Fig 1.
Study area in northern Republic of Congo.
50 acoustic recorders (forest type: black = mixed, yellow = monodominant, orange = open) in southern national park and adjacent logging concession (darker purple active logging, lighter purple inactive logging). Basemap files courtesy of ESRI. ESRI reserves the right to grant permission for any other use of the image.
Table 1.
Predominant vegetation within 600m of each recording site, by stratum.
Fig 2.
Zones of logging activity in the active logging stratum.
Exploitation areas for each year were drawn as minimum convex polygons around the actual sites of felled trees. Logging roads (red), rivers (blue), acoustic recording sites dots (black = mixed forest site, magenta = monodominant forest site). Active logging was situated southeast of Nouabalé-Ndoki National Park (green area).
Table 2.
Covariates used to model elephant behavior in the Nouabalé-Ndoki landscape and possible a priori predictions for nocturnal activity.
Fig 3.
Acoustically detected gunshot events by stratum.
Bar heights are standardized for total hours of recording in each stratum/year. Actual number of shot events over each bar. inactive logging—blue, active logging—red, national park—green.
Fig 4.
Change over time in proportion nocturnal activity across the study system.
All comparisons between years significant at p<0.001 except year one and two (ns). Error bars are SE of the LSM.
Table 3.
Likelihood ratio statistics for the binomial model applied to the whole study system and separately for each stratum.
Fig 5.
Plots of marginal means from binomial models applied to data from each stratum.
Error bars are standard errors. Note that ordinant axes differ in scale, but all have a reference line at 50% probability of a call being at night. For all strata the plotted relationships were significant predictors of nocturnal calling. Interaction plots of forest type vs season: blue = dry season, red = wet season.
Fig 6.
Behavioral response to exposure to logging activities in the active logging stratum.
Error bars are SE. Most contrasts significant at p<0.05 (ns contrasts: pre-exposure vs done 1styear, done 2ndyear; active vs done 2ndyear, done 4thyear; done 3rdyear–done 5thyear).
Fig 7.
Call density effects on nocturnal behavior.
Shaded areas are 95% confidence intervals. Blue = mixed forest, green = monodominant forest, red = open forest. Computed at study year = 2.
Fig 8.
Predicted probability of night calls as call density changes in active logging, sliced by levels of logging exposure.
Computed at study year = 2, forest type = mixed, with 95% confidence intervals indicated by shading.
Fig 9.
Change in numbers of calls near recording sites versus exposure to logging activity.
Error bars are SE. Pre-exposure vs done 4th yr, p = 0.04; active vs done 4th yr, p<0.001; all other contrasts ns.
Fig 10.
Relative call frequency in the three strata over 3.5 years of study.
Calls per week are standardized (see methods). blue = inactive logging, green = national park, red = active logging.