Small mammal communities as indicators of
This presentation is the property of its rightful owner.
Sponsored Links
1 / 36

Small mammal communities as indicators of biological integrity Nico Avenant PowerPoint PPT Presentation


  • 82 Views
  • Uploaded on
  • Presentation posted in: General

Small mammal communities as indicators of biological integrity Nico Avenant National Museum, Bloemfontein, South Africa. C. Schradin. Why small mammals?. Number of organisms: c . 66% of mammals species > 300/ha. Top predators. T.P. Jackson. Prey base. Biomass: > 10% of total

Download Presentation

Small mammal communities as indicators of biological integrity Nico Avenant

An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -

Presentation Transcript


Small mammal communities as indicators of biological integrity nico avenant

Small mammal communities as indicators of

biological integrity

Nico Avenant

National Museum, Bloemfontein, South Africa

C. Schradin


Small mammal communities as indicators of biological integrity nico avenant

Why small mammals?

Number of organisms:

c. 66% of mammals species

> 300/ha

Top predators

T.P. Jackson

Prey base

Biomass:> 10% of total

mammalian biomass

Secondary

users

Ecosystem engineers

Prey base

Primary users

Seed dispersers

Soil fertilisers

Primary producers

Growth stimulators


Small mammal communities as indicators of biological integrity nico avenant

c. 5% spend >90% of time

under ground

Most small mammals

“secretive”

Superstitions

Public poorly informed

c. 3% spend >90% of time

in disused termitaria

c. 60% are nocturnal


Why small mammals

Why small mammals?

* 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.

* they are found in comparatively large numbers (a single species up to 200/ha). Rodents are, therefore, more available than larger mammals.

* they are easy to handle, mark indiv’s, monitor movement, etc.

* we know detailed information regarding the biology & natural histories ….

* they reproduce fast (respond quickly to change)

* fairly easy to ID (compared to plants, invertebrates) – teach field personnel


Indirectly literature

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

a relatively quick and cheap method of indicating

healthy or unhealthy ecosystem functioning?


Small mammal communities as indicators of biological integrity nico avenant

D. MacFadyen

Mice/rats, Shrews,

Elephant shrews

HPH Photography

Shrews

7 species in Free State

W. Lubbe

TP Jackson


Small mammal communities as indicators of biological integrity nico avenant

Mice

22 species in Free State

13 species in BFN-area

Mice


Small mammal communities as indicators of biological integrity nico avenant

Small mammal survey

Standard method

  • A fixed number of traps (n = 100), are spaced 5 m

    apart (e.g. Ferreira & Avenant 2003) , on 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

Sampled by removal trapping

D. MacFadyen


Ecotones

Beware

Ecotones

  • Transition zones (ecological link) – area of active interaction between two or more ecosystems.

  • Edge effect – ecotones have different structures than neighbouring communities


Small mammal communities as indicators of biological integrity nico avenant

  • Our concerns are:

  • how to sample and / or monitor small

  • mammal biodiversity,

and then

* to interpret this in terms of ecosystem

integrity.


Small mammal communities as indicators of biological integrity nico avenant

Mammal monitoring: -   Density -   Species richness -   Diversity indices (e.g. Shannon, Simpson’s) - Relative abundance or evenness (e.g. Evar) - Reproductive or not - Indicator species (e.g. keystone, pioneer, generalist, specialist) - Indigenous, Endemic & Alien species- Threatened species - Protected species (e.g. CITES)


Small mammal communities as indicators of biological integrity nico avenant

Nature reserves:Willem Pretorius NR; Sandveld NR; Caledon NRTussen-die-Riviere NR; QwaQwa NP; Erfenisdam NRConservancies:Korannaberg Farms:Game Farm, Fauresmith; Small stock farm, PhillipolisGlen Agric. Coll.SA Army training base:De Brug Environmental Impact AssessmentsMaguga Dam, Swaziland; Mohale Dam, LesothoLetsa-la-Letsie, Lesotho; CMBSLMaluti-Drakensberg Transfrontier Biodiversity ProjectOther:Ezemvelo Nature Reserve; Namibian Airports

Examples


Small mammal communities as indicators of biological integrity nico avenant

Last 12 years:

6 sites; 44 transects


Small mammal communities as indicators of biological integrity nico avenant

Example 1 Nature reserve

AVENANT, N.L. 2000. S. Afr. J. Wildl. Res.


Small mammal communities as indicators of biological integrity nico avenant

M. minutoides

Rhabdomys

Aethomys

E. myurus

Mastomys

Number of species

2

2

3

2

2

3

2

3

vs 11 / 17

5


Korannaberg conservancy

Groups of farms on which the owners collectively practice co-operative nature conservation

Ranger patrols fences, cribs & water pumps

Removes snares

Report mortalities & stray dogs

Prevents unlawful hunting, game & cattle theft

Practices proper problem-animal control measures

Korannaberg Conservancy

Example 2

Increase total proclaimed conservation area in

the Free State Province by c. 6 times


Small mammal communities as indicators of biological integrity nico avenant

AVENANT, N.L. 2003. ACIAR Monograph


Small mammal communities as indicators of biological integrity nico avenant

n = 9

Why?

_ vs 6


Small mammal communities as indicators of biological integrity nico avenant

Example 3

Swaziland: Maguga Dam & Hydro-electric scheme


Small mammal communities as indicators of biological integrity nico avenant

Table 1 The percentage frequency of grass species, number of herbs, percentage basal cover and Ecological Index value of four plots in the Caledon Nature Reserve, Free State Province, South Africa. EI, Ecological Index; -, not found.

Example 4

Vegetation analysis

Caledon Nature Reserve

*EI, Ecological Index value

*

* Annual grass

* Annual grass


Small mammal communities as indicators of biological integrity nico avenant

The percentage contribution of small mammal species trapped on four transects at the Caledon Nature Reserve during four consecutive seasons in 2001/2.

*Significant correlation with EI value (Pearson Product-Moment, p<0.05)


Small mammal communities as indicators of biological integrity nico avenant

Our results

Specialists

Species richness

Mystromys

albicaudatus

Diversity

(evenness?)

Number of species

Indicator species

Generalists

Succession

Primary productivity


Small mammal communities as indicators of biological integrity nico avenant

some shrubs/trees;

mostly perennials

= climax grassveld

some herbs + shrubs/

trees + more perennials

Number of species

Annuals + more herbs + shrubs/trees + perennials

More annuals + more herbs + shrubs/trees

More annuals + herbs

Annuals

Disturbance

(Time after disturbance – Succession)

Primary productivity


Eia s

EIA’s

Constraints: time (=money)

Influence methods:

- type of traps

- trapping period / no. of seasons

- no. of habitats

Rely on Scientific studies


Small mammal communities as indicators of biological integrity nico avenant

Rodent density in Free State grasslands

c. 50%

Au

Au

W

Su

Sp


Small mammal communities as indicators of biological integrity nico avenant

Significant

seasonal effect

Tussen die Riviere Nature Reserve

AVENANT, N.L. & CAVALLINI, P. 2007. Integrative Zoology

Korannaberg Conservancy

AVENANT, N.L. 2000. Navors.nas.Mus.,Bloemfontein


Small mammal communities as indicators of biological integrity nico avenant

Seasonal effect

Mean small mammal species richness and trap success on four grassland plots in the Caledon Nature Reserve, Free State Province, South Africa.

Avenant, Watson & Schulze 2008. Mammalia


Small mammal communities as indicators of biological integrity nico avenant

Duration of trapping period

Korannaberg Conservancy

Reached mean maximum number of species after 78 hours (3.25 days) - Avenant 2003. ACIAR Monograph

Caledon Nature Reserve

Avenant et al. 2008. Mammalia


Small mammal communities as indicators of biological integrity nico avenant

Duration of trapping period

Tussen die Riviere Nature Reserve

AVENANT, N.L. & CAVALLINI, P. 2007. Integrative Zoology

During all seasons the total number of rodent species (mean = 7 ± 0.8)

were reached between 48 and 96 hours (mean = 3 ± 0.8 days), while

immigration started to have a significant effect from the sixth day

We standardize:

4 consecutive days and nights


Small mammal communities as indicators of biological integrity nico avenant

Our results

Specialists

Species richness

Mystromys

albicaudatus

Diversity

(evenness?)

Number of species

Implications …

Indicator species

Generalists

Succession

Primary productivity


Small mammal communities as indicators of biological integrity nico avenant

Thank you

Acknowledgements

Field assistants Jacob Senoge, Isak Sekhuni, Pieter Williamson & Jurie du Plessis

Council of the National Museum, Bloemfontein

National Research Foundation

D. MacFadyen


  • Login