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Are foraging patterns of aerial predators influencing diurnal activity of their prey?
There is often a reciprocal relationship between predators and their dominant prey. This results in continuous co-evolution, where the prey selects more efficient ways to avoid predation and the predator selects more efficient ways of catching prey. The aim of this study was to determine if aerial p...
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| Format: | Thesis |
| Language: | English |
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Department of Biological Sciences
2017
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| _version_ | 1867613300920942592 |
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| access_status_str | Open Access |
| author | Retief, Kirsten |
| author2 | Simmons, Robert E |
| author_browse | Retief, Kirsten Simmons, Robert E |
| author_facet | Simmons, Robert E Retief, Kirsten |
| author_sort | Retief, Kirsten |
| collection | Thesis |
| description | There is often a reciprocal relationship between predators and their dominant prey. This results in continuous co-evolution, where the prey selects more efficient ways to avoid predation and the predator selects more efficient ways of catching prey. The aim of this study was to determine if aerial predators (raptors) influence diurnal activity patterns of their prey (mice). Sampling of both raptors and mice was done simultaneously during autumn, winter and spring at two different study sites in three different habitats on South Africa's arid west coast. Sixty PVC mouse traps were checked every half hour throughout all daylight hours and raptors were observed using scan sampling every two minutes. A total of 1228 rodents were trapped consisting mainly of the diurnal mouse, Rhabodmys pumilio and a total of 197 hours was spent observing hunting behaviour of four raptor species: Black and African Marsh Harriers (Circus maurus and C. ranivorus), Black-shouldered Kite (Elanus caeruleus) and Rock Kestrel (Falco rupicolus). All birds hunt rodents on a regular basis and all were beginning to breed towards the end of my study. Results showed significantly higher small mammal activity during winter and in habitats with dense vegetation. Diurnal small mammal activity peaks appeared to shift randomly between sites, habitats and seasons, thereby avoiding predation through unpredictability of activity. Small mammal activity patterns deliberately avoided peak foraging times of raptors during winter at the Pelican site; however this relationship was not linked to any climatic variables to explain how mice avoid high predation periods. Raptors selected peak foraging times dming periods of high small mammal activity at the Dune site during winter; however wind speed and cloud cover were correlated with both raptor foraging and small mammal activity, thereby influencing the relationship between the predator and the prey. In conclusion, no reoccurring diurnal peaks in small mammal activity were seen across the three seasons and this may have been an anti-predation strategy, because predators would find it more difficult to predict high prey activity. However the raptors it seemed were selecting periods of high mice activity at one site when weather conditions allowed. |
| format | Thesis |
| id | oai:open.uct.ac.za:11427/23945 |
| institution | University of Cape Town (South Africa) |
| language | eng |
| last_indexed | 2026-06-10T12:33:57.504Z |
| 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 | Department of Biological Sciences |
| publisherStr | Department of Biological Sciences |
| record_format | dspace |
| source_str | UCTD — University of Cape Town Open Access Repository |
| spelling | oai:open.uct.ac.za:11427/23945 Are foraging patterns of aerial predators influencing diurnal activity of their prey? Retief, Kirsten Simmons, Robert E Botany Ornithology There is often a reciprocal relationship between predators and their dominant prey. This results in continuous co-evolution, where the prey selects more efficient ways to avoid predation and the predator selects more efficient ways of catching prey. The aim of this study was to determine if aerial predators (raptors) influence diurnal activity patterns of their prey (mice). Sampling of both raptors and mice was done simultaneously during autumn, winter and spring at two different study sites in three different habitats on South Africa's arid west coast. Sixty PVC mouse traps were checked every half hour throughout all daylight hours and raptors were observed using scan sampling every two minutes. A total of 1228 rodents were trapped consisting mainly of the diurnal mouse, Rhabodmys pumilio and a total of 197 hours was spent observing hunting behaviour of four raptor species: Black and African Marsh Harriers (Circus maurus and C. ranivorus), Black-shouldered Kite (Elanus caeruleus) and Rock Kestrel (Falco rupicolus). All birds hunt rodents on a regular basis and all were beginning to breed towards the end of my study. Results showed significantly higher small mammal activity during winter and in habitats with dense vegetation. Diurnal small mammal activity peaks appeared to shift randomly between sites, habitats and seasons, thereby avoiding predation through unpredictability of activity. Small mammal activity patterns deliberately avoided peak foraging times of raptors during winter at the Pelican site; however this relationship was not linked to any climatic variables to explain how mice avoid high predation periods. Raptors selected peak foraging times dming periods of high small mammal activity at the Dune site during winter; however wind speed and cloud cover were correlated with both raptor foraging and small mammal activity, thereby influencing the relationship between the predator and the prey. In conclusion, no reoccurring diurnal peaks in small mammal activity were seen across the three seasons and this may have been an anti-predation strategy, because predators would find it more difficult to predict high prey activity. However the raptors it seemed were selecting periods of high mice activity at one site when weather conditions allowed. 2017-02-14T08:24:14Z 2017-02-14T08:24:14Z 2011 2017-02-01T13:05:54Z Bachelor Thesis Honours BSc (Hons) http://hdl.handle.net/11427/23945 eng application/pdf Department of Biological Sciences Faculty of Science University of Cape Town |
| spellingShingle | Botany Ornithology Retief, Kirsten Are foraging patterns of aerial predators influencing diurnal activity of their prey? |
| thesis_degree_str | Bachelor's / Honours |
| title | Are foraging patterns of aerial predators influencing diurnal activity of their prey? |
| title_full | Are foraging patterns of aerial predators influencing diurnal activity of their prey? |
| title_fullStr | Are foraging patterns of aerial predators influencing diurnal activity of their prey? |
| title_full_unstemmed | Are foraging patterns of aerial predators influencing diurnal activity of their prey? |
| title_short | Are foraging patterns of aerial predators influencing diurnal activity of their prey? |
| title_sort | are foraging patterns of aerial predators influencing diurnal activity of their prey |
| topic | Botany Ornithology |
| url | http://hdl.handle.net/11427/23945 |
| work_keys_str_mv | AT retiefkirsten areforagingpatternsofaerialpredatorsinfluencingdiurnalactivityoftheirprey |