ClimateWatch

An initiative of Earthwatch Institute

Dr. Lynda Chambers answers your questions

February 2014

Lynda is a zoologist and climatologist based at the Centre for Australian Weather and Climate Research (Australian Bureau of Meteorology). She specialises in climate impact and adaptation research, in particular its interface with Australian flora and fauna.

Much of her current research involves understanding how climate drives phenology (timing of natural events), as well as the use of traditional ecolological knowledge for weather and climate forecasting.

Lynda is actively involved in community-based science programs, including research on Little Penguin and water quality monitoring, and she has been involved in the ClimateWatch program since its inception.

Interested in finding out more on climate change and how flora and fauna adapt to such changes? Ask Dr. Lynda Chambers a question here.

 

 

Butterfly population and the weather

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Common Brown Butterfly (Heteronympha merope)

 

Michael asks:

Down here in Melbourne we try to conserve wildlife within the City of Bayside (Brighton to Beaumaris). There seems to be low numbers of almost all our common butterflies, with Cabbage Whites a possible exception. Common Brown, Common Grass Blue, all the skippers, Saltbush (chequered) Blue are scarce compared with previous years.

I know butterfly populations vary enormously but could there be a common factor, like the impact of the warm winter and wet spring, that have affected them?

We would be interested in your thoughts.

Lynda answered:

Weather and climate do affect butterfly species, including their development rates and the timing of when they emerge.

A 2010 study of Common Brown butterflies in Melbourne showed that their survival and development varies with temperature. The study used 65 years of butterfly emergence dates and found that Common Browns are now emerging more than nine days earlier than they were in the 1940s.

The researchers also determined that very few caterpillars survive temperatures above 25 ºC and no eggs survive above 30 ºC. Warmer periods during the breeding period (like our recent warm spring) may therefore have a negative effect on the number of observed butterflies in southern Australia.

Other studies from cooler climates, such as in the UK and Europe, found that warmer and wetter weather actually lead to an increase in butterfly numbers. However, these regions may not reach the temperature thresholds experienced here in Australia.

Extreme events such as droughts and heatwaves also generally have a negative influence on butterfly abundance in these parts of the world. This means that while warmer temperatures lead to an increase in the abundance for some species, it is predicted that the majority of butterfly species will experience a decline in the presence of climate change.