Full Text Available
Note: Clicking the button above will open the full text document at the original institutional repository in a new window.
How does temperature affect Fork-tailed Drongo, Dicrurus adsimilis, foraging effort, nestling provisioning and growth rates?
Global average temperatures are predicted to increase by as much as 5ᵒC by 2100. Therefore, it is imperative to identify how species are affected by temperature increase to ensure that proper conservation and management of wildlife can be implemented. Species which already live in warmer climates, s...
Saved in:
| Main Author: | |
|---|---|
| Other Authors: | |
| Format: | Thesis |
| Language: | English |
| Published: |
Percy FitzPatrick Institute of African Ornithology
2017
|
| Subjects: | |
| Tags: |
No Tags, Be the first to tag this record!
|
| _version_ | 1867613756390899712 |
|---|---|
| access_status_str | Open Access |
| author | Olinger, Ryan |
| author2 | Cunningham, Susan J |
| author_browse | Cunningham, Susan J Olinger, Ryan |
| author_facet | Cunningham, Susan J Olinger, Ryan |
| author_sort | Olinger, Ryan |
| collection | Thesis |
| description | Global average temperatures are predicted to increase by as much as 5ᵒC by 2100. Therefore, it is imperative to identify how species are affected by temperature increase to ensure that proper conservation and management of wildlife can be implemented. Species which already live in warmer climates, such as deserts, may provide the first clues to the impacts of increasing temperatures. Birds represent an ideal indicator because research has shown that rising temperatures affect their behaviour, including foraging and provisioning of young, thereby reducing reproductive success. However, it remains unclear whether this results from physiological constraints on behaviour, from declining food availability and or access to prey items at high temperatures. In this study, I aimed to identify how temperature affects the foraging and provisioning behaviour of wild Fork-tailed Drongos, Dicrurus adsimilis, when supplemental food is provided. Additionally, I aimed to identify how nestling growth rates change with temperature. The results of two supplemental feeding experiments indicated that as temperatures increased, adults significantly reduced their willingness to forage, reduced provisioning to offspring and exhibited increased rates of heat dissipation behaviour. Furthermore, when provisioning nestlings, adult drongos consumed a larger proportion of supplementary food at higher air temperatures, and provisioned less. This suggests that they suffer greater provisioning costs at such times. Surprisingly, despite finding several negative effects of temperatures on adults' willingness to forage and provisioning, there was only a weak and non-significant effect of temperature on nestling growth rates. This suggests that adults may be able to compensate for reduced foraging at high temperatures. My study shows that the increased thermoregulatory costs of activity at high temperatures can constrain foraging and provisioning, even when food remains abundant. However, whether this impacts the fitness of current offspring or parents future reproductive success remains unclear. |
| format | Thesis |
| id | oai:open.uct.ac.za:11427/25053 |
| institution | University of Cape Town (South Africa) |
| language | eng |
| last_indexed | 2026-06-10T12:41:12.437Z |
| license_str | Not specified — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from UCTD — University of Cape Town Open Access Repository |
| publishDate | 2017 |
| publishDateRange | 2017 |
| publishDateSort | 2017 |
| publisher | Percy FitzPatrick Institute of African Ornithology |
| publisherStr | Percy FitzPatrick Institute of African Ornithology |
| record_format | dspace |
| source_str | UCTD — University of Cape Town Open Access Repository |
| spelling | oai:open.uct.ac.za:11427/25053 How does temperature affect Fork-tailed Drongo, Dicrurus adsimilis, foraging effort, nestling provisioning and growth rates? Olinger, Ryan Cunningham, Susan J Flower, Thomas Conservation Biology Ornithology Global average temperatures are predicted to increase by as much as 5ᵒC by 2100. Therefore, it is imperative to identify how species are affected by temperature increase to ensure that proper conservation and management of wildlife can be implemented. Species which already live in warmer climates, such as deserts, may provide the first clues to the impacts of increasing temperatures. Birds represent an ideal indicator because research has shown that rising temperatures affect their behaviour, including foraging and provisioning of young, thereby reducing reproductive success. However, it remains unclear whether this results from physiological constraints on behaviour, from declining food availability and or access to prey items at high temperatures. In this study, I aimed to identify how temperature affects the foraging and provisioning behaviour of wild Fork-tailed Drongos, Dicrurus adsimilis, when supplemental food is provided. Additionally, I aimed to identify how nestling growth rates change with temperature. The results of two supplemental feeding experiments indicated that as temperatures increased, adults significantly reduced their willingness to forage, reduced provisioning to offspring and exhibited increased rates of heat dissipation behaviour. Furthermore, when provisioning nestlings, adult drongos consumed a larger proportion of supplementary food at higher air temperatures, and provisioned less. This suggests that they suffer greater provisioning costs at such times. Surprisingly, despite finding several negative effects of temperatures on adults' willingness to forage and provisioning, there was only a weak and non-significant effect of temperature on nestling growth rates. This suggests that adults may be able to compensate for reduced foraging at high temperatures. My study shows that the increased thermoregulatory costs of activity at high temperatures can constrain foraging and provisioning, even when food remains abundant. However, whether this impacts the fitness of current offspring or parents future reproductive success remains unclear. 2017-09-06T07:00:23Z 2017-09-06T07:00:23Z 2017 Master Thesis Masters MSc http://hdl.handle.net/11427/25053 eng application/pdf Percy FitzPatrick Institute of African Ornithology Faculty of Science University of Cape Town |
| spellingShingle | Conservation Biology Ornithology Olinger, Ryan How does temperature affect Fork-tailed Drongo, Dicrurus adsimilis, foraging effort, nestling provisioning and growth rates? |
| thesis_degree_str | Master's |
| title | How does temperature affect Fork-tailed Drongo, Dicrurus adsimilis, foraging effort, nestling provisioning and growth rates? |
| title_full | How does temperature affect Fork-tailed Drongo, Dicrurus adsimilis, foraging effort, nestling provisioning and growth rates? |
| title_fullStr | How does temperature affect Fork-tailed Drongo, Dicrurus adsimilis, foraging effort, nestling provisioning and growth rates? |
| title_full_unstemmed | How does temperature affect Fork-tailed Drongo, Dicrurus adsimilis, foraging effort, nestling provisioning and growth rates? |
| title_short | How does temperature affect Fork-tailed Drongo, Dicrurus adsimilis, foraging effort, nestling provisioning and growth rates? |
| title_sort | how does temperature affect fork tailed drongo dicrurus adsimilis foraging effort nestling provisioning and growth rates |
| topic | Conservation Biology Ornithology |
| url | http://hdl.handle.net/11427/25053 |
| work_keys_str_mv | AT olingerryan howdoestemperatureaffectforktaileddrongodicrurusadsimilisforagingeffortnestlingprovisioningandgrowthrates |