The stage where most die isn't always the one to save
- The idea
- Predict
- See it
- Why
- Check
The idea
“Most chicks die, so saving chicks has to help the population the most.”
Most of the dying happens early, so saving the young looks like the biggest win. In long-lived species, saving adults usually does more.
The short version
The mistake: Most chicks die, so saving chicks has to help the population the most.
What's actually true: The same rise in survival can do very different things at different stages, so compare how much each change grows the population.
- The same rise in survival saves more birds in a bigger stage. Here there are half as many chicks as adults, so saving chicks adds half as many birds.
- When young take years to start breeding, many saved chicks still die before they breed. A saved adult can breed again next year.
- Which stage matters most depends on the species. With many young per pair, saving young can win. So compare the growth each change produces.
On the exam: Protect the stage whose change grows the population most in the data.