Desert Lions

Socio-ecology

Socio-ecology

Genealogy
There are currently eight distinct groups/units of lions, consisting of prides, sub-groups, and nomadic individuals, in the Kunene population. Long-term individual records reveal that, irrespective of the areas that the eight groups currently occupy, they all originate from one genetic lineage (Fig. 10).

Fig. 10. Genetic origins and relatedness of all known Kunene lions. (Blue squares = males; Red ovals = females; Green = unknown)

The Aub Pride (blue) is the largest and most significant group (Fig. 11), and all the lions that have re-populated new habitats, including the Agab group, originate from this pride. Individual records and almost five generations of life table and genealogy data of the Kunene lions provide valuable baseline data and an in-depth understanding of the socio-ecological parameters of dispersal and population growth. Some lions in this genealogy tree have subsequently died (Fig. 12). Of the 98 individually known lions, presented in the genealogy tree (Fig. 10), 26.5 % have died, but their role in, and contribution to, the genealogy of the Kunene lions remain important.

Fig. 11. Schematic layout of eight groups of lions the Kunene Region in relation to genetic origins and relatedness.	Fig. 12. Schematic layout depicting the lifespan of lions that have died, following the structure of genetic origins and relatedness presented in Fig. 10.

Grouping patterns
Adult lionesses in the Kunene, that belong to the same group or pride, frequently spend long periods apart. Such long separations are unusual in lion social behaviour. Adult females form the core of the social structure of lions, known as prides (Schaller 1972). Lionesses in a pride are normally related, and they form sub-groups that regularly rejoin. This typical fission-fusion strategy has a frequency pattern that is measured in days (Packer 1986). In the Kunene population, long-term data on the grouping patterns of the Aub Pride are analysed to demonstrate the unusual fission-fusion characteristics. During 396 observations of the five lionesses of the Aub Pride, the preference of individuals spending time together is presented in a matrix of association (Table 2). Lionesses spend most of the time alone, or with cubs, or adult males (50%), followed by groups of two lionesses (38%) and groups of 3 to 5 lionesses (12%). Average group size for the whole Kunene lion population is small (Table 3), with an average of 1.17 adult females per group.

Table 2. Matrix of association between lionesses of the Aub pride in the Kunene Region (N = 396). Rows depict an index of association between the lioness listed in the row heading with those in the column headings, where and index value of 1.0 will result when lionesses are always together. Yellow squares present the proportion of observations where lionesses were alone, or with males and/or cubs, but not with another lioness.

Table 3. Average group sizes of lions in the Kunene Region (N = 451; ¹ Mean group size).

Lionesses of the Aub pride regularly spent more than one month apart. In a rough monthly schematic presentation (Fig. 13) the patterns and frequency of association between individual lionesses is displayed on a monthly scale. The lioness, Xpl-2, lived in the centre of the Aub Pride’s home range, and the grouping patterns of the other lionesses are presented in relation to Xpl-2.

Fig. 13. Schematic presentation of the months, between 2000 and 2005, that lionesses of the Aub Pride where observed together or apart. The number of observation (N = 746) are listed for each month and the gray areas reflect the months where no data where collected. For Xpl-14, the X at the start and end of her records indicate the time when she was first radio-collared, and when she disappeared in October 2003.

For example, the lioness Xpl-11 was observed with Xpl-2 and Xpl-9 from January to June 2002. In July 2000 Xpl-11 and Xpl-9 separated from the rest and lived together for 14 months, until August 2001, when Xpl-11 moved away and lived alone for four months. In January 2002 she joined Xpl-5 and Xpl-14 for two months, and then stayed with Xpl-14 for the next seven months. In October 2002 she joined her old partner, Xpl-11, after a separation of 13 months. They remained together for two months before joining Xpl-2 (and Xpl-5 & Xpl-14), after 2 years and 4 months apart. For the remaining observations, Xpl-9 and Xpl-11 remaining together, spending some months with Xpl-2 and/or Xpl-5, but mostly in a separate sub-group.

Between January 2000 and January 2003, the longest period of continuous observation, there are 14 records of individual lionesses spending more than one month apart (Fig. 13). In this fission-fusion dataset, individual lionesses of the Aub Pride rejoined after being apart for an average of 17.9 months (range: 2 months – 2 years & 10 months). Such extended fission-fusion time periods have not previously been documented for lions. It is suggested that the unique fission-fusion grouping patterns of Kunene lionesses is a display of behavioural adaptation to the demanding condition imposed by the desert habitat.