Master of Science
Sherry, David F.
Daley, Mark J.
A stable nest environment is necessary for incubation and development of offspring. Birds vary behaviour to regulate temperature for successful hatchlings. I used a hidden Markov model (HMM) to test how environmental conditions affect incubation behaviour. I examined nest temperatures and behaviours collected from Zebra finches that incubated at 30 °C or 14 °C, then incubated in the same or opposite condition for a second clutch. Data loggers and cameras recorded nest temperature and number of parents on nest. The HMM inferred behaviour from recorded behaviours and temperatures. Temperature and offspring success affected incubation duration. Birds that had successful offspring incubated at higher temperatures than unsuccessful birds. The HMM could not accurately predict number of birds from the temperature data because birds maintained nest temperature irrespective of behaviour. This study shows that birds can change behaviour in relation to the environment. Previous offspring success and ambient temperature are drivers of change in incubation behaviour.
Summary for Lay Audience
Birds sit on nests to develop the embryos within the eggs they laid. However, the environment is not always good for embryo growth. One aspect of the environment which is important for embryo growth is the surrounding temperature. The birds have to change the way they sit on the nest because of the surrounding temperature. If the surrounding temperature is too warm or too cold, then the embryos may die or not develop correctly. I look at what birds do in these situations where the surrounding temperature is either cool or warm. I use a computer program I built to see if I can use a small sample of bird behaviour and nest temperature to predict how many birds are on the nest, given only the nest temperature. Zebra finches, birds that are native to Australia, laid eggs and sat on them in either 14 °C or 30 °C. The zebra finches then stayed in the same surrounding temperature or switched to the alternative for a second laying and sitting on eggs.
Birds need to consider the surrounding temperature, and their breeding experience at that temperature so that their chicks survive. I thought that if birds made mistakes in the first try in one of the surrounding temperature conditions, the second try in the same condition they would have more eggs hatched. If they were in a different condition for the second try, then they would not be as successful hatching eggs than if they were in the same condition. The surrounding temperature, and if the birds had hatched eggs had an effect on how long the birds needed to hatch an egg. Birds that had previously been successful hatching an egg had higher nest temperatures than unsuccessful pairs. My model was not able to predict behaviour from nest temperature. Birds can change how they sit on eggs to the surrounding temperature.
Shoot, Tanya T., "Analyzing avian incubation with a computer algorithm" (2019). Electronic Thesis and Dissertation Repository. 6311.
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