Desert Lions








Activity patterns

Activity patterns
During the direct visual observations (see above) lions were active from 17h00, throughout the night, and until 10h00 the following morning (Figure 18). There was a burst of activity before sundown, followed by another peak between 21h00 and 22h00. Notwithstanding, lions were most active between 04h00 and 09h00. Analysis of data from the GPS collar (see above) revealed a similar pattern of activity (Figure 19). The distances moved in 2-hour units is interpreted here as an index of activity, and reflect the flurry of activity before and after daybreak also observed during direct observations.

Figure 18. Activity patterns of lions based on direct visual observations (N = 721 hrs).

Figure 19. Distanced moved during 2-hour units as an index of activity, based on data collected by a GPS radio-collar (N = 182 days). The Proportion value for each 2-hour unit indicates the mean proportion, and standard error, of the total distance traveled per day.

Lions were most active, as measured by the mean distances moved per hour, during full moon and on nights when the phase of the moon was above half (Figure 20). During the new moon activity decreased, but was higher than the daytime activity. This pattern of increased activity associated with increasing moonlight, remained constant for all the night-time hours (Figure 21)

Figure 20. Distances moved per hour, as an index of activity, during different phases of the moon at night, and during daylight.

Figure 21. Distances moved (km/h) per 2-hour unit at night, as an index of activity, during different phases of the moon at night.

Previous records on predation and prey selection by Kunene lions were limited to daytime radio tracking observations. It was feared that these data were biased towards larger prey species and that lions may capture and totally consume smaller prey, like springbok, at night. During 2006 direct visual observations (N = 721 hrs) on lions in the Hoaruseb River presented an unbiased sample of prey selection. Surprisingly the results compared favourably with those based on daytime radio tracking (Table 3). Gemsbok and Hartmann’s zebra were the two most important prey species, followed by springbok and ostriches. The number of livestock killed by lions increased during the 2006 observations. The frequency that lions capture prey depends on the size of the prey and the group size of the lions. Visual observations on two lionesses in the Hoaruseb River (see above), feeding mainly on gemsbok, revealed that they killed every 6 – 8 days (n = 18).

Summary of previous data on prey species killed by Kunene lions up to December 2005 (N = 54).

Table 3. Summary of the prey species killed by Kunene lions from 2000 to 2006, and during intensive observations in 2006 (percentages in brackets).

Between July and December 2006 lions in the Hoaruseb and Hoanib Rivers were kept under visual observation for periods ranging from 24 to 264 hours (1-11 days), following techniques described elsewhere (Stander 1992). During these direct visual observations (N = 721 hrs / 29 days) lions moved an average of 9.85 km per night (SD = 8.53; range: 1-29 km). A GPS radio-collar was fitted to a lioness (Xpl-25) between the Hoanib and Hoaruseb Rivers in March 2006. The GPS unit recorded 10 fixed per day (17h00 – 10h00) between 3 March 2006 and 3 September 2006 (192 days, 1581 fixes). Geographic Information System (GIS) analysis of these data showed that, similar to the direct observations, the lioness moved a mean distance of 9.95 km per night (SD = 8.9; range: 0.1-48 km; Figure 17).

Figure 17. Distances traveled per day by a lioness, during 182 consecutive days.

Analysis of data from a GPS radio-collar (see above), representing two lionesses in the same area, calculated 6.96 days as the mean frequency between kills (SD = 3.36; range: 3–16 days; n = 27 kills). The distances lions traveled per night increased in a linear fashion with each sequential day following their last kill (Figure 22). On the fifth day since their last kill lionesses started moving further (12 km/day) than the overall mean of 10 km/day. The daily distances moved thereafter, increased to x = 29 km/day on the 15th day. As the lions became increasingly hungry with every passing day, they not only moved longer distances per day, but also did so with more consistency (Figure 23). The variance about the mean, measured by %CV, dropped to below 50% on the 10th day, when the mean distance reached 20 km/d, and decreased to 15% by the 15th day.

Figure 22. The relationship between the mean distance traveled per day, by two lionesses, and the time (days) since their last kill. Error bars indicate standard error of the mean.

Figure 23. The relationship between the mean distance traveled per day and the amount of variation, measured by coefficient of variance (SD as a percentage of the mean).

Last data analysis & update - March 2007