Increasing temperatures increase the risk of reproductive failure in a near threatened alpine groundnesting bird, the Cape Rockjumper Chaetops frenatus:
- Authors: Oswald, Krista N , Diener, Elizabeth F , Diener, John P , Cunningham, Susan J , Smit, Ben , Lee, Alan T K
- Date: 2020
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/149324 , vital:38825 , https://0-doi.org.wam.seals.ac.za/10.1111/ibi.12846
- Description: A major cause of reproductive failure in birds is nest predation. Predation risk depends on predator type, as predators vary in their ecology and sensory modalities (e.g. visual vs. olfactory). Snakes (generally olfactory predators) are a major nest predator for small birds, with predation strongly associated with higher temperatures. We investigated nest survival in a ground‐nesting alpine species, the Cape Rockjumper Chaetops frenatus , endemic to alpine fynbos in southwestern South Africa. We collected 3 years of nest data, testing whether nest survival was related to (1) habitat stage (early post‐fire vs. late post‐fire habitat, ≤ 3 and > 3 years since fire respectively), (2) nest concealment and (3) temperature. We found that nests had better survival at lower temperatures, with snake predation (our main source of predation) increasing in higher temperatures.
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- Date Issued: 2020
Multi-directional effects of warming temperatures on the reproductive success of a threatened alpine-endemic bird, and implications for conservation management
- 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.
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- Date Issued: 2019