Arctic skuas are the smaller but faster and more aerodynamic cousins of the Great skua.
While the large and noisy Great skuas can impress with their strength and forceful presence, Arctic skuas are unparalleled in their speed and agility in the air, traits which make them so successful at harrying other birds such as guillemots and kittiwakes to drop the food they are carrying as they race over the sea back towards their breeding ledge.
To emphasise the amazing flying ability - and courage - of the Arctic skua, we have seen Arctic skuas chasing a peregrine falcon over more than a kilometre.
Arctic skuas, like Great skuas, breed in back-to-back territories on the moorland of Handa, though their territories are smaller, usually with a diameter of between 10 and 20m.
As long as the colony is of a reasonable size, the breeding birds' proximity to each other enables them to engage in cooperative defence against predators, where several adults from different territories will join forces to repel any intruder (such as a bonxie, or a Great black-backed gull) which is trying to make a meal of either their eggs or chicks.
What results is often an amazing and cacophonous spectacle of aerial dog-fighting.
However, the Arctic skua is in decline across Britain (go to the conservation page for more details), and the Handa colony is no exception.
Here we have been able to show that predation of newly fledged and weak-flying Arctic skuas, while they are still on the island in August each year, is a major factor limiting expansion of the breeding population.