Habitat
utilisation
Habitat
preferences
Home ranges
Nocturnal movements
Coastal movements
Habitat
preferences
During 2006, four lionesses in the Hoaruseb
and Hoanib Rivers were monitored. They occupied an area of
4,309 km2 between the two river systems (see Figure 29). This
area was divided into eight distinct habitat types, using
ArcView Spatial Analyst (Table 4). Mountains, rocky outcrops,
dunes, and plains comprise 90% if the habitat, whilst the
ephemeral river systems and the coastal belt add up to only
10% (Figure 24). Habitat selection by the lions was calculated
from 1696 radio tracking fixes using Spatial Analyst. The
lions did not use the available habitat uniformly and spent
significantly more time in the two ephemeral river systems
and the Hoanib floodplain, than expected (Figure 25). Rocky
outcrops was the only habitat type that lions used equal to
its availability. Lions killed prey animals in all eight habitat
types, and mostly in the same proportions when compared with
the time they spent in each habitat (Figure 26). They were
most successful in catching prey along the Coast, whilst the
Mountain and Hoanib habitats produced less than the expected
number of kills.
Table
4. The surface areas of eight habitat types between the Hoanib
and Hoaruseb Rivers, and the number of radio tracking fixes
and kills in each habitat type by four lionesses in 2006.
Figure
24. Proportions of eight habitat types in a area utilised
by four lionesses between the Hoanib and Hoaruseb Rivers in
2006.
Figure
25. Preferential habitat selection, expressed by the 2 value,
of lions between the Hoanib and Hoaruseb Rivers in 2006. The
proportions of the eight habitat types and the number of fixes
in each habitat were compared using a 2 goodness-of-fit test.
If lions selected a habitat equal to the proportional size
of that habitat type, the Chi-sqr value [Sqrt(Observed/Expected)]
would be 1, and the value would increase if the habitat were
favoured.
 .
Figure
26. Preferential selection of habitat types, expressed by
the 2 value, where lions killed prey animals, between the
Hoanib and Hoaruseb Rivers in 2006. The number of fixes and
kills in each habitat type were compared using a 2 goodness-of-fit
test. If lions killed prey animals in a habitat equal to the
number of fixes in that habitat type, the Ch-sqr value [Sqrt(Observed/Expected)]
would be 1, and the value would increase if they were most
successful in that habitat.
 .
During daytime radio tracking sessions (N =
597) lions were observed in eight habitat categories (Fig.
A15). Ephemeral rivers, mountains (28%) and springs are the
three most important habitat types (total = 92%) that lions
utilise for daytime resting. During nocturnal movements and
foraging, lions are expected to utilise the habitat more uniformly
Fig.
A15. Summary of habitats favoured by Kunene lions (N = 597).
Home
ranges
The areas occupied by the Kunene lions are
the largest home ranges ever recorded for the species (Table
A4). With the increase in sample sizes the two methods (MCP
and Kernel) are calculating similar estimates of home ranges
size for most individuals. The home ranges of the Aub and
Agab prides, that utilise similar habitats, are similar in
size, for both the MCP and Kernel methods. There is extensive
overlap between the different groups, and especially so for
the male groups, where the size of the habitats they utilise
increase continuously. Land tenure systems appear to be driven
by ecological factors, such as prey availability, and density
dependent factors, but more research is needed to address
this.
Table
A4. Home ranges of Kunene lions.
1
The percentage of fixes where the MCP home range estimate
reached an asymptote of at least 95% of the total MCP-estimate,
based on bootstrap analyses.
Detailed
maps showing the home range size and areas utilised are presented
here for each group of lions.
(Click to view enlargement of maps)
The
home range of the Hoaruseb lionesses is dynamic.
During 2006 the group ranged in an area of 3,604 km2, between
the Hoanib and Hoaruseb Rivers (Figure 29). However, the founding
female of this group has been monitored since the age of 14
months, starting in October 1999. The long-term results highlight
a dynamic and evolving pattern of home range use (Table 6
& Figure 30). Xpl-10 was born in the Aub pride (see above)
in September 1998. Up to 2000 she moved in the area occupied
by the Aub pride, but dispersed in November 2000, extending
her home range to the Hoanib River in 2001. At the end of
2001 she moved to the Hoaruseb where she remained for the
period between 2002-2004. During 2005, Xpl-10 expanded her
home range to the Okongwe area, south east of the Hoaruseb
River. Intensive daily monitoring during 2006 highlights the
fluctuating pattern of range-use, and demonstrates a gradual
expansion to the Hoanib River that started in May 2006. By
September 2006 Xpl-10 were spending most of her time on the
Hoanib floodplain.
Figure
29. Locations and home range estimate (Kernel Contour) of
Xpl-10 and the Hoaruseb females during 2006.
 .
Table
6. The home ranges used by Xpl-10 and the Hoaruseb females
during eight periods between 1999 and 2006 (95% Kernel Contour).
Figure
30. Locations and home range estimate (Kernel Contour) of
Xpl-10 and the Hoaruseb females during eight period between
1999 and 2006.
2000 |
2001 |
2002-2004 |
2005 |
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 |
April
2006 |
May
2006 |
July
2006 |
September
2006 |
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Hobatere:
Two male lions (Xpl-19 & 20), born in the Aub pride during
August 2000, utilised an area of 2,457 km2 up until May 2005
(Figure 31). They then dispersed and settled permanently on
Hobatere. This was the first documented case of lions from
the desert population, dispersing towards the east and joining
the Etosha population. At the age of five years the two males
arrived at Hobatere late in June 2005. They ousted the local
male lion, took over tenure of the pride that live on Hobatere
and the Otjovasandu area of Western Etosha, and were seen
mating with the lionesses on 2 July 2005. Steve Braine of
Hobatere Lodge monitored their movements intensively. Since
their arrival the two males have remained in the Hobatere
Concession (Figure 32), using a home range of only 187 km2
(95% Kernel Contour).
| Figure
31. Locations and home range of Xpl-19 & 20 between
December 2001 and May 2005, prior to dispersing to Hobatere. |
Figure
32. Locations and home range estimate (Kernel Contour)
of Xpl-19 & 20 between June 2005 and December 2006,
after they dispersed and settled on Hobatere (N = 148,
Steve Braine). |
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Nocturnal
movements
Due to constraints imposed by the terrain,
observations on marked lions are restricted to daytime radio
tracking. Anecdotal observations suggest that lions move extensively
at night and that they may utilise habitats not reflected
by the conventional radio tracking data. To address this concern
a GPS radio collar (courtesy of Ingrid Wiesel) was fitted
to a lioness (Xpl-18) of the Agab Pride, for a three-month
period in July 2005. The GPS radio collar was programmed to
record daily position coordinates (fixes) every two hours,
between 17h00 and 10h00 (UTC). Over the three months the GPS
radio collar recorded 893 fixes during 104 nights (Table 5).
The lioness moved an average calculated distance of 8.3 km
per night, but utilised only 22% of the pride’s known
home range (Table 5). Over the same period Xpl-18 was also
located 17 times, using conventional VHF techniques (see Methods).
These aerial radio-tracking locations reflected only 8% of
the known home range, and 34% of the area recorded by the
GPS collar (Fig. 16).
Table
5. Summary of data collected by a GPS radio collar and aerial
tracking on the movements of Xpl-18 (Agab Pride), between
11 July and 22 October 2005.
1
Home range of the Agab Pride over 5 years 2656 km2 (MCP),
see Table 4 & maps.
Fig.
16. Locations of Xpl-18, of the Agab Pride from a GPS radio
collar and aerial radio tracking, 11 July - 22 October 2005.
(Click to view enlargement
of map)
Extended
nocturnal movements to the north and northeast, and outside
the ephemeral river systems (GPS collar data), was not captured
by the conventional daytime methods. The GPS data on nocturnal
movements of Xpl-18 revealed interesting patterns, not previously
known, and in support of the anecdotal information on extended
movements at night. In order to demonstrate these findings,
a sub-set of six nocturnal movements, is presented (Fig. 17).
| Fig.
17. Layout of nocturnal movements of Xpl-18 (Agab Pride)
during six nights. (Click to view enlargement) |
Table
A6. Summary of distances moved during six nights by Xpl-18
(Agab Pride), as recorded by a GPS radio collar between
11 July and 22 October 2005. |
 |
1
Total distance moved, calculated by joining all the
GPS fixes.
2 Distance between day-time-resting-spots
(point-to-point).
3 Day resting distance as a percentage of
the total distance moved.
|
The
movements of Xpl-18 were often erratic, as she crossed over
mountains, and between different tributaries of the ephemeral
river systems. With the exception of 23 July 2005 (blue line),
there were frequent and considerable changes in the direction
of movements. The distance between one day-time-resting-spot
and the next, is substantially less than the actual distance
moved during the night, as recorded by the GPS collar (Table
A6). Conventional radio-tracking techniques (daytime locations)
clearly produce inadequate data on movements and habitat use,
when compared with the GPS collar data.
Coastal
movements
During the latter half of 2006 lions moved
to the coast at four different locations. In August 2006 an
adult male lions, from the Ugab/Huab group, walked down the
Huab River and onto the beach at the Huab Lagoon, where he
killed and ate a Cape fur seal (Figure 36). An adult male
lion visited Sarusas spring and the mouth of the Khumib River
in September 2006 (Figure 37). The last recorded record of
a lion at this location was on 14 September 1987. The Hoaruseb
lionesses were at the mouth of the Hoaruseb River during August
& September 2006 (Figure 38) and then moved to the Hoanib
River between September and December 2006, where they spent
time at Auses spring and in the dunes, west of the floodplain
(Figure 39). Click to view enlargements.
Figure
36. Huab River (August 2006) |
Figure
37. Sarusas & the Khumib River |
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Figure
38. Hoaruseb River. |
Figure
39. Hoanib floodplain. |
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Last
data analysis & update - March 2007
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