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Bird Behavioral Modifications to Ensure Reproductive Success

Paper Reviewed
Carroll, R.L., Davis, C.A., Fuhlendorf, S.D., Elmore, R.D., DuRant, S.E., and Carroll, J.M. 2018. Avian parental behavior and nest success influenced by temperature fluctuations. Journal of Thermal Biology 74: 140-148.

Climate alarmists generally characterize global warming as being detrimental for most of the planet's animals, including birds, even suggesting that rising temperatures could drive many of them to extinction. However, when contemplating the special abilities of the winged creatures (like their ability to fly), one would think it would not be much of a problem for them to behaviorally compensate for whatever degree of stress a temperature increase might impose upon them. Such was the objective for a team of researchers (Carroll et al., 2018), who investigated the ability of two bird species (northern bobwhite [Colinus virginianus] and scaled quail [Callipepla squamata]) to make reproduction-related behavioral adjustments to buffer against suboptimal temperatures.

Their work was conducted over a period of 2 years at the Beaver River Wildlife Management Area in western Oklahoma. There, Carroll et al. collected data on quail and bobwhite nest site selection, nest site characteristics, and bird egg incubation behavior to "examine how temperature and precipitation directly influenced behavioral adjustments (i.e., off-bout duration, frequency, and nest attentiveness) and parental decisions (i.e., nest site selection), and indirectly influenced nest fate."

In describing their findings, the six scientists report that black bulb temperatures (an environmental index that incorporates ambient temperature, solar radiation and wind speed) of nesting sites were an average of 8.2°C and 5.7°C cooler than the surrounding environment for scaled quail and bobwhites, respectively, which suggests that "parents chose to nest in sites that were significantly cooler in temperature" than the proximal landscape.

Carroll et al. additionally found that the two bird species "made behavioral adjustments and parental decisions that allowed for the maintenance of more stable incubation temperatures for developing embryos." In this regard, parent off-bout frequency and duration were altered to maintain stable and optimal developmental temperatures for incubating eggs. During the heat of the afternoon the thermal environment of the incubating eggs was an average 6°C cooler than that of the surrounding environment, while during the cool of the night it was an average 12.5°C warmer.

In commenting on these important findings, Carroll et al. say their work "suggests that through parental decisions (i.e., nest site selection) and behavioral adjustments (i.e., off-bout frequency and duration, and nest attentiveness) each species was able to cope with the stressors exerted by the thermal environment." Continuing, they add that "these species rely on choosing nest sites that provide insulation, then use behavioral adjustments during incubation to further protect developing embryos from suboptimal temperatures," thereby effectively maintaining "the microclimate of developing embryos at relative stable temperatures during potentially thermally stressful periods."

Consequently, in light of all the above facts, it appears that having "bird brains" is not necessarily a detriment for scaled quail and bobwhite. These two species are rather smart and know how to alter their behavior to ensure their survival in a world of changing temperatures.

Posted 1 March 2019