How have upland butterflies fared this year?
A review of my 2025 butterfly surveys in Highland Perthshire
I have been collating and analysing the butterfly surveys I have done this year. I hope sharing what I’ve found will complement my two previous posts about the butterflies I usually see in Perthshire. Those were light-hearted descriptions of the characters of the different species I encounter:
The butterfly surveys are part of an annual environmental assessment, which includes surveying breeding birds and monitoring habitat changes, both done by Andrew. In this post I reflect on the fortunes of the species I observe and how that relates to the changing climate. The long, hot, dry summer has helped some butterflies, but been a challenge for others.
A special place
First a bit about the site where I do the butterfly surveys. It is a bit of Highland Perthshire dear to my heart – 40 acres (17 hectares) of woodland and rough grazing that I bought seven years ago and have been ‘rewilding’ with the aid of my partner. It is upland birch woodland clinging to a steep, bouldery slope with rough grazing below and regenerating heathland and woodland above. The bones of the land show through in exposed rock outcrops, ancient walls and stone clearance cairns. Hazel coppice casts a green shade and young stems shoot up from decaying rowans growing out of crags.
I have been hesitant to feature the place here because I have a half-written book about it stalled on my computer. The gap since I progressed the work that far has given me the space to realise that I can do better - if I radically cut and restructure my words then start again, going deeper than I have before. So I wonder whether to share any of the ‘old version’ or to keep it all under wraps until it has gestated. Comments and advice on this would be welcome!
Survey methodology
I record the butterflies that I see while walking transects across this special place. My approach is based on the Wider Countryside Butterfly Survey (WCBS)1, which aims to get a representative picture of the status of butterflies in widespread habitats such as lowland intensive farmland and upland grassland and moorland.
The WCBS is based on grid squares (1km x 1km) and involves walking two parallel 1km-long survey lines, around 500m apart, in a N-S or E-W direction across the square. As my piece of land is much smaller than a grid square and has many uncrossable features, my transect lines are far from parallel. In fact, they nearly converge on the highest ground in the north, where the plot narrows. My lines jink around to go through gates and over stiles, while avoiding crags, boulder fields and impenetrable thickets of blackthorn and broom.
The method entails recording butterflies in an imaginary 5m square around one’s course, walked at a steady pace. However, I often break off temporarily to photograph a butterfly to help confirm species, or just to get a pretty picture. Sometimes that means stalking them until they settle (if I’m lucky) before I return to my line.
The WCBS requires a minimum of two visits to each square, to be made in July and August, with optional visits in May and June. But I like to start in April, which is the only month in which I have seen the elusive Green Hairstreak. And to do another in May to catch the emergence of the delightful Orange Tips.
This year I actually did seven surveys: April x 1, May x 1, June x 1, July x 2 and August x 2. But as I was away doing walks research, I had a gap of over six weeks between the May and June surveys. In that time I missed the first flush of Small Pearl-bordered Fritillaries, some of whom were already looking a bit faded by the time I saw them at the end of June.
Survey Results
I saw a total of 14 species this year, which is quite respectable for an upland landscape that rises up to over 1050ft (320m). No Commas or Painted Lady butterflies put in an appearance and I also failed to spot any Green Hairstreaks, which I always feel have a fairy-like quality. Maybe I used the wrong magic.
The white ones
As usual I recorded small numbers of Small White and Large White butterflies on the lowest part of the land, close to gardens where they may find brassicas for their caterpillars to feed on.
It was a good year for Orange Tips, with higher numbers than I have seen before flying in April and May. They are a delight to see feeding on the nectar of spring flowers against a backdrop of young, emerald green grass.
Likewise, my count of Green-veined Whites exceeded previous years, reaching 100 in 2025. This made them the third commonest of the species I saw. They fly strongly and I found them at all elevations, although they particularly like damp areas. After a strong start in spring their numbers decreased during the hot, dry weather, but I saw them on every visit through to late August because they produce more than one generation in a year.
The wee ones
I don’t think this is a technical term, but it’s how I think of our most petite butterflies, which need keen eyes to spot. It was a poor year here for the brilliant little Small Copper butterfly. The lower pasture was heavily grazed by ewes and lambs in April and I have a suspicion that in eating down the sward they may have devoured developing caterpillars. Or maybe they didn’t lay so many eggs last year?
Similarly, it was an indifferent year for the Common Blue, the only blue butterfly present here, with only the occasional one observed. Another theory for these two species not thriving is that the habitat is gradually changing to become taller and denser – and therefore less attractive to them.
The bright ones
These are the Vanessids, the big bright butterflies that herald summer (although some of them overwinter as adults and can be seen in early spring). During the summer, I saw both Red Admirals and Small Tortoiseshells in small numbers – six and seven respectively. That is fairly average for this location.
Peacock butterflies were much more numerous, with one seen in April than 25 in late July and August when the 2025 generation emerged. Like many butterflies, they are drawn to the nectar of thistle flowers, especially the creeping thistle whose sweet scent wafted over the area on hot summer days. There is one patch surrounded by bracken where I could rely on seeing several.
The browns
The three grassland species on this site are the commonest butterflies I survey. The Meadow Brown has been steadily building in numbers over the past seven years and this year I encountered more than ever before – 173 across the seven visits. The females have brighter orange patches on their forewings than the males and I often saw them fluttering over the sward before crawling through tufts of grass to lay eggs. By contrast the males patrol above the grass heads, searching for a female to mate.
The much smaller but similarly marked Small Heath had a good year, but didn’t reach the levels of 2021 and 2022. I find more of them in the wilder upper grassland, which is less attractive to the Meadow Browns. This May I saw many of this species on the mountain Dun da Gaoithe on Mull, flying around up to and above 2000 feet (600m).
Ringlets also had the third best year that I’ve recorded. They remain the most populous species on this site. On my June visit I seemed to be kicking up clouds of them on each step through the long grasses. In my experience they like damp grassland and are happy to fly on dull and drizzly days. This year their numbers dropped sharply as the heat and drought accelerated the green grasses to wither to tawny leaves and seed heads.
The caterpillars of these three species all feed on range of grasses, which are well represented on this site with many varieties growing. Their butterflies were especially abundant in June and early July, responding to the good summer but declining quickly as autumn arrived early, turning the grassland biscuit dry.
The fritillaries
It is a constant source of delight to me that two species of fritillary breed on this ground. I often hope that the rarer Pearl-bordered Fritillary may also turn up, but that may be a vain hope as the species is in serious decline.
The Small Pearl-bordered Fritillary had a reasonable year and I suspect I would have recorded many more if I had made late May or early June visits. Their flying period is relatively short and I was lucky to see three still around in mid July.
The star of the show was the Dark Green Fritillary. This year I saw 73 in seven visits, more than ever before. This species seems to love the selection of nectar-bearing wildflowers in the area and the widespread ground cover of violets, the larval food plants. Almost as soon as it emerges from the egg, the caterpillar goes into hibernation and doesn’t start feeding until March the next year, where it benefits from the shelter of dead bracken, which creates a warmer microclimate for its development.
Other observations
These regular tours of the area enable me to note the plants and animals present and appreciate the changing seasons and fluctuating weather. One of my visits was two days after Storm Floris, whose winds had beaten down much of the vegetation and brought down branches.
As always I saw numerous moths on my transects. If I get a chance to photograph them I try to identify the macro moths afterwards and I’m now familiar with a few species – maybe another post? But I feel there is little hope of me mastering the micro moths, which flit in front of me like motes of dust then disappear when they land on a grass stem and close their wings along their body.
I try not to be too distracted by birds, although I thoroughly enjoy the woodland spring chorus, the convivial chatter of Long-tailed Tits and the scolding of a disturbed Stonechat. And who can resist looking up at a mewing Buzzard or gasping at a swooping Sparrowhawk? On a couple of visits I have paused on hearing a soft, motherly peeping to see a hen Pheasant leading her growing chicks away from me.
At different points in the season I have been noting the wildflowers in bloom, gradually compiling a lengthening list of species present, from the first splashes of yellow with Lesser Celandine and Primrose to the summer blooms of Chickweed Wintergreen, Yarrow and three varieties of heather: Bell Heather, Cross-leaved Heath and Ling.
It’s a pleasure to follow this routine of regular visits and it makes me feel intimately connected to the land. A part of me stays there and reawakens each time I return.
The Wider Countryside Butterfly Survey is organised by Butterfly Conservation and the Centre for Ecology and Hydrology in partnership with the British Trust for Ornithology. Its volunteers survey a random selection of grid squares across the country.
Beautiful images as always.
My butterfly observations this year have been very similar to yours. It looks really beautiful where you are.