Malham Tarn NNR

Dales National Park

Field Studies Centre

Site Details:

Recorders: Peter Walsh 2013-16 Denis Lord 2017- Distance: 3175 Altitude 393m Walk time : 1 hour

The National Trust’s National Nature Reserve at Malham Tarn is a very special place with an amazingly rare and dramatic array of plants and animals from the really unusual Tarn Fen (unique assemblage of fen plants and insects) to raised bog, orchid-rich wet flushes and limestone pavement and the tarn itself with crayfish, otters and many breeding birds.


S1 takes you from Home farm to the northern edge of the estate. S2 has the highest butterfly counts and follows the road verge with good numbers of Common Blue, Dark-green Fritillary and Small Heath plus Ringlets and Green viened White in the damper areas. Northern Brown Argus is also seen here. S3-S5 have low numbers with Green-viened White being dominant in the damp areas. S6-S8 score almost none. S9 across heathland sees Green hairstreak and Green-viened Whites and occasional Orange Tip. S10 through woodland sees only Green-viened whites. S11 enters the fine grassland in front of the field centre and a good array of the common grassland species with Meadow Borwn predominant along with Small Skipper, Ringlet and Small Heath. S12 scores zero but S13 climbing the bank to Highfolds Scar has very high numbers of grassland species but also Northern Brown Argus and Dark-green Fritillary occu . Returning past the Field centre, garden plants attract large numbers of Vanessids and even a Brimstome.

Results 2022

Counts over the last decade have near enough doubled mostly due large increases in the grassland species, in particular, Ringlet , Small Heath and Common Blue. Even the warmth lover small skipper has now made it to 400m altitude in the last 4 years and numbers this year are double last. Brimstone has also been seen for the first time last year . The whites had a poor year although Orange tip staged a come back after a very poor 21 and its trend long term is very much upwards. Brown Argus is only seen spasmodically and not this year as it has been a poorer year on most upland sites due to drought. Green Hairstreak peaked in 2018-19 and was somewhat down against the average. Meadow Brown had a very good year while the other browns were down. Small Heath had a exceptional 2020 but this has been followed by two poorer years. Vanessids had a terrible year as they did in most locations due to the drought and heat.

Transect reports

Results 2021

After three very good years 2021 was a bit of a fall 22% down . 2019 standing out as exceptional in the last 5 years. Small Skipper and Small Copper are showing a significant increases over the 5 year term in contrast to much of Yorkshire . The Whites have steadied down after the boom years 2018-19 as have Oraneg Tip. Brimstone made an appearance in 2021 which is encouraging for this spreading species. Common Blue had a very significant rise last year and is a little down this year back to their pre peak numbers. Peacock numbers have dropped back in common with most transects and Comma has not been seen for 2 years and had a exceptionally bad year on most transects . Dark-green Fritillary numbers peaked in 2019 and have dropped back a little while elsewhere they had a good year . Ringlet had a poorer year while Small Heath wasnt bad with second highest year and has been one of the exceptional winning species in Yorkshire in 2021. The Small Tortoiseshell boom continues as elsewhere but in contrast to other areas Red Admiral did well. Northern Brown Argus fluctuiate in numbers with no clear trends while in most of Yorkshire they increased substantially.