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The EFM Notebook

Photo by Robert Badger and Nita Winter

A Commentary on What’s New and Newsworthy

by Susan Holloway | Bio

NOTE: EFM Notebook is best viewed horizontally, when using your phone.                      EFM Notebook Index

Hummingbirds: The Hardest Working Pollinator of the Bird World

28 Jun 2021 4:44 PM | Gayle Marsh (Administrator)

Today we are talking about hummingbirds. Let’s start with a quiz.

True or False?

  1. Hummingbirds are endangered in California.
  2. A hummingbird egg is the size of a jellybean.
  3. Hummingbirds can fly upside down.
  4. A hummingbird’s tongue wraps around the inside of its skull, encircling the eyes.

Read on to find out how you did on the quiz!

Hummingbirds are endangered in California: FALSE!

Human habitation and roads can fragment and degrade natural habitat. But the Anna’s hummingbird is thriving, especially in urban and suburban areas! Whaaaat?! It’s mostly because they happily make use of the nectar in our flowery landscaping, and they very much enjoy the nectar feeders that we often put in our yards. 

Male Anna’s Hummingbird Female Anna’s Hummingbird Male Black-Chinned Hummingbird 
     

I think most of us would agree that hummingbirds are beautiful and amazing creatures. But what do they do besides looking great? Answer: they are great pollinators!

I confess that until now I thought that lots of birds were pollinators. But the reading I’ve done for this post has helped me realize that very few of them perform this vital function. In the US, it is the hummingbirds who are the premiere bird pollinators. The species that Californians see most commonly is the one that lives here year-round: Anna’s hummingbird.

Originally found only on the Pacific slope from Baja California to San Francisco, the Anna's hummingbird has expanded its breeding range north to British Columbia and east to Arizona and even Texas. They are plentiful in Marin, but also do well in more urban areas. In San Francisco, you can see them in the Presidio but also downtown, for example at Sue Bierman Park near the Ferry Building. 

California is also a rest stop for migrating Allen’s, Rufous, and Black-Chinned hummingbirds. (Hang on, does anyone really think that hummingbirds actually have a chin?)

A hummingbird egg is the size of a jelly bean: TRUE!

   
         

No one would expect Hummingbird eggs to be big. These are the smallest birds in the world, weighing little more than a penny. But let’s take a minute to appreciate their development from avian Tic Tac to independent bird. 

First the female constructs an intricately woven nest from plant down, mosses, and carefully placed lichen. She uses spiderweb silk to line the inside. The spiderweb silk can expand as the chicks get bigger. That is so cool! 

Click here to see more beautiful images from Tara Lemezis 

The female sits on the eggs until they hatch and then cares for the blind, bald babies, darting out every 20 minutes and returning to offer regurgitated nectar and partially digested insects. 

In 18-23 days, hummingbirds begin taking short forays out of the nest, and the mother focuses on helping them learn where to find nectar and how to forage for insects. And then they are off!

Hummingbirds can fly upside down: TRUE!

Flying backwards? No problem!

Upside down? No big deal!

   

When it comes to movement, I can’t think of a more agile creature than the hummingbird. Their seemingly effortless athletic skill is almost annoying!

A hummingbird can rotate each of its wings in a circle, and is the only bird that can fly forwards, backwards, up, down, and sideways or hover in place. They’re capable of flying up to 60 miles per hour, their wings beating 80 times per second. Hummingbirds can even fly short distances upside down, a helpful trick when they are being attacked by another bird. 

How can they do all this? Well, I can’t get deeply into hummingbird physiology here. But I will make an exception for one truly amazing thing – the construction of their tongues…Read on!

A hummingbird’s tongue wraps around the inside of its skull: TRUE!

  Hummingbird eating mosquitoes  
Before we geek out on hummingbird anatomy, let’s review the basics about what these little birds need to consume in order to keep up all their activity

Hummingbirds feed on nectar from flowers and feeders, as well as on small insects and spiders. They catch flying insects on the wing and they pluck spiders and trapped insects from spider webs. They also visit sapsucker holes and feed on sap and insects attracted to the holes. 

Hummingbirds need a lot of calories to fuel themselves and must eat several times their weight every day. They feed on nectar about 5-10 times per hour for 30-60 seconds each time. They have good eyesight, and they can see brightly colored red and orange flowers better than their insect competitors. 

Figure 1. The hummingbird tongue as described in research by Alejandro Rico-Guevara 


   

Given the exigency of their quest for nourishment, they are very lucky to have the most amazing tongues in the animal kingdom. If you asked me a month ago how hummingbirds get nectar from plants, I would have guessed that they lap it out like a dog or suck it up through a straw-shaped tongue. I would have been wrong.

As you can see in Figure 1, hummingbirds have a long thin tongue that darts into the flower's corolla for nectar. When retracted, the hummingbird’s tongue is curled up in the skull and encircles the eye cavity. They share this feature with woodpeckers, whose tongue mitigates potential brain damage caused by incessant pecking. 

But the precise mechanism by which the tongue captures nectar has been the focus of much scientific debate. Until recently, ornithologists thought the tongue functioned like a tiny, static tube, drawing up floral nectar via capillary action. However, ground-breaking research conducted by Alejandro Rico-Guevara at the University of Connecticut has shown that the tongue tip is a dynamic liquid-trapping device that changes its configuration and shape dramatically as it moves in and out of fluids. 

You can get a sense of his findings from the lower four panels in Figure 1. The tongue starts out in a tube-like conformation. The two tips are close together. When the tongue touches the nectar, little structures called lamellae unfurl and the tips separate. When the tongue withdraws from the nectar, the lamellae roll inward, trapping the nectar as if into little cups. The tongue goes back in the beak with the lamellae compressed together to contain the nectar.

Whether or not you are a science nerd, I guarantee that you will enjoy this brief PBS video on Rico-Guevara’s work on hummingbird tongues as well as this other short one on the same project.


What Can You Do to Attract Hummingbirds to Your Yard?

The Anna’s hummingbird is flourishing around here, but it can never hurt to expand their options, particularly in a drought. Also, it’s fun to watch them. Here are some ideas for what you can do to support your local hummingbirds. 

Provide Nourishment

 
California fuchsia (Epilobium canum)
 
   

The topic of hummingbird feeders is somewhat controversial, but my reading suggests that red plastic feeders filled with sugar water are OK. Just don’t add red dye to the nectar and be sure to keep the feeders filled and clean. You don’t need to buy nectar; it’s easy to make it because the only ingredients are sugar and water. Here’s a recipe from the National Zoo. 

The California Native Plant Society gives the feeders a tepid endorsement, noting that they “provide instant gratification” (I assume this means for the birds and the birdwatchers) but emphasizing the importance of also providing nectar-rich native plants that sustain hummingbirds without “additional human input.” 

Go Native if You Can

You can significantly improve the habitat in your yard by removing nonnative and invasive plants. Two that are quite problematic in Marin are English ivy and the less known Japanese knotweed.

One of the best native plants for hummingbirds is the California Fuchsia, a perennial with lots of bright red flowers in summer and autumn. This plant will readily self-seed, and also spreads by rhizomes. 

Keep Things a Bit Messy 

As I have recommended in the past, it’s always good to go for variety and dishevelment rather than a pristine look in your yard. Piles of brush, sticks or yard refuse offer shelter, nesting habitat, nest-building materials, and insects. If you can, maintain a variety of native plants of varying sizes and growth patterns and with varying schedules for fruiting and leafing. 

Don't Forget the Water!

Providing water is particularly important in summer and especially during a drought. Birds will drink it and they can also use it to cool off. From time to time, hummingbirds need to clean pollen and nectar from their feathers and beak, but they have very short legs so they don't like to bathe in deep water. They prefer rubbing against a wet surface, or flying through moving water such as a sprinkler. If they do venture into still water, it has to be less than a centimeter deep. For drinking, they like to sip from flowing water, or drink from little drops such as a raindrop on a leaf.

Keep Your Cats Indoors

Domestic cats kill billions of birds every year. So keep your cats inside, and do what you can to keep stray cats out of your yard. Here are some ideas for discouraging interlopers, which are also depicted in the image below. 

Avoid Pesticides and Rodenticides

Toxic chemicals can kill birds or cause severe problems like reduced appetite and eggshell thinning. Also, the birds need bugs to eat! 

Prevent Birds from Smacking into Your Windows.

The thud of a bird hitting the window is pretty sickening. As many as 1 billion birds die each year from collisions with windows. Try putting stickers or tape on the problematic windows to make them more visible to birds. 


FINAL THOUGHT: Give some love to the character actors of the bird world

California Towhee
Photo credit Becky Matsubara
 
   
I think of the hummingbird as the Meryl Streep of the local bird ecology. Brilliant and beautiful, versatile and charismatic. But where would we be without the wonderful character actors in our films, the Kathy Bates’ and Cloris Leachmans? We need everyone’s talent to create an effective ensemble. With that in mind, I want to give a shout out to the most ordinary character actor of our local bird population: the California Towhee.

Here is Jack Gedney’s description of the California Towhee:

California towhees are large, chunky and clumsy birds, almost uniformly plain brown except for a rusty patch under their tail… Each yard typically hosts one pair of towhees who will remain on site all year round, staying in touch with simple, “low battery warning” contact calls. Also known for entering open house doors and attacking their reflection in mirrors. So, they’re plain, unmusical, and unintelligent. But everyone loves them!” 

Much as I support the California Towhee, I must take issue with the final comment, as their incessant monotonous chirping has been known to drive some people in my family insane. 

And, OK, comparing Kathy Bates to a California Towhee does not seem at all fair to Bates, who is brilliant in her own right. But I hope to make the point that we easily fall in love with the scary, smart, beautiful, or ultra-cute animals, but let’s be there for the non-flashy ones too.


That’s it for this installment of the EFM Notebook. As always, please feel free to contact me with questions, comments and suggestions: susanh@marinefm.org.


As usual, thanks to Rob Badger and Nita Winter for sharing Rob’s beautiful image on the Notebook banner. Check out their award-winning book on wildflowers or visit their website to see more birds, flowers, and other images.




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