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A Ground-Nesting Galliform's Response to Thermal Heterogeneity: Implications for Ground-Dwelling Birds.

Carroll JM, Davis CA, Elmore RD, Fuhlendorf SD - PLoS ONE (2015)

Bottom Line: We found that thermal space within the study area exhibited differences in Tbb of up to 40°C during peak diurnal heating, resulting in a diverse thermal landscape available to ground-nesting birds.Models of future Tbb associated with 2080 climate change projections indicate that nesting bobwhites will face substantially greater Tbb throughout the landscape for longer durations, placing an even greater importance on thermal choices for nest sites in the future.These results highlight the capacity of landscape features to act as moderators of thermal extremes and demonstrate how thermal complexity at organism-specific scales can dictate habitat selection.

View Article: PubMed Central - PubMed

Affiliation: Department of Natural Resource Ecology and Management, Oklahoma State University, 008C Ag Hall, Stillwater, Oklahoma, United States of America.

ABSTRACT
The habitat selection choices that individuals make in response to thermal environments influence both survival and reproduction. Importantly, the way that organisms behaviorally respond to thermal environments depends on the availability and juxtaposition of sites affording tolerable or preferred microclimates. Although, ground nesting birds are especially susceptible to heat extremes across many reproductive stages (i.e., breeding, nesting, brood rearing), the mechanistic drivers of nest site selection for these species are not well established from a thermal perspective. Our goal was to assess nest site selection relative to the configuration of the thermal landscape by quantifying thermal environments available to a ground-nesting bird species inhabiting a climatically stressful environment. Using northern bobwhite (Colinus virginanus) as a model species, we measured black bulb temperature (Tbb) and vegetation parameters at 87 nests, 87 paired sites and 205 random landscape sites in Western Oklahoma during spring and summer 2013 and 2014. We found that thermal space within the study area exhibited differences in Tbb of up to 40°C during peak diurnal heating, resulting in a diverse thermal landscape available to ground-nesting birds. Within this thermally heterogeneous landscape, nest sites moderated Tbb by more than 12°C compared to random landscape sites. Furthermore, successful nests remained on average 6°C cooler than unsuccessful nests on days experiencing ambient temperatures ≥ 39°C. Models of future Tbb associated with 2080 climate change projections indicate that nesting bobwhites will face substantially greater Tbb throughout the landscape for longer durations, placing an even greater importance on thermal choices for nest sites in the future. These results highlight the capacity of landscape features to act as moderators of thermal extremes and demonstrate how thermal complexity at organism-specific scales can dictate habitat selection.

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Within a thermally heterogeneous landscape, nest sites moderate thermal environments, especially during high heat.(A) Distribution of diurnal black bulb temperature (Tbb) observed from 09:00–19:00 h (n = 3,212) and (B) linear models of Tbb as a function of ambient temperature (Tair) recorded during the full sampling period (00:00–24:00 h) (B) at northern bobwhite nest and landscape sites at the Packsaddle WMA, Oklahoma, USA (2013–2014) (n = 7,008).
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pone.0143676.g001: Within a thermally heterogeneous landscape, nest sites moderate thermal environments, especially during high heat.(A) Distribution of diurnal black bulb temperature (Tbb) observed from 09:00–19:00 h (n = 3,212) and (B) linear models of Tbb as a function of ambient temperature (Tair) recorded during the full sampling period (00:00–24:00 h) (B) at northern bobwhite nest and landscape sites at the Packsaddle WMA, Oklahoma, USA (2013–2014) (n = 7,008).

Mentions: We found that the landscape exhibited substantial thermal heterogeneity with differences in Tbb ranging by up to 40°C when Tair > 35°C (Fig 1A). Within this thermally heterogeneous landscape, nest sites moderated Tbb substantially more than locations on the surrounding landscape which exhibited the potential to reach Tbb > 70°C (Fig 1A and 1B). Models of nest and landscape site Tbb showed that Tair and Srad recorded at meteorological stations and their interaction were effective at explaining the variation in fine scale Tbb measurements (86%) (Table 1); however, site specific differences in microclimates were likely driven by fine scale vegetation cover.


A Ground-Nesting Galliform's Response to Thermal Heterogeneity: Implications for Ground-Dwelling Birds.

Carroll JM, Davis CA, Elmore RD, Fuhlendorf SD - PLoS ONE (2015)

Within a thermally heterogeneous landscape, nest sites moderate thermal environments, especially during high heat.(A) Distribution of diurnal black bulb temperature (Tbb) observed from 09:00–19:00 h (n = 3,212) and (B) linear models of Tbb as a function of ambient temperature (Tair) recorded during the full sampling period (00:00–24:00 h) (B) at northern bobwhite nest and landscape sites at the Packsaddle WMA, Oklahoma, USA (2013–2014) (n = 7,008).
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4664423&req=5

pone.0143676.g001: Within a thermally heterogeneous landscape, nest sites moderate thermal environments, especially during high heat.(A) Distribution of diurnal black bulb temperature (Tbb) observed from 09:00–19:00 h (n = 3,212) and (B) linear models of Tbb as a function of ambient temperature (Tair) recorded during the full sampling period (00:00–24:00 h) (B) at northern bobwhite nest and landscape sites at the Packsaddle WMA, Oklahoma, USA (2013–2014) (n = 7,008).
Mentions: We found that the landscape exhibited substantial thermal heterogeneity with differences in Tbb ranging by up to 40°C when Tair > 35°C (Fig 1A). Within this thermally heterogeneous landscape, nest sites moderated Tbb substantially more than locations on the surrounding landscape which exhibited the potential to reach Tbb > 70°C (Fig 1A and 1B). Models of nest and landscape site Tbb showed that Tair and Srad recorded at meteorological stations and their interaction were effective at explaining the variation in fine scale Tbb measurements (86%) (Table 1); however, site specific differences in microclimates were likely driven by fine scale vegetation cover.

Bottom Line: We found that thermal space within the study area exhibited differences in Tbb of up to 40°C during peak diurnal heating, resulting in a diverse thermal landscape available to ground-nesting birds.Models of future Tbb associated with 2080 climate change projections indicate that nesting bobwhites will face substantially greater Tbb throughout the landscape for longer durations, placing an even greater importance on thermal choices for nest sites in the future.These results highlight the capacity of landscape features to act as moderators of thermal extremes and demonstrate how thermal complexity at organism-specific scales can dictate habitat selection.

View Article: PubMed Central - PubMed

Affiliation: Department of Natural Resource Ecology and Management, Oklahoma State University, 008C Ag Hall, Stillwater, Oklahoma, United States of America.

ABSTRACT
The habitat selection choices that individuals make in response to thermal environments influence both survival and reproduction. Importantly, the way that organisms behaviorally respond to thermal environments depends on the availability and juxtaposition of sites affording tolerable or preferred microclimates. Although, ground nesting birds are especially susceptible to heat extremes across many reproductive stages (i.e., breeding, nesting, brood rearing), the mechanistic drivers of nest site selection for these species are not well established from a thermal perspective. Our goal was to assess nest site selection relative to the configuration of the thermal landscape by quantifying thermal environments available to a ground-nesting bird species inhabiting a climatically stressful environment. Using northern bobwhite (Colinus virginanus) as a model species, we measured black bulb temperature (Tbb) and vegetation parameters at 87 nests, 87 paired sites and 205 random landscape sites in Western Oklahoma during spring and summer 2013 and 2014. We found that thermal space within the study area exhibited differences in Tbb of up to 40°C during peak diurnal heating, resulting in a diverse thermal landscape available to ground-nesting birds. Within this thermally heterogeneous landscape, nest sites moderated Tbb by more than 12°C compared to random landscape sites. Furthermore, successful nests remained on average 6°C cooler than unsuccessful nests on days experiencing ambient temperatures ≥ 39°C. Models of future Tbb associated with 2080 climate change projections indicate that nesting bobwhites will face substantially greater Tbb throughout the landscape for longer durations, placing an even greater importance on thermal choices for nest sites in the future. These results highlight the capacity of landscape features to act as moderators of thermal extremes and demonstrate how thermal complexity at organism-specific scales can dictate habitat selection.

Show MeSH
Related in: MedlinePlus