Though mostly found singly or in pairs, larger numbers may concentrate at favourite flowering trees, where they act aggressively towards other sunbird species.

[7] On seaward-facing slopes, they are very common residents up to 1,800 metres,[7] with high reporting rates in afromontane forest and valley bushveld.

[9] Amethyst sunbirds can be found along an altitudinal gradient in South Africa from the Drakensberg mountain range to the coast of KwaZulu-Natal.

[10] During warmer months, the sunbird's hematocrit levels will increase with higher altitudes (where there is also a dramatic drop in temperature) and with lower oxygen concentrations in the atmosphere.

[11] Higher hematocrit levels may be attributed to its small body size and can help with oxygen carrying capacity and the metabolic cost of flying.

[12] On the Mashonaland plateau, race kirkii has declined in favour of scarlet-chested sunbird, after fragmentation of its native miombo woodlands.