Relationships between migrating monarchs’ flower color preference, monarch wing
loading, and the monarchs’ preference for native or non-native flowers in North
Texas
Crystal Buchko (R), Tiffany Harrison (C), and Joylynn S. Woodruff (L)
Decatur High School
Decatur, TX
Abstract | Introduction |
Methods | Results | Discussion
| Acknowledgements | Literature Cited | Authors | Research Projects
We investigated the following questions: Is there a difference in flower preference,
is there a correlation between flower color preference and wing loading, and do
migrating monarchs prefer native or non-native flower types? The tests for flower
color preference indicated that migrating monarchs do indeed have a flower color
preference, with that preference being white. The tests for flower color preference
and wing loading suggested that relatively heavy and light butterflies do not differ
in flower color preferences. Finally, the tests for preference of native or non-native
flower types did not show that migrating monarchs have a preference. These results
offered us insight into the preferences monarchs have during their migration from
the northern United States and Canada, to their over-wintering sites in Mexico.
These tests should be repeated to verify the results, and perhaps another study
should be included considering the sex of the monarchs.
Introduction
Nutrition is a key factor in the survival of migrating monarch butterflies. As they
migrate southward, the vegetation changes drastically with the changing climate.
Therefore, migrating monarchs probably do not become acclimated to flowers native
to a specific area, but they can develop a color preference (Kondo, 1970).
Further research indicates that butterflies are attracted to brightly colored objects,
and that males are prone to nectar on white flowers whereas females prefer colored
ones (Gynup, 2000). Our objective is to determine if there is a correlation among
the migrating monarchs’ flower color preference and their wing loading (the
mass of the butterfly in relation to its wing length), and also whether monarchs
prefer native or non-native flowers in North Texas.
In a preliminary experiment, we observed that some migrating monarchs nectared from
many flower colors while others appeared to nectar primarily on one color of flower
(team observation). We used wing loading in relation to flower color preference
because we thought that skinny butterflies might not be choosy because they were
hungrier, whereas fat butterflies could afford to be choosy about which flowers
they nectar from. To determine our outcome, we observed the feeding habits of adult
monarchs on diversely colored native and non-native North Texas flowers while measuring
the wing loading of the individuals. Our observation was conducted in a laboratory
setting using monarch butterflies raised from eggs with no prior exposure to flowers.
The questions we investigated and the hypotheses for each follow:
- Is there a difference in flower color preference in migrating monarchs?
- Ho: Migrating monarchs have no flower color preference.
- Ha: Migrating monarchs have a flower color preference.
- Is there a correlation between flower color preference and the wing loading of
migrating monarchs?
- Ho: There is no correlation between the flower color preference and
the wing loading of migrating monarchs.
- Ha: There is a correlation between the flower color preference and
the wing loading of migrating monarchs.
- Do migrating monarchs prefer native or non-native flower types?
- Ho: Migrating monarchs have no preference for native or non-native
flower types.
- Ha1: Migrating monarchs prefer native to non-native flower types.
- Ha2: Migrating monarchs prefer non-native to native flower types.
Methods
We started our project by identifying native flowers in bloom. From the schoolyard
we obtained four different flowers with a similar structure: a purple Slender Vervain
(Funnelform epigynous), a white Plains Yarrow (Achillea lanulosa),
a yellow Partridge Pea (Chamaecrista fusciculata), and a yellow Berlandier’s
Golden Aster (Chrysopsis berlandieri). We then located four non-native flower
types (with as similar structure and color to the native flower types as possible)
which included a purple New England Aster (Aster chilensis), white Baby’s
Breath (Gypsophila paniculata), a yellow sunflower (Helianthus annuus),
and a yellow chrysanthemum (Anthemideae parthenium). Equal numbers of each
color of flower, for a total of about 32, were placed in four vases in the observation
hood of our classroom. The vases were alternated with native and non-native flower
types in one row across the middle of the hood (Pictures 1 and 2).
The experimental butterflies were donated by Mississippi Heights Middle School in
Sauk Rapids, Minnesota and sent to Texas as eggs. The butterflies were allowed to
mature, and as adults were allowed to nectar on sponges with 10% honey water for
five minutes per day until 13 adults had emerged. When the adults emerged, butterflies
were marked and wing loading was determined by dividing the butterfly mass by wing
length. Six butterflies were determined to be of lower wing loading .056-.092gr/cm
(Babies) and seven butterflies were determined to be of higher wing loading >.092-.130gr/cm
(Bubbas).
We placed all 13 monarch butterflies into the hood at one time, and observed the
butterflies nectaring. (We counted a butterfly that stuck its proboscis out and
into a flower as nectaring.) For fifteen minutes once each day for three consecutive
days, each butterfly was monitored for the number of nectaring visits on specific
flowers. After 15 minutes of observing, the butterflies were allowed to nectar on
fresh honey water sponges for five minutes. All butterflies successfully nectared
from the sponges. We performed Chi Square tests to determine if the monarchs had
a color preference, if there was a relationship between color preference and wing
loading, and if there was a preference for native or non-native flowers.
Pictures 1 and 2. Experimental set-up.
During the three days of data collection, all 13 monarch butterflies nectared on
white, yellow, and purple flowers. We rejected our null hypothesis, which stated
that migrating monarchs have no flower color preference. (X2=9.1, df=2, p=< .01)
The monarchs nectared 13 times on white flowers, 4 on yellow, and 3 on purple, totaling
20 visits. Migrating monarchs preferred white flower colors, with respect to the
flower colors tested. The following graph shows the flower color preferences exhibited.
(Figure 1.)
Figure 1. Flower color preferences of migrating monarchs.
When considering the wing loading and flower color preference, we failed to reject
our null hypothesis which stated that there is no correlation between the flower
color preference and the wing loading of migrating monarchs. (X2 = .4, df=2, p>0.1)
The higher wing loading monarchs ("Bubbas") nectared 7 times on white
flowers, 2 on yellow, and 1 on purple, totaling 10 visits. The lower wing loading
monarchs ("Babies") nectared 6 times on white flowers, 2 on yellow, and
2 on purple, totaling 10 visits. The following graph shows wing loading and flower
color preferences exhibited. (Figure 2.)
Figure 2. Flower color preferences of monarchs with high wing loading (Bubbas) and
low wing loading (Babies).
In our last test, considering preference for native and non-native flowers we failed
to reject our null hypothesis, which stated that migrating monarchs have no preference
for native or non-native flower types. (X2=.8, df= 1, p>0.1)
12 monarchs nectared on native flowers and 8 on non-native flowers. The following
graph shows monarch preferences to native or non-native flowers. (Figure 3.)
Figure 3. Nectaring visits of migrating monarchs to native and non-native flower
types.
Discussion
The first question we investigated resulted in rejecting the hypothesis that migrating
monarchs have no flower color preference. White appears to be preferred. In the
second question, wing loading and flower color preference, we failed to reject the
null hypothesis, that there is no correlation between the flower color preference
and wing loading. In testing whether migrating monarchs prefer native or non-native
flower types, we failed to reject our null hypothesis, monarchs have no preference
for native or non-native flower types.
Similar studies indicate that there is a correlation between the sex of the monarch
and their feeding habits, stating that males prefer white flower types while females
prefer colored flower types (Gynup, 2000). Other results have shown that monarchs
are attracted to brightly colored objects (Kondo, 1970). Our results showed
that there was a preference to white instead of brightly colored flowers, looking
at males and females combined. These results may have been affected by the fact
that during the time this experiment was conducted white flowers were the dominant
color in the field. Wing loading did not appear to be a factor in choice of color
or native/non-native flowers but this should be investigated further using wild
monarchs captured during an actual migration.
Our results could have been affected by the fact that our project was conducted
in the lab. The original research plan was to conduct a field study, but due to
inclement weather and the fragile health of our monarchs, we transferred our studies
to the classroom. However had we conducted a field study, our results might have
been affected by environmental factors such as the wind, other insects, and the
larger amount of space. One factor that was an unexpected variable was, once the
monarchs began the honey water supplemental feedings the wing loading difference
was probably insignificant. Another significant factor was the low number of monarchs
that were available for the experiments; more data would be preferred to verify
these results. Further studies could be conducted to determine if feeding habits
are similar along the entire migratory route during actual migration, as well as
a study comparing males and females.
Acknowledgments
We would like to thank the National Science Foundation (ESI-9731429) and Decatur
High School for financial support, our University of Minnesota instructors for working
with us, and Mrs. Woodruff’s classes for help with feeding, weighing, and babysitting
the monarchs and larvae. We also owe special thanks to Mississippi Heights Middle
School in Sauk Rapids, Minnesota for the butterfly eggs, to Decatur and surrounding
communities for contributing supplies, field sites, and financial support, and to
our scientist mentors, Bethann Lavoie and Michelle Solensky.
Literature Cited
Kondo, Herbert. "Monarch Butterflies." Grolier’s Amazing World of
Animals, 1972, 16,8.
Guynup, Sharon. "Homeless Butterflies" Science News 3 November,
2000, p. 4.
Monarch Lab website, http://www.monarchlab.umn.edu
Swan, Lester and Papp, Charles. The Common Insects of North America. Canada,
1972, 218.
Authors
Crystal Buchko is currently a junior at Decatur High School in
Decatur, Texas. She is active in the high school community service organization,
"The EarthSavers" and participates in other activities with her church
youth group. She is a native of Minnesota and hopes to return to her home state
to pursue a degree from the University of Minnesota.
Tiffany Harrison is currently a junior at Decatur High School in
Decatur, Texas. She is a member of the state qualifying cross-country team and the
DHS track team. She participates in charity races throughout the state of Texas.
After graduation from DHS, Tiffany plans to attend Stephen F. Austin University,
pursuing a degree in psychology.
Joylynn Woodruff has been teaching biology (all levels) 23 years
in Texas public schools. She is the EarthSaver sponsor, Science Fair Coordinator,
District Curriculum Team member, and mentor teacher to at-risk students. Joylynn
enjoys working with students because they teach her new things as she teaches them,
in her classroom "learning is a shared experience".
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