Behaviour of an alpine range-restricted species is described by interactions between microsite use and temperature
- Oswald, Krista N, Smit, Ben, Lee, Alan T K, Cunningham, Susan J
- Authors: Oswald, Krista N , Smit, Ben , Lee, Alan T K , Cunningham, Susan J
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/441531 , vital:73896 , https://doi.org/10.1016/j.anbehav.2019.09.006
- Description: Climate change predictions include increased mean temperatures and increased frequency of heatwaves. Short-term responses to high air temperatures can allow animals to conserve water while maintaining a safe body temperature. For birds, cooling is often through evaporative water loss, which can be physiologically costly. Microsite use is an effective means of conserving water via reducing environmental heat load, so long as there are no negative trade-offs with other necessary functions, such as foraging. We examined behavioural responses to temperature in Cape rockjumpers, Chaetops frenatus (hereafter: ‘rockjumper’), an alpine specialist bird. We hypothesized that rockjumper behaviours would be temperature and microsite dependent. We collected data on rockjumper microsite use (sun, rock shade), behaviour (activity, foraging, preening, panting) and temperature (air, environmental). Rockjumpers made increased use of rock shade as air temperature increased. However, birds in rock shade foraged less. Depending on where their main food source is located, this suggests that when foraging demands are high, birds may need to remain in the sun despite risks of high thermal load, or else may suffer costs of lost foraging opportunities when using shade. The relationship between air temperature and heat dissipation behaviour (panting) was also mediated by microsite: birds showed significant increases in panting with increasing air temperature only when in the sun. The lack of increase in panting for birds in rock shade suggests that shade seeking may buffer physiological thermoregulatory costs (i.e. water expenditure). Individuals may therefore be able to mitigate some potential negative effects of high temperatures by making use of cooler microsites, although this could come at a cost to foraging.
- Full Text:
- Date Issued: 2019
- Authors: Oswald, Krista N , Smit, Ben , Lee, Alan T K , Cunningham, Susan J
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/441531 , vital:73896 , https://doi.org/10.1016/j.anbehav.2019.09.006
- Description: Climate change predictions include increased mean temperatures and increased frequency of heatwaves. Short-term responses to high air temperatures can allow animals to conserve water while maintaining a safe body temperature. For birds, cooling is often through evaporative water loss, which can be physiologically costly. Microsite use is an effective means of conserving water via reducing environmental heat load, so long as there are no negative trade-offs with other necessary functions, such as foraging. We examined behavioural responses to temperature in Cape rockjumpers, Chaetops frenatus (hereafter: ‘rockjumper’), an alpine specialist bird. We hypothesized that rockjumper behaviours would be temperature and microsite dependent. We collected data on rockjumper microsite use (sun, rock shade), behaviour (activity, foraging, preening, panting) and temperature (air, environmental). Rockjumpers made increased use of rock shade as air temperature increased. However, birds in rock shade foraged less. Depending on where their main food source is located, this suggests that when foraging demands are high, birds may need to remain in the sun despite risks of high thermal load, or else may suffer costs of lost foraging opportunities when using shade. The relationship between air temperature and heat dissipation behaviour (panting) was also mediated by microsite: birds showed significant increases in panting with increasing air temperature only when in the sun. The lack of increase in panting for birds in rock shade suggests that shade seeking may buffer physiological thermoregulatory costs (i.e. water expenditure). Individuals may therefore be able to mitigate some potential negative effects of high temperatures by making use of cooler microsites, although this could come at a cost to foraging.
- Full Text:
- Date Issued: 2019
Multi-directional effects of warming temperatures on the reproductive success of a threatened alpine-endemic bird, and implications for conservation management
- Oswald, Krista N, Lee, Alan T K, Diener, John P, Diener, Elizabeth F, Cunningham, Susan J, Smit, Ben
- Authors: Oswald, Krista N , Lee, Alan T K , Diener, John P , Diener, Elizabeth F , Cunningham, Susan J , Smit, Ben
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/441624 , vital:73902 , https://eco.confex.com/eco/2019/meetingapp.cgi/Paper/78223
- Description: Mitigating the current biodiversity crisis requires a better understanding of how species will respond to future climate change and human impacts on habi-tat. Decreased reproductive capability, due to changes in phenology, output, and success, is one of the main indicators of species’ vulnerability. For terres-trial ground-nesting birds, overall reproductive success is often related to nest-site selection (e.g. increased nest concealment), and weather changes (e.g. higher air temperatures alter nest success). We investigated the reproductive success of Cape Rockjumpers (Chaetops frenatus; “Rockjumpers”), a ground-nesting alpine bird, endemic to the Fynbos biome of South Africa, whose popu-lation decline correlates to warmer temperatures. We predicted that breeding success would be positively correlated with increased nest concealment, and negatively correlated with increasing temperature. We collected data over three years, including two full breeding seasons, from 2016 to 2018 (n=5, n=20 and n=43 respectively), which included nest-site selection variables (i.e. vege-tative cover, rock cover, time since fire in years), success or failure (whether nest resulted in ≥ fledgling), and cause if nest failed (i.e. predation events, weather). We tested the overall success in relation to nest-site selection varia-bles, and then examined how nest failure (specifically snake predation) was correlated with air temperature.
- Full Text:
- Date Issued: 2019
- Authors: Oswald, Krista N , Lee, Alan T K , Diener, John P , Diener, Elizabeth F , Cunningham, Susan J , Smit, Ben
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/441624 , vital:73902 , https://eco.confex.com/eco/2019/meetingapp.cgi/Paper/78223
- Description: Mitigating the current biodiversity crisis requires a better understanding of how species will respond to future climate change and human impacts on habi-tat. Decreased reproductive capability, due to changes in phenology, output, and success, is one of the main indicators of species’ vulnerability. For terres-trial ground-nesting birds, overall reproductive success is often related to nest-site selection (e.g. increased nest concealment), and weather changes (e.g. higher air temperatures alter nest success). We investigated the reproductive success of Cape Rockjumpers (Chaetops frenatus; “Rockjumpers”), a ground-nesting alpine bird, endemic to the Fynbos biome of South Africa, whose popu-lation decline correlates to warmer temperatures. We predicted that breeding success would be positively correlated with increased nest concealment, and negatively correlated with increasing temperature. We collected data over three years, including two full breeding seasons, from 2016 to 2018 (n=5, n=20 and n=43 respectively), which included nest-site selection variables (i.e. vege-tative cover, rock cover, time since fire in years), success or failure (whether nest resulted in ≥ fledgling), and cause if nest failed (i.e. predation events, weather). We tested the overall success in relation to nest-site selection varia-bles, and then examined how nest failure (specifically snake predation) was correlated with air temperature.
- Full Text:
- Date Issued: 2019
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