Elephant Rewilding Indirectly Affects Rodent Site-Use and Behavior by Moderating Coarse Woody Debris Density

Area of Science:

• Ecology
• Conservation Biology
• Wildlife Management

Background:

• Megaherbivores, like African savannah elephants (Loxodonta africana), are crucial ecosystem engineers altering vegetation structure through activities such as felling trees and breaking branches.
• The cascading effects of these habitat modifications on smaller fauna, particularly rodents, are not well understood.
• Understanding these impacts is vital for effective conservation and rewilding strategies.

Purpose of the Study:

• To investigate how elephant rewilding affects coarse woody debris (CWD) density in South African lowveld savannah.
• To examine the influence of CWD on the behavior of Natal multimammate mice (Mastomys natalensis), including site visitation, activity, and giving-up density (GUD).
• To assess the role of elephants in restoring fine-scale habitat heterogeneity and behaviorally mediated ecosystem functions.

Main Methods:

• Field surveys were conducted in rewilded and non-rewilded reserves to quantify CWD abundance.
• Manipulative experiments were used to measure rodent site visitation, behavior, and GUD in CWD and adjacent open microhabitats.
• Bayesian models were employed to analyze the data and determine the statistical significance of observed effects.

Main Results:

• CWD density (medium and large sizes) was substantially higher (5.5 and 18.0 times, respectively) in areas with restored elephants.
• Rodent visitation, feeding, and resting behaviors were significantly higher (1.66, 1.76, and 7.75 times, respectively) in CWD compared to open areas.
• Rodents exhibited higher GUD values in open areas, suggesting increased perceived predation risk and a preference for CWD as a refuge.

Conclusions:

• Elephant-induced habitat modifications create structural refugia that positively influence rodent foraging behavior and reduce perceived predation risk, aligning with the landscape of fear framework.
• By enhancing habitat heterogeneity, elephants indirectly shape small-mammal behavior, impacting crucial ecological processes like seed predation and dispersal.
• Megafauna rewilding can effectively reinstate lost trophic interactions and behaviorally mediated ecosystem functions, highlighting the importance of considering these pathways in restoration ecology.