Populations. Topic 5.3. Death. Population. Immigration. Emigration. Birth. Factors that increase population size : Natality (Birth rate) is recruitment to a population through reproduction Immigration from external populations e.g. Bird migration Factor reducing population size :
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Factors that increase population size:
Natality (Birth rate) is recruitment to a population through reproduction
Immigration from external populations e.g. Bird migration
Factor reducing population size:
Mortality (death rate) which is the death rate from any source e.g. predation
Emigration, where individuals leave the population for another habitat
+ Natality + Mortality
The gestation period for a rabbit averages 31 days. 72 partridges and released them on his property, in Victoria.
A rabbit can live as long as 10 years
Rabbits can start breeding as early as 3-4 months of age
European Rabbits have an average litter size of 7 – 9 but may be as high as 15!
8 Rabbits eat as much grass as 1 sheep!
So in 1950, after research carried out by Frank Fenner, Myxomatosis was deliberately released into the rabbit population, causing it to drop from an estimated 600 million to around 100 million.
The Australian Government refuses to legalise a vaccine to protect pet rabbits against Myxomatosis, for fear the rabbit may escape and transmit resistance to the disease. A legal vaccine exists in Australia for RHD. There is no cure for either Myxomatosis or RHD, and many affected pets are euthanised.
A lynx causing untold environmental damage:
-Eats Snowshoe hares
A Snowshoe Hare. causing untold environmental damage:
- Eaten by Lynxs.