Grade Level:
Elementary, Middle School, High School
Ecological Concepts: Behavior, Preferences, Competition
Arizona Science Standards: Science as Inquiry; Life Science
Materials:
1) Cane sugar
2) Water
3) Hummingbird feeders
4) Bowl, spoon and heat source for mixing sugar and water
5) Measuring cups
6) Writing/drawing materials
7) Colored Paper
BACKGROUND
Hummingbirds and many insects feed on the nectar (sugar fluid) of
flowers. This nectar provides food for the animal and the actions
of the insect or bird often pollinate the flower. Pollination is the
transfer of pollen from one flower to another flower of the same species.
The pollen is the male genetic material of a plant needed to fertilize
the ovules (eggs) of the flower in order to produce seeds. Flowers
come in many sizes, shapes, colors and levels of sugar in their nectar.
Hummingbirds usually feed on a flower one bird at a time. Male birds
are particularly territorial about "their" flowers. Even at a large
artificial feeder only one male hummingbird will feed at a time. Females
can usually feed along with males or other females.
GUIDED INQUIRY
Observation/Exploration Period: Observe hummingbirds
in the habitat. Some behaviors to look for are where the hummingbirds
go, what flowers or feeders they go to, how long they feed at a flower
or feeder, and where and how long they rest.
Group Discussion and Question Period: What causes a hummingbird to be attracted to a flower? Do hummingbirds prefer some flowers to others? What flowers do they go to? What are the colors, sizes and shapes of those flowers? How much time do they spend at each flower?
Important aspects of guided inquiry are encouraging students to
generate multiple
hypotheses, and letting students make decisions about
what data are important and create their own data sheets.
Keeping these ideas in mind, the sample in the box below illustrates
how ONE OF MANY possible investigations around this topic might develop.
Sample
Hypothesis: We need to set up a fair test of what
attracts hummingbirds to certain flowers. To do that, we want
to test one characteristic, or factor, at a time. A single factor
would be one like color. Our hypothesis might be, "Hummingbirds
are more attracted to red flowers than blue flowers because
they can see red better." Or, "As the color red increases,
hummingbirds are more attracted to the flower/feeder."
Sample Experiment Design: We set up feeders
of different colors to test which color, if any, the birds prefer
to eat from. The color of the feeder is the independent
variable. Several feeding stations need to be set
up to be as exactly alike as possible, except for the one factor
being tested, color. This way the experiment is controlled
as much as possible. Set up a minimum of two feeders of each
color being tested so that there is replication
of the experimental
units. Fill each feeder with the same amount and
concentration of sugar water. (Use 1/4 cup sugar to 1 cup hot
water. Stir to dissolve the sugar, then let cool.) Wrap and
tape colored paper around the feeder. (Do not use food coloring
in the water— it could harm the birds.) Hang all the feeders
at the same height above the ground, in the same general area,
but at least 3 meters apart. All should be in either the sun
or the shade to be consistent. Hang all the feeders at the same
time, and then move away to some place comfortable, but within
easy view of the feeders. Let the feeders sit for five to ten
minutes before recording data so the hummingbirds in the area
have time to find the new feeders. Groups of two-three students
can watch individual feeders and record data.
Sample Prediction: More hummingbirds will visit feeders that are red than any other color.
Record Results: Record the number of visits
to the feeder within a pre-determined time period such as fifteen
minutes. You could also do multiple observation periods over
several days. Use tally marks to keep track of the number of
visits. The data recorded (number of visits to the feeder) is
the dependent
variable.
Sample Analysis of Data and Presentation: At
the end of the allotted time period, group all the data on a
large sheet or board. Calculate the average
number of visits to each feeder color. An average
is the number of visits to all feeders of one color divided
by the number of feeders of that color. Example: ten visits
to the two blue feeders would be an average of five visits.
Make a bar
graph with the average number on the vertical axis
and the feeder color on the horizontal axis.
Discussion: Was your hypothesis supported? If yes, go on to test other hypotheses. If not, why not? What did happen? Why? This is a great opportunity to revise your hypothesis and do another test.
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MORE:
(1) Elementary:
(a) Other possible factors to test are flower shape
and sugar concentration. Keep in mind that in nature multiple factors
are often not separate, but work together. To discover this, however,
we first test each factor separately. For the sugar concentration
test make solutions that are 1/8 cup sugar to 1 cup water and 1/2
cup sugar to 1 cup water, as well as the normal concentration of
1/4 cup to 1 cup water. These are 1/2 normal and 2 times normal
concentration.
(b) Observing two species of plants with the same
color flower but different shapes can test preference for flower
shape. Another way would be to buy or make flowers to put on hummingbird
feeders that are of the same color but two different shapes (tubular
versus flat and round).
(2) Middle School:
(a) Find the mean,
median,
mode
and range
of the data.
(b) Record how many times two or more hummingbirds
attempt to use the same feeder at the same time, and if both birds
feed or only one. This will be an indicator of competition
for the food resource. If possible, determine the sex and species
of the birds.
(c) Use stopwatches to record how long each bird
stays at a feeder. Or record length of visits as short, medium and
long.
(3) High School:
(a) Calculate the variance
and standard
deviation of the averaged data. |
