WHEN DO THEY GET DARKER?
Animals from humid habitats have darker colour than those living in dry areas. This phenomenon, known as Gloger’s rule, can be nicely illustrated with tigers: Sumatran tigers from humid tropical regions have a dark orange coat with well-defined black stripes, while the extinct Caspian tigers from dry Central Asia had faint stripes, sometimes so faded as to be nearly invisible.

WHY ARE THEY OF VARIOUS SIZES?
The further from the equator, the larger and more robust animals tend to be compared to their tropical relatives. We call this phenomenon Bergmann’s rule and it is caused by the need to retain body heat: larger bodies lose less heat than smaller ones. Additionally, tigers from the south are smaller because they live on islands, which provide only limited space and food sources for large animals, forcing them to evolve into smaller island forms—a phenomenon known as insular dwarfism.

SIBERIAN TIGER
shoulder height: 110 cm
weight: 120–220 kg (exceptionally even more than 300 kg)

MALAYAN TIGER
shoulder height: 95 cm
weight: 100–165 kg

SUMATRAN TIGER
shoulder height: 80 cm
weight: 60–140 kg

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