You can tell a lot by the traits of any creature
Everyone interested in nature knows the frustration of getting a fleeting glimpse of something unusual but often not getting enough information to make a definitive identification.
When I was walking on my local sand dunes I spotted a departing large white butterfly that I instinctively knew was something out of the ordinary. It teasingly gave me a fleeting glimpse as it flew away at speed and disappeared from view over the top of a tall sand hill.
Familiarity with seeing my local dune plants and animals told me it was something out of the ordinary; I was left asking myself: 'What was that?' While it was a butterfly and it was white in colour, it certainly wasn't any of our five resident white butterflies as its jizz was totally at odds.
Jizz is a term originally used by birdwatchers but now used by many field biologists to refer to the overall impression of the general characteristics of a plant, animal or habitat. For a bird, its jizz is the overall impression one gets from its size, colouration, shape, posture, style of walking, style of flying, etc.
Habitat jizz is the indefinable quality that a place has. We all develop a feel for what comprises the seashore, a woodland, a bog, and so on.
We use jizz with people too. We recognise our neighbours in a crowd in the distance even identifying them from behind by their carriage, walk and general appearance without being able to put into words the individual distinguishing features that allow us to accurately identify them. They may wear many different colours of clothes, but we still recognise them.
So it was with my butterfly. While what I saw had a white background, the jizz of its large size and powerful flight told me it wasn't one of our five resident white butterflies.
Not really expecting to see it again, curiosity drove me to leave the track and follow the trail of the departed mystery insect. To my surprise I located it again and, ignoring its colour, its jizz told me it was a Dark Green Fritillary; its large size suggested a female.
As luck would have it, she settled to feed affording me a brief opportunity to capture the above mobile 'phone image of the unusual white aberration of a normally orange-brown butterfly. She momentarily sucked nectar from the purple flowers of Common Knapweed before taking off and flying rapidly out of view.