Earlier spring in Arctic could hit caribou diet

• Ian Sample, science correspondent
• The Guardian,
• Wednesday May 21 2008

The early arrival of spring in the Arctic threatens to drive down populations of migrating animals such as caribou, climate scientists warned yesterday.

Researchers working in western Greenland found that rising temperatures disrupted spring plant growth enough to cause a fall in the number of caribou born. The finding has alarmed some scientists who expected that migrating animals would find it easier to adapt to the shifting seasons and the impact it has on plants that form the staples of their diet.

Scientists led by Eric Post at Penn State University set up an experiment to investigate the impact of future warming on plants in Greenland. They fenced off six plots in the Kangerlussuaq settlement, and in three of them built glazed enclosures that gradually warmed up more than their surroundings. Over the next seven years, the team recorded when plants unfurled their leaves in each plot, and which species grew where.

The researchers showed that increasing spring temperatures not only caused plants to emerge sooner, but also reduced the range of land they grew over. Both effects are expected to cause a fall in caribou populations because females produce fewer calves if less food is available.

Post said the effect of climate change on the distribution of plants has largely been overlooked by climate scientists.

Earlier this month, a study of great tits living in Wytham Woods near Oxford showed the birds are capable of adapting to climate change better than many scientists expected. Over the past half century, the birds have brought forward the date that they lay their eggs by two weeks, so that young are born when plant-eating grubs are most plentiful.