Hummingbirds – miracles of evolution

Of all birds hummingbirds are one of the most fun to watch.  They are fast, colorful, and tiny, the smallest ones roughly the same size as a large moth or butterfly.  They are probably best known for their maneuverability.

Anna’s Hummingbird (Calypte anna) coming in for a landing. Note the small tail, the curve of the body, and the large wing muscles.

These birds are compact and extremely well muscled.  Their tails are short and flexible, notice how the tail of the Anna’s Hummingbird in the above photo is curved to the side and folded to cup the air to assist in guiding the bird in to its landing spot.  Their wings are short with thick muscles covering the limbs and have a range of motion far greater than that of other birds.

The name Hummingbird comes from the noise of their wings beating at 25 beats per second, about 1500 beats per minute. This high wing-beat and the extraordinary wing flexibility allows hummingbirds to hover far more effectively and energy efficiently than any other bird.

To hover they flap their wings in a figure-8 pattern, generating lift on both the down and upstroke.  Approximately 75% of the life of generated on the down-stroke with the remainder on the up-stroke.  The University of Texas has some nice graphs and charts providing more detailed information on how this works.

Anna’s Hummingbird hovering in front of Tobacco Tree (Nicotiana glauca) flowers

In to achieve this maneuverability hummingbirds give up the ability to glide.  In effect they have no low energy flight, they are always running at near full speed.  A 170 pound person would need to eat (and metabolize) 130 pounds of bread a day to keep up with energy output of a hummingbird.  Their energy output is so great that they enter torpor at night, a sort of hibernation.  If they did not do this the hummingbird would starve to death during the night.

Hummingbird flight characteristics are very nearly a blend of bird and insect methods of achieving lift.

Hummingbirds are generally extremely colorful, especially the males.  Like many birds this color is not pigment generated, but is the result of highly specialized feathers light refracting feathers.  Think of oil on water, that rainbow sheen that you see when light reflects from it.  Birds use the same technique, but in a far more specialized way.  Rather than an undifferentiated rainbow of colors the micro-structure of the feathers refracts only specific colors.  The natural color of the feathers is a dark brown, almost black.

Anna’s Hummingbird (Calypte anna) perched on a non-native Tobacco Tree (Nicotiana glauca)

I know I’ve used this photo before, but it illustrates the refraction vs pigment issue well.  The bold purple-pink behind the bird’s eyes is the color we associate with the male Anna’s Hummingbird’s head and gorget (the throat portion).  The dark, almost black, feathers are at the wrong angle to reflect the light and show the natural dark color of their pigment.

The tree in these photos is a Tobacco Tree (Nicotiana glauca), not native to North America, but native to South America, a place where there is a stunning variety of hummingbirds.  This tree and hummingbirds have a long relationship and have mutually evolved to reinforce that relationship.  Hummingbirds and may other birds and insects (and not a few mammals and reptiles as it turns out) drink nectar from flowers.  Not everyone who drinks the nectar will pollinate the plant, thus special relationships evolve.  Plants with long tube-like flowers (penstemon, humming-bird sage, tobacco, monkey flowers, heliconia, etc) are specialized to provide nectar for animals with long tongues that can reach the nectar.

Hummingbird tongue

Hummingbirds not only have long, narrow beaks, they have long, feathery tongues with which to lap up nectar hidden deep inside the tube-like flowers.  As they drink the plant deposits pollen on the beak and sometimes the bird’s head (two photos up you can see the pollen discoloring the hummingbird’s beak).  The next flower the bird visits gets a little pollen from the previous flower and the plant is happy.

A quick look at the shape and color of flowers will often give you a good sense of what type of animal the plant relies on for pollination.

Hummingbird catching insects under a Coast Live Oak

Hummingbirds need protein as well.  Some, such as the Anna’s Hummingbird, catch insects in flight, many others raid spiderwebs for insects.  Here in North America this is a relatively safe prospect, but in parts of South America there are spiders that will happily catch and eat a hummingbird and spin webs more than strong enough to trap the birds.

Hummingbirds have such a need for vast quantities of high energy foods that they are often extremely territorial, engaging in vicious fights and high speed chases.  Like most animals they would rather warn opponents off than waste energy fighting them.  Different species have various methods of letting others know how tough they are.

Anna’s Hummingbird staking out its territory

The little fellow above is marking out territory by fluffing out his head feathers.

One of the most amazing things about hummingbirds to me is that they migrate long distance, some species crossing the Gulf of Mexico in one long flight with no food.  At the shortest distance this is a flight of 480 miles, many birds fly closer to 600 miles to make this open water trip.  For a bird that only weights several ounces, cannot glide, and needs to eat constantly this is a truly remarkable voyage.

On a final note, hummingbirds are far more intelligent than most people realize.  Their memories are phenomenal, allowing them to keep track of individual flowers within their territories and when they were last visited for nectar.  They have the largest brain-to-body size of any bird.

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How Does the Acorn Get from Here to There? – Scrub Jays and Oak Trees

With a few exceptions trees in the Oak genus (Quercus) are easily, if not immediately, recognizable.  There are approximately 600 species in the genus divided into two sub-genera.  Oaks are found in North and South America, Europe, North Africa, and Asia.  The oaks in Asia are in the sub-genera, the Ring-Cupped Oaks (Cyclobalanopsis), whereas oaks in the rest of the world are members of the Quercus sub-genera.

Oaks have complicated relationships with a number of other species ranging from symbiotic fungus to parasitic wasps to humans.  Oaks feature in our mythology, we use the bark of Quercus suber, Cork Oak, to make stoppers for wine and for soft flooring, we make furniture and barrels from some species of oak, we made cart and early car axles from particularity strong species, they make excellent firewood, and they are fun to climb.

Climbing a Coast Live Oak (Quercus agrifolia) when I was little

Oaks also make acorns.  Sometimes, particularly when mast fruiting, oaks produce enormous quantities of acorns.  Most of these acorns are eaten by animals; insects, humans, pigs, squirrels, birds, and a host of other animals.  The survival and reseeding rate for acorns is low, but oak trees tend to be long-lived, some reaching ages of 500 years or more.  In the absence of other factors this low seedling success rate is not an issue as the tree produces thousands of acorns each year for hundreds of years.  Some seeds are bound to survive and turn into new trees.

Oaks have a particular problem.  Their seeds (acorns) are large.

Coast Live Oak (Quercus agrifolia) acorns

By themselves the trees can only drop the acorns under their own drip-line, in the shade where they will not sprout.  How does the tree send its seeds to a new place where they can sprout and are not left in a dense mat of easily found and eaten food?

Plants, being clever and manipulative in their slow vegetative manner, have all manner of methods for getting animals to carry their seeds far and wide.  Oaks harness many species to do this work, bribing them with the highly nutritious seeds they produce.  Across much of North America scrub and blue jays are put to work distributing acorns across the landscape.

Western Scrub Jay (Aphelocoma californica) in the Santa Monica Mountains – possibly Belding’s Scrub Jay (Aphelocoma californica obscura)

Meet the Western Scrub Jay (Aphelocoma californica), also known as the California Scrub Jay, and sometimes known as, “That damned bird!”  It is a mid-sized bird, perhaps a foot long including tail, loud, strong, clever, and imperious.  Like all jays it is in the Crow family (Corvidae), one of, if not the, smartest of bird types.  Corvids are renowned for their problem solving abilities and feats of memorization.  Scrub jays are no exception.

When the acorns are ripe jays congregate on the trees, grab as many acorns as they can, and fly off to stash them for future use.

Scrub Jay carrying acorns to hide for lean times

Each bird seems able to carry 3 or 4 acorns at a time, in the picture above there are two in the jay’s beak and at least one more in its crop.

Jays will carry acorns up to a mile and a half, hiding them in widely distributed caches of 1-3 acorns per cache.  The bird memorizes the locations of each cache, that of any other caches it sees other birds store, and will move its own caches if it knows it has been observed making its own cache.  Some of these caches will be forgotten and in some of those the seeds will sprout.

One bird doesn’t seem like it would make much of an impact, but one must recognize both the diligence of each bird and the number of birds engaged in this activity.

Scrub Jays harvesting acorns (@ 40 photographs taken over @ 10 minutes)

The photo above is a compilation of about 40 photographs taken over roughly 10 minutes.  This level of activity has been constant on this tree throughout the day over the past 2 or 3 weeks.  The scale of the endeavor starts to become apparent.  Beneath the tree ground squirrels and gray squirrels gather seeds from the ground to add to their own larders as well.

The oak tree has effectively expanded its dispersal distance from a few feet to over a mile.  Not only that, the oak tree has found a way to have its seeds hidden in safe locations and planted in the ground.  Only a small proportion of the acorns will survive to make new trees, but over the 350 year expected life-span of this particular tree it is not unreasonable that several hundred acorns will survive to produce trees that will live long enough to produce seeds of their own.

Scrub Jay enjoying the sun

+++ Cathy commented that any discussion of oak trees in California is incomplete if Acorn Woodpeckers (Melanerpes formicivorus) are not included.  They don’t live where I am at the moment, but last week I was up in my old stomping grounds and visited one of my favorite grainery trees.  Grainery trees are where these communal woodpeckers store and dry their collected acorns.  This particular tree is an ancient, wind-blasted Douglas Fir atop Mt Tamalpais, has a nearly 4 foot diameter, has been lightening struck numerous times, and sits amidst a copse of large moss enshrouded oak trees.

Old grainery trees will be used by many generations of these little woodpeckers and the trees look like an art project .

In any event, here is a photo of part of a grainery.+++

Acorn Woodpeckers (Melanerpes formicivorus) use all surfaces of a tree to make their larders. They will use fence-posts and the sides of barns as well.

*   *  * *** *  *   *

As a final note, in many areas, but in California in particular, oaks of all species are severely imperiled.  Oak woodlands are often considered to be the most important ecosystem in the region, but they have been subject to a number of stresses.  Oaks have been extensively cleared for orchards, vineyards, farmland, and urban use.  Saplings are eaten by cattle in range-lands, non-native feral pigs sniff out and eat all the acorns they can find, sometimes damaging tree roots in the process, and an ill-considered introduction of turkeys to the state by Fish & Wildlife to raise hunting revenue has led to even more acorns consumed by these overly prolific birds.

On top of all this, Phytophthora ramorum, a pathogen in the fungus-like family of water-molds, was accidentally introduced to the state via exotic ornamental plants and is causing wide-spread devastation.  This is commonly called Sudden Oak Death Syndrome and foresters strongly recommend not transporting oak firewood and washing cutting tools and boots when moving between oak growing regions.

California Bay Laurel – one of the scents of home

The idea of home is a strange one to me.  Moving as often as I have my version of home is more of a set of environmental conditions rather than a living space or a house.  Last week I had an opportunity to pass through the place that feels most like home.

It is a cloudy, damp, foggy portion of land on the northwest coast of California, a place where the land falls sharply into the chilly Pacific and the beaches are as often rocky as sandy.  The hills are steep sided with sensuously rounded tops, sometimes grassy, other times thickly covered in evergreen trees, and much of the region is protected open space.

West Marin, looking at Bolinas and north along the San Andreas fault. Inverness Ridge and Drake’s Bay are visible in the background.

When I was little, West Marin, more specifically the Point Reyes National Seashore, Inverness, Tomales Bay, and Mt. Tamalpais were where I spent much of my time rambling about, climbing trees, playing in shallow cold streams, swimming in the ocean, eating berries, and watching the wildlife.  Whenever I can I return to let the fog play over my skin and to breath the air flavored with the scents of California Bay Laurel (Umbellularia californica), Douglas Fir needles (Pseudotsuga menziesii), and invasive eucalyptus trees.

To the east of the San Andreas fault the land is open, primarily coastal prairie, with the trees safely nestled into the hollows or up against boulders to avoid the strong ocean winds.  The California Bay trees are particularity well adapted to this environment and form dense wind-sculpted stands, looking like glacier scoured boulders.

Low California Bay Laurel (Umbellularia californica) trees sculpted by the ever-present coastal winds

Umbellularia californica trees are tolerant of a variety of conditions and wide spread through California.  They reach into southern Oregon, but, as is true of many plants, California is their epicenter.  In stressful conditions, windy or dry, they only grow to a few feet in height, more of a resilient shrub than a tree.  Where they are protected from the wind and have a good supply of water they reach tremendous proportions, 150 feet or more tall, narrow and slender if competing with redwoods and Douglas fir trees, broad and robust when growing in the open.  Colonies of these trees will sometimes root-graft together, covering a portion of a hill in a single tangled mass of roots and trunks.  The wood decays quickly in the damp and large California bay trees often have multiple hollow trunks, providing homes to numerous animals and giving them a dark and mysterious appearance. The trunks are often covered in dense moss.

Umbellularia californica trunk with a characteristic coat of moss

Umbellularia californica is the only species within its genus and is known by a great variety of common names, Pepperwood, Spicebush, Cinnamon Bush, Peppernut, Oregon Myrtle, Mountain Laurel, Headache Tree, Balm of Heaven, and California Bay to list just a few.  The variety of names reflects its wide range of uses, uses that include medicine, food, insect repellent, timber, and, oddly, currency.  In the early 1930s the bank in the town of North Bend Oregon closed and the local currency collapsed.  The town adopted a currency of coins carved from the wood of this tree.  In North Bend, this currency is still legal tender, though few coins survive to this day.

Leaves, flower buds, and a ripe bay nut

The leaves are rich in pungent oils.  As children we used to put green leaf-covered branches on the fire to watch them flare up as the oil spat and burned.  When dried the leaves are as good for seasoning as the Mediterranean bay laurel, though much stronger and more spicy in flavor.  As with eucalyptus leaves, inhaling the steam from boiled leaves does wonders for stuffy sinuses, and the bay nuts can be roasted and eaten once the fleshy exterior is peeled off.  The fruit looks a bit like the small wild avocado fruits one finds in Central and South America, which makes sense as both the California bay laurel and avocados are in the Laurel (Lauraceae) family.

A dense understory of ferns is common where California bay trees are large

Where the California bay laurels are large and healthy a dense understory of shrubs and ferns is common, California Huckleberry (Vaccinium ovatum) and Western Sword Ferns (Polystichum munitum) are particularly abundant in West Marin.

Western Sword Ferns (Polystichum munitum) growing under a large, multi-trunked California bay laurel

These evergreen ferns grow large, individual fronds often reaching 2.5 to 3 feet in length.  The fronds are waxy and leathery studded long the edges with small teeth and points.  Most people are familiar with these ferns from the moon of Endor in Return of the Jedi, the place the Ewoks live.

Western Shield Ferns look like primordial Christmas Ferns

For those of you in New England the western sword fern will be immediately recognizable as an enormous Christmas fern.  One can easily imagine tough mouthed dinosaurs grazing on these giant ferns.  Today they are rarely eaten by anything except when the fronds are young, or an intrepid insect cuts free a chunk of leaf.

Home is the gentle drip of tangy flavored fog-born moisture dripping from the leaves of the California bay laurels falling onto glistening ferns.  The deeply textured gray of low hanging fog drifting through the forest, the salty bite of cold wind whipping down from the north Pacific, and the constant rustle of animals and water in the underbrush.

One of my homes.

Chamise – a key chaparral plant

The chaparral ecosystem in California is comprised of a dense and diverse collection of small to mid-sized woody shrubs.   It covers the hills in a shallow cloak of gray-green vegetation just thick enough to soften the contours of the land, but not to hide them.  In some places the chaparral is dense and thick, so much so that it is nearly impossible to penetrate it, other places it is sparse and low.  Animal trails riddle the chaparral and the bones of the land show through with a dramatic abruptness.

Sandstone outcrops above a chaparral covered hillside at Red Rocks State Park in Topanga

Chaparral grows primarily in dry, hot areas, as such the plants have a number of moisture saving adaptations that are most easily seen in their leaves which tend to be either small or waxy, or both in many cases.  The ecosystem is surprisngly diverse in both plants and animals, but despite this there are a small handful that are common from Mexico through most of California and that, taken together, could be considered to be the background matrix of chaparral plants.  Sage (Artemisia) and Ceanothus both are broad genus level plants with many individual members.

These plants are common in the chaparral, and taken with another extremely common plant, Chamise (Adenostoma fasciculatum), comprise what I think of as the matrix plants for the California wide chaparral.

Chamise (Adenostoma fasciculatum) flowers are small and clustered in tight bundles at the tips of the branches

Chamise, also known as greasewood, is in the rose family and produces clusters of small white flowers that look much like another rose family genus, Spiraea, which includes hardhack and meadowsweet.  The flowers set seed and dry on the branch, remaining affixed to the stalk for several seasons after blooming.

The leaves of Chamise are needle-like, clustered in little bundles called fascicles, the word the scientific name derives from.  On the whole, the plant looks something like a cross between rosemary and juniper with shredding bark, gnarled limbs, and and regularly placed leaf clusters.

Old Chamise plant on a ridge in the Santa Monica Mountains

Like many chaparral plants Chamise seeds require fire to germinate.  This ensures that the seedlings will be able to take advantage of the temporary increase of nutrients and open sunlight in the plant’s early stages of growth.  Estimates of the longevity of Chamise vary, but range from 100-200 years.

Chamise is not generally considered to be good browse for animals, but it is common to find extensive patches of heavily browsed plants.  In some places the browse is so heavy that the bushes look like sculpted hedges, in other places they look like carefully trimmed bonsai trees.

Browsed Chamise branches

When it has not been browsed Chamise produces a relatively dense growth of vertical shoots.  Over time many of these will die, with the dead stalks being retained by the plant.  Some estimates of the total volume of retained deadwood on old plants reaches 60-70%, greatly adding to the potential combustibility of the Chamise.

Young Chamise branches

California Buckwheat (Eriogonum fasciculatum) can sometimes be mistaken for Chamise by the casual eye, but the leaves are broader and flatter and the flower structure is very different.

California Buckwheat (Eriogonum fasciculatum)

Chamise is found primarily in California, though northwest Mexico and western Nevada also host populations of this plant.  Within California it is found in nearly all of the chaparral habitats as is shown on the digital Jepson Herbaria hosted by UC Berkeley.

Chaparral types with Chamise

This is a tough plant.  It grows with little water, on hard, rocky soil, and can even grow in serpentine soils, a soil type that kills many plants.  Many people do not like Chamise due to its flammability, but it is an excellent erosion control plant, provides cover for a number of birds and small animals, and serves as a last resort browse as well.

It is not the only chaparral plant by any stretch, nor even the most typical in any given area, but it is the one I have seen in the most places through California.