The Yellow-rumped Warblers Return

Yesterday, as I was walking across the U.C. Davis campus I heard, and then saw, my first Yellow-rumped Warbler of the fall!  It was a Myrtle’s subspecies foraging in the top of a small eucalyptus tree next to Wellman Hall.  Throughout the winter, the whole town of Davis will be covered with thousands of Yellow-rumped Warblers.  They are a spectacular, ubiquitous, site!  It is a sure sign that fall has arrived.  It will be interesting to see if West Sacramento also get showered with flocks of these birds.

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Wetland Land Management

This past weekend, as I was driving across the causeway that runs over the wetlands between Davis and Sacramento I saw that the ponds at the north end of the Yolo Bypass National Wildlife Refuge were flooded!  This is in preparation for the coming massive migration of waterfowl through the central valley of California that occurs each winter.

Managing land for waterfowl and other wetland bird species requires a lot of planning.  One of the most common strategies is something called Moist Soil Management.  In this technique, water levels are changed throughout the year to maximize the amount of plant grow that will benefit migrating birds.  Generally, this means that the water is slowly drained off in early spring.  The land is usually disked or plowed to aerate the soil to provide the best growing conditions.  The land is then left alone for the spring and summer to allow plants to seed and grow.  By altering exactly when the draw-down of water occurs, undesirable plant species can be discouraged in favor of plant species that produce food and cover for waterfowl.  These species include rice, millet, ragweed, and smartweed. Like many grasses and crop species, these plants can grow in very dense expanses.  To break up such areas, patches are frequently ploughed into the stands of plants to create a more heterogeneous habitat with dense areas of cover, edges or patches, and open spaces all mixed together.  Such habitats provide a great deal of high quality habitat for wetland birds.  Then, usually sometime between the first of September and the first of October, water is allowed to start to flow back in to flood the low-lying areas.  The flooding process is slow, and the whole area may not be flooded until as much as six weeks after the process began.  Most dabbling ducks feed by picking seeds and other food items off the bottom of a pond, so good ponds do not have to be deep, 18 inches or less, to attract birds.  Once the water has been brought back in, the area will remain flooded until the birds leave to head back north to their breeding grounds.  But even during the fall and winter, water levels are not static.  Changing how deep different areas are the impact of feeding waterfowl can be spread across all available land.

So, as you can see, managing land for migratory birds is a pretty involved process.  It is certainly a full time job, and research is continuously going on to figure out the best ways of creating the best possible habitats for the millions of birds that migrate to or through California each fall.  Seeing the water returning to the area is one of the more dramatic steps in the annual cycle of a managed freshwater wetland, but it is by no means the only step needed in the creation of high quality habitat.

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First Avian Visitor

A bit after moving into our new place I cleared out the dead plants from the back yard and, on the 5th of September, I set up our bird feeders.  I was very eager to see what birds found the feeders and of what species they might be.  I waited and waited, watching the feeders every morning, but no birds found them.  Brewer’s Blackbirds, Red-winged Blackbirds, Western Scrub Jay, American Crows, and House Finches (all of which visit seed bird feeders at least occasionally) fly over our yard daily, yet none explored our yard.  I was quite surprised when a week passed without a single visitor.  I had fully expected the birds to search over their habitat regularly and thoroughly enough to find a new food source much faster than this.  To make our yard more attractive to passing birds I placed a few handfuls of seeds on top of garden wall that is near the spot where the feeders are hanging.  A couple more days passed without incident.  Then, two days ago, I say a Western Scrub Jay on our roof looking at the seeds on the wall.  It considered them briefly before flying off without coming down.  Yesterday, I saw what I am guessing to be the same bird on our roof again.  It flew back and forth from of the roof of the house to the roof of the garage a few times looking at the seeds from every angle, but again it flew away without coming down.  This morning, I again saw a Western Scrub Jay on the roof of the garage.  It perched there for a few minutes, and then made the decision to drop down onto the top of the wall where the black oil sunflower seeds lay scattered.  One by one, it quickly picked out about a half dozen in its bill and then departed to eat them elsewhere!  Our first avian visitor!  I wonder what will happen next!

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Urban Birding

My  wife and I moved into our new place in West Sacramento a couple of weeks ago, and I have started exploring the nearby area to discover its birding potential.  Even though there is a fair bit of industrial development, and a lot of residential development, the birding is actually quite good.  This area has an extensive network of canals that help to manage water flow around the Port of Sacramento and in the Sacramento River.  These canals are all lined with Cattails and Tules which provide habitat for a number of species.  Associated with these canals are a number of bodies of open water.  These range in size from only about a quarter of and acre to large lakes like Lake Washington.  Many of these bodies of water are lined with willows, oaks, and cottonwood trees which create edges of riparian habitat.  Together the open water and riparian corridors attract even more species.  The list of species I have seen so far is at the bottom of this post.  I have not seen anything particularly unusual, but fall migration is still building up, so there are lots more birds on their way through.

Walking these canals and water edges has really impressed upon me how important even small areas of habitat can be.  These waterways provide stopover sites for lots of birds and they are pretty much in peoples back yards.  They take up pretty small amounts of space, yet yield a  very large benefit to wildlife.  I will certainly be spending a fair bit of time exploring these urban waterways and seeing what turns up.

Birds: Red-winged Blackbird, Marsh Wren, Common Yellowthroat, Wilson’s Warbler, Yellow Warbler, Long-billed Dowitcher, Black-necked Stilt, Canada Goose, Lesser Scaup, Mallard, Killdeer, Great Horned Owl, Red-tailed Hawk, Red-shouldered Hawk, American Kestrel, Western Scrub Jay, Anna’s Hummingbird, Bewick’s Wren, Lesser Goldfinch, House Finch, White-crowned Sparrow, Mourning Dove, American Coot, California Towhee, Spotted Towhee, Song Sparrow, American Crow, European Starling, Rock Pigeon, Black Phoebe, Chestnut-backed Chickadee, Oak Titmouse, Green Heron, Great Egret, Snowy Egret, Great Blue Heron.

Mammals: Sacramento Cottontail, Raccoon, River Otter, Eastern Fox Squirrel.

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Multispecies Mobbing

The day before yesterday, I was walking along the edge of Lake Washington, which is very close to our new home in West Sacramento, CA.  It was a great morning of birding with several of the early fall migrating Wilson’s Warblers, an adult Red-shouldered Hawk, a Lesser Scaup feeding on the lake and about 300 Long-billed Dowitchers resting on one muddy portion of shore.

As I walked around a bend in the cattails and tules, I saw a female American Kestrel swooping and diving back and forth at the top of an oak tree.  She was also screaming like crazy.  Nearby, perched on a bare branch of a sapling was a male American Kestrel.  He was calling like crazy as well!  As I stood there, I also heard several Western Scrub Jays also making a loud ruckus in the tree.  I was certainly curious to see what was causing all this fuss.  I walked closer, and as I did so, a Red-tailed Hawk flew past.  As it neared the tree it dipped low and dropped its legs down to strafe the tree top!  As I got even closer, two Anna’s Hummingbirds joined in to start darting in and out of the tree top at whatever was there.  What could cause this much commotion and attract this much ferocious attention from so many very different species?  I got my answer a few moments later when a Great Horned Owl launched itself out of the tree top and flew towards a different group of tree some distance away.  After the owl left, most of the birds seemed to calm down, expect for the American Kestrels which both followed the owl to its new perch site and continued to berate it there.

Not only was the commotion quite impressive, it was interesting how all these different species, with their very diverse natural histories, would all feel threatened by one owl!

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