What is going on under the canopy? Quantifying the human-wildlife interface using the Human Disturbance Index

While most of existing methods successfully use satellite imagery for quantifying
anthropogenic impacts on forest fragments, little is known about disturbances occurring
beneath the canopy. These insights are nonetheless crucial in “One Health” contexts where the interactions between human communities and wildlife are close. Because researchers currently lack an objective tool to assess this proximity, we are developing the Human Disturbance Index (HDI), a novel tool that integrates local community interviews, transects,
and satellite imagery to quantify the human-wildlife interface. We conducted 110 interviews
using Kobotoolbox® and collected data from three transects (3x1,3km) opened in Black Lion Tamarins’ home ranges (BLT, Leonthopithecus chrysopygus). Two study sites (Buri, São Paulo) were empirically classified as “highly anthropized” and one site (Caetetus Ecological Station, SP) as “preserved”. After running pilots refining the intra- and inter-observer reliabilities, testing for seasonal variability (mean variability = 0,21) and testing multiple calculation methods, our final index assigns a category (0 – absent to 2 - highly present) and
a weight (0 -2; according to the stress/transmission risk) to each disturbance parameter (ex. number of items of waste). To date, the HDI, ranging from 0 (no disturbance) to 1 (extreme disturbance), has been successfully applied to characterise six BLT habitats (HDI values ranging from 0.14 to 1). This tool aims to provide primatologists with a robust yet practical method for assessing human disturbances within forest fragments.