The effect of nest cup heating during incubation on the cold tolerance of Blue Tit (Cyanistes caeruleus) chicks

Page, Jennifer (2021) The effect of nest cup heating during incubation on the cold tolerance of Blue Tit (Cyanistes caeruleus) chicks. MSc(R) thesis, University of Glasgow.

Abstract

Climate change and stochastic weather events can affect many aspects of avian life cycles, including reproduction. For birds living in hot environments, rising temperatures are often detrimental because they constrain parental provisioning and chick growth. Currently, most of our knowledge regarding temperature effects during avian reproduction comes from correlative data, where cause and effect cannot be determined. More recently, evidence suggests that birds breeding in cooler environments are also affected by rising temperature.
For example, increasing spring temperature and a higher frequency of heatwaves may change both parental behaviour and the parent’s capacity to maintain optimal egg temperature during incubation, with a range of phenotypic consequences for developing offspring. These effects are not well understood. This study tested whether experimentally increasing nest cup temperature during incubation would influence cold tolerance of Blue Tit (Cyanistes caeruleus) chicks in a study area in Western Scotland. This is relevant, because there is a putative trade-off between nestling growth and thermoregulation and manipulating developmental temperature may alter resource allocation between the two. I predicted that a high nest cup temperature would influence the subsequent thermogenic capacity of chicks, the direction of the effect dependent on whether lower incubation temperatures are adaptive or constraining for offspring development. Nests were either experimentally heated during the incubation stage of reproduction or were sham manipulated (controls). After hatching, cooling challenges were performed across the ages of 4 to 10 days, during which chicks were exposed to temperatures of 10-15°C, which is below their thermoneutral zone, for 5 minutes and changes in body surface temperatures were recorded. Chicks from both heated and control nests showed a decrease in cooling rate with age but chicks from heated nests cooled slower than controls. Chicks became more homeothermic with age, but there was no difference in the development of homeothermy between heated and control nests. However, chicks from heated nests had a greater body mass during the first 12 days of life compared to chicks from control nests. My results indicate that nest microclimate can impact thermoregulation in offspring. In light of climate projections for Western Scotland, where average temperatures are expected to increase across seasons, these results may be used to predict some of the future physiological responses of birds to climate change during breeding.

• Item Type: Thesis (MSc(R))
• Qualification Level: Masters
• Keywords: body temperature, homeothermy, thermoregulation, endothermy, climate change, avian physiology.
• Subjects: Q Science > QH Natural history; Q Science > QL Zoology
• Colleges/Schools: College of Medical Veterinary and Life Sciences > Institute of Biodiversity Animal Health and Comparative Medicine
• Supervisor's Name: McCafferty, Dr. Dominic and Dominoni, Dr. Davide
• Date of Award: 2021
• Depositing User: Miss Jennifer Page
• Unique ID: glathesis:2021-82228
• Copyright: Copyright of this thesis is held by the author.
• Date Deposited: 28 May 2021 13:15
• Last Modified: 03 Jun 2021 19:29
• Thesis DOI: 10.5525/gla.thesis.82228
• URI: https://theses.gla.ac.uk/id/eprint/82228