Grandma Got Run Over by a Reindeer Quiz

Answer: Buoyancy

Winter calls for reindeer to survive temperatures of -40 C (-40 F) or lower. Having a layer of air-filled fur provides a layer of insulation against the frigid temperatures. When it comes time for the reindeer to migrate, they may need to cross many rivers to get to their desired location. Their air-filled fur helps with buoyancy when crossing waterways.

Reindeer are proficient swimmers. They can cross wide rivers or lakes, doing so at up to ten kilometres per hour (6.2 mph).

Answer: They soften to walk across grasslands

Reindeer hoofs need to be hard in winter. By shrinking and tightening, the hoof exposes its rim. This hardened hoof assists with maintaining traction in the snow and ice of a tundra winter. This tough formation also allows the reindeer to dig into the ice and snow with a hard 'implement' to obtain food. As the weather warms with the change of seasons, the hoofs become softer and more sponge-like. Their habitat is soft and wet, so soft footpads help reindeer to move around the environment without sinking or creating great divots in the surface.

Answer: Reindeer herds can move over twenty miles a day

The vast majority of reindeer calves are born in early June. Within an hour and a half of their birth they are up and running and within hours they can gallop at up to 75 km per hour (45 mph). The reindeer of North America make the longest migration of any land mammal, travelling up to 5,000 km (over 3,000 miles) between their summer and winter homes. Other species of reindeer don't need to migrate or have a limited area in which to move such as on islands.

The reindeer of North America travel between their summer homes in the northern regions of the continent where they calve in June, and then travel south for the winter where food is easier to find. The photo in this question was taken near Kuusamo in Finland. Reindeer on their travels are a common-enough sight on the roads in northern Finland.

Twin reindeer births have been recorded but the norm for reindeer reproduction is a single birth. The calves don't play with wolf or bear cubs - these animals will become reindeer predators. Within a reindeer's first year, up to half will succumb to predators, illness or other factors. Once fully grown, a male reindeer usually weighs about 170kg (374 lbs), be up to 214cm (7 feet) in length and measure up to 150cm (5 ft) at the shoulder. Females are generally smaller. Reindeer bulls of extraordinary size have weighed up to 318 kg (701 lbs)!

Answer: Svalbard Archipelago

Reindeer (Rangifer tarandus) can be classified into over ten subspecies. They all live in the northern reaches of Asia, Europe and North America. The Svalbard reindeer (R. t. platyrhynchus) is the smallest of the subspecies with the males only reaching about 90 kg (200 lbs) at their peak in summer.

Their height, in contrast to other reindeer which may reach 150cm at the shoulder, reaches only 80cm (31 in). Living as they do on the Svalbard archipelago well to the north of Norway, their short stature follows a rule posited by a biologist called Joel Asaph Allen.

He suggested that animals in colder climates have shorter legs and stouter bodies to maintain heat while animals in warmer climes have elongated features and lither bodies to increase heat loss.

Answer: Too well - they overgrazed and culling had to occur

Introduced to the islands by Norwegian whalers, the reindeer were to be a food source and hunting them a means of recreation. The reindeer took to their new home with alacrity. They assumed their new homes in the snow-free areas of the islands which were also the most productive agriculturally. Hunting did contain the populations for a few decades but when hunting ceased in the 1980s, the population of reindeer expanded.

Tracts of land were denuded of native grasses and the topsoil was eroded, causing the homes of native burrowing birds to be in danger of collapse and exposing the birds to predators. The decision to cull the reindeer was made in 2010. In two phases between 2013 and 2014, thousands of reindeer were culled. The South Georgia and Sandwich Islands also aim to eradicate invasive species such as rodents and exotic plants.

Answer: Snow shovelling

In winter when the reindeers' food is hidden under the snow, they must dig into the snow and ice to find a source of nourishment. A keen sense of smell is the reindeer's friend in the search for lichen which may be hidden by up to 150 cm (5 ft) of snow. Their hoofs can help break up the frozen surface but they also shovel into the snow with their noses to feast on one of their favourite foods which is colloquially called reindeer moss. From this comes the name 'caribou'.

Answer: A combination of algae and fungus

A lichen is a organism which results from algae and/or cyanobacteria living amongst a type of fungus. A symbiotic relationship endures within the lichen - the algae providing photosynthesis and therefore food for the fungus while the fungus gives the algae a place to call home. While several species of lichen are called reindeer moss or similar, they are not a moss. Mosses are true plants while lichens are not.

Like cattle, reindeer have a four-chambered stomach. Reindeer are the only mammal known to be able to digest lichen. An enzyme called lichenase breaks the lichen to usable glucose for the reindeer. This enzyme has only been found in a few gastropods. Reindeer will also eat leaves and grasses. Towards the end of winter and in early spring when the reindeer are nutritionally stressed, their diet can extend to other food sources such are char, birds' eggs and small rodents such as lemmings. Mushrooms in late summer can be a reindeer's favourite seasonal food item.

Answer: Both males and females

Both male and female reindeer have antlers but they grow and shed at different times of the year depending on the gender of the reindeer. Older males will grow antlers which are complete by the mating season in autumn and they will be shed (usually) in December. Younger males will keep their antlers until early spring while female reindeer keep their antlers until summer. This means that Santa's reindeer are young males (which need to be replaced and trained up every year or so) or female. Older bull reindeer won't have antlers at Christmas time.

Development of antlers is dependent on the length of the day, with varying hours of sunlight through the seasons determining the growth and shedding cycle of antlers. Reindeer kept in artificial day/nights cycles in tests failed to shed their antlers when living in an environment with twelve hours of night and day. When placed in an environment with constant light, bucks grew three sets of antlers within a 24-month period.

A reindeer's antlers can grow up to 100 cm wide (39 in). Compared with the size of their bodies, reindeers grown the largest antlers of any extant deer species. Moose antlers are the largest in the deer family. The older the reindeer, the larger the antlers will be. Calves will start growing their first set of antlers in their first year.

Answer: True

Gold eyes are found in reindeer in summer, while in the winter months, they are blue. Why? I'm so glad you asked. It has nothing to do with driving sleighs. Research by the UCL Institute of Ophthalmology and the University of Tromsų, Norway, showed that the different colours assist reindeer to see in different light conditions. The tapetum lucidum, the reflective layer of the eyeball, is golden in summer which reflects more light out of the retina. This protects the eyes from excess amounts of light in summer. In winter, the tapetum lucidum turns a blue shade which scatters less light out of the eye, helping the reindeer see in limited or absent light conditions.

This is the first known instance of mammals changing the formation of their retinas to adapt to seasonal variations in light. It is thought that the change in colour is due to the pressure within the eyeball changing, forcing the fibres of the tapetum lucidum together and changing its colour.
It's also thought that this function enables or assists reindeer to see UV light.

Answer: UV (ultraviolet) light

The ability to see UV light in the tundra has more than one benefit for reindeer. Their winter food source, reindeer moss, absorbs UV light. The surrounding snow reflects UV light and this makes the moss stand out against the white backdrop. This makes food hunting easier for reindeer. The reindeers' predator, the wolf, also absorbs UV light so the wolf's presence is easier to detect.

Scorpions don't live anywhere near reindeer but they do glow under UV light. Why they glow is still a mystery to science.