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Behavioral Plasticity in Bird Nest Building at Different Temperatures

Paper Reviewed
Campbell, B.L., Hurley, L.L. and Griffith, S.C. 2018. Behavioural plasticity under a changing climate; how an experimental local climate affects the nest construction of the zebra finch Taeniopygia guttata. Journal of Avian Biology 49: e01717, doi: 10.111/jav.01717.

Introducing their work, Campbell et al. (2018) write that "beyond altering a suite of phenological, morphological and physiological adaptations, birds can potentially ameliorate the effects of climate change, particularly those affecting reproduction and early development, through the protective qualities of their nests." However the three scientists note that, to date, there "have been no attempts to experimentally determine the role that local climate plays in the construction of a suitable nest." Thus, it became their objective to examine temperature-induced differences in nest construction and composition in the zebra finch (Taeniopygia guttata). It was their hypothesis that "if nest building was behaviorally plastic with respect to climate, then a difference in the mass and composition of nests would be observed," such that they expected to find nests constructed at cooler temperatures to contain a greater mass of material to provide better insulation than nests constructed at warmer temperatures.

In accomplishing their objective, Campbell et al. housed domestically-bred zebra finch pairs in cages within climate-controlled environments at one of two ecologically-relevant average temperatures (18 or 30°C) during the breeding season of this species. Adequate food and nest building supplies were provided to each breeding pair; and nest construction was monitored throughout the entire egg-laying period, after which the nests were removed for drying and subsequent examination nine days after the clutch was completed. After an interim period, the entire process was repeated for each bird breeding pair. However, this time birds that were subjected to the 18°C temperature treatment in the initial experimental period were now subjected to examination in the 30°C temperature treatment and vice versa. Upon completion of this secondary analysis, Campbell et al. once again assessed multiple characteristics of nest morphology.

In the words of the authors, results of their study revealed that "the ambient air temperature experienced during nest construction influenced the weight and composition of the zebra finch nests built," such that "nests built in the 18°C treatment were significantly heavier than those built in the 30°C [environments]." Indeed, total nest, hood and cup masses were 24, 27 and 25% higher in the 18°C treatment. What is more, Campbell et al. report that the nest walls were 19% thicker in the lower-temperature environment and were constructed of 78% more thread mass and 18% less grass mass than that of the nests constructed at 30°C.

Commenting on these several findings, Campbell et al. say that their results "highlight the degree of plasticity in nest building behavior in relation to local ambient conditions" and they suggest that "nest building behavior 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 [temperature] conditions."

Posted 20 August 2018