From the blind…

The hummingbirds have been quite active lately in the wildflower garden, so I set up the blind this morning to see if I could capture some of the action.

I don’t normally keep so much of the window space open — just enough to poke my telephoto through the open space toward the garden.  The blind is about 10-20 feet from the plants the hummers prefer.

There seem to be four hummingbirds buzzing around the cardinal flowers and the nectar feeder — one very shy but aggressive male, and three female-looking birds that could be a female and her two juvenile offspring.

Lots of bees in this photo as well as the hummer probing the red cardinal flower

Every now and then, one would perch on the tomato cages in the vegetable garden, about 10 feet away.

My goal was to get some photos of the very shy (or wary) male Ruby-throated Hummingbird who dashes in to drink from the nectar feeder, but rarely goes to the flowers.

He seems bigger than the others and has a darker throat, so he is easy to spot, but very difficult to photograph.

He even hides behind the nectar feeder, giving an obstructed view of his ruby throat.

At last, one quick shot of him next to (instead of in back of) the Cardinal Flowers.  Those wings beat 53 times a second while they hover, so cranking up the shutter speed is required.

The hummingbirds are probably feeding voraciously now, stockpiling calories to store as fat for their long migratory journey south to wintering areas in Mexico and Central America.  Apparently a particular hummingbird follows the same route each year, but they don’t migrate in a flock, nor do young hummers necessarily follow their parents.  They just know the way south.

A perfect fit

Ruby-throated Hummingbirds love red flowers.  In my garden, they particularly like the Cardinal Flower, which sends up 4 foot tall stalks with a bright red plume of flowers that develop sequentially from bottom to top of the stalk over a 4-6 week period. Apparently, it produces some really good nectar too, because it is the first flower they visit in the morning.

Here I come — bring out the nectar.  This little female Ruby-throated Hummingbird was extremely cooperative, foraging for several minutes on a clump of cardinal flowers, while I sat in a very hot blind about 15 feet away.

Sometimes the probing is just a test to see what might be there, as the bird tastes with the tip of its tongue.

In this shot, her bill is inserted only part way into the flower, and her head is completely clear of the flower structures.  This foraging position won’t accomplish what the plant intended the bird to do in return for a nectar reward.

When there is sufficient nectar at the base of the flower, hummingbirds hover for several seconds in place while they mop up every drop.  In this case, the bird’s head almost disappears into the flower as it inserts the bill all the way in.

It looks like the hummingbird is getting a pat on the head from the flower. In this case, the bird is indeed performing a vital service for the plant — moving pollen from one flower to another.

The bill of the Ruby-throated Hummingbird is the perfect size and shape for this flower.  When it dips its bill deep into the base of the flower, the top of its head brushes a fringe of anthers which deposit pollen on the surface of its head feathers.  Later when it visits a different flower, perhaps on a different plant, the pollen will be rubbed against that flower’s stigma, adhering to the sticky surface.  If it is the right type of pollen, it will germinate and a pollen tube will grow down the stalk supporting the stigma (the style) into the ovary. Sperm can then leave the pollen grain, swim down the tube, and fertilize the ova to begin the process of seed production.

The contact between the stigma of the flower and the hummingbird’s head is more obvious in this close-up.

Hummingbirds don’t care which flowers deposit pollen on their head, but the plants want to ensure that a particular flower receives pollen from a different individual (i.e., avoid self-pollination).  To maximize the potential for out-crossing, Cardinal flowers develop the male parts first — promoting pollen donation, and after a few days, the style and stigma emerge to protrude beyond the anthers — promoting pollen reception.

The anthers look like a white fuzzy fringe on the end of a gray stalk that sits above the petals and the opening of the flower.  The flower on the left shows the pink stigma just beginning to grow beyond the level of the anthers.  The flower on the right is newer and does not yet have female reproductive parts showing.

A mature Cardinal flower, with the stigma (and style) protruding beyond the anthers. This stigma could easily pick up pollen from the back of a hummingbird’s head.

Coevolution of cardinal flower structure and Ruby-throated Hummingbird sugar appetite has made this system a perfect fit for both.

The End.

Mighty mite

The summer blooms are at peak color in the garden, and there is a bouquet of red, pink, purple, yellow, orange, and white right now.  They are a month late, but finally we are seeing quite a few bees of all sorts and a few butterflies in the garden.  For the past week, another tiny visitor has been making the rounds of the red and orange flowers.

It’s hard to believe that these Butterfly weed flowers have enough nectar in them to make them worthwhile to this female Ruby-throated hummingbird, but she keeps coming back for more.

She sampled the flowers of the cup plant, but those were really duds as far as nectar is concerned, as were the bee balm and the coneflowers. But red cardinal flowers were promising, although only a few were open.

Of course the fall-back is to tank up on the sugar water in the feeder.

Ah, that’s better.

After all that feeding, it’s time for a rest, to process some of that liquid so she doesn’t have to carry it around.

You don’t often see hummingbirds perch, but if they do, chances are there will be some voiding of excess liquid occurring. Best not to stand under the tree where they perch.

Ruby-throated Hummingbirds weigh less than 4 grams, but can store up to 1 ml of nectar in their digestive tract while they process the nutrients in the nectar.  If we assume that 1 ml weighs about 1 gram (as plain water would), then the bird has just gained 25% of its body mass during its feeding bout, and it doesn’t make sense energetically to try to fly with all that extra weight.  The Hummingbird gut is specially adapted to absorb sugar and other nutrients in nectar across the lining very quickly and efficiently, removing more than 90% of the calories in the nectar on its first pass through.  Then the excess liquid in their diet can simply be excreted in just a few minutes.

Doesn’t that give them a sugar-high?  I suppose it does, but hummingbirds can also quickly metabolize that sugar and turn it into body fat, which they will use to keep them warm overnight.  Altogether an amazing metabolic marvel, the mighty mite.