Group territoriality of the African lion

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Group territoriality of the African lion
Linking behavior to landscape in Serengeti
lions
Anna Mosser Craig Packer University of
Minnesota Serengeti Lion Project
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What are the benefits of the lion social group?
Group hunting Lions get just as much to eat
when hunting alone. Defense of cubs Females
stay in groups even without cubs. Territorial
defense Females are sensitive the relative
number of simulated intruders (McComb et al.
1994).
YES, BUT
YES, BUT
GOOD QUESTION
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Resource defense strategy
Typical grouping pattern
Typical habitat
territorial territorial territorial territorial
territorial territorial
Lion (Panthera leo)
social solitary solitary solitary solitary so
litary
savanna forest mostly forest widespread forest
steppe forest/arboreal
Tiger (Panthera tigris)
Jaguar (Panthera onca)
Leopard (Panthera pardus)
Snow leopard (Panthera uncia)
Clouded leopard (Neofelis nebulosa)
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Group territoriality of the African lion
The role of territorial defense in the evolution
of lion sociality.
Linking behavior to landscape
How landscape structure shapes the evolution
of social behavior.
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Group territoriality
Many animals are territorial and live in groups.
Individuals of a group-territorial species gain
an advantage through the mutual defense of shared
space and resources.
Timber wolves
Acorn woodpeckers
Carpenter ants
Chimpanzees
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Group territoriality of the African lion
If lions are a group-territorial species H1
Territorial behavior inflicts costs on
neighbors The number of neighbors will have a
negative impact on female reproductive
success. H2 Defensive costs influence optimal
group size Adult females will remain in larger
pride subgroups if they have more neighbors. H3
Group size influences access to better
habitat Larger groups will gain and maintain
access to higher quality habitat.
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Study system Serengeti National Park, Tanzania

• Data set
• -1966 to present
• -Radio tracked
• Individual IDs
• (2696 id.s in 45 prides)
• -Spatially referenced

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H1 Territorial behavior inflicts costs on
neighbors
Per capita reproductive success of cubs
surviving to one year adult females in pride
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H1 Territorial behavior inflicts costs on
neighbors
Calculating the number of neighbors for each pride
Pride maps 2001, 50 kernels
4.4 ? 0.0 ? 11.7 T
1.7 ? 2.7 ? 5.3 T
2.3 ? 0.0 ? 10.0 T
1.5 km
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H1 Territorial behavior inflicts costs on
neighbors
The effect of neighbors on reproductive success

• Multivariate analysis also accounting for
  demographic and landscape variables.
• Generalized liner model, with repeated measure
  for pride (SAS 9.1, PROC GENMOD).

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H1 Territorial behavior inflicts costs on
neighbors
The effect of neighbors on reproductive success
Percent of prides with RS0
Total number of adult female neighbors
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Group territoriality of the African lion
If lions are a group-territorial species H1
Territorial behavior inflicts costs on
neighbors YES H2 Defensive costs influence
optimal group size H3 Group size influences
access to better habitat
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H2 Defensive costs influence optimal group size
Fission-fusion social system and subgroups
A pride of four adult females may be seen in a
full range of subgroup types
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H2 Defensive costs influence optimal group size
Data set used to calculate pride subgroup sizes

• Adult females located by radio tracking
• Not at kills
• With no current cubs
• Not with resident males
• 407 observations

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H2 Defensive costs influence optimal group size
Subgroup calculations Relative subgroup size
expected proportion
observed proportion
-
-
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H2 Defensive costs influence optimal group size
The effect of neighbors on subgroups of size 1
effect - 0.0144 p 0.0002
Relative subgroup size
Total number of adult female neighbors
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H2 Defensive costs influence optimal group size
The effect of neighbors on subgroups of size 2
effect - 0.0056 p 0.043
Relative subgroup size
Total number of adult female neighbors
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H2 Defensive costs influence optimal group size
The effect of neighbors on subgroups of size 3-9
not significant
Relative subgroup size
Total number of adult female neighbors
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H2 Defensive costs influence optimal group size
Small subgroup sizes are less likely when a pride
has more neighbors.
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Group territoriality of the African lion
If lions are a group-territorial species H1
Territorial behavior inflicts costs on
neighbors YES H2 Defensive costs influence
optimal group size YES H3 Group size
influences access to better habitat
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H3 Group size influences access to better habitat
First Quantify the value of the landscape to a
female lion
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Assessing lion habitat quality
Avg. reproductive success 1966-2004
Distance (km) to nearest river confluence
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Assessing lion habitat quality
Average reproductive success 1966-2004
Dry season vegetation (NDVI)
Distance (km) to nearest kopje
Average rainfall 1966-2004
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Assessing lion habitat quality
Avg. reproductive success
Multivariate analysis of average reproductive
success (p
Distance to confluence
Mixed model accounting for spatial
autocorrelation (SAS 9.1, PROC MIXED)
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Assessing lion habitat quality
Good lion habitat
Poor lion habitat
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H3 Group size influences access to better habitat
Territory dynamics calculating changes in
territory quality

• Kibumbu pride
• 1987 1989
• Territory quality
• based on distance to confluence, scaled
  from 0-100
• Territory quality
• 90.7
• 1989 95.9
• Change 5.2

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H3 Group size influences access to better habitat
Number of pride females and changes in territory
quality
Average change in territory quality
Number of adult females in pride
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H3 Group size influences access to better habitat
Number of pride males and changes in territory
quality
Average change in territory quality
Number of resident males in pride
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H3 Group size influences access to better habitat
Multivariate analysis of change in territory
quality
Generalized liner model, with repeated measure
for pride (SAS 9.1, PROC GENMOD).
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Group territoriality of the African lion
If lions are a group-territorial species H1
Territorial behavior inflicts costs on
neighbors YES H2 Defensive costs influence
optimal group size YES H3 Group size
influences access to better habitat YES, if
males and neighbors are taken into account
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Group territoriality of the African lion
LIONS ARE A GROUP-TERRITORIAL SPECIES
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What are the benefits of the lion social group?
Group hunting Defense of cubs Territorial
defense
Territorial defense Defense of cubs Group
hunting
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Linking behavior to landscape
TERRITORIAL BEHAVIOR IS DRIVEN BY THE STRUCTURE
OF THE LANDSCAPE.
1997-98
1999-00
2001-02
1967-68
1969-70
1971-72
1973-74
1975-76
1977-78
1979-80
1981-82
1983-84
1985-86
1987-88
1989-90
1991-92
1993-94
1995-96
2003-04
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Acknowledgements

• Many thanks to
• My thesis advisor (Craig Packer)
• Thesis committee (Dave Stephens, Anne
  Pusey, and Paul Bolstad)
• U. of Minnesota behavior lab group
• The countless number of field researchers, 1966
  present!
• Funding
• NSF DDIG, LTREB Biocomplexity
• U. of Minnesota dissertation fellowship, travel
  and Dayton-Wilkie grants