Goats feel climate change effects

GOATS, the first hoofed animals to be domesticated, are remarkable creatures. 

There are almost a thousand million of them throughout the world today. The wild ancestors of most farm animals are extinct, but the original goat survives in Europe, the Middle East and Asia. Males are known as ‘bucks’, females are ‘nannies’, while the word ‘kid’ has ‘gone viral’. Do children resemble young goats? You must be ‘kidding’!

Chamois live in the Alps, Pyrenees, Carpathians and several other ranges. There are two closely related species. Both are difficult to find and approach, the steep mountain terrain in which they live is so inaccessible. The Alpine one is about three quarters of metre tall, with a brown coat and short slightly-curved horns. Bucks lead solitary lives, competing fiercely for females in the mating season. The nannies and kids live in herds, young males being expelled at the age of three or four. The chamois’ main enemies are wolves and lynxes. Avalanches are a threat and kids can be taken by large birds of prey. Maximum life expectancy is about 17 years.

Mountains, everywhere, are being invaded by skiers, climbers, trekkers, hang-gliding enthusiasts and parachutists but, despite the disturbance, the chamois is holding its own; its IUCN designation is ‘Least Concern’. This does not mean, however, that the species is unaffected by change. Far from it; a paper appearing in the September edition of Frontiers in Zoology claims that chamois in Italy are becoming smaller as their environment heats up.

Goats are hunted under licence each autumn in the Trento province of the Italian Alps. More than 10,000 young animals were shot, in three districts, between 1979 and 2010 and the weights of the carcasses logged. Scientists from Durham University, examining the records, noticed something odd.

Body mass will vary, depending on food availability and weather conditions, during the hunting season and from year to year. Using statistical techniques, the Durham team were able to allow for these fluctuations and come up with figures for the underlying trends in the weights. The young chamois shot recently, they found, are only 75% as heavy as their equivalents were 30 years ago. Such a dramatic drop in a relatively short period is astonishing but another change occurred at the same time; temperatures in the Italian Alps rose by three to four degrees Celsius. It seems that mountain goats are becoming smaller as a result of climate change.

In the early 19th Century, the German anatomist Carl Bergmann noticed that animals living in cold places tend to be bigger than those found in warmer ones. Large bodies have smaller surface areas, compared to their volumes, than little ones, so heat loss is slower. Able to retain heat for longer, big animals cope better with the cold. Small ones, on the other hand, lose body heat more quickly and that can be an advantage during hot summers. Coping with the cold, it might be argued, is less of a problem for chamois nowadays, so they can afford to become smaller. Bergmann’s Rule, however, can’t really explain so large a drop in body size in such a short time. Something else must be going on.

If hunters persistently targeted the biggest individuals year after year, the average size of animals would fall over time. However, analysis of the bag records shows that no such selection took place. Nor is food availability a problem; the same amount of vegetation is available to the goats and its nutrient quality has not declined. However, there has been a change in feeding behaviour. Chamois retire and rest during the heat of the day; they don’t feed when it’s hot. With the prolonged high temperatures of recent years, it remains hot for longer and less time is available each day to forage. The goats are eating less and so their body mass is declining. Climate change impacts in unlikely ways!

  • Environmental change and long-term body mass declines in an alpine mammal. T. Mason et al. Frontiers in Zoology. 2014.


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