Comparison of physiological responses to high temperatures in juvenile and adult Cape Rockjumpers Chaetops frenatus
- Oswald, Krista N, Lee, Alan T K, Smit, Ben
- Authors: Oswald, Krista N , Lee, Alan T K , Smit, Ben
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/441559 , vital:73898 , https://doi.org/10.2989/00306525.2018.1509905
- Description: Concerns about climate change have led to an increase in studies on physiological mechanisms birds possess to cope with increasing temperatures. For range-restricted species such as Cape Rockjumpers Chaetops frenatus, whose population declines are correlated with habitat warming, we identified juvenile physiological responses to high temperature as a potential gap in current knowledge. We compared metabolic rate, evaporative water loss, evaporative cooling efficiency (calculated from evaporative water loss and resting metabolic rate) and body temperature in juveniles (n = 5) with adult birds (n = 10) to a ramped temperature profile (30–42 °C). Although juveniles exhibited no significant difference in cooling efficiency, they had higher evaporative water loss, resting metabolic rate and body temperature. This suggests that while juvenile birds show similar abilities to dissipate metabolic heat evaporatively, they face higher overall water and energy demands, and thus higher thermoregulatory costs in maintaining body temperature as overall temperatures continue to increase.
- Full Text:
- Date Issued: 2018
- Authors: Oswald, Krista N , Lee, Alan T K , Smit, Ben
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/441559 , vital:73898 , https://doi.org/10.2989/00306525.2018.1509905
- Description: Concerns about climate change have led to an increase in studies on physiological mechanisms birds possess to cope with increasing temperatures. For range-restricted species such as Cape Rockjumpers Chaetops frenatus, whose population declines are correlated with habitat warming, we identified juvenile physiological responses to high temperature as a potential gap in current knowledge. We compared metabolic rate, evaporative water loss, evaporative cooling efficiency (calculated from evaporative water loss and resting metabolic rate) and body temperature in juveniles (n = 5) with adult birds (n = 10) to a ramped temperature profile (30–42 °C). Although juveniles exhibited no significant difference in cooling efficiency, they had higher evaporative water loss, resting metabolic rate and body temperature. This suggests that while juvenile birds show similar abilities to dissipate metabolic heat evaporatively, they face higher overall water and energy demands, and thus higher thermoregulatory costs in maintaining body temperature as overall temperatures continue to increase.
- Full Text:
- Date Issued: 2018
Comparison of physiological responses to high temperatures in juvenile and adult Cape Rockjumpers Chaetops frenatus
- Oswald, Krista N, Lee, Alan T K, Smit, Ben
- Authors: Oswald, Krista N , Lee, Alan T K , Smit, Ben
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/448398 , vital:74727 , https://doi.org/10.2989/00306525.2018.1509905
- Description: Concerns about climate change have led to an increase in studies on physiological mechanisms birds possess to cope with increasing temperatures. For range-restricted species such as Cape Rockjumpers Chaetops frenatus, whose population declines are correlated with habitat warming, we identified juvenile physiological responses to high temperature as a potential gap in current knowledge. We compared metabolic rate, evaporative water loss, evaporative cooling efficiency (calculated from evaporative water loss and resting metabolic rate) and body temperature in juveniles (n = 5) with adult birds (n = 10) to a ramped temperature profile (30–42 °C). Although juveniles exhibited no significant difference in cooling efficiency, they had higher evaporative water loss, resting metabolic rate and body temperature. This suggests that while juvenile birds show similar abilities to dissipate metabolic heat evaporatively, they face higher overall water and energy demands, and thus higher thermoregulatory costs in maintaining body temperature as overall temperatures continue to increase.
- Full Text:
- Date Issued: 2018
- Authors: Oswald, Krista N , Lee, Alan T K , Smit, Ben
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/448398 , vital:74727 , https://doi.org/10.2989/00306525.2018.1509905
- Description: Concerns about climate change have led to an increase in studies on physiological mechanisms birds possess to cope with increasing temperatures. For range-restricted species such as Cape Rockjumpers Chaetops frenatus, whose population declines are correlated with habitat warming, we identified juvenile physiological responses to high temperature as a potential gap in current knowledge. We compared metabolic rate, evaporative water loss, evaporative cooling efficiency (calculated from evaporative water loss and resting metabolic rate) and body temperature in juveniles (n = 5) with adult birds (n = 10) to a ramped temperature profile (30–42 °C). Although juveniles exhibited no significant difference in cooling efficiency, they had higher evaporative water loss, resting metabolic rate and body temperature. This suggests that while juvenile birds show similar abilities to dissipate metabolic heat evaporatively, they face higher overall water and energy demands, and thus higher thermoregulatory costs in maintaining body temperature as overall temperatures continue to increase.
- Full Text:
- Date Issued: 2018
Seasonal physiological responses to heat in an alpine range-restricted bird: the Cape Rockjumper (Chaetops frenatus)
- Oswald, Krista N, Lee, Alan T K, Smit, Ben
- Authors: Oswald, Krista N , Lee, Alan T K , Smit, Ben
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/441655 , vital:73904 , https://doi.org/10.1007/s10336-018-1582-8
- Description: Hot, dry summer conditions impose physiological stress on endotherms, yet we have a poor understanding of how endotherms seasonally adjust their costs of thermoregulation under hot conditions. We determined whether seasonal phenotypic plasticity in evaporative cooling capacity at high temperatures explained how the range-restricted Cape Rockjumper (Chaetops frenatus; hereafter ‘Rockjumper’), copes with hot and dry summer temperatures of the temperate mountain peaks of southwest South Africa. We measured evaporative water loss (EWL), resting metabolic rate (RMR), and body temperature at high air temperatures (30–42 °C) of individuals from a wild population of Rockjumpers during winter and summer (n = 11 winter, 4 females, 7 males; n = 10 summer, 6 females, 4 males). We found Rockjumper evaporative cooling in summer imposes higher EWL (i.e. greater water costs) compared to winter, although an accompanying lack of change in RMR resulted in increased summer cooling efficiency. These patterns are similar to those observed in species that inhabit regions where summer temperatures are routinely high but the species are not water stressed. Our findings indicate that avian seasonal physiological adjustments to heat can be diverse. Further seasonal studies on thermoregulation in response to heat will greatly improve our knowledge of the functional value of traits such as evaporative cooling efficiency and heat tolerance and how they contribute to the physiological stress organisms experience in heterogenous environments.
- Full Text:
- Date Issued: 2018
- Authors: Oswald, Krista N , Lee, Alan T K , Smit, Ben
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/441655 , vital:73904 , https://doi.org/10.1007/s10336-018-1582-8
- Description: Hot, dry summer conditions impose physiological stress on endotherms, yet we have a poor understanding of how endotherms seasonally adjust their costs of thermoregulation under hot conditions. We determined whether seasonal phenotypic plasticity in evaporative cooling capacity at high temperatures explained how the range-restricted Cape Rockjumper (Chaetops frenatus; hereafter ‘Rockjumper’), copes with hot and dry summer temperatures of the temperate mountain peaks of southwest South Africa. We measured evaporative water loss (EWL), resting metabolic rate (RMR), and body temperature at high air temperatures (30–42 °C) of individuals from a wild population of Rockjumpers during winter and summer (n = 11 winter, 4 females, 7 males; n = 10 summer, 6 females, 4 males). We found Rockjumper evaporative cooling in summer imposes higher EWL (i.e. greater water costs) compared to winter, although an accompanying lack of change in RMR resulted in increased summer cooling efficiency. These patterns are similar to those observed in species that inhabit regions where summer temperatures are routinely high but the species are not water stressed. Our findings indicate that avian seasonal physiological adjustments to heat can be diverse. Further seasonal studies on thermoregulation in response to heat will greatly improve our knowledge of the functional value of traits such as evaporative cooling efficiency and heat tolerance and how they contribute to the physiological stress organisms experience in heterogenous environments.
- Full Text:
- Date Issued: 2018
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