10 most difficult ecology riddles

Owl's eye colour depends on the time of day in which they hunt. The ones that hunt during daylight have yellow eyes. The ones that hunt at night but also at the evenings and mornings have orange eyes. Black eyes are typical to owls that hunt only at night.

Low carbon dioxide emission in France is a result of large investments in nuclear technology. Most electricity produced by France is generated by 59 nuclear power plants. As a side-effect renewable energies are having difficulty taking off.

Found in open woods, parks, hedges and cultivated land, the mistle thrush feeds on a wide variety of invertebrates, seeds and berries. Its preferred fruits including those of the mistletoe, holly and yew. Mistletoe is favoured where it is available, and this is reflected in the thrush's English and scientific names.

Xylophagy is a term used in ecology to describe the habits of an animal whose diet consists of wood. The word derives from Greek xylon "wood" (similarly to xylophone)

A synanthrope is a member of a species of wild animals and plants of various kinds that live near, and benefit from, an association with humans and the somewhat artificial habitats that humans create around them.

Lake Karachay is a small lake in central Russia. It is often referred to as the most polluted site on earth. Containing just one square mile of water, the lake formed a dumping ground for nuclear waste by for around 12 years.High level radioactive waste makes up almost the entire lake-bed to a depth of around 3.4 meters. Some areas surrounding the lake have radiation measurements of around 6 Sv/hour, which is enough to give a lethal dose to a human in as little as 30 minutes¹.

Northeast Greenland National Park is the largest protected land area in the world. Established in 1974 and expanded to its present size in 1988, it protects 972,001 km2 and is bigger than all but twenty-nine countries in the world.

As the name suggests, bee-eaters predominantly eat insects, especially bees, wasps, and hornets. They catch insects in flight, in sorties from an open perch. Before eating a bee, the European bee-eater removes the sting by repeatedly hitting the insect on a hard surface.

Altricial species are those in which the young are incapable of moving around on their own soon after hatching or being born. The word is derived from the Latin root alere, meaning "to nurse, to rear, or to nourish" and indicates the need for young to be fed and taken care of for a long duration.

Red-backed shrike hunts for its food on the ground. It eats smaller prey right away, but bigger ones like rodents and insects are kept for later, impaled on trees and bushes.