Hummingbirds in the Real World: evolution, physiology and relationship

800px-Giant_hummingbird_Patagonia_Gigas_on_cactus_in_Peru_by_Devon_Pike

Giant Hummingbird, Patagona gigas on Cactus in Peru, by Devon Pike

Hummingbirds are clearly fascinating and engaging creatures.  They are biological wonders of ‘invention’, little gems that sparkle in their airborne dances through sunlight, with the seductive power to capture the attention of even the most incognizant of us lumbering earthbound humans, including many of those pretty much blind to the natural world.  I did not set out to write this piece, I was researching several Puya species of the South American Andes, curious about their survival and pollination and became intrigued by these miraculous little fliers.  Part of our fascination with them I think is attributable to their size.  There are 338 known species today, 104 genera, which as a group comprise the entire Hummingbird family, the Trochilidae, the second largest bird family found in the Americas, numbers that speak to their success that many ornithologists say ‘could’ continue to increase over the next several million years!  The species range in size from the tiny Bee Hummingbird, of Cuba, about 2″ long and less than 2 grams in weight to the 9″ long, 24 grams, that’s around 3/4 of an ounce, of the behemoth, Giant Hummingbird found in much of the more arid western Andes from Ecuador south into central Chile.  The Giant, Patagona gigas, is the sole species of its genus, though there is a subgenus that is found into Ecuador,  and it is thought to be about as large as any Hummingbird can be.  Any bigger and it is thought that those characteristics that differentiate Hummers from other birds become more difficult to sustain.

Hummingbirds as a unique family among birds

Hummingbirds, as birds, share much with their ‘brethren’, while they are often very different from the many other species and families.  They share many similar structures and capacities though the particulars are often just that, unique and characteristic to themselves as Hummingbirds, Trochilidae.  All birds possess feathers and produce eggs rather than live young.  They share a common digestive anatomy with varying capacities.  They all possess ‘wings’ though not all can fly and both their skeletons and musculatures reflects this.  All birds produce their own body heat through their own metabolism, they are endothermic, but Hummers stray here, uniquely, from most bird species, by being poikilotherms, they are able to ‘adjust’ their body temperatures to meet their needs under various conditions….Between genera and species of Hummer , of course, there are  differences.  As a family, Hummingbirds, are relatively little studied, as many of their species live only in very remote areas.  Species are differentiated by their grosser morphological features including feather color.  The genus Selasphorus, all have some portion of the feathers on their bodies colored russet, like our own Rufous Hummingbird, Selasphorus rufus.

Ask anyone about Hummingbirds and they will describe them as tiny…in the world of birds they include the smallest species, though at the big end they overlap with many other species.  People will also commonly remark about their habits and capacities for flight, their ability to hover as if unaffected by everything around, absolutely still, suspended in mid-air as well as their ability to dart about, to quickly accelerate in one direction or another, in abrupt, zig-zagging, changes of direction.  They will also know of their propensity for nectar.  More broadly most people understand that birds, in order to fly have developed in such a way as to minimize their body weight, particularly by having ‘hollow bones’…and because of this are rather ‘fragile’.  (These people have not watched an Osprey dive, at full speed, into the water to nab a fish producing what would seem to be a bird crushing impact.)  Like most generalizations about birds, this hollow bones thing is not completely true, for either Hummers or other species of flying birds.  Some of their bones, particularly those that anchor a bird’s largest and most powerful flight muscles are solid, while other less structurally critical bones are porous and the bones of their wings, hollow.  There are several reasons for this.

Hummers and Flight

The flight of anything is dependent on its ability to produce ‘lift’.  If an object moving through the air produces no lift, it is subject t0 the physics of ‘ballistics’, which strictly limits the distance it will ‘fly’ and can be precisely calculated mathematically utilizing the constant, 32 ft./ sec2.  An object unable to produce lift is in a state of falling and is subject to the inevitability of gravity.  Flight is possible only because of the physical property of air, of density.  If you could fit a bird with a breathing apparatus and put it in a vacuum chamber, no matter how hard it works, it will be unable to fly.  Lift is created by either forcing air down, compressing it beneath the wing or through the wing’s forward motion, creating a difference in the pressure above and beneath the wing…lower pressure above the wing resulting in a lifting pressure against the bottom of the wing.

Birds have wings formed in the original airfoil shape, noted by early designers of aircraft.  Air streams smoothly and evenly beneath the wing.  The pressure beneath the wing remaining constant and equal to the surrounding air…but, as the air is forced up smoothly over the upper curved surface of the wing it must travel a greater distance spreading and thinning the air, accelerating it, which effectively lowers the density of the air above the wing, creating lift.  The faster a wing moves forward through the air the more ‘lift’ it generates.  Vultures and buzzards are particularly well designed for this, they are consummate gliders, supported on broad wings continuously and nearly effortlessly floating on the rising air thermals from the warming earth below. To generate forward speed a bird either angles its wings ‘forward’, in effect ‘falling’ or by pushing the air behind itself working with the natural resistance and compressibility of air. Most birds can glide to some extent, but even these require a substantial expense of energy to power them initially both to lift them and  to maintain their forward motion.  Some birds reduce this expenditure by coming to rest on branches, in treetops or on cliffs from which they ‘push’ off, developing forward speed in their initial drop before beginning to generate much lift.  Those that hunt animals on the ground or fish in water must be able to produce enough lift to lift both themselves and their prey, in the case of fish, also against the impediment of rising out of water.

Air provides everything within it with a degree of buoyancy, as it is ‘filled’ with molecules of the several atmospheric gases, much as water does…we and everything else, ‘floating’ in it, but it is not ‘dense’ enough for even a bird to float in it.  Water, as a fluid cannot be compressed, its density does not increase with depth, but air does.  At sea level there is more ‘air’ in air than there is at higher elevations, the ‘weight’ of the air above it pushes the molecules closer together, not only providing more for animals to breathe in a given breath, but also making it possible to produce more lift from a given effort.  A bird must expend more energy to produce the same amount of lift at higher elevations.  This is the same reason why helicopters have a maximum operational altitude above which they simply can’t safely perform.

Hummingbirds share the airfoil shaped wing of other birds…plus.  Unlike other birds they have a ‘shoulder’ that they can rotate into positions others birds can’t allowing them to produce lift in a variety of directions.  The speed with which they can move their wings gives them the ability to accelerate at a rate no other birds can match.  As they angle the direction of their wing beats they move ‘forward’ and in the direction they wish to go.  Their largest group of flight muscles pull their wings down and ‘back’.  Another set pulls them back up and they coordinate this movement in such a way that controls their acceleration…intricately.  In flight, their wings are in constant motion, downward motions lifting and moving them ‘forward’, upward movements, moderating that lift and direction.  Altogether, this gives Hummers the unique, for birds, capacity to hover.

As a swimmer in water our own buoyancy, isn’t quite sufficient for us to confidently float with our heavy heads held above its surface, so we are taught to ‘skull’, waving our arms in a motion much like a Hummer does its wings while it hovers in a fixed position, only we move our arms much slower as we adjust our hand position directing our force directing it downward against the water below.  We are no where near as powerful and effective at this as are Hummers in air.  The fluidity with which they do this combined with the degree of control that they have over not just the speed of their wingbeats, but the precise motion of its ‘wave’ moves them 3-dimensionally and directly wherever they desire to go.  This ability even allows them to fly backwards and hover upside down.  How they do this is not an easily answerable question, but Hummingbirds possess proportionately larger brain centers and capacities that are unique or extreme to them amongst even birds, that permit a degree of control no other birds have.

A Hummingbird’s underlying wing structure is more akin to a hand than an arm and hand.  The complexity of this structure allows its unique patterns of motion.  Imagine the complex motion of a pianist’s hands as they play, in rhythmic and coordinated patterns, striking each key precisely as desired.  Then imagine the ‘music’ being played as completely ‘improvisational’, responsive to the conditions of the moment, dependent upon what just immediately preceded it and where one desires to go next.  This requires both a muscular power and control that goes beyond simple mechanical function.  Anyone who watches a high speed video of a flying Hummingbird at slow speed will recognize the grace and fluidity of the movement that belies the blur of its motion.  Anyone who has watched a Hummingbird hover motionless, its head absolutely still despite all of the work being performed to maintain its position, can only marvel at it.  Hummingbirds have centers in their brains that are more fully developed than those in any other brain so far examined, which are able to rapidly ‘calculate’ precise body position and send signals back to the muscles to move it in increments so tiny we cannot see them ourselves.  This demands a precision and capacity in their eye to detect motion that is far more advanced than ours.  The same abilities enable them to capture insects as necessary to consume for their needed protein.

Evolution and Their Role as Pollinators

The evolution of Hummingbirds follows closely with the uprise of the Andes Mountains, a process which began around 21 million years ago, and the region remains as their center of species diversity.  There are several plant genera including Puya, most of the other species of the Bromeliad family as well, along with South American species of Lobelia, Fuchsia and Passiflora, which were speciating, evolving, over this same period, plants which have evolved in relationship with regional Hummers.  They are thought to have spun off from earlier insect eating Swifts.  At some point the line that would become Hummingbirds developed the ability to ‘taste’ sweet and from that point on the relations between the two groups was sealed and each group, the Hummers and the flowers that they grew to depend upon evolved along a shared path.

Birds_Trochilidae-600x330It is interesting to note that the vast majority of Hummingbird species is coincident with the highest concentration of members of the Bromeliad plant family, not just the Puya spp.  The center of diversity for Bromeliads is the forested lands around and above the Amazon Basin up the wet eastern flank of the Andes and the Venezuelan Highlands of the north.  For many of this large plant family Hummingbirds are the primary pollinators and in some cases they are the exclusive pollinators.

At first this relationship in which Hummers began to emerge as a unique group was probably one in which the birds were much more heavily reliant upon the same insects for food that their predecessors were, slowly ‘moving’ toward a diet more dependent upon flower nectar as they and the flowers changed their physiology and function in response to one another.  This relationship ‘worked’, the various species successful over this relatively rapid period of speciation and adaptation…they would never have evolved had this not been true.  This suggests how important the relationship between the two, pollinator and food source, was and still is.  The relationship between the various bird or other pollinator species and a particular plant species can be quite specific and narrow while in other cases they are more generalist.

Plants whose flowers are pollinated predominately by insects generally produce relatively small amounts of nectar.  Plants pollinated by birds and bats, because of the generally higher energy requirements of their flight, produce more and more energy rich food, in this case, nectar.  For insect pollinated plants large quantities and high sugar concentrations of nectar would be more of a waste of resources.  In general, high nectar production, especially of nectar containing high concentrations of sugar, tend to be pollinated by birds and bats.  There probably isn’t too much cross over between species pollinated by bats and birds as bats, being night time flyers aren’t attracted by flower color which birds are and bats are drawn strongly to those flowers that are night scented, plants tend to release their nectar in evening hours, frequently drawing nectar feeding Moths as well.  Tubular or at least deep flowers, that are scentless, bright colored and produce nectar are likely pollinated by Hummingbirds.  One source estimated that some 7,000 flowering plant species are primarily pollinated by the 338 Hummer species.  In the SW US one of the significant genera are Epilobium, some of which were once known as Zauschneria, otherwise known as California Fuchsia, a genera with a long bloom season of brightly colored, tubular flowers that provides a large and consistent nectar source for much of the summer, often long after many other species have ceased flowering.

0

Brugmansia sanguinea, an endemic to the Andes mountains from Colombia to northern Chile, at elevations from 2,000 to 3,000 m (6,600 to 9,800 ft), unlike most of its sister species, which release aromatics in the evening to attract Hawk Moths to pollinate them, isn’t fragrant at all and is thought to be pollinated by long beaked Hummingbirds. I don’t know if our resident Anna’s can enter and reach to the nectaries in this 8″ deep  flower.  from my garden.

Pollinators do not fly around randomly, nor do they simply target the nearest flower, that would be extremely inefficient in terms of the time and energy spent.  Pollinators learn the best sources, what they are, where they are and when they are available and they can return to the precise location of a previous successful visit…it is a matter of survival and a skill they share with Honeybees.  Like most birds Hummers have acute vision with a range that likely goes into the infrared and ultraviolet part of the spectrum (The brains and eyes of many bird species also allow them to see and respond much more quickly than most other higher animals a capacity which allows them to capture quick flying insects, other birds, rodents even fish swimming beneath the waters surface).  They do not seem to be drawn to particular colors of flowers, but do tend to be attracted toward flowers that share the color of whatever they’ve been recently feeding upon…if red then more red, if yellow then more yellow.  It has been found that like other birds they lack organs that can detect scent so they are directed by visual cues alone.

Hummers among birds have the unique ability to discern ‘sweet’ from other tastes and seem to have some ability to gage its concentration, its ‘sweetness’, perhaps even to the type of sugar, which helps them decide between nectar sources…they have a tendency to visit flowers with higher sugar concentrations.  While nectars can contain small concentrations of other compounds they are highest in sugars.  Each plant will have nectars containing different proportions of fructose, glucose and sucrose.  Sucrose is our name for ‘table sugar’…and the sucrose molecule is actually made up of one fructose molecule and one glucose molecule.  For sucrose to be ‘useful’ to an animal it must be able to digest it and to do this the animal must first be able to produce the particular enzyme that can break it down into its parts.  Hummingbirds are particularly efficient at breaking down sucrose.  Not all birds can do this.  For those the energy locked up in sucrose is unavailable.  Glucose and fructose are more readily available to all birds, there are other birds which are nectarivorous besides Hummingbirds, and can be directly absorbed into the blood.  Our gut is different.  Humans can break down sucrose, but fructose must first be converted into glucose by our liver before our blood can absorb it and use it for energy.  If we eat more fructose than our liver can ‘handle’, the excess is turned into cholesterol and triglycerides.  Digestive systems and their capacities vary between animals.  This ability to digest these plant based sugars serves Hummingbirds well as gram for gram they have among the highest energy demands of any warm blooded animal.  They have very high caloric requirements even at minimal function levels.

Hummingbirds: On Physiology, Capacity and Metabolism

The hearts of Ruby Throated hummingbirds beat at around 250 beats per minute…at rest and can reach over 1,200 under flight or while hovering.  Their hearts comprise 2.5% of their body weight, which means they have proportionately the largest hearts of any animal.  It is four-chambered and functions much like ours.  They maintain their body temperature while active during the day at 105ºF, other Hummer species maintain their temperatures within a couple of degrees of this.  To live as they do, their ‘stripped down’ and efficient bodies require an almost continuous supply of energy rich sugars.  One source noted that a Hummingbird living at the edge, with no fat reserves, given the rapidity of their digestive and circulatory systems, in order to meet their metabolism requirements, must consume sugars every 30 minutes or so while they remain awake and active…or risk collapse….Consuming much more than that which is needed immediately and they quickly convert the surplus portion to lipid fats to store away in their livers where it remains until needed.  Hummers can call upon this fat for use quickly to fill their sugar ‘gap’.  Typically they consume around 1.5 times their body weight each day.  Hummers don’t store fats within their muscle tissues like mammals, they strictly limit their fat production as weight is a critical matter of survival.  As lumbering land beasts we don’t have any problem with packing on fat…well beyond any level that we might ever practically call upon for our survival.  This would be fatal for Hummers.

Hummers have evolved several strategies to help regulate their use of energy including when they sleep or when it is too cold for them to actively forage, by going into a self-induced state of torpor, similar to hibernation.  When in torpor they slow their metabolism and energy requirements to 1/15th of normal at rest.  Their heart rate and breathing reduce drastically.  The body temperatures of the Ruby Throated, for example, drop from 105ºF down to 71º!   For humans hypothermia sets in when our body temperature drops below 95º.  Below this and we are unable to produce enough heat on our own to recover and require treatment.  Hummingbirds, again are poikilotherms, able to regulate their core body temperature across a range.  To come out of their state of torpor they must boost their body temp back up to operational levels and they do this by utilizing the energy rich fats, lipids, they’ve stored when they release them from their liver, switching back to sugars after they begin feeding.  While ‘waking’ they activate their muscles in a manner analogous to our shivering producing heat to raise their body temperatures.  Their relatively tiny size both complicates their maintenance of the their body temp while it reduces their energy expenditure while ‘waking’, their tiny body mass losing body heat at a very high rate, but requiring less heat to bring their body temps back up to normal active level.  This low body mass, which is an advantage to any bird in flight and an absolute necessity for them as frequent ‘hoverers’, can work against them in their survival, when they live in cool to cold environments.  This probably goes to explaining why there are so many more species that inhabit tropical areas as compared to the few species that reside in or migrate to cooler temperate areas like Alaska in summer.  On the other hand their metabolism’s production of heat requires them to take frequent ‘rests’ to cool themselves because they must maintain their body heat within a relatively narrow range while active.  Hummers, metabolically speaking, walk a variety ‘tightropes’ for daily survival that change based on conditions which vary from region to region.

Hummingbirds have devised ways to greatly improve their efficiency maximizing what they have.  If sugars are their fuel, and they have maximized both their abilities to consume and digest them, the limiting factor becomes their ability to uptake the Oxygen, O2, to metabolize them.  O2 is a necessary component of the biological function of respiration, a necessity for any organism when consuming food for energy…even plants respire as they consume the carbohydrates they themselves produced earlier to fuel their own growth.  As a  biological organism when Obecomes less available to animals, when our need exceeds our capacity, muscle tissue can become hypoxic, Opoor, causing the organism to process sugars less completely, often producing lactic acid which is released into the bloodstream further impeding performance.  Hummingbirds, however, can do two things that most other animals either can’t or don’t do when Ois not available in sufficient quantities…Hummers can still metabolize under quite hypoxic conditions, without producing lactic acid and still perform at peak levels.   Some high level human athletes are able to do this, but even then not to the same degree.  In some of us training enhances these abilities, but much of it is due to genetics.  When it comes to Hummingbirds this level of performance is necessary for survival and because of this it has been passed on through natural selection from generation to generation.  It has become a trait common to the individuals within not just a single species, but the entire family, though some are better at it than others.

Another advantage that Hummingbirds have is their capacity for Oxygen.  Their red blood corpuscles, the ones containing hemoglobin, which carries Othrough the blood from the lungs to the organism’s cells and tissues, are very good at this…they have a higher capacity for this in comparison to other organisms.  In fact those several species of Hummingbird that live most of their lives at high elevation have independently developed enhanced Oxygen binding properties well beyond even the capacities of other Hummers.  The several high altitude species have independently developed this capacity, having modified the same specific genes which they can pass on to their young. Typically the average Hummer can consume energy at ten times the rate of an elite human athlete, when considered on a gram by gram comparison of body mass.  Our ability to process the needed Oxygen to do this at their level is impossible as we exist today.  A hummingbirds ability to do this is remarkable.

It is also important to note the Hummers while feeding, don’t ‘suck’ nectar up using their long bills and specialized tongue as if they were a ‘straw’.  No, Hummers tongue are split with a relatively large surface area.  While feeding at a flower they poke their bills in and then extend their tongue into the nectar which ‘sticks’ to its surfaces and is drawn up the length of the split by capillary action, filling the intervening space. The Hummers then quickly draws their tongues back, squeezing the nectar into their mouths to swallow…and they can do this 13, to as many as 17 times per second!  In many species Hummers will have bills of a specialized shape that fit the curving form of particular flower types giving them an advantage at reaching the nectar, while the majority, including the few species found in the US are more generalist feeders with simple straight bills.

Hummers’ metabolic efficiency is also supported by their extensive capillary system that carries blood closer to tissues requiring less time for it to diffuse into cells and oxygenate them.  Of course the diffusion of Oxygen through their tissues is also enhanced by their small size the process of gas exchange quicker simply because of their compact size.  Small size and the relatively short distances that muscles and wings move means that these movement require less energy to accomplish.  Scaled up to anywhere near human size a Hummingbird could not ‘work’.  Yet another factor maybe that they don’t have a diaphragm as do we mammals,  and instead rely on the rapid contractions of their flight muscles to force air in and out of their lungs drawing air into and forcing it back out at a rate somewhat proportional to the ‘work’ they are doing.

One might think that such a rapid metabolism might result in a relatively short lifespan, perhaps comparable to insects, but this isn’t true.  Researchers in Arizona who commonly band captured Hummers with dated bands once recaptured a Broad-billed Hummingbird that had been captured 9 years before.  Similarly, in Texas, a Black-chinned Hummingbird was recaptured and found to be over 11 years old!

Hummingbirds and Their Fuel: Nectar

Hummingbirds on average have been observed to visit 2,000-3,000 flowers per day.  They are busy and don’t have time to waste on flowers that produce little or no nectar.

Nectar is their fuel.  It also contains minimal amounts of proteins necessary for their own growth, maintenance and the production of eggs in females.  Hummers know which flowers to visit, the birds and these flowers are in a long term relationship which extends across many generations, they have become attuned to one another.  It is an intimate and essential relationship and they have evolved together!  There is a bit of a ‘quid pro quo’ at work here in them, the more that one does ‘for’ the other one, the more it does in return.  The ‘strength’ of the link between these species speaks to their degree of ‘compatibility’, if you will.  If a plant is dependent on a given pollinator species, or a closely related range of pollinators, the plant will adapt, over time, to better meet the ‘requirements’ of the pollinators for its own survival purposes as these will be more completely pollinated.  They in turn, over time, will tend to manifest characteristics which are even more supportive in their particulars.  When close enough, when the relationship is ‘specialized’, the two go so far as to develop physical structural affinities to one another, the Hummingbird ‘reflecting’ the structure of the flower in the length and shape of its beak, the flower’s nectar adapting its composition to what best meets the hummer’s nutritional needs.  If a plant can be pollinated by a variety of pollinators then its flowers will be less specialized, more generic, than otherwise.

Christopher C. Witt The buff-tailed sicklebill (Eutoxeres condamini) is one of many hummingbird species adapted to the ecosystems of the eastern Andes.

The buff-tailed sicklebill (Eutoxeres condamini) is one of many hummingbird species adapted to the ecosystems of the eastern Andes. Christopher C. Witt

The relationship works both ways.  In the case of Puya spp. its flowers are effected, but not solely dependent upon their relationship with Hummers and can still be ‘serviced’ by more generalist pollinators, the nectars of the various species ‘tending’ more toward one more broad group than others in a kind of ‘blended’ response, meeting the survival needs of all sharing association.  This goes toward ‘explaining’ how Hummers, certain passerine bird species and bees can all serve as potential pollinators with particular Puya spp., being more or less better, more specific, nectar sources for one group than they are for another.  Andean Hummers, having evolved closely with the local and regional Puya spp. have made subtle adaptations to one another, while other Hummer species have made more specific ‘adjustments’ aligned with Passiflora spp. common and frequently visited in other regions.  What ‘ties’ all Hummers together is their predominately nectarivorous, habit which they supplement to a much lesser degree with insects.

The Giant Andean Hummingbird and the Future of the Family

This brings up a point about the Giant Andean Hummingbirds, these much larger birds, have an even higher operational requirement in terms of their energy consumption due to their physical size and weight.  Not quite so simple Newtonian physics.  Gram for gram, these larger birds require proportionately higher energy consumption than their smaller cousins.  Patagona gigas hovers at an average of 15 wing beats per second, very slow for a hummingbird.  Its resting heart rate is 300 per minute, with a peak rate of 1020 per minute, a higher resting rate and lower maximum rate.  P. gigas requires more energy per gram to hover than a smaller bird.  Their larger wings require more energy to accelerate them in one direction which they must then reverse by utilizing opposing muscles to pull them in the other direction, both actions being necessary for hovering.   P. gigas requires an estimated maximum of 4,300 calories per hour to sustain itself in flight.  You read that correctly! 4,300 calories per hour!  There are 140 calories in a 12oz. can of original Coke….This huge requirement, along with the low oxygen availability of the thin air found at the high altitudes at which the giant hummingbird usually lives, (requiring greater energy expenditure to generate lift in the less dense air) suggests that P. gigas is likely to be very close to the viable maximum size for a hummingbird.

Patagona gigas is strongly linked to regional Puya spp., but it doesn’t specialize in them, it is more of a generalist feeder, seeking out the flowers of local Cacti species and Salvia among others as well.  It cannot afford to be overly picky with its high requirement for carbohydrates.  Ornithologists think that a larger species would be unable to consume and metabolize enough energy to sustain itself.  This species has already begun to adopt alternative ‘behaviors’ or strategies like perching when they can while feeding, as hovering is so energy expensive.  Additionally it is known to sometimes glide in flight, something that Hummingbirds generally do not do.  To ‘conserve’ more energy a Hummingbird would have to alter its structure and mechanics even more and, in the process, cease being a ‘Hummingbird’.

Migration

Hummingbirds which migrate, generally follow regional bloom cycles.  Hummers like the Andean Giant move north and south along mountains between the latitudes of 28º to 44ºS, a range that covers 1,100 miles while ranging east and west down to the coastline in search of appropriate flowers, but spending the majority of its time at higher elevation.  This represents a lot of ground to be travelled a distance across which the birds must rely on their fat stores if they don’t have ready access to their desired nectar producing flowers.

The small Rufous Hummingbird, a summer resident here in the Pacific Northwest, can range as far north as south-central Alaska in summer.  One of these, banded in the Florida panhandle in January of ’10 was  found by another ‘Hummbander’ in the Prince William Sound area of southern Alaska, 3,530 miles away, about 6 months later in late June, an observation record for any Hummingbird.  (Other populations of Rufous spend their winters in Mexico.)  Biologists believe that the distance is actually greater than that because their migratory path tends to take them more westerly along the Gulf coast and then up the Pacific coast, a distance another 1,000 miles greater.  4,500 miles, which would take 150 hours of continuous flying while averaging 30mph.  Add in time for rest, sleep and foraging and this fete becomes all the more remarkable…then consider that a young one, hatched in early summer in Alaska, must be capable of flying back to its winter range, which it does by itself.  Hummers do not migrate in flocks.  Hummers that do such migrations accumulate body fat over the course of the flower season before they embark, but, obviously must have some sources along the way, no small fete for such a tiny bird.

_______________________________________________________________

While working on this post the concept of ‘keystone species’ came to mind.  A keystone is a species that holds a particular biotic community together, it is essential for its continuing existence, the species without which the integrity of the community would degrade and collapse, whatever other actions we might take to ‘rescue’ it.  I’ve always had trouble with this in the living world.  It asks us to designate one species, or perhaps a small handful, as essential to a biotic community’s survival, its health, its integrity…suggesting that the loss or removal of any other species poses no essential threat, that adjustments can be made within the remaining community that will assure its healthy continuation.  Is this true though?  Is it more true in the much more biotically complex communities of the wet tropics than it is in less diverse arid or temperate communities?  What about those species that live in very specific and narrow relationships with another species?  Such closely related species decline together.  At what point do we consider the losses to have resulted in community collapse?

The Giant Hummingbird lives in close relationship with several of the Puya spp. that occur within its wide range, but it also relies on other food sources.  Would the loss of Puya raimondii, in portions of its high elevation range within the Altiplano, put this Hummer in danger?  This Puya is in decline, its continuing existence is questionable…will the Hummer be able to continue on?  My guess is that yes it likely will, but other plants are under threat at the same time.  At what point do we change how we view the other species that we share the world with?  How long can we say, “Well, this one isn’t really that important.”  Species, biotic communities, have all evolved in relationship with one another.  Removing anyone species changes the nature of a community’s relationships with consequences for the future.

Hummingbirds, as I noted at the beginning of this, are charismatic creatures.  We are drawn to them.  Does this mean that when we perceive them to be under threat that we will act in their defense or will we only sadly remark about the state of the world and our own short-sightedness.  It always comes back to a question of valuation, how much do we value something, do we do so enough to act? to change our behavior? or will we still continue to see ourselves as outside of the living world, removed and protected from it, even though every shred of evidence stands against that supposition, pointing out instead our absolute dependence upon  the living world.  Every species should be considered to be ‘keystone’ until ‘proven’ otherwise.

All species, not just birds and Hummers, are magical wonders!  Each time I take the time to examine any one of them I am reminded of just how true this is.  We must lose this habit of bland reductionism, dismissing other species as ‘only’, reserving value for the few we’ve bothered to know or include.  This is not a world of objects after all, fixed and unchanging, or set out for our exclusive use, it is far more marvelous than that, far more powerful, and fragile at the same time, and we, as discerning, thinking, actionable beasts, need to understand this before we’ve pushed these living communities beyond a state which can support all of us.  Are we already beyond that point?  I don’t know.  Why wait to be certain?

The Seven Different Species of Hummingbird Found in Oregon…at Least Part Time

A good site for detailed information on these birds is Hummingbirds Plus! and each bird’s Wiki page.  Only 330 more to go!

  • Rufous Hummingbird

 

1024px-Selasphorus_rufus_on_Saltspring_Island

A hovering male Rufous Hummingbird, Selasphorus rufus, the most common species ranging along coastal areas north into southern Alaska. from Wikipedia

  • Anna’s Hummingbird

    1280px-Anna's_hummingbird

    A male Anna’s Hummingbird, Calypte anna, resident west of the Cascades, their entire heads can show the striking red iridescent color, depending on the light and your angle. from Wikipedia

  • Calliope Hummingbird

    1280px-Pause_in_Flight;_Calliope_Hummingbird_(Stellula_calliope)

    A hovering male Calliope Hummingbird, Selasphorus calliope, with its striking purple ‘gorget’, generally found in mountainous to desert areas of the western US, in Oregon, east of the Cascade crest in more open forested areas to scrub. This is the smallest bird in the US that breeds here.  from Wikipedia

  • Costa’s Hummingbird

    Hummingbird

    A male Costa’s Hummingbird, Calypte costae, more often found in the desert’s of the American SW, these can range up into the arid SE Oregon while wintering in Mexico.

  • Allen’s Hummingbird

    1280px-Allen's_Hummingbird_Guarding_Flower_Patch

    A male Allen’s Hummingbird, Selasphorus sasin. This species is generally restricted to a narrow coastal band along California as far north as part of southern Oregon. from Wikipedia

  • Broad-tailed Hummingbird

    1024px-Male_Broad-tailed_Hummingbird_1

    A male Broad-tailed Hummingbird, Selasphorus platycercus, this less commonly observed species has a summer, breeding range, that extends into mountainous areas of eastern Oregon where it will forage in open Pine woodlands and adjacent grasslands. from Wikipedia

  • Black-chinned Hummingbird

    1280px-Archilochus-alexandri-003

    A male Black-chinned Hummingbird, Archilochus alexandri, one of the most adaptable and common Hummers in the US. They are found throughout the western US in forests and woodlands to grassland and chaparral, including eastern Oregon. from Wikipedia

 

Other Resources:

Operation Ruby Throat and their ‘The Hummingbird Project’, has an informative page the “Hummingbird Internal Anatomy and Physiology”, that is clear and concise.  It helped form a framework for the above.

Here’s a little article on Hummingbird migration, focused particularly on the Rufous, the species with the longest recorded migration.

Check out the Wiki page for Hummingbirds.  There is lots of good information there.

Curious about the plants that comprise Puya spp.? check out my blog posting.

A totally geeky article by GRRL Scientist, “How do Hummingbirds Thrive in the Andes”, about how hummingbirds have evolved through specific gene mutation which changed to form proteins in hemoglobin which improve their capacity to bind and carry Oxygen in the blood.

This article discusses the consensus position that the family is still in a process of ‘adaptive radiation’ a period over which new species are still forming to fill available and transforming niches.  Interesting.

Live on the west coast and want to plant plants attractive to Hummingbirds? Look for lists like this one from California nursery, Las Pilatas in Santa Margaritaville.  Their list is more extensive and specific than the typical limited numbers of natives most such lists present.  They also offer other info on behavior, health and feeding of Hummers.

The Hummingbird Society posted this list of good nectar producing plants that are attractive to Hummers.  These are not strictly Oregon native species, but genera that are all suitable which include a few native species.  The intention is to provide nectar sources over a longer season rather than relying on artificial feeders, the use of which some advocates question.  Hummingbird researches are finding that Hummers are increasing their ranges, at least in part due to urban development as we transform local landscapes, providing plants for them and increasingly set out feeders, supporting the more ‘social’ of the species.  Add some of these plants to the native species in your garden….Don’t forget to add those nectar producing Bromeliad family members!

Watch this high speed video played in slow motion…It shows a hummingbird in flight, hovering and feeding…amazing! and beautiful!

This article has a particularly interesting discussion section that compares the metabolisms of high altitude Hummingbird species with that of humans who have lived for generations at comparable altitudes.  It speaks to the stability of conditions and populations to the process of genetic change and evolution in the process.

Read the Introduction and Discussion sections of the paper, Morphology, nectar characteristics and avian pollinators in five Andean Puya species (Bromeliaceae).  Acta Oecologica, vol 51, August 2013, pages 54-61, by C.T. Hornung-Leoni, P.L. Gonzalez-Gomez and A.J. Troncoso, to see the research supporting some of what I say above.  I found this on line at Academia.edu and was able to download it. The Materials and Methods as well as the Results sections read a little confusingly, but the other sections lay it out pretty well.  It is a complex issue with multiple factors, but the tendency is to the pattern I discuss above, the structure of the inflorescence and flowers themselves are an element, as are nectar quantity, concentration and composition to which species dominates as pollinator.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s