Friday, September 22, 2017

Fall Goings-on in Central California

Every year after the long, hot summer, I eagerly await the arrival of fall.  The transition between seasons may be gradual or abrupt, but each year there is one moment when you sense it: change is coming.  There is a hint of autumn in the smell of the air, a certain color to the morning light, a crispness in the breeze that has long been absent.  As dusty browns mellow into pleasant gold and the cool wind blows, creatures begin to stir.

The wild world is waking up after a drowsy summer.

Yosemite Valley (mid-November of last year)

In central California, the changing of the seasons is not as vividly dramatic as New England postcards, but it can be just as markedly beautiful if you know where to look.  Fall is an excellent season to see wildlife, as many species are on the move.  Shorebirds and songbirds migrate, Sandhill Cranes and other northern breeding birds return to the valley from the Arctic; monarch butterflies migrate to their overwintering grounds on the coast; salmon make their way from the Pacific all the way up valley rivers to spawn.  Fall offers the last good opportunity to see Humpback and Blue whales off the coast before they begin their southern migration, and is the time to see (and hear) Tule Elk during their rut season.  And of course, the star of the autumn woods will always be fall foliage!

Below is a list of some of my favorite fall goings-on in central California.

Cedar Waxwings arrive in the Central Valley every autumn


* Shorebird and seabird migration along the coast.  September is peak season, and Monterey Bay is a great location for birding (I love Point Pinos and Moss Landing).

* Songbird migration in the Central Valley.  During the fall, the diversity of songbirds in the valley is at its highest.  Try riparian areas and wetlands (wildlife refuges) in the valley as well as near the coast.

* Sandhill Cranes return to the Central Valley!  These impressive birds return in September, but their numbers will peak near the end of November.  Look for them in valley wetlands (especially Merced National Wildlife Refuge).

* Monarch migration.  These well-known butterflies are migrating across the Central Valley now, so you may spot one at any time.  But the best chance to see monarchs en masse is at their overwintering sites along the coast, most notably in Pacific Grove and Santa Cruz, between November and February.

* Tule elk rut.  If you're not even sure what that means, it's time for a trip!  Visit the San Luis National Wildlife Refuge or Point Reyes National Seashore to experience the bugling of bull elk.

Salmon run.  The fall run of Chinook Salmon takes place each year as these special creatures make their journey from the sea to freshwater spawning grounds in rivers across the Central Valley.  November seems to be the peak of the salmon run, and the bridge over the Stanislaus River in Knight's Ferry is a great place to watch.

Pinecrest Lake (October)

Fall colors:

The star of the fall foliage show across the western United States is the Aspen.  But other deciduous trees put on quite the display as well.  Look for Big Leaf Maple, Black Oak, Mountain Dogwood, Black Cottonwood, willows and even golden ferns!  Also of note, Poison Oak, a beautiful keystone species in our woodlands, develops lovely red fall color (just don't touch it!).

* Eastern Sierra: Mono and Inyo counties are well-known for their splendid show of Aspens, which generally reach peak color in mid-to-late October.

* Western Sierra: Lassen, Plumas and Tahoe National Forests put on a display of mellow fall color in October and even into November.  More southerly national forests are worth investigating as well, like El Dorado, Stanislaus and Sierra National Forests.  In my experience, fall color in Yosemite Valley seems to peak during the first two or three weeks of November.

* North Coast: Not to be left out, Big Leaf Maples and other trees color the north coast forests of California as well. 

In California's forests, expect pockets of color rather than sweeping New England hillsides of fiery red maples.  Often, hidden gems of color are found along rivers and streams.  Weather plays a big role in intensity and timing of fall colors, so no two years are quite the same.  But the fall color show lasts quite a while in California, slowly progressing from high elevations to low over the season.

Black Oaks turn yellow and reddish-bronze in the fall

Even though summer is over, the outdoors are as enticing as ever!  Hiking, camping, wildlife viewing - it only gets better as the season progresses.  Don't let changing seasons keep you indoors; mild fall temperatures are ideal for exploring the wonderful world of nature!  Head out to explore today!

Thursday, September 21, 2017

California Sister Butterfly

I have lamented before my lack of entomological knowledge.  Yet, armed with field guides, binoculars, a hand lens and the trusty internet, I slog on in my attempt to learn more about the fascinating world of insects.  Perhaps most interesting to me (and every other nature-loving child or adult, I imagine) are butterflies, if for no other reason than that they are often the most conspicuous!  (I also love finding other lepidopterans - namely moths - as well as dragonflies and damselflies.)

An abundance of butterflies seem to be out and about in our local wild lands this time of year.  I'm working on honing my butterfly identification skills (though personally, I find them even more difficult and flighty than warblers!) 

An easy butterfly to start with is the California Sister (Adelpha bredowii californica).  They are frequently seen in California's foothills and at mid-elevations in the mountains, most frequently in oak woodlands and mixed coniferous forests.  Oaks (Quercus spp.) are the larval host plant for California Sisters, meaning the larvae feed exclusively on native oaks.  (You begin to see the great value in preserving and planting California native plant species!)  Adults feed on rotting fruit and sometimes flowers, and can be found sipping at mud puddles, an act known as "puddling."  Essential minerals and amino acids are derived from the mud.

Many butterflies have surprisingly short lifespans; some species don't even feed as adults, but reproduce immediately and then die.  The lifespan of an adult California Sister is about one month long.  California Sisters are active from spring to fall; during one season there are two generations, or broods, of butterflies.  This means that this particular species goes through the whole reproductive cycle (egg, larva, pupa, adult) twice during the season (spring to fall).  (Monarch butterflies go through this process four times during one season.)  The first generation emerges in the spring, reproduces and dies; the second generation then reproduces in the summer or fall and dies, leaving its offspring to overwinter as larvae and emerge in the spring as the first generation of the following season. 
If you too are interested in learning more about the butterflies of California and the rest of North America, I can recommend two resources I have found particularly helpful.  (I'm sure there are many more than just two good ones out there, however!)
For a more in-depth look at the California Sister, check out Kate Marianchild's beautiful book, "Secrets of the Oak Woodlands" (a favorite of mine!)

Tuesday, September 19, 2017

Belding's Ground Squirrels

Summer in the high Sierra is rapidly coming to an end.  Nighttime temperatures are already dipping below freezing, and daytime highs remain in the sixties (Fahrenheit) or lower.  The seasons are changing, grading gently from summer into autumn, and Sierra Nevadan wildlife are busily preparing for the long winter ahead.  On a recent visit to Yosemite's Tuolumne Meadows, the Belding's ground squirrels (Urocitellus beldingi, syn. of Spermophilus beldingi) were particularly busy.

Belding's ground squirrels live in high meadows between 6,500 and nearly 12,000 feet in elevation.  Other open areas favored by Belding's ground squirrels include sagebrush flats and areas of mixed shrubs and grasses.  In addition to the Sierra Nevada, Belding's ground squirrels can be found in eastern Oregon, southwestern Idaho, and parts of Nevada.  They typically remain fairly close to a source of water.

Belding's ground squirrels eat a variety of grasses, herbaceous meadow plants, seeds and occasionally insects or carrion.  The common sight of these squirrels standing or seated upright in open areas has earned them the nickname "picket pins," since their upright forms resemble the pins that were used to picket horses in meadows.  This posture serves as the squirrel's defense, giving them a better vantage point from which to watch for predators.  Their alarm call is a familiar sound to alpine hikers.  Natural predators of the Belding's ground squirrel include coyotes, badgers, weasels and raptors.

Belding's ground squirrels spend nearly three-fourths of their lives hibernating in underground burrows.  Hibernation begins in September at the end of the short, high-elevation summer, and continues through May or June.  Generally, juvenile squirrels remain active longer into the summer than adults, eating as much as they can in preparation for hibernation.  During their first winter, up to 60% of juveniles may starve.  Belding's ground squirrels do not store food for use during the winter.

Monday, September 18, 2017

Wetland Report: Merced National Wildlife Refuge

Late summer is a quiet time at our local Central Valley wildlife refuges, but anticipation hangs in the air.  The wetlands have been dry since the early part of summer, as they are drained after the departure of our migratory birds.  But in September, the dry marshes slowly return to life.  Soon, very soon, the birds will return!

Last week, we took a quick trip out to Merced NWR to see how the wetlands are looking.  The marshes closest to the parking area and main observation deck are still dry, but three separate marsh areas along the back leg of the auto loop are filling with water.  Right now, Black-necked Stilts, Killdeer, White-faced Ibis and Great Egrets abound!  I was surprised by the number of shorebirds we saw!  There are yellowlegs, dowitchers and a few Least Sandpipers as well.  The first of the Northern Shovelers have also arrived.

Sandhill Cranes will start showing up at San Joaquin Valley wetlands by the end of this month - maybe even by the end of this week!  According to a quick glance at ebird, a few cranes were spotted as far south as the Elk Grove area over the weekend.  The arrival of the cranes is an exciting time indeed!  By winter, upwards of 20,000 Sandhill Cranes will fill the wetlands and surrounding fields at Merced NWR.

Golden, late-summer tule reeds

For now, a trip to the wetlands will still reveal a surprising number of birds - especially shorebirds.  The tules are as lovely golden-brown as they are green, and sunflower and milkweed seed heads are picturesque in the late afternoon sun.  You might even spot a few hardy wildflowers still hanging on through the heat.

 Heliotrope  (Heliotropium curassavicum)

Late summer is also dragonfly season in California!  Never a dull moment for the naturalist!

Thursday, September 14, 2017

The Sign of the Beaver in the Great Central Valley

The North American Beaver (Castor canadensis) is unapologetically one of my favorite mammals.  Considered pests by some, this large rodent is a master ecosystem engineer and keystone species in its environment.

During the 19th century, the humble beaver was nearly eradicated from the western United States, including California, through habitat loss, hunting and trapping for fur, and deliberate extermination.  The beaver is sometimes considered a nuisance species, since their enthusiastic lumberjack work may cause trees to fall across roadways, and their dams, ponds and levee burrows can cause flooding.  But it turns out that the beaver provides a suite of unexpected ecosystem services, including increasing wildlife habitat and water storage potential in the arid, drought-prone west. 

Beaver lodge at San Luis National Wildlife Refuge, April 2017

Beavers are hydro-engineers and excel at altering the flow of water though the environment.  The familiar "beaver dams" these large rodents create form small reservoirs, pools of quiet water in otherwise rapidly flowing aquatic environments.  Without beaver and their log-and-stick dams, water rushes downstream, eroding stream channels and sweeping fish down the river.  In the quiet waters of beaver ponds, however, valuable fish such as juvenile salmon are able to thrive.  Some speculate that the decline of salmon in the west is due in part to the loss of beaver and the habitat they create. 

Beaver track in wet sand, San Joaquin River National Wildlife Refuge, January 2017

Beaver ponds are thriving ecosystems in themselves, creating habitat for a number of wildlife species.  The California Department of Fish and Game states,

          "Beaver dams create habitat for many other animals and plants of California. Deer and
          elk frequent beaver ponds to forage on shrubby plants that grow where beavers cut down
          trees for food or for use in constructing their dams and lodges. Weasels, raccoons, and
          herons hunt frogs and other prey along the marshy edges of beaver ponds. Sensitive
          species such as red-legged, yellow-legged and Cascade frogs all benefit from habitat
          created by beaver wetlands. Migratory water birds use beaver ponds as nesting areas and
          resting stops during migration. Ducks and geese often nest on top of beaver lodges since
          they offer warmth and protection, especially when lodges are formed in the middle of a
          pond. Willow flycatchers use the shrubby re-growth of chewed willow stumps to seek
          shelter and find food. The trees that die as a result of rising water levels attract insects,
          which in turn feed woodpeckers, whose holes later provide homes for other wildlife. In
          coastal rivers and streams, young coho salmon and steelhead may use beaver ponds to
          find food and protection from high flows and predators while waiting to grow big enough
          to go out to sea." 
          Source: California Department of Fish and Wildlife publication, Living With Beavers

Evidence of beaver activity along the Tuolumne River, Stanislaus county, March 2016

In addition to wildlife habitat, beavers and their ponds provide hydrologic benefits to arid, often drought-stricken regions.  Beaver ponds capture and hold water, preventing it from rushing quickly downstream and eventually being lost to the sea.  Water held in beaver ponds is able to slowly percolate into the ground, increasing groundwater storage and soil hydration.  This ability of the soil to recharge itself makes the land much more resilient in the face of drought.

Evidence of beaver activity along the Tuolumne River, Stanislaus county, March 2016

In California, beaver sill occur in the Great Central Valley, parts of the Sierra Nevada and the Cascades, and most of the northern third of the state.  Historically, beaver occurred along the coast of California as well.  I have seen evidence of beaver activity in the Great Central Valley as well as in the Sierra in the form of fallen trees and tooth marks, tracks, and stick lodges.  A beaver siting is always an exciting event!

Beaver track in wet sand, San Joaquin River National Wildlife Refuge, January 2017

After years of the systematic depredation of the beaver, interest in California's beaver population is growing.  In light of the potential benefits of beaver ponds to fish (specifically salmon) and other wildlife, as well as ponds' potential for surface water storage and ground water recharge, it seems that beavers and their activity benefit the entire watershed.

Beaver tooth marks on a cottonwood log along the Tuolumne River, March 2016 

Tuesday, September 12, 2017

Hummingbird Nest

Birds' nests are some of the most intricate, strong and beautiful structures found in nature.  They range in design from little more than a divot in the earth to elaborate mud condos and woven wonders, from enormous stick platforms to diminutive, delicate cups.  Nests of North and South America's hummingbirds are among the smallest nests found in the world.

While out for our daily walk a few weeks ago, I happened to look down at just the right moment and was delighted to find a hummingbird nest on the ground.  The nest was below a eucalyptus tree that is frequented by Anna's Hummingbirds (Calypte anna), and this nest almost certainly was built by a member of that species.  Presumably, the nest served its purpose and the young successfully fledged before it fell from the tree.  (That's what I choose to believe!)  I was excited by this discovery, since I have long wanted to closely examine a hummingbird nest, and they are quite difficult to find!  

At the beginning of the breeding season, which can start as early as December in California, the female Anna's Hummingbird chooses a location for her nest.  Nests are typically placed on horizontal branches of trees or shrubs, usually between 6 and 20 feet above the ground, near a source of nectar.  Eucalyptus trees are a favorite for nesting hummingbirds, and the introduction of this tree across California has contributed to the spread of the Anna's Hummingbird.  Construction of the nest is undertaken by the female alone, and takes about a week.

Nests are constructed of plant down (such as willow, cattail or thistle fluff) and small feathers, bound together by spider silk.  The outside of the nest is covered with a layer comprised of miniscule fragments of bark, lichen and moss.  This serves to camouflage the nest.  From below, a nest is hidden by the horizontal branch on which it sits; from above, it is obscured by leaves; and from the side, it is designed to look like no more than a knot on a branch. 

To construct the nest, the female hummingbird creates a platform on her chosen branch, sits on it and builds the nest cup up around her.  Nests of Anna's Hummingbirds measure about one inch high and 1.5 inches in diameter; the nest pictured here was found slightly flattened.

Anna's Hummingbirds raise two or even three broods of young during a breeding season.  Each time, the female lays a clutch of two very small, white eggs.  Each egg is about 0.5 inches long and 0.3 inches wide, roughly the size of a jelly bean.  The female incubates her eggs for 14 - 16 days, after which the young hatch.  At the time of hatching, the young hummingbirds are naked and helpless, their eyes sealed shut.  The female feeds her young a regurgitated mixture of tiny insects and nectar by inserting her bill deep into their mouths.  The young remain in the nest, growing quickly, for just 20 days before fledging.

Sunday, September 10, 2017

A Shorebird Primer: Godwits, Curlews, Willets and Whimbrels

For those of us living in the Great Central Valley, autumn is the time to head to the coast.  Of course, there is no bad time to visit California's magnificent coastline.  But as the heat and haze of summer drag on in the Valley, the sea becomes increasingly tantalizing: September and the onset of autumn bring sunny weather and an abundance of migratory seabirds and shorebirds to our coast.

A new birder visiting California's Central Coast will undoubtedly be met with a splendid array of very confusing birds.  Among these are small shorebirds like "peeps" (sandpipers), Sanderlings and various plovers.  But the larger birds can be just as confusing, until you learn a few distinguishing features. 

Four large shorebirds that are commonly seen (and commonly confused) along California's Central Coast are Godwits, Curlews, Willets and Whimbrels.

Marbled Godwit (upper left), Whimbrel (upper right), Long-billed Curlew (center front)

The distinguishing feature of the Marbled Godwit (Limosa fedoa) is its bill: slightly up-turned and two-toned, grading from reddish at the base to black at the tip.  Godwits are often found in flocks, probing for food on sandy beaches and mudflats.

Marbled Godwit

Marbled Godwit
The largest of our shorebirds, and sporting the longest bill, is the Long-billed Curlew (Numenius americanus).  An obviously long, down-curved bill is characteristic of the curlew.  These birds are often seen as solitary individuals, foraging on sandy beaches and mudflats.  In the winter, Long-billed Curlews are common visitors to the wetlands of the Great Central Valley.
Long-billed Curlew

Long-billed Curlew
Willets (Tringa semipalmata) are more often associated with the swash zone of sandy beaches (the part that is covered and uncovered by each wave), but they also feed on rocky shores and mudflats.  At first glance, Willets may look hopelessly gray and dull, but even that can be used to your advantage in making an identification.  The straight bill of the Willet is lighter at the base and darker at the tip.  The really striking field mark of the Willet is the black-and-white wing striping shown in flight.

Whimbrels (Numenius phaeopus) most closely resemble Long-billed Curlews, and they are in fact a type of curlew.  But Whimbrels show more pronounced striping on their heads and have a noticeably shorter down-curved bill.  Whimbrels favor mudflats, but are equally likely to be found on rocky shores and sandy beaches.

Learn these four birds, and a birding trip to the coast will become much less intimidating!
Note: The coastal area I visit most frequently is the Monterey Bay area, roughly from Sunset State Beach south to Point Lobos.  The photos here were all taken within that area, and my personal experience is based largely on this area.  Monterey Bay is special for a number of reasons, one of which being its high biodiversity.  Here, northern species of birds, plants, and intertidal creatures reach their southern limit, and southern species reach their northern limit.  It is an excellent place to visit as a naturalist!