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Small mammal monitoring
Kolomela Mine
Nico Avenant1, 2
1Department
of Mammalogy, National Museum, Bloemfontein, South Africa
2Centre for Environmental Management, University of the Free State, Bloemfontein , South
Africa
Mammal monitoring:
-
Density
Species richness
Diversity (e.g. Shannon Index)
Relative abundance or evenness (Evar)
Indicator species
Indigenous, Endemic & Alien species
Threatened species
Protected species (e.g. CITES, CMS)
Indicators
Top Predator
Herbivores
Primary producers
Carnivores
Indicators
Indicators
Exotic mammals
Small mammals…
Food chain:
Number of organisms:
Top predators
c. 66% of mammals species
> 300/ha
Biomass: > 10% of total
mammalian biomass
Secondary
users
Primary users
Primary producers
Small mammal sampling are, for a number of reasons, considered to be a relatively easy,
quick, inexpensive and effective “tool” in achieving all of these:
(1) As primary & secondary users small mammals have an important direct & indirect influence on
a number of levels in ecosystems
(2) they make out a fairly large percentage of all mammal species (up to >60%).
(3) specialized and adapted for survival in “smaller” habitats (than larger mammals) – and are better
indicators of ecosystem integrity on the scale that we (e.g. EIA consultants) are working on.
(4) they are found in comparatively large numbers (a single species up to 200/ha). Small mammals
are, therefore, more available than larger mammals.
(5) they contribute largely (> 20%?) of total mammalian biomass and, due to their relatively high
metabolism, consume an even larger percentage of total mammalian consumption
(6) they are easy to handle, mark and monitor their movement, etc.
(7) we know detailed information regarding their biology & natural histories ….
(8) they reproduce fast (important if you do removal trapping)
(9)
are fairly easy to ID (compared to plants & invertebrates) – teach field personnel
(10) can sample throughout the year (with vegetation you are often limited to a specific season e.g. when grasses are in flower/seed/ influorescences still attached
(11) due to clear (and easy to observe) reproductive seasons and consequent fluctuations in
densities, studies on this important prey group ideal for indicating short term dynamics (connected to
e.g. “fat & lean periods”) in an ecosystem.
In literature:
Small mammals related to biotic and abiotic
variables
- habitat structure
- habitat complexity
- area
- productivity
- trampling and grazing
- surrounding landscape
- distance between similar habitats
- maturity of the habitat (succession)
- presence of exotics / absence of predators.
So, indirectly literature …
• changes in small mammal habitats are associated
with changes in small mammal diversity
• ecological disturbance of these habitats is
generally associated with a decrease in small
mammal species richness
• a connection between the presence or absence of
small mammal indicator species and disturbance
in natural ecosystems
Specialists
Species richness
Diversity
Generalists
Succession
Primary productivity
Mice
Eulipotyphla
Macroscelidae
Small mammal survey
Standard method
Sampled by mark-release trapping
 A fixed number of traps (n = 100), are spaced 5 m
apart, along a number of transects at each site/plot
 Baited with a mixture of peanut butter, rolled oats,
sunflower oil and marmite
 Left open for 4 consecutive nights and days
 Each trap checked at dusk and dawn;
rebaited when necessary
7&8
1&2
11 & 12
9 & 10
34 5 6
Transect 1
Transect 2
Transect
3
Transect
5
Transect 7
Transect 8
Transect 9
Transect
10
Transect
11
Transect
12
Tatera
leucogaste
r
Tatera
leucogaster
Tatera
leucogaste
r
Tatera
leucogaste
r
Tatera
leucogaster
Tatera
leucogaster
Tatera
leucogaste
r
Tatera
leucogaster
Tatera
leucogaste
r
Tatera
leucogaster
Rhabdomy
s pumilio
Rhabdomys
pumilio
Rhabdomys
pumilio
Rhabdomys
pumilio
Rhabdomy
s pumilio
Rhabdomys
pumilio
Rhabdomy
s pumilio
Rhabdomys
pumilio
Elephantulu
s sp.
Elephantulu
s sp.
Mus
minutoide
s
Mus
minutoides
Mus
minutoides
Saccostomu
s
campestris
Saccostomu
s
campestris
Mastomys
coucha
Mastomys
coucha
Mastomys
coucha
Mastomys
coucha
Elephantulu
s sp.
Mastomys
coucha
Mastomys
coucha
Dendromus
melanotis
Crocidura
sp.
20% trap success
16% trap success
Crocidura
sp.
42% trap success
22% trap success
21% trap success
Specialists
Species richness
Diversity
Generalists
Succession
Primary productivity
Thank you