Reindeer are shrinking - will Santa need more to pull his sleigh?

“The implications are that there may well be further smaller reindeer in the Arctic in the coming decades but possibly at risk of extensive die-offs because of increased ice on the ground

Often portrayed as pulling Santa’s sleigh, reindeer are a Christmas staple. Now, ecologists have found that reindeer are shrinking due to the impact of climate change on their food supplies.

Speaking at the British Ecological Society annual meeting in Liverpool this week, researchers revealed that over the past 20 years – during a period of noticeable summer and winter warming in the Arctic – reindeer on the Svalbard archipelago have got smaller and lighter.

Ecologists from the James Hutton Institute, the Norwegian Institute for Nature Research and Norwegian University of Life Sciences have worked in the high Arctic since 1994, measuring and weighing the reindeer. Each winter they catch, mark and measure 10-month-old calves, returning each year to recapture them and track their size and weight as adults.

The survey shows that over 17 consecutive cohorts, the adult reindeers' weight declined by 12% – from 55 kg for those born in 1994 to just over 48 kg for those born in 2010.

Study leader Professor Steve Albon, of the James Hutton Institute’s Ecological Sciences group, believes that three factors – all influenced by climate change – are responsible for the shrinking reindeer.

“In Svalbard, snow covers the ground for eight months of the year, and low temperatures typically limit grass growth to June and July. But as summer temperatures have increased by 1.5°C, pastures have become more productive, allowing female reindeer to gain more weight by the autumn and therefore conceive more calves,” he explains.

Warmer winters, however, mean more rain. The rain falls on snow, where it freezes, thus locking out the reindeer from the food beneath the snow. As a result, the reindeer starve, aborting their calves or giving birth to much lighter young.

The third factor at play is that over the past 20 years, reindeer numbers have doubled, so greater competition for food in winter could also help explain the shrinking reindeer.

All of which could spell disaster for this iconic Christmas species, Albon warns: “The implications are that there may well be further smaller reindeer in the Arctic in the coming decades but possibly at risk of extensive die-offs because of increased ice on the ground.”

The British Ecological Society Annual Meeting is on 11-14 December 2016 at ACC Liverpool. The programme is available at https://eventmobi.com/bes2016. For more information on the meeting please contact Kate Luckett, British Ecological Society Press Intern, +44 (0)7762 200469, or Becky Allen, BES Press Officer, +44 (0)7949 804317.

The British Ecological Society was established in 1913 making it the oldest ecological learned society in the world. The BES promotes the study of ecology through publishing a range of scientific literature, organising and sponsoring a wide variety of meetings and funding grant schemes, education initiatives and policy work. The society has almost 5,000 members from 80 different countries. www.britishecologicalsociety.org