Redwing Blackbirds
Some
ornithologists believe that red-winged blackbirds are the most abundant birds in
North America. They spend the breeding season in marshes and wetlands with
cattails--the more abundant the cattails, the more redwings can breed. And in
the Dakotas, there are a LOT of cattails--about 750,000 acres of cattails in
North Dakota alone. Most of these aren't native plants. They belong to a
narrow-leafed variety that invaded the Dakotas in the 1940s, and their
proliferation has contributed to the population explosion in
redwings.
Just how many redwings are there? It's impossible to be precise, since there is no way someone can check every single place where they might be and count them all. Back in the winter of 1974-1975, scientists estimated that 190 million redwings were wintering in the U.S. Since then, redwings have declined in some areas where wetlands were filled, and increased in other areas where cattails have flourished in ponds. In North and South Dakota, the redwing population has increased about 33% from 1996 through 1999.
In any given year, about half of all redwings die. So how can their overall population increase so dramatically? Females usually start breeding their second year, and each female produces about 3-5 eggs, which they raise with the help of their mate. That keeps the males VERY busy, because each male who succeeds in obtaining a territory mates mates with 2-6 females, and sometimes even more! If a nest fails, females will often renest the same season. Overall, one study found that females produce a maximum of 24 surviving babies during their lives, and one male produced 176 fledglings on his territory. That's a lot of new red-winged blackbirds!
One thing that has helped them is the increase in cattails that are growing in Dakota wetlands. The cattails are actually not a native variety, and as their population has exploded, the redwings that nest in them have increased to fill the added habitat.
As beautiful and exciting as redwings are when they
return to their marshes in spring, they cause problems for farmers, especially
when their population gets very high. In 2001, the U.S. Department of
Agriculture proposed a program to poison 6 million redwings. The U.S. Fish and
Wildlife Service refused to grant the proposal, but farmers are having trouble
trying to figure out how to deal with the overabundance of red-wings.
In 2001, the U.S. Department of Agriculture's Animal and Plant Health Inspection Service (APHIS) proposed a three-year plan to kill 6 million Red-winged Blackbirds in North and South Dakota by setting out poisoned rice to kill them during spring migration. The U.S. Fish and Wildlife Service refused to grant the permits required to kill these birds during spring, when the red-wings are not causing damage. However, during late summer and fall when red-wings are causing damage to crops, farmers are allowed to kill them. This lesson will provide you with background to understand what the problem is and one proposed solution, and will show you how governmental agencies made their decision about it. Students will learn how scientists and governing agencies collect data, determine how serious a problem is, and make decisions about possible solutions.
Imagine that you are a beautiful three-year-old male red-winged blackbird. You arrived on your marsh on March 1, while ice still covered most of the pond. You set up a territory and defended it against all the other males, attracted three females and helped each of them to raise four babies. A crow flew in and stole three babies from one nest, and one baby died from a parasite, but you've successfully fledged eight babies. Two of the females nested again, and again you helped them raise their babies. Raccoons killed all the babies in one of these nests, and a crow killed two in the other, but two other babies survived. Whew! You've been busy!
Now it's the end of July and you're ready for a well-deserved rest. You join a huge flock of blackbirds and set off for a new feeding habitat--fields where you can find seeds to replenish your stores of fat after the hard breeding season and before winter.
Now imagine you're a farmer. This spring and summer you spent hundreds of hours planting a crop and tending to it, and watched it ripen over the summer. The money you will earn from the crop will go to pay your mortgage payment on your house, buy food and clothes for you and your family, and pay for many of your other needs. But just before you're ready to harvest it, in fly thousands of blackbirds. You desperately try to scare them off, but they keep coming back until they've eaten most of your crop. How would you feel?
Blackbird Population Explosion
From 1996 to
1999, the red-winged blackbird population in the Dakotas rose 33%! That's an
enormous increase. During spring and the breeding season, even so many redwings
don't cause problems for humans because they eat mostly insects. But once the
baby blackbirds have fledged, families join huge flocks and switch their diets
to grain and seeds. During the day they feed in fields, and they spend the night
in thick stands of cattails, in "roosts" that can number over a million birds.
Because they do most of their feeding near the roost, farm fields farther than 5
miles from roosts are usually fairly safe from blackbird damage.
How Big Is the Problem?
Every year, sunflower
growers throughout the U.S. suffer losses to their crops. On average, they lose
Over most of the nation, loss to blackbirds is negligible, but in North and South Dakota, they lose about 1 - 2% of the crop every year. This sounds negligible, too, but a few farmers lose an enormous portion of their sunflowers. Every year about 500 growers lose more than 25% of their crops to blackbirds. But interestingly, a recent APHIS study estimates that Red-winged Blackbird populations have increased by 33% from 1996 to 1999 while damage to sunflower crops has stayed about the same.
Different Solutions
Here are some of the
solutions some people have tried or considered:
How the Government Made the Decision
Two
U.S. government agencies had important roles in this issue. The U.S. Fish and
Wildlife Service is charged with protecting native American birds and other
resources, to ensure that they will last for future generations. The U.S.
Department of Agriculture (USDA) is charged with helping farmers to succeed, in
order to ensure healthy food supplies for all American. Farmers are allowed to
kill blackbirds that are causing damage, if they catch them in the act. The USDA
is allowed to poison birds that are causing problems, too. But without permits
from the U.S. Fish and Wildlife Service, the USDA is NOT allowed to poison birds
that are not causing immediate damage. This red-wing proposal was to bait and
kill migrating birds that were not causing damage.
In its findings, the US Fish and Wildlife Service decided against the permits because
Meanwhile, farmers who are losing their crops are strongly petitioning the U.S. Department of Agriculture and APHIS to do something about the blackbird problem, and many of the farmers feel that the only solution is to kill as many blackbirds as possible. The U.S.F&WS continues to conduct studies and may give their approval to some poisoning projects if studies indicate that the blackbirds likely to be killed in these projects are from the same population that feeds in the sunflower fields in fall, that other species are not likely to be killed, and that the project has at least some likelihood of solving the problem.
For this role-playing game, some students as individuals or teams should take the following roles, and research and brainstorm about what their needs and wishes are, and how they could go about getting their way. Then the players must present their viewpoints, and the rest of the class will listen to the different points of view and make a decision about what they'd do to solve the problem. These are the roles. You may add more if you like.
To help students research their roles, they might want to check out:
Discussion and Journaling Questions:
Exposing All Sides
Guide to Making Informed Opinions
Where do you stand on an issue? How do you come to make your stand and form
an opinion on any particular topic of controversy? This activity provides
opportunities for paraphrasing, making inferences, and building opinions using a
cognitive organizer called a PMI.Use it for a guide to take you through a
process for making an educated stand on any issue/debate of current interest and
study.
Materials:
Activity:
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P/+ |
M/- |
I/? |
Extensions:
Choose some related
activities: