Reproductive success best predictor for bear, dolphin population forecasting

Dec. 11 (UPI) -- New research suggests reproductive success, not survival rates, is the most important factor for predicting the longterm population health of slow-growing species like bears and dolphins.

Scientists at the University of New South Wales conducted a survey of dolphin studies in Australia and bear studies in North America. Their analysis of population forecasting efforts -- detailed this week in the Journal of Applied Ecology -- showed rates of reproduction best predict the population's longterm viability.

The revelation upends the longhand assumption that survival rates are the most telling factor when forecasting population health.

"Our analysis suggests that conservation planners are often getting it wrong," UNSW scientist Oliver Manlik said in a news release. "We believe our research will set a new course for wildlife biologists who are trying to minimize extinction. It shows them how to identify whether to focus on alleviating threats to reproduction, or to survival."

Manlik and his colleagues were inspired by a study comparing two populations of wild dolphins in Western Australia. The study's data revealed the importance of rates of reproduction over survival rates. Manlik and his research partners found similar patterns among population forecasting data from North American bear studies.

Researchers used their new survey to identify flaws in some of the population forecasting models used by wildlife management officials.

"These methods often investigate potential changes in reproduction and survival that are quite unrealistic, assessing fluctuations of survival and reproduction that are unlikely or even impossible. This can lead to wildlife management actions that are ineffective," Manlik said.

Researchers hope their findings can help conservation and wildlife management officials better target the threats that most directly affect a population's longterm viability.