The Sacramento Delta

Great Horned Owl - Bubo Virginianus

Oh WOW an OWL!!!  This stunning Great Horned Owl was just one of the amazing birds we saw down in the Sacramento Delta last week!  These owls are mainly nocturnal and not commonly seen during the day!  We REALLY lucked out!!!  They are the top avian, nocturnal predator in North America!  They are "perch and pounce" hunters.  Ninety percent of their diet consists of mammals, such as mice, voles, ground squirrels, rats, gophers, hares, raccoons, rabbits, porcupines, skunks, carrion, and sometimes house cats!  They can carry up to three times their weight, or approximately 9 lbs!  Ten percent of their diet consists of birds including owls, raptors, waterfowl (even herons!), starlings, pigeons and nestlings.  They will also occasionally eat reptiles, amphibians, and insects.  They are found year-round across Alaska, Canada, the U.S., Mexico, and Costa Rica.

  

Great Horned Owl - Bubo Virginianus

Great Horned Owls are usually solitary except during breeding season, which is in winter.  Egg laying occurs as early as January!  They do not build their own nests, but rather occupy large, abandoned, raptor nests.  Their "horns" are technically called "plumicorns" and are neither horns nor ears, just elongated feather tufts.  Scientists haven't figured out the purpose of these tufts, but suggest that they may aid in camouflage, or in the identification of an owl by its mate.  When I first saw this owl it had its back turned to me, and its plumicorns made me think it was a cat!!!

Red-shouldered Hawk - Buteo lineatus

Owls are raptors along with eagles, hawks, kites, falcons, harriers, ospreys, and vultures. Wikipedia states that a raptor is "a species of bird that primarily hunts and feeds on vertebrates that are large relative to the hunter. Additionally, they have keen eyesight for detecting food at a distance or during flight, strong feet equipped with talons for grasping or killing prey, and powerful, curved beaks for tearing flesh."

In winter when trees are bare and prey is scarce, you will often see raptors perched in the open, searching for food.  On our delta trip, we saw a lot of raptors, especially  Red-shouldered Hawks. These beautifully marked hawks feed on small mammals, amphibians, reptiles, crayfish, insects and birds.  The one above left, was pretty wet from the morning rains!  I think they're gorgeous

Red-tailed Hawk - Buteo jamaicensis

We also saw several Red-tailed Hawks perching and searching for prey. These large raptors feed on small mammals, birds, reptiles, amphibians, and carrion. The open wetlands of the Sacramento Delta provide a variety of prey for these handsome birds.

View off the Staten Island road

The Sacramento Delta currently contains 550,000 acres of cultivated rice.  Historic farming practice was to burn the rice fields after harvest.  This created an air pollution problem for the surrounding areas.  In 1991 the California state Rice Straw Burning Reduction Act was created.  The plan was to gradually decrease the practice of rice straw burning, with the intent of eliminating the practice completely by 2000.  (The further history of the implementation of this bill is too lengthy to include in my blog, and is available on a variety of websites.)  Currently, approximately 90% of the rice fields are now flooded post-harvest, rather than burned.  

In 2015, the rice growers and several government agencies united to form the Waterbird Habitat Enhancement Program (WHEP). The following text, from the calrice.org website, explains the purpose and effects of this program.

"This program emerged from a cooperative effort between the United States Department of Agriculture’s Natural Resources Conservation Service (NRCS), California Rice Commission, rice growers, Audubon California, Point Blue Conservation Science and The Nature Conservancy to find ways to both grow rice and improve the habitat for birds. Collaborative research that documented the benefits of on-farm management for birds led to the adoption of on-farm conservation management practices included in WHEP.

One of the greatest benefits from rice farming in the Central Valley is the environmental gains that accrue to wildlife. California ricelands provide valuable open space and habitat for 230 species of wildlife, many of which are species of special concern, threatened or endangered. This is especially important today, given that 95 percent of California's historical wetlands in the Central Valley are now gone. As many as seven million wintering waterfowl rely on the Central Valley, and rice fields provide nearly 60 percent of all of their food resources."

American White Pelican - Pelecanus erythrorhynchos

We saw so many birds during the two days we were in the delta!  One unexpected species were these American White Pelicans!  They were standing on a man-made levee, and later on they all sat down close to each other!  Such a beautiful sight!  These large birds are mainly fish eaters.  They don't dive for fish, but work together in groups and herd fish towards shallow water where they are easier to catch.  They will also eat crayfish and amphibians.  They are winter residents of the Central Valley, as well as the coast of California, Baja, Mexico, and Central/South America.

American White Pelican - Pelecanus erythrorhynchos

American White Pelicans are almost always in groups of 10 or more.  They are colonial breeders, with up to 5,000 pairs in one site!  They leave their winter grounds in late February for the breeding grounds in the north central part of North America. I was astounded at the beauty of this group of them!  Such closeness!

Sandhill Cranes - Antigone canadensis

We saw Sandhill Cranes everywhere this year!  We spotted them initially in the fields of corn stubble along the road.  They eat any roots, leftover corn, small mammals, snails, reptiles and amphibians, and insects that they can find! 

Sandhill Cranes - Northern Shovelers - Tundra Swans
 Antigone canadensis - Ana clypeata - Cygnus columbianus

At dusk they flew in and landed in the shallow wetlands along the road.  There were so many of them!  The cumulative honks of the cranes, along with the quacking of the ducks, and the hoots of the swans created quite a symphony!

Sandhill Cranes - Antigone canadensis

We woke up to rain on our second day (yahoo!) and drove out on the delta to see what we could see!  The cranes were still in the same area and we got to watch a few of them "dance"!  We weren't sure if we were seeing a mating dance, or if they were just drying out their wing feathers!  Apparently their mating dance is quite elaborate.

Sandhill Cranes & Gulls (?) - Antigone canadensis & unknown genus/species

We drove around on levees and bird-watched for hours!  It was an amazing dream come true!  Cranes were in large groups throughout the wetlands.  More than I've ever seen before!  They will be leaving in late February for their breeding grounds as far north as British Columbia, or as close as northern-eastern California.  Pairs bond for life!

Tundra Swans - Cygnus columbianus

There were more Tundra Swans in the delta than I've ever seen before!  These gracefully elegant large birds fly down from the high Arctic to spend the winter in California's Central Valley, a round-trip distance of 5,000 miles!  They feed on the leaves, stems, seeds, and tubers of aquatic plants, including rice.  They will leave for their high Arctic breeding grounds in mid February.  Two months later they will reach the high Arctic and start breeding!!!  Once pairs are bonded, they mate for life!

Red-winged Blackbird - Agelaius phoeniceus

On one of the last stops on our delta trip we came across this field covered in Red-winged Blackbirds!!!  WOW!  They were incredible to see and hear!!!  

What a beautiful way to end an absolutely amazing day!

How much snow has fallen lately?

What's happening on the river?

How's Project Feederwatch Going?

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

If all of a sudden you haven't been getting email notices of my blog being published, just sign up again on my blog. I don't know why you got "unsubscribed". It's some kind of problem with Blogspot.com and/or FeedBurner.com. I apologize for this glitch!

Your questions and comments are greatly appreciated!

Please email me at northyubanaturalist@gmail.com