Vulnerability of vulture populations to elephant impacts in KwaZulu-Natal

Abstract

Elephant were previously widespread in savanna and coastal systems of KwaZulu-Natal (KZN), but were virtually extirpated by 1870. Over time, elephant have been reintroduced into their former range in KZN, but always onto small fenced systems (mean size 191.3 km2 ± 87.8 km2, median size 107.0 km2, range 14 km2 – 900 km2). These populations have increased rapidly (8.4% per annum), and although a number of populations are now being managed using contraception, the majority of the populations (66.7%, 14 out of 21) are stocked above the ‘preferred density’ as defined in their approved management plans, while others will soon exceed the preferred density. Vulture populations in KZN are small, declining and already at risk of extinction. In KZN, 94.2% of tree-nesting vulture nests occur in areas with elephant; this could increase to 99.5% in the near future if proposed land-use change takes place. Anthropogenic impacts in the broader landscape mean that there are limited opportunities for vultures to nest elsewhere, and we hypothesise that loss of suitable nesting habitat in existing areas, including through impact of elephant on large trees, could result in declines and even extirpation of these species as breeding residents. Given the demonstrated and potential impacts of elephants on large trees necessary for vulture nesting, it is essential that the role of protected areas and extensive wildlife systems for vultures be adequately taken into account when managing elephant populations. It is important that a precautionary and adaptive management approach is taken regarding management of elephant in areas important for vultures, at least until the ecological interactions between vultures, vegetation, elephant and other drivers are better understood, and until the willingness and ability to manage elephant numbers and impact according to the elephant management plans are demonstrated.

Management of African elephant populations in small fenced areas: Current practices, constraints and recommendations

“…Elephants introduced into an area to increase tourism potential may compromise other conservation objectives. Rushworth et al (2018) highlight the complexities of managing elephants in small areas, while at the same time seeking to conserve highly threatened vulture populations. Blackmore and Trouwborst (2018) explore the evolution of South African regulatory jurisprudence applicable to wildlife and analyse the norms and standards in relation to international and national legislation and common law as it applies to elephants.…”

Elephant rewilding affects landscape openness and fauna habitat across a 92‐year period

“…In sub‐Saharan savannah, elephants actively promote herbaceous vegetation cover and increase landscape openness by reducing tree and shrub density and canopy size (Guldemond et al, 2017), which should indirectly impact fauna by selecting for species that prefer “open” rather than “closed” savannah (Gordon et al, 2021; Nasseri et al, 2011). By breaking tree branches and toppling trees, elephants are thought to promote herbaceous plant cover/diversity through nursery effects (Coverdale et al, 2016); however, they may compromise the abundance of some larger tree species, which may then negatively affect fauna requiring larger trees (Rushworth et al, 2018). Elephants’ impacts on tree persistence also moderates the amount of coarse woody debris, which may impact fire regimes (Kimuyu et al, 2014) and advantage smaller mammalian fauna, such as rodents or lagomorphs, by creating habitat refugia (Manning et al, 2013) but disadvantage larger species such as antelope by reducing predator detection (Kuijper et al, 2013).…”

The hard lives of trees in African savanna—Even without elephants

“…Trees are integral to ecosystem functioning in savannas as they provide food and habitat for animals (Dean et al, 1999; Rushworth et al, 2018) and play an important role in increasing local nutrient pools (Belsky et al, 1993; Ludwig et al, 2001, 2003; Treydte et al, 2009). The continued loss of tall trees in African savannas, especially those taller than 5 m, is a topic that receives much attention (Davies et al, 2018; Levick & Asner, 2013; O'Connor & Goodall, 2017; Shannon et al, 2008, 2011; Smit et al, 2010; Vanak et al, 2012).…”