# Scientists have found evidence that climate change is causing shifts in the seasonal timing of biological events, such as flowering in plants and egg-laying in birds. Explain how a mismatch in seasonal timing between a prey species and its predator could affect the population size of the predator over time.

> Pearson Edexcel A-Level Biology A (9BI0) — 3.3 Climate change · Explain · 5 marks

> Many migratory birds time their arrival and egg-laying to coincide with peak availability of insect prey. Rising global temperatures are causing insects to emerge earlier in spring, but some bird species have not adjusted their migration and breeding times at the same rate.

## Mark scheme (5 marks)

1. Climate change causes insects to emerge earlier in the year (phenological shift / change in seasonal timing)
2. The bird's breeding / egg-laying season does not shift at the same rate, creating a mismatch between peak insect availability and peak chick demand for food
3. Chicks/offspring receive less food / are food-deprived during the critical growth period
4. Fewer chicks survive / increased mortality in offspring, reducing reproductive success
5. Over time the predator (bird) population size decreases / declines because birth rate falls below death rate

## Key terms

- [climate change](https://www.gradenine.co.uk/glossary/climate-change)
- [seasonal timing](https://www.gradenine.co.uk/glossary/seasonal-timing)
- [mismatch](https://www.gradenine.co.uk/glossary/mismatch)
- [population size](https://www.gradenine.co.uk/glossary/population-size)

## Related

- [Revision notes for Pearson Edexcel A-Level Biology A (9BI0)](https://www.gradenine.co.uk/learn)
- [How to answer "Explain" questions](https://www.gradenine.co.uk/tools/command-word-cheatsheet)
- [Practice this with AI marking (free)](https://www.gradenine.co.uk/start)

---
Source: [GradeNine](https://www.gradenine.co.uk/q/scientists-have-found-evidence-that-climate-22fa8f55) · Published by Druglandscape Ltd.