Commentary: A Bird in the House: The Challenge of Being Ecologically Relevant in Captivity

Journal of Avian Biology

Andrew

McCowan

et al. 2020

Self Cite

In many birds, there is significant variation in egg size both across and within clutches that remains to be explained. Birds lay one egg per day and in hot climates, the first laid eggs may start to develop before the laying of the rest of the clutch is complete, through warming by the ambient air temperature. Here, we test the hypothesis that in hot conditions, skews in egg size across the laying sequence may be more pronounced, as females use egg size to compensate for hatching asynchrony, providing a higher level of provisioning to the later laid eggs that would hatch later due to ambient incubation. We have focused on the zebra finch Taeniopygia guttata, a species that typically breeds over an extended period of the year, and therefore across a particularly wide range of ambient temperatures. We characterised the variation in egg size using data from over 700 clutches, including historical specimens, a wild population, and both domesticated and wild birds breeding in captivity, in addition to clutches produced experimentally in controlled‐temperature rooms. Here, we document significant variation in egg size between and within clutches, with eggs increasing in size over the laying order, with both maternal identity and population differences playing an important role (domesticated birds laid eggs that were much larger than their wild counterparts). However, we found no support for the idea that variation in egg size either within a clutch, and across clutches and populations, is related to variation in ambient temperature, despite the large range of thermal environments experienced during laying. In conclusion, whilst egg size is clearly a labile characteristic there is no evidence this is flexibly adjusted to local ambient temperatures before and during laying.

Section: Populationsupporting

confidence: 93%

Section: Discussionmentioning

confidence: 99%

Egg size is unrelated to ambient temperature in the opportunistically breeding zebra finch

Journal of Avian Biology

Andrew

McCowan

et al. 2020

Self Cite

“…In contrast, air temperatures follow a clear seasonal pattern, with hot summers and physiologically extreme air temperatures occurring from October through to February (in the Austral spring and summer). The average air temperature in which laboratory populations of Zebra Finches are held (approximately 21 • C) fairly closely reflect the average conditions during breeding in the wild, across an extended breeding period (approximately 19 • C; [39]). However, this value (19 • C) was the long-term average, and Zebra Finches breeding in the early spring will face average, minimal, and maximal conditions that are very different to those experienced by birds breeding a few months later in the summer.…”

Section: Climatic Extremes During Breeding and Developmentmentioning

confidence: 85%

The Ecology of the Zebra Finch Makes It a Great Laboratory Model but an Outlier amongst Passerine Birds

Ton

Hurley

et al. 2021

Birds

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Zebra Finches have become the most widely researched bird species outside of those used in agricultural production. Their adoption as the avian model of choice is largely down to a number of characteristics that make them easy to obtain and use in captivity. The main point of our paper is that the very characteristics that make the Zebra Finch a highly amenable laboratory model species mean that it is by definition different from many other passerine birds, and therefore not a good general model for many research areas. The Zebra Finch is likely to be particularly resilient to the effects of stress early in life, and is likely to show great flexibility in dealing with a wide variety of conditions later in life. Whilst it is tempting for researchers to turn to species such as the Zebra Finch, that can be the focus of manipulative work in the laboratory, we caution that the findings of such studies may confound our understanding of general avian biology. The Zebra Finch will remain an excellent species for laboratory work, and our paper should help to direct and interpret future work in the laboratory and the field.

“…It is interesting that they still have a response to the variation in temperature to which we exposed them (18 and 30°C). In the wild, temperature varies to a much greater extent, and eggs are laid in wild nests in periods with a mean daily minimums of around 12°C and mean daily maximum temperatures of 26°C (Griffith et al 2017a). The absolute maximum temperatures in the arid zone are much greater and, during periods of active breeding, ambient conditions regularly exceed 40°C (Griffith et al 2016).…”

Section: Nestmentioning

confidence: 99%

“…In this species, a facultative response to climactic variation is particularly relevant because in the wild, zebra finches breed over an extended period of the year, with mean daily temperatures varying from just 10°C to over 26°C during the breeding period (Griffith et al 2017a), and in the summer, temperatures inside the nest can exceed 50°C (Griffith et al 2016). We have used ecologically relevant average temperatures (18°C and 30°C) to reflect the average conditions in the cooler period in early spring and the hotter period experienced later in the breeding season (based on descriptions of relevant climate in Griffith et al 2016Griffith et al , 2017a. Nests built under the two different temperature treatments were compared and it was hypothesized that if nest building was behaviourally plastic with respect to climate, then a difference in the mass and composition of nests would be observed.…”

Section: Introductionmentioning

confidence: 99%

Behavioural plasticity under a changing climate; how an experimental local climate affects the nest construction of the zebra finchTaeniopygia guttata

Campbell

Hurley

Journal of Avian Biology

2018

Self Cite

Successful reproduction in most avian species is dependent on the construction of a nest that provides protection and a suitable microclimate for the eggs and developing nestlings. Observational studies suggest that climatic variation may affect the structure of the nest, but to date there have been no attempts to experimentally determine the role that local climate plays in the construction of a suitable nest. Using a within‐individual counter balanced design we investigated how nest composition and construction differ in zebra finches breeding in ambient conditions of 18°C and 30°C. We found that at 18°C birds built nests that were over 20% heavier, and with significantly more thread and less grass than those built at 30°C. Our results highlight the degree of plasticity in nest building behaviour in relation to local ambient conditions. These results suggest that nest building behaviour is one route through which birds can respond to a changing climate and modify the microclimate of their nest in line with projected changes in ambient conditions.