Development of a Thermocouple Device to Measure Zebra Finch Nest
Temperature During Incubation
JL Heiman & DE Christensen
Dept of Environmental Science & Policy, Dept of Biology, College of Arts and Science, Drake University
Methods
• Test the feasibility of 3 types of thermocouples inserted either into the
cavity of the nest or into surrogate eggs to measure nest/egg
temperature
• Test the durability of the thermocouple wires to normal nest activity
• A second egg was filled with the elastomer and an ADInstruments IT-23
thermocouple (figure 2a) using the same procedure.
COMPARISON TESTING: Both thermocouple-embedded eggs were placed in the
nest of an incubating zebra finch pair for over 24 hours. An ADInstruments
HT-1 thermocouple (figure 2a) was also placed in the nest to compare the
accuracy and feasibility of the two egg-embedded thermocouples (IT-18 and
IT-23) and one simply embedded in the nest box (HT-1). A video camera
recorded the behavior of the finches. The temperature data was collected
with an ADInstruments PowerLab (figure 3).
Results
IT-18 (°C)
Figure 2a:
ADInstruments
thermocouples (left to
right) IT-18, IT-23, and
HT-1.
• After drying for several days at room temperature, the thermocouple tested
firmly in place with no change in the condition of the elastomer.
It-23 (°C)
Figure 1: Emptying the finch egg
A
28.0
27.5
27.0
26.5
26.0
25.5
12:33:56.398 PM
40
B
35
30
25
C
40
35
30
25
Figure 4: (left) Thermocouple-embedded egg after 24 hours in the nest.
(middle) Damage done to the thermocouple-embedded egg. (top right) Thermocouple
egg (circled) secured in nest with wire hidden. (bottom right) Finished thermocouple
• Data recorded from the embedded thermocouples were consistent with
each other (figure 3). When compared with video footage, both the IT-18
and IT-23 egg-embedded thermocouples were very sensitive to parental
behaviors and incubation activity.
• Data from the HT-1 thermocouple was inconsistent with the readings from
the embedded thermocouples (figure 3).
• Parents ejected thermocouple-embedded eggs within 24 hours of
placement (figure 4).
• Damage to both thermocouple-embedded eggs was isolated to the area
where the thermocouple wires protruded from the eggs (figure 4).
Conclusions
• When properly positioned in the nest, thermocouple-embedded eggs are a
feasible and affordable way to monitor nest temperature of incubating
zebra finches.
• Thermocouple wires must be secured so as not to be mistaken by the
finches as nesting material. When this is done, thermocouple eggs are
accepted and incubated along with the rest of the clutch (figure 4).
3
2
• Both IT-18 and IT-23 thermocouples are viable options. The IT-18
thermocouple is recommended due to its thicker wiring and durability when
compared to the IT-23.
5
6
• The HT-1 thermocouple is not a good option because it does not stay in
1
position near the eggs and recordings do not accurately represent nesting
Figure 3: Recordings made from three thermocouples placed in the same nest.
behavior.
Channel A recorded nest temperature from the nest box chamber. Channels B & C
12:40:00
Figure 2b: Placement of thermocoupleembedded eggs while drying
Three thermocouple test 1 saved again.adicht
Video recording started again
• Determine if monitoring nest temperature of incubated bird eggs can be
used as a measure of parental care
ATTEMPT TWO: An emptied egg was filled as described above using a silicone
elastomer (Sylgard 184) with the IT-18 thermocouple.
Superdad returned to cage
• Determine an effective and feasible method to monitor nest incubation
behavior in breeding zebra finches (Taeniopygia guttata)
• After several days at room temperature, the agar had dessicated
dramatically, rendering the thermocouple unstable within the egg.
Spooled smallest thermocouple
Study Objectives
Returned thermocouple/egg to nest
• Video monitoring requires time-intensive labor and expensive equipment
and is not feasible for long-term observations of multiple nests.
ATTEMPT ONE: A prepared egg was filled with a 15% agar solution using an 18
gauge needle and 5 cc syringe. An ADInstruments IT-18 thermocouple
(figure 2a) was inserted into the egg lumen and secured by taping it to an
overturned test tube rack (figure 2b). The filled egg dried for 24 hours.
Touched small thermocouple end to test
• Birds are sensitive to nest intruders and disturbances may cause nest
abandonment and damage to expensive monitoring equipment.
• Emptied eggs were rinsed thoroughly by repeatedly injecting and
withdrawing distilled water to ensure all residual yolk and albumin were
removed. Eggs were stored at 4°C until refilled.
Eggs found displaced from nest at approx 7 am
• Measuring and quantifying parental care can be difficult because the
monitoring activity itself can alter parents’ behaviors.
• Non-fertile finch eggs were collected from an all-female cage and emptied
using a 26 gauge, 3/8’needle and a 5 cc syringe (figure 1).
HT-1 (°C)
Introduction
13:00:00
13:20:00
13:40:00
14:00:00
14:20:00
4
14:40:00
15:00:00
15:20:00
were recorded from thermocouples embedded in eggs. Large drops in temperature
• Thermocouple embedded eggs allow for monitoring of parental behavior by
indicate when the eggs were ejected from the nest.
proxy of nest temperature.
Acknowledgements:
Protocols were approved by IACUC. Funding was provided by a Faculty Development Grant to DEC. Dr. Debora Christensen provided materials, birds, and her lab for this project. Julia Tucci helped to empty
and fill countless eggs. Dr. Christensen’s lab group helped to collect zebra finch eggs.