Ecologically relevant cooling early in life does not affect expression of neophobia in zebra finch chicks (Taeniopygia guttatta)

Student: Anna James
Major: Biology
Minor: Spanish
Advisor: Dr. Sharon Lynn

Altricial chicks depend on their parents for warmth during early development. When parents leave the nest, chicks can readily cool to suboptimal temperatures. In response to cooling, altricial chicks exhibit activation of the hypothalamic-pituitary-adrenal axis, resulting in secretion of corticosterone. Repeated exposure to cooling, as a result of females brooding less often, may lead to repeated corticosterone exposure and development of a dampened stress response, both of which affect neophobia (fear of novelty). To study whether cooling affects neophobia, I repeatedly cooled zebra finch (Taeniopygia guttatta) chicks to ecologically relevant temperatures (temperatures they would experience when parents are off the nest) in their first week of life and tested them for neophobia at six weeks of age. My results indicate that Cool and Control chicks did not respond significantly differently to novelty. Thus, variation in nestling temperatures, which is associated with variation in brooding patterns, may not affect offspring neophobia.

Description

For my senior Independent Study, I investigated if ecologically relevant cooling affects expression of neophobia in zebra finch chicks. Young, altricial chicks (featherless, immobile, and nest-bound) are highly dependent on their parents for warmth. When the parents leave the nest, the chicks are exposed to ambient temperatures and can readily cool to suboptimal temperatures. In response to such cooling, altricial chicks secrete a stress hormone called corticosterone. If the parents repeatedly leave the nest, the chicks are repeatedly cooled and likely repeatedly exposed to corticosterone, which can have dampening effects on the stress response. Furthermore, development of a dampened stress response is linked with reduced expression of neophobia (fear of novelty) later in life. My study focused on the question: Do repeated bouts of cooling, which can lead to the development of a dampened stress response, affect expression of neophobia? I hypothesized that repeated bouts of cooling early in life would promote reduced expression of neophobia. I predicted that chicks that underwent repeated cooling would more quickly approach a novel object on a perch (reduced latency), spend more time close to that novel object, and spend more time on the perch with the object.

To study this question, I bred adult zebra finches and used the resulting chicks in my study. After hatching, I randomly assigned chicks to two treatment groups, Cool and Control. Cool chicks were cooled to temperatures that mimic temperatures they would experience when the mother is off the nest. Control chicks were kept at temperatures that mimic normal brooding temperatures. All chicks underwent four 18-minute temperature treatments between days 1 – 6 post-hatch. At six weeks of age, I tested the birds for expression of neophobia by presenting them with a perch that had a novel object (a green bow) on it. I measured the birds’ latency to approach the bow, time spent close to the bow, and total time spent on the perch.

The results of my study indicate that repeated cooling did not affect expression of neophobia as the Cool chicks did not have reduced latencies to approach the novel object, did not spend more time close to the object, and did not spend more time on the perch overall. Therefore, variation in chick temperature, which is associated with variation in parental brooding behavior (how long and how often parents leave the nest), may not greatly affect the development of neophobia in zebra finch chicks.

Anna will be online to field comments on May 8:
2-4pm EDT (PST 11am-1pm, Africa/Europe: evening)

14 thoughts on “Ecologically relevant cooling early in life does not affect expression of neophobia in zebra finch chicks (Taeniopygia guttatta)”

  1. Hi, Anna:
    Congratulations on your project, and your upcoming graduation. Best wishes for the future.

  2. Hi Anna,

    Your project is so well developed and articulated that I do not have a question to pose. I believe that your future will include many such projects and their resultant contributions to relevant research. Congratulations!

  3. You did a masterful job of presenting your process and results in an approachable format. Even a non-scientist like me could grasp your project. Congratulations, Anna!

  4. Well done Anna,
    Your poster is very clear and succinct.
    Questions: What was the temperature drop and how fast did it occur? How was it achieved?Any thoughts on what it would take in your experiment for there to be an effect?
    Way to persevere. Congratulations

    1. Thank you! I lowered the Cool chicks to about 20-22 ºC and kept the Control chicks above 25 ºC. The temperature drop was pretty quick as the chicks are small and lose heat readily. To cool the chicks or keep them warm, I placed them in small igloo coolers that had either ice blocks or hand warmers, and I monitored chick surface temperature every 6 minutes of the temperature treatment to make sure they weren’t getting too cold or too warm. There are many other variables that affect the development of neophobia, such as parental behaviors (if the parents are more neophobic, that personality can be transferred to the offspring), genetic components (some offspring may be genetically more neophobic than others), and environment (how much novelty the chicks are exposed to as they develop), so I don’t think cooling alone would determine neophobia.

  5. Hi Anna,
    You did a fabulous job–what a lot of work!! I’m so impressed, but I knew I would be! Your poster is gorgeous and everything is really well presented. If we could chat in person, as in a regular poster session, I’d love to ask you some questions. I’m so glad there’s this opportunity, so until we can meet in person, I’ll ask some questions now and then we can talk later–over crepes.
    1. How many chicks were included in each group in the study?
    2. For the four times of temperature treatments, were those times chosen randomly or were there specific times you did the treatments?
    3. I’m not sure what the Y axis is on the first bar graph. Could you please tell me more? I know it’s latency, but I’m not sure about the scale.
    4. Were the parents around the chicks as usual, or were the chicks isolated from parents during this time?
    5. At 6 weeks, how many times did you test the birds for expression of neophobia?

    Thanks for letting me know. I’d love to ask you more about how you actually did some of these things, but that can wait till later. I’m so excited for you and how much you enjoyed the research and the whole process. I love it!!!!

    1. Hi Cyndy!
      1. I had 9 chicks in each treatment group (18 total). Many more chicks resulted from the breeding, but due to siblings being so genetically similar and parents often having two broods, we had to limit the number of chicks involved to reduce pseudo-replication. We did a paired design, using two chicks from each nest (full siblings from the same brood), and one chick was assigned to the Cool treatment while the other was assigned to the Control treatment.

      2. I did the four treatments within the first week of life, and the treatments were done at least 24 hours apart. There wasn’t really a pattern for all of the chicks, but they all went through all treatments before day 7.

      3. The y-axis for all graphs was in seconds. The bars show mean latency to approach the object, mean time spent next to the object, and mean time on the perch in seconds for both Cool and Control groups.

      4. The parents were not around during the temperature treatments or the neophobia trials. However, chicks were returned to their nests after each temperature treatment and we did not separate the chicks from their parents until they were nutritionally independent. Prior to the neophobia trials (48 hours before testing), the chicks were placed in smaller cages that mimicked the testing cage with their nest mates.

      5. I just tested them once for neophobia due to the time restraints of my study.

      Thank you for visiting my page! I’d love to talk about it more in person when we can.

      1. Wonderful!! Thanks so much for the great information. I’m looking forward to learning more!! And to going for lunch!!!

        Cyndy

  6. Congratulations Anna! Your project is so thorough and your responses to the questions demonstrate how well you know your research topic. I am very proud of you and everything you have accomplished!!

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