It's about nine-tenths as heavy as a Horse.
In other words, 387 kilograms is 0.92 times the weight of a Horse, and the weight of a Horse is 1.1 times that amount.(Equus ferus caballus) (Arabian, adult)
It's about nine-tenths as heavy as a Grand Piano.
In other words, 387 kilograms is 0.86 times the weight of a Grand Piano, and the weight of a Grand Piano is 1.2 times that amount.(for Steinway & Sons, Model D Concert Grand Piano)
It's about three-fourths as heavy as a Polar Bear.
In other words, the weight of a Polar Bear is 1.33 times 387 kilograms.(Ursus maritimus) (adult, male)
It's about three-fourths as heavy as a Grizzly Bear.
In other words, 387 kilograms is 0.743 times the weight of a Grizzly Bear, and the weight of a Grizzly Bear is 1.35 times that amount.(a.k.a. brown bear, a.k.a. silver bear, Ursus arctos horribilis) (Adult, male, coastal area population average)
An adult, male grizzly bear from a coastal area (where food is plentiful) can weigh up to 521 kg. In spite of their tremendous size, grizzly bears can run at speeds of up to 55 kph (34 mph).
It's about one-and-a-half times as heavy as a Pig.
In other words, the weight of a Pig is 0.67 times 387 kilograms.(Domestic pig, Sus scrofa domesticus, a.k.a. S. domesticus) (adult)
It's about three-fifths as heavy as The Heart of a Blue Whale.
It's about one-and-seven-tenths times as heavy as a cubic meter of Snow.
In other words, the weight of a cubic meter of Snow is 0.59 times 387 kilograms.(Freshly fallen, standard conditions; measurements taken in Norway, 1965-68)