DOI: 10.5061/dryad.5d48n33
title: Data from: Zebra diel migrations reduce encounter risk with lions at night.

description: 1. Diel migrations (DM; back and forth diel movements along an ecological
 gradient) undertaken by prey to avoid predators during the day have been
 demonstrated in many taxa in aquatic ecosystems. In terrestrial
 ecosystems, prey often shift between various vegetation types whose cover
 determine their vulnerability (i.e. likelihood of being killed when
 attacked). 2. We conceptualized that in terrestrial ecosystems DM could
 also occur, and that the contribution of DM and shifts in vegetation cover
 use in reducing predation risk should depend upon the predator behaviour
 and the correlation between encounter risk and vulnerability across
 vegetation types. We further hypothesized that when the predator
 distribution is predictable, terrestrial prey could have evolved DM
 strategies taking them away from the predator when it is active or
 efficient. 3. We investigated whether plains zebras Equus quagga perform
 DM in Hwange National Park (Zimbabwe). There, zebras can forage in large
 patches of open grasslands located near waterholes where they can also
 easily detect predators. However, they are there at high risk of
 encountering their main predator, lions Panthera leo, especially at night.
 4. We found out that zebras employ a DM anti-predator strategy. Zebras
 forage near waterholes during the day but move away from them at sunset,
 when lions become active. We demonstrated that this DM, occurring over a
 few kilometres, dramatically reduces their nighttime risk of encountering
 lions, which generally remain close to waterholes. Zebra changes in
 nighttime selection for vegetation cover types reduced their risk of
 encountering lions much less. This may arise from a trade-off between
 encounter risk and vulnerability across vegetation types, with zebras
 favouring low vulnerability once DM has reduced encounter risk. 5. In
 summary, here we (1) quantify, in a terrestrial system, the effect of a
 predator-induced DM on the likelihood of encountering a predator, and (2)
 distinguish the effects of the DM on encounter risk from those related to
 day/night changes in selection for vegetation types. We discuss how prey
 partition their risk between encounter risk and habitat-driven
 vulnerability and why it is likely critical to understand the emergence of
 anti-predator behavioural strategies.
description: data_zebra_locationTable with information for zebra GPS locations. ZebraID = identification of individual ; DateTimeLocal = date and time in POSIXct format, Year = year, Season = Dry or Wet, isNight = 1 for locations at night and 0 for locations at day ; TimeSinceSunriseSunset = time spent since the last sunrise or sunset ; NbDayTrack = id of the day track for a given individual ; VegetType = type of vegetation ; DistanceToWaterhole = distance to waterhole in kmdata_lion_IPP_Dry_DayLion data used to assess the RSF during the dry season and day period. id = individual id ; response = the variable response used in the IPP, weight = the variable used as weight in the regression ; veget_type = type of vegetation ; dist2water = distance to waterhole in km ; dist2water_log = log(1+ distance to waterhole in km)data_lion_IPP_Dry_NightLion data used to assess the RSF during the dry season and night period. id = individual id ; response = the variable response used in the IPP, weight = the variable used as weight in the regression ; veget_type = type of vegetation ; dist2water = distance to waterhole in km ; dist2water_log = log(1+ distance to waterhole in km)data_lion_IPP_Wet_DayLion data used to assess the RSF during the wet season and day period. id = individual id ; response = the variable response used in the IPP, weight = the variable used as weight in the regression ; veget_type = type of vegetation ; dist2water = distance to waterhole in km ; dist2water_log = log(1+ distance to waterhole in km)data_lion_IPP_Wet_NightLion data used to assess the RSF during the wet season and night period. id = individual id ; response = the variable response used in the IPP, weight = the variable used as weight in the regression ; veget_type = type of vegetation ; dist2water = distance to waterhole in km ; dist2water_log = log(1+ distance to waterhole in km)data_zebra_encounter_risk_DryZebra data used to assess the relative effect of diel migration and change in vegetation cover on decrease in encounter risk with lions during the dry season. id = individual ID ; daytrack = the daytrack ID ; median_distwater_day = the median distance to waterhole (in km) over all GPS locations at day in a given daytrack ; median_distwater_night = the median distance to waterhole (in km) over all GPS locations at night in a given daytrack ; daytime_risk = actual daytime risk (situation 1) ; nighttime_risk_no_adjustment = hypothetical nighttime risk in absence of behavioural adjustments (situation 3) ; nighttime_risk_dm = hypothetical nighttime risk with diel migration only (situation 4) ; nighttime_risk = actual nighttime risk (situation 2) ; DM = diel migration away from waterholes in kmdata_zebra_encounter_risk_WetZebra data used to assess the relative effect of diel migration and change in vegetation cover on decrease in encounter risk with lions during the wet season. id = individual ID ; daytrack = the daytrack ID ; median_distwater_day = the median distance to waterhole (in km) over all GPS locations at day in a given daytrack ; median_distwater_night = the median distance to waterhole (in km) over all GPS locations at night in a given daytrack ; daytime_risk = actual daytime risk (situation 1) ; nighttime_risk_no_adjustment = hypothetical nighttime risk in absence of behavioural adjustments (situation 3) ; nighttime_risk_dm = hypothetical nighttime risk with diel migration only (situation 4) ; nighttime_risk = actual nighttime risk (situation 2) ; DM = diel migration away from waterholes in km