evolution of polygyny—i.e., why a female might choose to pair with an already-mated male rather than with a bachelor. A great disparity occurs in breeding success among males, and sexual selection appears to have escalated the complexity of vocal behaviors used to acquire resources, both territories and females. In their zeal, the males also build multiple nests, typically at least a half dozen dummy nests for every breeding nest used by a female.

Perhaps another consequence of intense competition for resources in these marsh environments is this species' habit of destroying eggs, not only of other species but also of other Marsh Wrens."

Marsh Wren (adult) - Cistothorus palustris

"If female approaches male's territory, he flies toward her and, with tail cocked over his head, delivers rapid volley of songs. If she enters his territory, he flies toward his courting center (where his nests are under construction; see Breeding: nest, below), and she sometimes follows. Escorted by male, female then visits and often enters several nests in succession. During this courtship, male does little singing but much displaying, often leading females from one nest to another, “nervously” bowing with tail held high, commonly touching back of his head. By destroying nearby nests, wrens undoubtedly reduce competition for food, both intra- and interspecifically, in immediate area around their own nests."

Horned Lark - Eremophila alpestris

Horned Larks probably overwinter in California at lower elevations. They will breed and raise their young in Sierra Valley. The female alone makes the nest. She starts by digging out a cavity in the ground, which may take 2-4 days! She then weaves a nest of fine plant material gathered nearby, such as grass, small roots, and shredded plant stocks. The inner part of the nest is lined with finer material such as down, fur, feathers, fine rootlets; even lint and string are sometimes used!

Sand Lily - Leucocrinum montanum

There were only a handful of wildflower species in bloom when we were last in Sierra Valley. Most of them were ground hugging plants, probably because of the frequent winds that sweep across the valley. One of the showiest were the Sandy Lilies that grew in the middle of a bare track! These lovely low-to-the-ground clusters of small white lilies were a treat to see!

Hooker's Balsam Root - Balsamhoriza hookeri

This large low-to-the-ground composite smells exactly like chocolate! You have to get down on your hands and knees to smell them, but the fragrance is amazing!

California Hesperochiron - Hesperochiron nanus

There were LOTS of these ground-hugging California Hesperochirons in bloom!

Tansyleaf Evening Primrose - Taraxia tanacetifolia

These bright yellow primroses were commonly seen along the sides of the roads! We're going back to Sierra Valley again this week and I'll report on what other wildflowers we encounter in my next blog!

American Dipper babies and flying adult - Cinclus mexicanus

I apologize but I have run out of time. I promise to report on my local neighborhood happenings next time!

After 8 years of posting my blog, I've decided that I'm only going to post my blog every TWO weeks from now on. Check back in two weeks, on May, 24th for my next natural history blog.

Also, check out my latest post on my newly re-opened Damp Earth Blog at dampearthart.blogspot.com