Large Herbivorous Mammals: Exotic Species In Northern Australia

By: W.J. Freeland

Reviewed By:Joy Bryson & Angela Maresco

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PurposeThe purpose of this article is to examine

the effects of man’s deliberate introduction of large, herbivorous ungulates on their non-native environment of Northern Australian savannas.

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Vocabulary WordsCo-evolution- when 2 interdependent species adapt to one another

Feral- wild; untamed

Inter-specific competition- when 2 or more species compete for the same resources

Megafauna- large animals

Pathogen- agents that cause disease

Ungulates- hoofed mammals

The Problem

• Northern Australian savannas only have 6 large, herbivorous mammal species while Asian and African savannas have more

• Environmental changes developed

• Man’s arrival to Australia probably is the cause

Effects of Europeans Arriving in Northern Australia

• Extinction of large, herbivorous marsupials, flightless birds and lizard predators• Possible climate changes• Hunting• Native habitat modification

• Due to fire

• Large ungulates from Europe, Asia and Africa were introduced

Herbivorous Mammals Quiz Directions: Match the scientific name of the

following herbivorous mammals with their picture 1. Mus musculus2. Rattus exulans3. Orycytolagus cuniculus4. Sus scrofa5. Capra hircus6. Bos banteng7. Equus asinus8. Equus caballus

9. Bubalus bubalis

a

b

c d e f g

h

i

Herbivorous Mammals Quiz Answers

1. Mus musculus a2. Rattus exulans e3. Orycytolagus cuniculus d 4. Sus scrofa g5. Capra hircus i6. Bos banteng h7. Equus asinus b8. Equus caballus f9. Bubalus bubalis c

a

b

c d e f g

h

i

Picture References1. http://genome.ucsc.edu/images/Mus_musculus.jpg mouse2. http://www.fieldmuseum

.org/philippine_mammals/RODENTIA/Muridae/RATTUS_exulans2.JPG rat3. http://fotoohota.spb.ru/members/mikhailov/02.jpg rabbit4. http://www.retamatour

.com/web/02web/fauna/fichas/fotos/mamifer/Sus-scrofa.jpg Boar5. http://www.hilozoo.com/images/animals/m_goat.jpg goat6. http://www.csew.com/cattletag/Cattle%20Website/Images/banteng

%20flehmen.jpg ox7. http://www.roztocze.pl/zoo/img/Osiol1w.jpg ass8. http://www.ultimateungulate.com/Images/Equus_caballus/E_caballus3.jpg

horse9. http://www.ultimateungulate.com/Images/Equus_caballus/E_caballus3.jpg

buffalo

New Feral Species• Spread throughout the region

• Bos taurus (cow)• equus caballus (horse)

• Retained localized distribution• Bos banteng (ox)• Cervus unicolor (deer)

• Expanding ranges• Camelus dromedarius (camel)

Predicted vs. Actual Densities of Herbivorous Mammals

• Based on Damuth relationship

• Two surveys used:• Aerial• Capture-

Recapture

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are needed to see this picture.

Table 35.1 The Human Impact Reader

“Big is Beautiful But Lonely”

• Illustrates concept of the Damuth relationship

• Density and body size are inversely related

http://www.sciencemag.org/cgi/content/full/289/5484/1487/F1

Explanations for High Population Density

1. Competition

2. Predators

3. Pathogens

4. Plant Defenses

***All have a significant impact on herbivorous mammal population in the natural setting

Competition• Influenced by the combination of species in a

community (man-made or natural)

• Australian man-made community’s deficits compared to Asian/African natural communities• Absence of time for co-evolution=more competition• Absence of large herbivores=impossible to predict• Absence of browsing species=more competition

• Influenced by biomass • Biomass was found to be both inversely and directly related to

inter-specific competition

Predators• Low population of large predators

• Lack of predators=higher density of introduced herbivores in Australia

• Dingo • Consumed large species of herbivores

• Its effects cannot equate with that of species rich natural communities of predators with larger body sizes

QuickTime™ and aTIFF (Uncompressed) decompressorare needed to see this picture.

http://www.thewildones.org/Gifs/dingo.gif

Pathogens

• Few native pathogens are capable of infecting the introduced species

• Few pathogens accompanied ungulates in Northern Australia compared to native herbivores

• Disease causes death in natural population of herbivorous mammals• Less significant in feral herds

Plant Defenses

• Plants in Australia are similar to plants in other areas• cause no harm to native or

introduced species because of co-evolution

Possible Solution For Population Control

• Introduce pathogen• Low cost• Low environmental disturbance

• No human involvement• No introduced predators

Summary• Humans transported ungulates to Northern

Australia and changed the environment

• There were undesirable changes in the environmental conditions for the native herbivores due to the deliberate introduction of feral ungulates into Northern Australia

• The introduced ungulates did not have natural factors to help control their population

• A solution is needed to control the feral ungulate population

Related Study“Extinctions of Herbivorous Mammals in the

Late Pleistocene of Australia in Relation to their Feeding Ecology: No Evidence for

Environmental Change as Cause of Extinction”

In this study, scientists tried to determine the cause of extinction of the megafauna species in Northern Australia. This article included information about the survival rate of browsers and grazers and how their body mass was related to their probability of extinction.

http://www.ingentaconnect.com/content/bsc/aec/2004/00000029/00000005/art00007