Investigating the effects of environmental variables on martial eagle breeding performance in the Kruger National Park

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dc.contributor.advisorAmar, Arjun
dc.contributor.advisorMurgatroyd, Megan
dc.contributor.authorVan Der Merwe, Daryl
dc.date.accessioned2020-05-06T12:48:39Z
dc.date.available2020-05-06T12:48:39Z
dc.date.issued2019
dc.date.updated2020-05-06T01:38:44Z
dc.description.abstractWithin South Africa martial eagles reporting rates have decreased by almost 60% over the last two decades. Similar declines have also been reported within Kruger National Park (KNP), which is regarded as a stronghold for this species. Declines within KNP have been attributed to the low productivity rates. As apex predators, marital eagles are considered to be good indicators of ecosystem health, being sensitive to the cumulative effects of disturbance down the food chain. Changes in the breeding performance of martial eagles may therefore indicate broader environmental change within the ecosystem. In this study, we aim to explore which environmental variables (e.g. climate, land cover, tree cover, fire and elephant abundance) within each territory correlated with martial eagle breeding performance in the hope that we may better understand which variables affect martial eagles breeding performance and whether these may have changed over time to cause the low levels of fecundity presently seen within KNP. We found that breeding productivity (young per territorial pair) was positively influenced by higher precipitation and Normalized Difference Vegetation Index (NDVI) and negatively impacted by high temperatures during the previous year. Breeding rate (breeding attempt per territorial pair) appeared to be negatively influenced by higher tree cover within 6 km of the nest site. Nesting success (outcome of a breeding attempt) was correlated with higher NDVI and lower relative levels of precipitation during the previous year. Using longer term climatic data and the relationship between climate in the previous year and productivity, (the variable which directly relates to annual fecundity), we hindcast the predicted productivity over the last three decades (2018-1986) to explore whether change in climate conditions (precipitation, temperature and NDVI) might reveal declines in productivity. No such declines were predicted, thus, our results do not explain why productivity has declined within KNP.
dc.identifier.apacitationVan Der Merwe, D. (2019). <i>Investigating the effects of environmental variables on martial eagle breeding performance in the Kruger National Park</i>. (). ,Faculty of Science ,Department of Biological Sciences. Retrieved from en_ZA
dc.identifier.chicagocitationVan Der Merwe, Daryl. <i>"Investigating the effects of environmental variables on martial eagle breeding performance in the Kruger National Park."</i> ., ,Faculty of Science ,Department of Biological Sciences, 2019. en_ZA
dc.identifier.citationVan Der Merwe, D. 2019. Investigating the effects of environmental variables on martial eagle breeding performance in the Kruger National Park. . ,Faculty of Science ,Department of Biological Sciences. en_ZA
dc.identifier.ris TY - Thesis / Dissertation AU - Van Der Merwe, Daryl AB - Within South Africa martial eagles reporting rates have decreased by almost 60% over the last two decades. Similar declines have also been reported within Kruger National Park (KNP), which is regarded as a stronghold for this species. Declines within KNP have been attributed to the low productivity rates. As apex predators, marital eagles are considered to be good indicators of ecosystem health, being sensitive to the cumulative effects of disturbance down the food chain. Changes in the breeding performance of martial eagles may therefore indicate broader environmental change within the ecosystem. In this study, we aim to explore which environmental variables (e.g. climate, land cover, tree cover, fire and elephant abundance) within each territory correlated with martial eagle breeding performance in the hope that we may better understand which variables affect martial eagles breeding performance and whether these may have changed over time to cause the low levels of fecundity presently seen within KNP. We found that breeding productivity (young per territorial pair) was positively influenced by higher precipitation and Normalized Difference Vegetation Index (NDVI) and negatively impacted by high temperatures during the previous year. Breeding rate (breeding attempt per territorial pair) appeared to be negatively influenced by higher tree cover within 6 km of the nest site. Nesting success (outcome of a breeding attempt) was correlated with higher NDVI and lower relative levels of precipitation during the previous year. Using longer term climatic data and the relationship between climate in the previous year and productivity, (the variable which directly relates to annual fecundity), we hindcast the predicted productivity over the last three decades (2018-1986) to explore whether change in climate conditions (precipitation, temperature and NDVI) might reveal declines in productivity. No such declines were predicted, thus, our results do not explain why productivity has declined within KNP. DA - 2019 DB - OpenUCT DP - University of Cape Town KW - Conservation Biology LK - https://open.uct.ac.za PY - 2019 T1 - Investigating the effects of environmental variables on martial eagle breeding performance in the Kruger National Park TI - Investigating the effects of environmental variables on martial eagle breeding performance in the Kruger National Park UR - ER - en_ZA
dc.identifier.urihttps://hdl.handle.net/11427/31813
dc.identifier.vancouvercitationVan Der Merwe D. Investigating the effects of environmental variables on martial eagle breeding performance in the Kruger National Park. []. ,Faculty of Science ,Department of Biological Sciences, 2019 [cited yyyy month dd]. Available from: en_ZA
dc.language.rfc3066eng
dc.publisher.departmentDepartment of Biological Sciences
dc.publisher.facultyFaculty of Science
dc.subjectConservation Biology
dc.titleInvestigating the effects of environmental variables on martial eagle breeding performance in the Kruger National Park
dc.typeMaster Thesis
dc.type.qualificationlevelMasters
dc.type.qualificationnameMSc
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