Hummingbird Migration Update: May 11, 2000
Today's Report Includes
Latest Migration Maps and Data
Wow! Did the same strong south winds that blew monarchs so far north also help the hummingbirds along? Hummers have nearly reached the full extent of their breeding range! Only two Canadian provinces, Alberta and Saskatchewan, are awaiting their first Ruby-throats of the year. As you look at the data for Rufous hummingbirds, you'll see additional sightings in the Rocky Mountains--a sure sign that spring is reaching the higher elevations.
The recent sightings below are reminders that hummers arrive HUNGRY, and they know what they're looking for. You'll want to make sure your feeders are up, clean, and full!
Julie's Hummer is Back! Challenge Question #3 Solved
Last time Lanny Chambers reported his hummer's return on April 16. This time we can report the happy announcement from Julie, received May 5:
"From your Observation Post in Victoria Minnesota, I'm happy to report that I saw my first Ruby-throated Hummingbird today at exactly 1:27 p.m.! It's a sunny, very warm day (approximately 21 degrees above normal) with strong South, Southwest winds. (Previous arrival dates were 05/06/99 and 05/10/98.)"
Now let's wonder a little more about Team 7B's comment about the hummers making a lot of stops on their trip. You might be surprised to know exactly what's going on!
Feeding As Fast As They Can
Ecologists William Karasov, Duong Phan, Jared Diamond, and Lynn Carpenter were curious. They did a clever experiment and discovered the answer. The ecologists used radioactive isotopes as tracers to follow what happens to the nectar. They found that the hummers pass nectar through their digestive tracts very rapidly, in an average time of less than an hour. In this short time, they are able to extract about 97 percent of the sugars from the nectar. So why do they sit around "doing nothing" when they could be sipping more nectar? The hummers don't have room to take in any more nectar until the crop is partly drained! As the hummers perch quietly, they are emptying their crops--the parts of their digestive system that store food immediately after it is taken in. The birds apparently wait until the crop is about half empty, which takes about four minutes, before foraging again.
Hummingbirds forage only as often as necessary to keep up with how fast the crop can pass nectar into the rest of the digestive system; it wouldn't help a hummer to forage more frequently, but it would carry a high energy cost. Perching quietly while emptying its crop helps the bird conserve energy. What limits the rate of crop emptying is not clear. It may be how fast the intestine can absorb the sugar. It may be how fast the stomach can acidify what's in the crops, an important step in digestion. To sum it up, Jared Diamond and his colleagues say that hummingbirds may taking in energy as rapidly as their digestive processes permit.
Next time you're lucky enough to see a hummingbird perch, you'll know it isn't "doing nothing!"
Hummer Summer Chore List
Hummingbirds spend their summers in the north every year, but half of them--the females--don't get much vacation. Check out all the chores a female Ruby-throat must do before fall:
Tips for Summer With a Hummer
If you live near hummingbirds of any species, watch them this summer.
Spunky and Pugnacious
Any male or female hummingbird that enters another's territory gets chased. It doesn't even have to be a REAL hummer, according to Naturalist Sarah Dalton, who told us: "I hung a brightly colored stained glass hummingbird by the feeder one day. Hummer #1 showed up, tried to drive it off, and set it swinging. Hummer #2 showed up as if to say 'What are you doing here?' and they both got into it. Later, one of the hummers (?) came back and tried again to drive the stained glass bird away. When it found it wouldn't go, the hummer finally ended up sitting on the stained glass bird's back, trying to peck its eyes out!!! Pugnacious, yeah!"
Try This! Origami Hummer
Thanks to Sarah's directions, you can create your own origami hummingbird decoys and test their effect around your feeders. Start with a 4.25" square of green paper (the standard size for origami paper), follow the folding directions, and remember to put red glitter on the throat!
Get the Red Out
Hummingbirds are said to be attracted to the color red. That's the reason many people and manufacturers add red food dye to their sugar-water solutions for hummers and orioles. Because the liquid is red, some people also say they can more easily see when feeders need to be refilled. We want to point out that Journey North's "nectar" recipe does NOT contain any food dye. The reason is that using red food dye in sugar-water solutions has been a controversy. Here's the story:
In 1975 the United States Food and Drug Administration took red food dye #2 off the market because of its questionable safety for human consumption. (Some of you may remember that this also meant no red M&M candies for a while!) The Food and Drug Administration says all red food dyes now on the market have been extensively studied and approved safe for human and animal consumption, but no specific tests have been done on birds. Since this is an area that needs a lot more study before we can be sure red dye won't harm birds, many people choose not to use red food dye in their feeders. We want to be on the safe side for the health of the birds, and we hope you will too. Also, change the "nectar" in your feeder and wash the feeder at least once a week to keep the nectar safe for the birds. You'll find our "no-red" sugar-water recipe and other hummer helps at:
Legends and Final Words
You've shared and heard a lot about these tiny, feisty, fearless fliers called hummingbirds. Some time ago, Lanny Chambers received this story from Peter Guanikeyu Torres, President and Council Chief of the Taino Indigenous Nation of the Caribbean and Florida:
"The Taino Native American people were the first people to meet Columbus in 1492. The Hummingbird is the symbol of the spreader of life on the Earth. It also symbolizes the rebirth of the Taino Indian Nation of the Caribbean and Florida. Our Warriors are called Colibri Warriors (Hummingbird Warriors), as the Hummingbird is very peaceful, yet protects its own homeland with the heart of an eagle. Our history tells us that hummingbirds were at one time small flies that Agueybaba, the Sun Father, transformed one day into little birds."
Just one more Hummingbird Migration Data Report remains for spring 2000. We hope you enjoyed learning about these avian jewels with the hearts of eagles as much as we enjoyed learning about YOUR hummingbird migrants! See you next year!
Response to Challenge Question #11
Last time we asked, "Why do you think Rufous hummingbirds reach the Canadian border BEFORE they reach Idaho?"
The places that hummers arrive near the Canadian border are near the coast. The ocean keeps coastal land warmer than inland places in winter and spring. Idaho is not only inland, but also mountainous. Land at high elevations is colder than land at lower elevations. So the hummers wait to invade Idaho until they can be sure spring will really be there!
Response to Challenge Question #12
"Why do hummingbirds move northward so gradually, for 8-10 weeks from March to mid-May, while orioles push northward during a single week in late April or early May?"
Hummingbirds eat a wide variety of tiny flying insects swarming about the tips of newly budding branches, and they also feed on the sap from sapsucker borings. So even if the weather is unpredictable, they can count on plenty of food when they first arrive. Orioles require much larger insects, such as caterpillars, which don't hatch until buds emerge. So orioles must wait until leaf-out. By then, their hormones are urging them forward so they can set up their territories and start nesting, so they move north FAST!
Response to Challenge Question #13
"What reasons might explain the variation of 14-31 days in the Ruby-throat nestling phase?"
Michael sent this answer: "We think that the reason the ruby-throated hummers nest longer because of the climate along the eastern portion of the U.S. Spring may take longer to arrive than in areas such as California that have milder climates (where the Rufous hummers are). The hummers nest longer so that they have more time to develop and protect themselves from any late cold weather that may occur." (firstname.lastname@example.org)
Our compliments for good thinking! Experts say there is no clear explanation yet, but indeed it may have to do with varying weather conditions and availability of food.
The FINAL Hummingbird Migration DATA ONLY Report will be posted May 18.
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