For each event in a population of wild geese, name the process (natality, mortality, immigration or…
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
For each event in a population of wild geese, name the process (natality, mortality, immigration or emigration), and say whether it raises or lowers the density.
- Twelve goslings hatch.
- A flock of 30 geese of the same species arrives from the north.
- A fox kills 5 geese.
- Eight geese leave for a lake in another valley.
- After the events, the number of births plus immigrants is 42, and the number of deaths plus emigrants is 13. Does the density go up or down, and by how many geese?
Need a reminder? The key ideaShow
A population changes by . The birth rate is and the death rate is for each individual in a stated time. The density can also be given as a biomass or a percent cover.
The worked solution
Have you tried it?
Work it out on paper first. It is fine to get stuck or make a mistake: that is how we learn. When you are ready, go through the solution one step at a time, and check each step against your own.
Step 1. (a) Natality. It raises the density.
Step 2. (b) Immigration. It raises the density.
Step 3. (c) Mortality. It lowers the density.
Step 4. (d) Emigration. It lowers the density.
Step 5. (e) . The density goes up by geese.
Answer: (a) natality, up; (b) immigration, up; (c) mortality, down; (d) emigration, down; (e) up by .
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