Photo of Gotland ponies walking towards the camera outdoors during the summer.

Gotland ponies as conservationists

Page reviewed:  11/10/2025

The Gotland pony as a conservationist – a way to promote biodiversity and preserve an endangered domestic animal breed.

Background

Despite international conventions and extensive national measures, biodiversity in Sweden is declining. The most endangered species are found in environments that require open, grazed landscapes. We have investigated whether Gotland ponies grazing year-round could be a method to halt this negative trend and at the same time contribute to the preservation of the pony, which is an endangered Swedish domestic animal breed.

The Gotland pony is an old horse breed that not so long ago roamed freely on Gotland, and our hypothesis was that there are individuals that still have characteristics that enable them to graze year-round with good function and health. An important aspect of the study has therefore been to investigate how the ponies cope with grazing and to investigate individual variations in characteristics. This knowledge is also important from an international “rewilding” perspective. Projects are underway around the world that attempt to recreate or preserve landscapes and ecosystems by allowing grazing animals to live freely there. Since the wild horse is extinct, domesticated horses are used without any scientific investigation of whether they still have the appropriate characteristics for a wild life.

About this project

The project has received support from SLU, the World Wildlife Fund, the Helge Ax:son Johnsson Foundation, and the general public via crowdfunding. The practical part of the project began in the spring of 2014, when twelve one-year-old Gotland pony stallions were released into three enclosures south of Uppsala consisting of approximately 3 hectares of grassland and 7 hectares of forest (four roe deer in each). The roe deer remained there until autumn 2016, and various types of data were collected throughout the period. Some of this data has been processed and published, both scientifically and in popular science. Below are the results, conclusions, and links to the publications that are currently available, but more publications are expected.

Results

Year-round grazing with Gotland ponies can increase biodiversity and prevent the overgrowth of open land. There are individuals within the Gotland pony breed that have suitable characteristics for year-round grazing and perhaps even “rewilding,” but there are also individuals that do not have these characteristics, even though the Gotland pony is considered a hardy breed.

Below you will find results, conclusions, and references for all areas studied:

The impact of horses on plants, butterflies, and bumblebees has been studied. The results show that plant species richness was higher where horses grazed, that bumblebees and butterflies preferred the horse-grazed areas (compared to the enclosures where horses could not graze), and that there was a positive correlation between plant richness and pollinators. The conclusion is that this form of horse husbandry can limit the loss of biodiversity and thus become an important tool for preserving the species richness of the grazed open landscape.

The impact of horses on different tree species and forest development has been studied. The results show that the grazing of the horses created a more open landscape by limiting the amount of scrub and bushes. The conclusion is that year-round grazing horses can contribute to the conservation and restoration of species-rich forest pastures and meadows. The impact of horses on the number of grasshoppers (of different species) has been studied. Observations were made in places where: 1) horses grazed, 2) horses did not have access to grazing (enclosures), and 3) in rator (places that horses use as toilets and avoid grazing). The study showed that there were more grasshoppers in the rator areas than where the horses grazed and where they were unable to graze. The conclusion is that the presence of horses in the fields created environments that appeared to be favorable for grasshoppers.

References:

  • Garrido P, Mårell A, Öckinger E, Skarin A, Jansson A, Thulin C-G (2019). Experimental rewilding enhances grassland functional composition and pollinator habitat use. Journal of Applied Ecology 56 (4), 946-955 Länk: https://besjournals.onlinelibrary.wiley.com/doi/abs/10.1111/1365-2664.13338
  • Garrido P, Edenius L, Mikusiński G, Skarin A, Jansson A, Thulin C-G (2020). Experimental rewilding may restore abandoned wood-pastures if policy allows. Ambio (online) Länk: https://link.springer.com/article/10.1007/s13280-020-01320-0
  • Garrido P, Jansson A, Mikusiński G, Naumov V, Öckinger E, Skarin A, Uboni A, Thulin C-G (2020). Åretruntbete med gotlandsruss – gynnar biologisk mångfald och bevarar ängs- och hagmarker. Fakta Skog 2 (svenska) Länk: https://www.slu.se/globalassets/ew/ew-centrala/forskn/popvet-dok/faktaskog/faktaskog20/faktaskog_02_2020.pdf
  • Thulin C-G, Jansson A (2020). Ecosystem function of semi-feral horses with specific focus on orthopteran density. Conference Abstract No 33477 EAAP 2020, Porto, Dec 1-4, 2020 (virtual conference) Länk: http://www.eaap.org/eaap-2020-virtual-meeting-1st-4th-december/

 

The effects of the horses' grazing on the energy and protein content of the pasture have been investigated through sampling and analysis once a month. The results were also compared with areas where the horses were not allowed to graze but were instead mowed once a month. The grazing of the horses increased the variation in energy and protein content between different locations, and both energy and protein content increased over time where the horses grazed, while it decreased where the grass was mowed.

The protein content was high enough to meet the horses' needs throughout the year, but the energy content and amount of grazing were limited for five months, which meant that the horses had to use their fat reserves for energy. In this study, an energy supply in November equivalent to 12,000 MJ per hectare (grass area) was sufficient to ensure that no horse would fall below the body condition score (4 on a 9-point scale) that we considered critical later in the winter. Of the three paddocks we studied, only one met this requirement in both winters. We therefore recommend that those who intend to keep horses on pasture year-round with the aim of also promoting biodiversity should, for safety's sake, harvest the land late (i.e., fence off an area in early summer, which is then harvested, and allow the regrowth to be grazed). This can then be used as feed during January-March if the grazing area is on the small side or conditions otherwise limit energy intake. 

Information:

  • The Gotland ponies wore GPS transmitters, and we currently have preliminary results from their choice of habitat. They spent most of their time on grasslands and less time in forests, but increased their use of forests during winter and also at night. On average over the year, they spent 48 minutes a day in the wind and rain shelters that were available. The shelters seemed to be used mostly when the temperature was above 15°C.

  • The Gotland ponies had no problem grazing in winter as long as the snow could be scraped away, even if it was 20 cm deep. However, under certain weather and ground conditions, this was not possible. In the three enclosures, the grasslands were largely located at the lowest point in the area. During a winter period when days with rainfall were mixed with days with sub-zero temperatures, a layer of ice built up on the grasslands, making grazing there impossible. As a result, the ponies grazed more in the forest (where there was never any ice or even frost) and consumed their summer and autumn reserves at a faster rate than before. During this period, some reindeer had to be removed from the project due to low body condition. However, this was never necessary in one of the enclosures, which was characterized by the forest having more grass (more open and dominated by deciduous trees) and by a large ditch at the lowest point of the enclosure that could quickly carry away large amounts of precipitation. The nature of the land therefore seems to be decisive in how well it works for year-round grazing. 

  • The crude protein content in Gotland pony manure showed a positive correlation with the crude protein content in the pasture. Manure analysis can therefore be used to roughly estimate the quality of the pasture grazed by the horses. The manure content corresponds to approximately 80% of the crude protein content in the pasture.
    • In a study, we present data on the energy and protein content of pasture throughout the year, month by month, which can serve as a guide for livestock farmers who use pasture year-round in Sweden (see Ringmark et al. 2019).

References:

  • Ringmark, S., Skarin, A., Jansson, A. 2019. Impact of Year-Round Grazing by Horses on   Pasture Nutrient Dynamics and the Correlation with Pasture Nutrient Content   and Fecal Nutrient Composition. Animals 9(8), article number 500. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6720502/
  • Skarin A, C-G Thulin C-G, Ringmark S, Dahlborn K and   Jansson A, Saving a threatened breed –   Conditions for maintenance and habitat selection of extensively kept Gotland   Russ (Equus caballus). (Abstract – Oral presentation) Grazing in a   Changing Nordic Region, 12th-15th of September, 2016, Reykjavík, Iceland.

The body condition of the Gotland ponies was recorded weekly, their weight every two weeks, and their height at the withers and some other body measurements once a month. Eight of the twelve ponies managed to maintain a functional body condition (> 4 on a 9-point scale) throughout the year, but four needed supplementary feeding in another paddock for a few weeks during the late winter.

We compared the average weight, body condition, and growth curve of the Gotland ponies with a group of warmblood trotting horses of the same age that had free access to highly energy-rich haylage throughout the year. The trotting horses maintained fairly constant body condition and weight gain throughout the period, while both body condition and body weight decreased during the winter in the Gotland ponies. Despite this, the Gotland ponies reached 99% of their expected withers height as three-year-olds based on the withers height growth of the trotting horses, and all individuals also achieved a withers height considered optimal for the breed. The growth of the Gotland ponies thus did not appear to be affected by the winter periods with a negative energy balance.   

Once every season, a blood sample was also taken and the Gotland ponies' insulin levels were analyzed. Insulin levels were significantly lower during the winter compared to the other seasons, and there was a certain correlation between the horses' body condition and insulin levels. The higher the body condition, the higher the insulin levels. High insulin levels may be linked to an increased risk of laminitis, but no such observations were made in the Gotland ponies. We can conclude that the Gotland ponies showed clear seasonal variations in both body condition and insulin levels, with the highest insulin levels observed in the spring and the highest body condition scores in late summer and autumn. This scenario differs from the risk profile for laminitis that we know of for conventionally kept horses, where body condition and insulin levels are high at the same time and may have been so for a long time.

The horses' coat length was measured every two weeks. There was individual variation in coat length. There was no difference in coat length between individuals that were given coat conditioners and those that were not (see below), nor between individuals that were occasionally observed to shiver and those that never did.

References:

  • Ringmark, S. and Jansson, A. Growth performance   in 1.5-3 year old extensively kept Gotland ponies in comparison with   Standardbred horses fed a forage-only diet ad libitum. European Workshop of   Equine Nutrition, Dijon, France, 16-17 June 2016. 
  • Skarin A, C-G Thulin C-G, Ringmark S, Dahlborn K and   Jansson A, Saving a threatened breed –   Conditions for maintenance and habitat selection of extensively kept Gotland   Russ (Equus caballus). (Abstract – Oral presentation) Grazing in a   Changing Nordic Region, 12th-15th of September, 2016, Reykjavík, Iceland.
  • Ringmark, S., Dahlborn, K. and Jansson, A. Seasonal   variation in plasma insulin concentration and body condition in free ranging   Gotlandsruss. European   Workshop of Equine Nutrition, Uppsala, Sweden, 16-18 August 2018.
  • Ringmark, S., Dahlborn, K. and Jansson, A.   Individual coat traits in a native horse breed kept under semi-wild Nordic   conditions' with abstract number. Conference   Abstract No 34625 EAAP 2020,   Porto, Dec 1-4, 2020 (virtual conference) http://www.eaap.org/eaap-2020-virtual-meeting-1st-4th-december/

The presence of parasites was monitored continuously and faecal samples were analysed once a month. At the start of the study, the fields had not been grazed by horses and all Gotland ponies were dewormed with Ivermectin prior to introduction. After just three months, we found that the average number of bloodworm eggs exceeded the limit we had set for deworming (200 bloodworm eggs/g of feces). The horses were then dewormed five times based on the above limit criterion. There was significant individual variation in egg excretion, with some individuals excreting an average of only 25 eggs/g of manure, while others excreted 12 times as much. Excretion was highest in the summer and increased year after year.

During the study, individuals with roundworms, tapeworms, pinworms, and botflies were also observed, but large bloodworms were never observed. Fur eaters were also observed. Three of the Gotland ponies were never observed with any parasite other than the small bloodworm (which all Gotland ponies had), which may indicate a strong resistance to parasites. It is known from other animal species that there is a genetic component to resistance to parasites, and two of these individuals were also from the same father.

The initial strategy in the project was to deworm horses with pyrantel when deworming was necessary, as it is not toxic to other animals when excreted in the feces. However, with this strategy, we were unable to keep egg excretion down, and on a couple of occasions we had to use another preparation that is toxic to invertebrates such as insects, worms, and snails. This highlights the problems in nature conservation where domesticated animals are used and the importance of using individuals that are highly resistant to parasites.

Studies of feral horses have shown a correlation between high parasite load and low body condition. There was no correlation between the number of eggs excreted by the Gotland ponies and their body condition in this study. The individuals that had to be temporarily removed from the study due to low body condition even had lower excretion than the other Gotland ponies. This may mean that with the body condition limit we had for Gotland ponies to remain in the study, there were still resources to invest in resistance to parasites, which is not the case if energy reserves become too low. The estimated body fat content of Gotland ponies when it was at its lowest was roughly equivalent to that of well-trained trotting and galloping horses.

Six out of 12 Gotland ponies were observed with fur mites. There was no difference in coat, mane, and tail length between those with fur mites and those without. We found that only the brown Gotland ponies had fur mites, not the chestnuts or the Isabelles. We studied how much the horses scratched themselves and found no difference compared to horses that did not have hair lice. Nor could we see any effect from the hairless patches (they did not shiver, for example). We concluded that hairworms in the quantities observed (1-2.2 eggs or adults per cm2 in the mane and forelock) did not pose a health and welfare problem. 

Springworms were the only parasites that appeared to affect the horses' well-being, as they were occasionally observed scratching their tails during that period. One horse also secreted mucus from the anus in connection with the pinworm infection, which has previously been described by other researchers.

The results show the need to monitor the occurrence of parasites in this type of horse husbandry, even if the land has not previously been grazed by horses and the horses have been dewormed.

References:

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