Consequences of Parental
Care:
Male and Female Eastern Bluebird
Delivery of Food to Chicks
India Peek Jensen: REACH Program
Spring Lake High School
Mentors: Dr. Kathy Winnett-Murray
and Dr. Greg Fraley
animals.nationalgeographic.com/.../bluebird.html
Introduction
• From a scientific standpoint
– Parental effort is a large part of understanding
how the environment influences the social
and mating systems of animals.
• From a wildlife management standpoint
– We want to know how changes in the
environment are influencing the sustainability
of this population through behaviors like
parental care.
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Background
• Eastern Bluebird (Sialia
sialis)
– 1970s-80s EB
population in MI
plummeted.
• Reproductive Habits
– Typically
monogamous
– 4-6 eggs
– Primarily insectivorous
J.H. Campbell Complex,
Consumers Energy
http://www.pbase.com/uncledave/image/74457096
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Bird Composition in Nest Boxes
Since 1992
Species Composition of Bird Species, Percent of
Total Active Nests
80%
BC
60%
HW
40%
TS
20%
EB
07
20
06
20
05
20
03
20
02
20
01
20
99
19
98
19
97
19
95
19
94
19
92
0%
19
Percent
100%
Year
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Research Questions
12
Female
Male
10
Individuals
• Difference between
sexes in food
delivery?
• Do differences affect
reproductive
success?
• How is this related to
nest defense?
8
6
4
2
0
Pecks
Hovers
Dives
Behavior
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Male and Female Eastern Bluebird
www.nebraskabirds.com/bluebirds.php
Male
flickr.com/photos/12369485@N05/1361846793/
Female
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What I did…
• Behavior
Observations
• Nest Checks
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Example
of
Behavior
Data
Sheet
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Delivery of Food to Chicks by Male and
Female
Delivery Trips Per Minute
0.20
0.15
0.10
0.05
0.00
F
M
Sex
Wilcoxon z=0.15698, df=1, P=0.8753, no significant difference
between males and females in delivery trips per minute
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Proportion of Large Loads to Total Loads
Proportion of Deliveries That Were Large
Insects
1.0
0.8
0.6
0.4
0.2
0.0
F
M
Sex
Wilcoxon z=-0.1778608, df=1, P=0.8588324, no significant
difference between male and female load sizes
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Brood Time by Male and Female
Brood Time Per Minute
1.0
0.8
0.6
0.4
0.2
0.0
-0.2
F
M
Sex
Wilcoxon z=-2.6679113, df=1, P= 0.0076324, significant difference
between males and females in brood time per minute
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Delivery Rates to Young and Old Chicks by
Male and Female
Trips Per Minute
0.20
0.15
0.10
0.05
Chick Age (Days)
0.00
F
M
1-8 days old
over 8 days old
Sex
Mann Whitney U (Females)= 12.50, df=1, P=0.1227; Mann Whitney U
(Males)= 33.00, df=1, P=0.2764, no significant difference between
male and female delivery rates to young and old chicks
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Energetic Tradeoff in Parental Care
Energy available for selfmaintenance, reproduction
Energy spent in nest
defense, vigilance
Energy Cost
High
0
Energy Spent
100
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Conclusion
• Males and females exhibit similar effort in
feeding chicks, both in the number of deliveries
to the nest and the relative size of those food
loads.
• Although responsibilities may differ at different
stages of chick development (e.g. brooding vs.
feeding) the overall effort appears to be similar,
just as in the equal effort males and females
show in nest defense.
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Acknowledgements
• REACH Program
• Dean of the Natural Sciences Division at Hope
College, Dr. Moses Lee
• Mentors, Dr. Winnett-Murray and Dr. Fraley
• Fellow Research Students: Joel Evenhouse,
Jillian Greshel, Jacquelyn Randolet, Tim Paver,
Brian Puls, Joel Evenhouse
• Mrs. Schanhals, Spring Lake High School
• Consumer’s Energy
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