Assessing translocation effects on an African elephant (Loxodonta africana) source population: demographics, landscape use and response to drones in Majete Wildlife Reserve, Malawi.

Hartmann, Wesley Laurence (2020-03)

Thesis (MSc)--Stellenbosch University, 2020.

Thesis

ENGLISH ABSTRACT: Translocations are increasingly common as a wildlife management strategy to reintroduce species that have undergone a local extirpation or to reinforce populations that have become isolated. Translocation effects have been well documented on the moved animals, however, much less is known about the effects these large-scale anthropogenic events have on source populations. The African elephant (Loxodonta africana) is a keystone species which plays a pivotal role in the ecosystems it inhabits. With their wide-ranging impacts, understanding how elephants utilize the space available to them, or how anthropogenic events such as translocations, could influence these patterns, is vital for the effective management of elephant populations. An additional human-associated disturbance on wildlife populations, although on a much smaller scale, is the use of technology for observational purposes. Generally, these technologies have enabled an unobtrusive means by which to detect and observe wildlife (i.e. remote-sensing camera traps), but increasingly the wildlife sciences are using unmanned aerial vehicles, more commonly known as drones, which are not unobtrusive. A great number of review papers have summarized and emphasized the drone’s capabilities in the wildlife sciences, but few have investigated the effect drones have on animals themselves. This study reviews all published translocation events that occurred on the African continent between the years 2000 and 2019 in an attempt to determine the factors that influence the success of translocations in an African context, and investigates how a source elephant population responded demographically and spatially to a large translocation event in Majete Wildlife Reserve where (n=154) 42% of elephants were removed and 70% of adult females. The study also investigated how this population responded behaviourally, post translocation, to the approach and presence of a drone. The demographic status of the Majete elephants was assessed via a combination of aerial survey data and individual identification techniques. Since the translocation, the population has increased from an estimated 200 individuals to 232 over a two-year period. A sex ratio of 5:2 male to female was found for adult elephants (older than 10 years) and a population growth rate of 7% per annum was estimated. The current growth rate is likely due to conception prior to the translocation event and is expected to decrease due to the extreme adult male bias in the current population. The removal of herds, primarily from one region within the reserve, significantly influenced the diversity of use of artificial water points by elephant herds. Herds historically only found in peripheral regions of the reserve were sighted more frequently in the areas other elephant herds had been removed from. While the population tolerated drone use reasonably well, increasing approach speeds and an approach angle of 90° (as opposed to 45°), were found to have significant negative effects on the likelihood of a successful drone approach towards elephants, regardless of sex and herd/group size. No flight or environmental variables were found to significantly influence the success of a sustained drone flight, however the outcome of the preceding approach was found to significantly influence success (GLZ, Estimate = 2.39497, p < 0.0001) i.e. a successful approach was more likely to result in a successful presence flight.

AFRIKAANSE OPSOMMING: Die gebruik van translokasies as ‘n metode van wildbestuur word al hoe meer algemeen benut om spesies wat plaaslik uitgesterf het terug te plaas in hul natuurlike omgewing, of om dierebevolkings wat drasties geïsoleer geword het weer te versterk. Die impak van translokasie op hervestigde individue is goed gedokumenteer, maar minder kennis bestaan oor die impak van hierdie grootskaalse antropogeniese gebeurtenisse op bronbevolkings. Die Afrika-olifant (Loxodonta africana) is ‘n hoeksteen-spesie wat ‘n sleutelrol vervul in die ekosisteme waarin dit voorkom. As gevolg van hul alomvattende impak op die omgewing is dit noodsaaklik vir die effektiewe bestuur van olifantbevolkings om te verstaan hoe olifante beskikbare ruimte benut, en hoe antropogeniese gebeure soos translokasies hierdie patrone kan beïnvloed. Die gebruik van tegnologie vir waarnemingsdoeleindes is ‘n bykomende mens-geassosieerde steuring op wildbevolkings, hoewel op ‘n veel kleiner skaal. Oor die algemeen het hierdie tegnologieë grotendeels op ‘n onopsigtelike wyse plaasgevind en sodane die opsporing van dierelewe moontlik gemaak (d.w.s. deur die gebruik van afgeleë kamera-lokvalle), maar wildnavorsing maak toenemend gebruik van onbemande lugvoertuie, meer algemeen bekend as hommeltuie oftewel ‘drones’, wat nie onopvallend is nie. ‘n Groot aantal hersieningsartikels het alreeds die funksies van die hommeltuig in wildnavorsing opgesom en beklemtoon, maar enkele het al die effek wat hommeltuie op die dier self het ondersoek. Dié studie hersien alle gepubliseerde translokasie gebeure wat tussen die jare 2000 en 2019 op die Afrika-vasteland plaasgevind het, in ‘n poging om die faktore wat die sukses van translokasies in die Afrika-konteks bepaal te identifiseer, en ondersoek die demografiese en ruimtelike reaksie van ‘n olifant-bronbevolking op ‘n grootskaalse translokasiegebeurtenis in Majete wildreservaat waar 42% (n=154) van die olifante geherlokeer is, insluitende 70% van die volwasse wyfies. Die gedragsreaksie van hierdie bevolking op die benadering en teenwoordigheid van ‘n hommeltuig ná translokasie word ook in die studie ondersoek. Die demografiese status van die Majete-olifante was geevalueer deur middel van ‘n kombinasie van lugopnames en individuele identifikasietegnieke. Sedert die translokasie het die bevolking oor ‘n periode van twee jaar van na raming 200 individue tot 232 toegeneem. ‘n Manlike tot vroulike geslagsverhouding van 5:2 was gevind vir volwasse olifante (ouer as 10 jaar), en ‘n bevolkingsgroeikoers van 7% per jaar word geskat. Die huidige groeikoers is waarskynlik te danke aan bevrugting voor die translokasiegebeurtenis, en sal na verwagting afneem as gevolg van die groot aantal volwasse manlike olifante in die huidige bevolking. Die verwydering van kuddes, hoofsaaklik van ‘n enkele streek in die reservaat, het die diversiteit in die benutting van kunsmatige waterpunte deur olifantkuddes beduidend beïnvloed. Kudde wat voorheen slegs in die perifere streke van die reservaat aangetref is, was meer gereeld waargeneem in die gebiede waarvandaan die ander olifantkuddes verwyder is. Alhoewel die bevolking die gebruik van die hommeltuig redelik goed verdra het, was daar gevind dat ‘n toenemende benaderingsnelheid en ‘n benaderingshoek van 90° (in teenstelling met 45°) ‘n beduidende negatiewe uitwerking op die waarskynlikheid van ‘n suksesvolle hommeltuig-benadering tot olifante gehad het, ongeag van die geslag en kuddegrootte. Daar was gevind dat geen vlug- of omgewingsveranderlikes die sukses van ‘n volgehoue hommeltuig-vlug beduidend beïnvloed het nie, maar die uitkoms van die voorafgaande benadering het wel die sukses daarvan beduidend beïnvloed (GLZ, Estimate = 2.39497, p <0.0001), d.w.s. dat ‘n suksesvolle benadering meer waarskynlik was om in ‘n suksesvolle teenwoordigheidsvlug te ontaard.

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