Robin Migration Update: April 22, 1998
Today's Report Includes:
Happy Earth Day!
All across the continent, from Alabama to Alaska, robins are singing today. But if it weren't for Rachel Carson--and her courage--the songs of spring wouldn't be what they are today.
Rachel Carson wrote a landmark book called "Silent Spring". In it she told the world about the dangers of chemical pesticides. She warned that many were poisonous and had spread throughout the environment. Even the backyard robin was threatened. One example: Beginning in the spring of 1955, as each wave of migrating robins appeared on the Michigan State Campus, they would die within a week. People first suspected a disease, but after several years they concluded that, "in spite of the assurances of the insecticide people that their sprays were harmless to birds, the robins were really dying of insecticidal poisoning."
This full story is told in Silent Spring. Find a copy and then see if you can answer this question:
Remember: When you hear a robin singing in your backyard today, you have Rachel Carson to thank!
According to observers in the far north, the robins have almost reached the end of the road. This morning, Bill
Shuster wrote from Seward:
Still Waiting for Robins....
"Robins DO go further north," writes Kipi Asicksik. "Shaktoolik is a small Eskimo village on Norton Sound (64.20N, - 161.9W). We have robins every summer. They are not plentiful, but they come. (firstname.lastname@example.org)
No word yet of robins arriving in Fairbanks, and Kodiak has been waiting for 10,000 years for robins to fly the mere 15 extra miles to their island. Richard MacIntosh explains:
"Islands tend to have fewer plant and animal species on them than adjacent mainlands. This is definitely true on Kodiak where we are lacking several species of birds, including robins (and White-crowned Sparrows and flycatchers) that are common on the adjacent mainland.
"In the last glacial period, some 10,000 years ago, robin habitat was probably enirely eliminated here by ice and snow. Why it has taken robins thousands of years to invade post-glacial Kodiak is a mystery to me. We are, however, on the verge of having them nest here, as we see and hear an occasional bird singing in the spring. All its going to take is for a female to find one of these singing males they will be on their way to populating (or perhaps re-populating) the island. I'm going to ask a bird expert in Anchorage to respond to you if she has any better ideas on why robins might be rare here."
Finally, from her village at the tip of a peninsula on the Chukchi Sea, Sheila Gaquin reports from Point Hope, Alaska, "We have never seen robins in our area." (email@example.com)
You must be wondering why!
This range map shows the northern limits of robin nesting territory. Challenge Question # 11 asked, "Why don't robins go even further north? What factors influence the northern limits of their nesting range?"
From Isaac in Ms. Brundage's 5th grade class in Penobscot, ME: "Robins don't go further north because they cannot get worms in ice and snow-covered country and they don't like barren lands." (firstname.lastname@example.org,me.us )
Rose Wong from Iselin Middle School also thought this through: "We don't think robins go further north than places that reach the 36 degree isotherm.. When you go into the Northwest Territories and further north, you are in a Tundra Biome where the ground is permafrost. The factors that influence the northern limits of their nesting range are cold temperatures and no food. It is so cold, that the ground is permanently frozen. Worms could not dig out here and plants cannot grow. Without plants, there are no berries and the insects that eat the plants cannot live. Therefore, the robin could not survive." (email@example.com)
"We see robins in the tundra near Seward, but suspect all nesting is lower in alders or trees in lower elevations," notes Bill Shuster. (firstname.lastname@example.org)
Jeff Bouton of Fairbanks, Alaska suspects this is the case across Alaska:
"Robins are both ubiquitous and successful in nearly all habitats here in Alaska. If you look at the range map for this species in the National Geo Guide, you see they occur throughout the state except for the northernmost portion. This is the Arctic Coastal Plain and, as the name implies, there are no shrubs to speak of here.
"The shrubbery that is present is spread out, and usually quite short in height. While I've never seen Robins in my few visits to the Coastal Plain, I would not be surprised to see one here. They are regular through the north slope of the Brooks Range along stream beds and on the tundra alike where there are small willow patches.
"It seems that if there is food available and more than two or three willows (up to 4-5 foot in height) together, Robins can successfully nest.
"While they are not abundant in this habitat they are certainly regular and to be expected in nearly all habitats throughout the state. In my mind, it is simply the lack of taller willows that limits their breeding.
"Despite this there are no roads through most of Alaska, and places like the Arctic coast are extremely difficult and expensive to visit. As a result, our knowledge of the distribution of many species is inadequate to say the least, and I fully suspect the American Robin breeds all the way to the coast where it can find a toe hold. They are an extremely successful species. Hope this is helpful."
How to Respond to Today's Challenge Question
1. Address an e-mail message to: email@example.com
The Next Robin Migration Update Will be Posted on May 5, 1998.
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