# Jensen’s Inequality and the Impact of Short-Term Environmental Variability on Long-Term Population Growth Rates

## TL;DR

This study shows that temperature fluctuations, especially seasonal ones, significantly reduce the long-term growth of an endangered bird species.

## Contribution

First empirical demonstration that current temperature variability impacts long-term population growth rates of an endothermic species.

## Key findings

- Seasonal temperature variability is large enough to reduce long-term population growth rates.
- Population growth rates follow a concave relationship with temperature.
- Climate variability, not just average conditions, should be considered in ecological studies.

## Abstract

It is well established in theory that short-term environmental fluctuations could affect the long-term growth rates of wildlife populations, but this theory has rarely been tested and there remains little empirical evidence that the effect is actually important in practice. Here we develop models to quantify the effects of daily, seasonal, and yearly temperature fluctuations on the average population growth rates, and we apply them to long-term data on the endangered Black-faced Spoonbill (Platalea minor); an endothermic species whose population growth rates follow a concave relationship with temperature. We demonstrate for the first time that the current levels of temperature variability, particularly seasonal variability, are already large enough to substantially reduce long-term population growth rates. As the climate changes, our results highlight the importance of considering the ecological effects of climate variability and not just average conditions.