Bird Migration

Sutter Buttes from the Marysville Rice Fields

About and hour and a half from our home are the Marysville Rice Fields. In the winter they are flooded, and lots of waterfowl migrate there to spend the winter. We went down this week to see if there were any birds yet, and were totally surprised by the thousands of birds that had recently arrived! Some of them have traveled thousands of miles to reach these rice fields!

It is difficult to briefly summarize where bird species breed or spend the winter. For this blog I have only summarized where they go once they're in California. This doesn't mean that they don't travel outside of California. If you are interested in learning a particular bird's migratory behavior, https://birdsoftheworld.org/ is an excellent resource to peruse.

The following information on bird migration is from the Cornell website https://www.allaboutbirds.org

"Why Do Birds Migrate?

Birds migrate to move from areas of low or decreasing resources to areas of high or increasing resources. The two primary resources being sought are food and nesting locations.

Birds that nest in the Northern Hemisphere tend to migrate northward in the spring to take advantage of burgeoning insect populations, budding plants and an abundance of nesting locations. As winter approaches and the availability of insects and other food drops, the birds move south again. Escaping the cold is a motivating factor but many species, including hummingbirds, can withstand freezing temperatures as long as an adequate supply of food is available.

Types Of Migration

The term migration describes periodic, large-scale movements of populations of animals. One way to look at migration is to consider the distances traveled.

Permanent residents do not migrate. They are able to find adequate supplies of food year-round.

Short-distance migrants make relatively small movements, as from higher to lower elevations on a mountainside.

Medium-distance migrants cover distances that span a few hundred miles.

Long-distance migrants typically move from breeding ranges in the United States and Canada to wintering grounds in Central and South America. Despite the arduous journeys involved, long-distance migration is a feature of some 350 species of North American birds."

White-faced Ibis - Plegadis chihi

We also saw White-faced Ibis feeding in the fields. In California, White-faced Ibis breed in the northern end of the state. In California, White-fronted Ibis will overwinter in the Central Valley, Los Banos or even the Salton Sea!

"What Triggers Migration?

The mechanisms initiating migratory behavior vary and are not always completely understood. Migration can be triggered by a combination of changes in day length, lower temperatures, changes in food supplies, and genetic predisposition."

White-faced Ibis - Plegadis chihi

We didn't see thousands of Ibis, but there were several hundred together in some areas! More than I've ever seen together before!

"How Do Birds Navigate?

Birds can get compass information from the sun, the stars, and by sensing the earth’s magnetic field. They also get information from the position of the setting sun and from landmarks seen during the day. There’s even evidence that sense of smell plays a role, at least for homing pigeons.

Some species, particularly waterfowl and cranes, follow preferred pathways on their annual migrations. These pathways are often related to important stopover locations that provide food supplies critical to the birds’ survival. Smaller birds tend to migrate in broad fronts across the landscape."

Greater White-fronted Geese (Northern Pintails in the background)

Anser albifrons

Greater White-fronted Geese also migrate down from the arctic to spend the winter in the Central Valley of California. They feed on marsh grasses, sedges, berries, and seeds from agricultural crops. They are primarily diurnal feeders, and roost in wetlands at night.

Greater White-fronted Geese - Anser albifrons

We saw several thousand of these geese in the rice fields!

Tundra Swans - Cygnus columbianus 

Tundra Swans. They have just arrived in the past two weeks, from their breeding grounds in the arctic! They do not dive, but submerge their heads to forage for the leaves, stems, seeds, and tubers of aquatic plants, such as rice. In California, they spend their winters in the Central Valley.

Tundra Swans - Cygnus columbianus

These large swans have 7' wingspans, are about 4.5' tall, and can weigh up to 16 lbs!I find them to be beautifully elegant

Northern Pintail (males & females) - Anas acuta

Northern Pintail males have distinctive white lines on the back sides of their heads. These lines, along with their dark heads, thin pointed tails (not visible), and white breasts make them easy to identify. In California, these lovely ducks breed in no. CA. and overwinter in the Central Valley or on the coast. 

Northern Pintail (males & females) - Anas acuta

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They primarily feed on marsh plants, aquatic invertebrates, and grains in shallow water and dry fields. We saw thousands of them in the rice fields, more than I've ever seen before! Such beauty!!

The North Yuba River Corridor

Wood Ducks (males) - Aix Sponsa

Just this week I was surprised to see four male Wood Ducks in the North Yuba River!!! They must be on their way to the Central Valley for the winter. They come up from the Valley to breed and raise their young in the foothills. I've seen them a few times in the river before, but never four males together!

Varied Thrush (male) - Ixoreus naevius

To my delight I have had several different sightings of Varied Thrushes in our area the past two weeks. They are so beautifully feathered! They pass through our neighborhood, but don't stay here. In California, most of them stay on the Coast or the Central Valley in the winter

Ruby-Crowned Kinglet - Corthylio calendula

In California, Ruby-Crowned Kinglets breed in the higher elevations, and come down to the lower elevations for the winter. I often see them in my neighborhood, in the winter! They are quite tiny, being only 4.25" in length!

White-crowned Sparrows (first year and adult) - Zonotrichia leucophrys

White-crowned Sparrows breed in western Canada and Alaska. They overwinter in the California foothills, central valley, and coast.

View south from the Steel Bridge - 10/16/24

I went out to the Steel Bridge almost a month ago, and saw several resident hawks, and a few migratory birds. It was wonderful to be out there as always! Rainy weather may make the road to the Steel Bridge impassable this winter. Fingers crossed I get out there soon before winter arrives!

Light adult Red-tailed Hawk - Buteo jamaicensis

A few weeks ago I wrote about a light juvenile Red-tailed Hawk. This is a light adult of the same species! I love the rusty-colored feathering on his breast! Red-tailed Hawks live in Sierra Valley year-round.

Light adult Red-tailed Hawk - Prarie Falcon

Buteo jamaicensis - Falco mexicanus

The telltale "moustache" on the face, made this Prarie Falcon easily identifiable! This is only the third time I've seen this species of falcon! They too live in Sierra Valley year-round.

Northern Harrier (female) - Circus hudsonius

Northern Harriers were fairly abundant, and easily identifiable with the bright white band at the topside base of their tail. Also, they are the hawks that fly low right above the grasses when they're hunting. Their wingspans measure 43"!!! They live in Sierra Valley year-round.

American Wigeon (male & female in foreground) - Mallard (female)

Mareca americana - Anas platyrhynchos

In California, American Wigeons overwinter in the Central Valley and the coast. They breed across Canada and Alaska. I saw these at the Steel Bridge, presumably on their way to the Central Valley/Coast. The female Mallard in the background will probably join them in their journey!

Stormy day near the Steel Bridge

What kind of fish are these?

How are the Fall colors this year?

Are any mushrooms popping up yet?

Please check back in two weeks, on November 22nd, for my next blog.

Your questions and comments are greatly appreciated. Please email me at northyubanaturalist@gmail.com. Thanks!