Sunday, August 11, 2019

Evolved For Each Other: Bird and Flower


Like the glass slipper that fit the princess, this flower fits this bird. As you will see, in photos. 

Insect eyes don’t perceive red. Blue or yellow or white blooms are designed for them. Bugs have pollinated for more than 200 million years. Nectar-feeding hummingbirds have been in action for only 30 million. (It took a while for dinosaurs to get this small.)

Red flowers are for hummingbirds. In the photos below, the magic of hummers and plant sex is revealed. The pollen (male) of cardinal flower travels to the (female) ovaries on hummingbird heads. I can’t find any published reference to this precise adaptation, but if you doubt, look below. Each separate flower is topped by a long tubular structure that ends in gray and white reproductive organs. To appreciate the sequence of five photographs below, watch that structure in relation to the bird's head.





  
Yes - like the glass slipper that fit the princess, this flower fits this bird.

Lisa Culp Musgrave got these great photos at Somme - only because we restored the tiny birds' red-flower habitat. Until 2012, no hummingbirds had nested in Somme Woods for decades. Then we hacked out the invasive brush and gathered hundreds of species of rare seeds. Among those species were many that were crucial for butterflies, bees, fungi, and other interdependent species. But it was the red flowers that the hummers had waited for. 
Cardinal flowers, great blue lobelias and sweet black-eyed Susans
bloom by the hundreds where brush was cut and seeds were planted.
Adaptation: it is “costly” for a plant to develop a pollinating relationship with hummingbirds. Cardinal flower (Lobelia cardinalis) is the only one of the 19 lobelia species in the eastern U.S. that has done it (other lobelias are blue). In exchange for moving pollen to ovaries, the bird requires a great deal of nectar and a specialized form of sugar, and the robust ruby-throat is pretty rough on the plant, compared to butterflies or bees. Cardinal flowers thrive in isolated wetlands; hummingbirds fly long distances to find red flowers. Perhaps that's part of why they need each other. 

Somme has six true-red, hummingbird-pollinated wildflower species, spanning the seasons. After spring's scarlet painted cup and columbine - there's prairie lily, Michigan lily, and an occasional fire pink in summer. But the crowning glory of the hummingbird year is August and September's cardinal flowers.

Hummingbird wings beat 55 times per second when hovering, 61 when slowly backing up, and at least 75 times per second when zooming forward. They have a high metabolism.

In addition to nectar, ruby-throats also eat large numbers of tiny insects and thus no doubt regulate and enrich the complexity, health and balance of the woodland ecosystem. They also perform. In an opening among the trees, the male performs dramatic U-shaped flights, something like a skateboarder on one of those U-shaped ramps - but way faster - up to 60 miles per hour. Then, the female, if she decides he's her choice, hums over to face him and they fly up and down, together in aerial ballet. Their tiny nest of lichens, spider silk, and plant down, often on a horizontal tree branch over a stream, will hold two eggs.

We've witnessed that spectacular drama as Somme. Lisa has not videoed it, but she has photographed some flirting. It's then you see the male's ruby throat to best advantage.
That throat is intense - when focused in your direction.
But move a little to one side of the other, and it goes black. 
Here, the female is on the left, pretending not to notice.
The male is on the right, focusing the red of his throat on her!
She notices, a bit. He notices, a lot. The camera still sees his throat as black.
A dance: they change places, hover, flit back and forth, often too fast to follow, and then alight again. 
These photos were taken at Somme by co-steward Lisa Culp Musgrave, who had a splendid time of it. The female in the pollination close-up photos got quite tame, as Lisa sat very still in a quiet woodland glade. Except for her trigger finger.

Thanks to Lisa for great photos. Thanks to hundreds of like-minded volunteers for restoring great habitat. 

References: 

http://www.illinoiswildflowers.info/wetland/plants/cardinal.htm
Ehrlich, Paul R. David S. Dobkin, and Darryl Wheye. 1988. The Birder's Handgook

The dramatic (to us at least) first report of hummingbirds in Somme Woods was posted in 2013.