We’ve released 803 squirrels at an airport - here’s why

Attractive to the eye, this small, bushy-tailed rodent likes to sit upright on its hind legs to peer across fields with its large, dark eyes on the lookout for predators. They are slender animals, equipped with strong legs and sharp claws, enabling them to excavate tunnel systems up to 2 metres deep with multiple entrances. Working together, they alert the colony to danger by letting out a distinct call allowing them to scuttle and seek shelter from predators. 

They hibernate individually in their underground chambers during the winter where they draw on vital body fat stores (using up to 90% of stores). This makes summer a crucial time when squirrels need to forage for a large part of the day to build up fat reserves. When they are not foraging, ground squirrels are busy burrowing, grooming, scurrying around, scent marking or looking out for danger. Contrary to popular belief, ground squirrels do not take seeds from fields to stock for winter as they hibernate in the winter months.

The European ground squirrel’s main range of distribution covers south-eastern Europe. Their range is divided by the Carpathian Mountains: to the west it extends to Czech Republic, Austria, Slovakia and Hungary into the Pannonian area of Serbia and Croatia; and to the east, the Transcarpathian region of Ukraine, Romania, part of Moldova, Bulgaria, south-east of the Former Yugoslav Republic of Macedonia (FYROM), north-east of Greece and the European part of Turkey. 

Typical habitat of the European ground squirrel is in the open, non-forested steppe grassland landscapes. Since many grasslands in Slovakia have been lost to agriculture and urbanisation, airports, golf courses and playgrounds have become modern day refuges for the remaining ground squirrel colonies. Slovakia’s largest ground squirrel colony (an estimated 15,000) lives at the Bratislava airport where they are safe from the threats of agriculture and urban sprawl. Other endangered species, like the grey partridge, also prosper in these man-made environments as they are mowed regularly to keep the grass suitably short (so they can spot predators) and are not treated with poisonous agrochemicals. 

An Important Figure of Grassland Ecosystems

As well as being a lovable, endemic animal, the European ground squirrel can some extent be considered a keystone species. Although not fundamental for maintaining the ecosystem, its presence supports other species of mammals, birds and insects and helps to limit the spread of invasive plant species. When ground squirrels vacate their burrows, others opportunistically move in. The European green toad (Bufotes viridis) or the smooth snake (Coronella austriaca) are two protected species that take shelter in empty ground squirrel burrows. 

Ground squirrels are an important prey for predators such as foxes (Vulpes vulpes), wild cats (Felis silvestris) and birds of prey such as the imperial eagle (Aquila heliaca), lesser spotted eagle (Aquila pomarina) and the saker falcon (Falco cherrug). Certain rare species have also learnt to co-exist with European ground squirrels. This includes coprophagous species that feed on ground squirrel’s excrements such as beetles (Ontophagus vitulus and Aphodius citellorum). 

The ecological impact of ground squirrels also extends to some plant communities. As an important consumer of plant matter, they help control the spread of some species, including invasive species like the harmful silver-leaved nightshade (Solanum elaeagnifolium). 

Until recent decades, ground squirrel populations had been abundant, to such an extent that they were deemed ‘pests’ as recently as the 1960s. However, the situation has swung drastically in the other direction to the point that recently the species went extinct in both Poland and Germany. Sharp population declines have also occurred in the Czech Republic, Slovakia, Moldova, Northern Greece, and Macedonia. As such, in 2019, European ground squirrels were classified as critically endangered on the European IUCN Red List. In Slovakia since the 1970s, a population decrease of 99% has seen this once familiar grassland rodent become restricted to small isolated populations. The most serious threats causing this alarming decline are:

Habitat Loss: due to agricultural expansion and urbanisation. 

Habitat Degradation: driven by changes in land use where traditional grassland management activities like extensive grazing and mowing are being abandoned.

Habitat Fragmentation: which decreases genetic diversity as the colonies cannot disperse and mix as easily. This has led to genetic drift and inbreeding which negatively affects the overall health of the species, decreases resistance to diseases and also the ability to successfully reproduce. Inbreeding causes females to produce fewer offspring (as few as 3 as opposed to as much as 8). Currently, only 3 of the 40 known populations in Slovakia have healthy genetics.

Further to this, ground squirrel population growth is also impacted by:

Food Availability: the lack of flowering meadows, insects and fruit trees in open landscapes.

Predation: by domestic cats and dogs also poses a threat. 

With such a long list of threats facing this species, its fate is dependent on collective conservation action that is swift and targeted. Should the worrying trend of genetic drift and inbreeding continue, inevitably the remaining isolated populations in Slovakia will further shrink and eventually disappear. The need to intervene now is vital to avoid a scenario where population reductions are so great that they can no longer reproduce successfully. 

As the species’ decline continues across Europe, effective conservation efforts by our partner BROZ in Slovakia have seen ground squirrel populations double in the last few years. This impressive outcome achieved as part of the LIFE Sysel project has been attributed to three key interventions:

Restoring habitat through improved grazing of grasslands.

Translocating individuals between isolated populations.

 In partnership with BROZ, we are focusing on continuing this upwards population trajectory by conducting more translocations. This effort is part of the wider LIFE project with national partners: Comenius University, ZOO Bojnice the Slovak State Nature Conservancy. 

The objective of this project is to translocate ground squirrels between populations to help facilitate gene flow and counteract the loss of genetic diversity caused by the fragmentation of their habitat. 

Details of the translocation are as follows:

To trap and translocate at least 600 individuals per year in the period 2023-2027 from 3 donor populations to simulate the natural dispersal process.

Individuals from 3 donor sites (the only remaining strong populations of ground squirrels with healthy genetics) will be released to 40 recipient sites during a 5-year period, where the small colonies have low genetic diversity. This translocation targets all known colonies of ground squirrels in Slovakia.

Two waves of capture and release will take place: spring and summer 2023. Young males and pregnant females are targeted in spring and juveniles during summer to mimic the natural dispersal when males seek mating partners, pregnant females build new burrows to give birth and juveniles disperse to establish new colonies.

A percentage of released individuals are marked for monitoring purposes.

The squirrels are transported in purpose-built wooden or plastic boxes. As ground squirrels are mainly diurnal (active during the day), the release takes place on the same day for those squirrels caught in the morning or on the next day if they are caught in late afternoon. The boxes are specially designed to reduce the risk of causing injury to the squirrels.

The squirrels are released into existing burrows called ‘shelter burrows’ which are 30 to 40 cm deep and excavated at an angle to help the animals quickly escape predators.

The recipient populations are monitored and the number of offspring recorded over the next few years. At the end of the project a genetic study will be carried out by BROZ to compare with the baseline genetic study done at the beginning of the project.

The translocations are informed by the results of a genetic screening study and expert guidance. This is based on the Action Plan for the Conservation of the European Ground Squirrel in the European Union and following a methodology from a Methodical Handbook on the restitution of ground squirrels in Slovakia as well as experience from previous ground squirrel restitution projects across Europe. Additionally, new colonies will be established on suitable sites throughout the project as recommended by the head zoologist.

This series of translocations follows on from the previous translocation in 2022 where 840 individuals were translocated. 

This project is pioneering in that it is the first known ground squirrel translocation project of this scale to include baseline data and follow up genetic screening studies. Prior translocations have predominantly focused on restitutions - creating colonies in areas where ground squirrels had gone extinct.

Mossy Earth members have supported the funding of €13,700 each year to cover staff and travel costs for the project. This builds on a previous project in which we supported dwindling ground squirrel colonies in Slovakia by providing supplementary feed and reducing predation pressure.

Before and after genetic screening studies will take place, conducted by researchers from project partners, University TUZVO - Technical university in Zvolen. The data to be collected and analysed includes basic biometrics of the ground squirrels such as weight, body length, tail length and the length of hind legs.

BROZ will compute a list of all translocated individuals and will monitor the squirrels in the new sites with the help of staff from Faculty of Natural Sciences, State Nature Conservancy and local farmers and volunteers. 

The results will be published by experts on genetics and small mammals and will also appear in the European Conference on ground squirrels in 2027 organised by BROZ.  

Further interventions will be assessed based on the results of the follow up genetic study to be conducted in 2026.

The chosen sites where the ground squirrels will be translocated to are eligible for a special programme of Agro-environmental subsidies in Slovakia. This will allow stakeholders who manage the sites to receive higher subsidies for the presence of the ground squirrels and favourable management of their habitats.  

The majority of the farmers are in favour of having ground squirrels on their land with some wishing for new colonies to be established (through restitution). This represents an opportunity for continuity of this wider effort, although restitution would only be possible providing ground squirrel numbers in Slovakia increase sufficiently and with good genetic fitness. Nevertheless, this is a positive sign and to add to this, awareness among farmers is improving. They usually come to witness the release of ground squirrels and are involved in reporting ground squirrel sightings of released squirrels. 

This project also has the potential to boost ecotourism. Ground squirrels are known as an attractive species capable of drawing in crowds.

Some images from the translocations in 2023

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Management plan_GS Translocations.docx.pdf

Translocations are deemed key in protecting the critically endangered European ground squirrel. Learn more about this project which is the most comprehensive translocation effort to date in Europe.

Translocating European Ground Squirrels

Boosting genetic diversity of a critically endangered grassland species

The European ground squirrel, aka the European souslik (Spermophilus citellus), is a charismatic rodent iconic to the open steppe grasslands of southeastern Europe. They are regarded as an umbrella species, which means having healthy squirrel colonies positively impacts other species in the ecosystem. Unfortunately, the numbers of ground squirrels are declining rapidly in much of the species range due to a destructive combination of habitat loss, degradation and fragmentation. In Slovakia, populations, which had numbered in the millions, have declined by 99% in just 50 years, making the species critically endangered. However, restoration efforts led by BROZ have seen remarkable results, doubling the number of ground squirrels in just 2 years. Translocating ground squirrels is believed to be a key factor to this success. Mossy Earth is proudly supporting the next series of translocations aimed at mimicking natural dispersal cycles and ensuring gene flow between isolated populations.

How we are reviving an Ancient Icelandic Wetland

A vital breeding ground for international waders

Iceland is a crucial hub for migratory birds, hosting the breeding population of 52% of the world’s Eurasian Golden Plovers, 27% of Eurasian Whimbrels, and 12% of all Common Redshanks. After breeding, these birds migrate south, linking Iceland to ecosystems across Europe and Africa. The Mýrar-Löngufjörur area is one of the country’s protected natural areas, where these birds of international importance come every year to nest alongside others, like waterfowl species. Its low-lying aquatic vegetation provides perfect shelter, with rich food sources available from plant material, invertebrates and other species.

In our project areas in the Kálfalækur and Blöndulækur watersheds, a combination of peatlands, shallow lakes and small wetland streams are home to a diversity of flora and fauna. Some of the species in the area include: Brown Trout (Salmo trutta), Dunlin (Calidris alpina), Black-tailed Godwit (Limosa limosa), Common Snipe (Gallinago gallinago), Whimbrel (Numenius phaeopus), Spiny quillwort (Isoetes echinospora), Lake quillwort (Isoetes lacustris), Rusty Hook-moss (corpidium revolvens), Lustrous Bog-moss (Sphagnum subnitens subsp. Subnitens), and the critically endangered European eel Eel (Anguilla anguilla).

One of the most remarkable lifecycles supported by Mýrar’s wetland ecosystems is that of the European eel (Anguilla anguilla). Traversing thousands of kilometres and transforming dramatically at different life stages, it's a story of endurance, metamorphosis, and survival.

Beginning life in its sole spawning grounds in the Sargasso Sea, eel larvae are carried up to 6,000 km via ocean currents to the coasts of Europe, where they metamorphose into glass eels. Icelandic wetlands become their home during a crucial growth phase that can last up to 20 years. Here, eels play important ecological roles as both predator and prey, before beginning their migration (without feeding!) back to the Sargasso Sea, where they spawn and die.

Peatlands are unique wetlands where waterlogged soils preserve partially decayed plant matter over thousands of years. The low oxygen levels slow decomposition, creating rich, carbon-storing soils in conditions that support specially adapted plants like mosses, sedges and grasses. Many of Iceland’s wetlands are special in that they contain soil properties, such Andosol and Histosol, not commonly found elsewhere in the world. Their fertile grounds often consist of deep intact layers of peat with high organic content. Soils can extend 1-3 metres in thickness that can store 33 to >100 kg C m−2, which exceeds global averages of carbon storage.

The peatland vegetation in our project area is mainly characterised by Common cotton-grass, which provides food and habitat suited to numerous species, particularly wading birds. While this vegetation still shows signs of its original wetland character, historic land use has altered water flow and plant communities significantly. 

A landscape impacted by drainage and channels

Last century, widespread drainage and channelisation reshaped Iceland’s wetlands. Between 1960s and 1990s, in attempts to improve food security and rural livelihoods, the government subsidised access to large excavators, which farmers in Mýrar used to drain peatlands, lakes and straighten natural stream channels to expand agricultural land. While areas of land were converted, not all attempts were successful in improving conditions for farming. Today, only small areas of land are kept for horses and sheep grazing. 

In the Kálfalækur and Blöndulækur watersheds, the channelised streams have led to the formation of barriers that disconnect freshwater habitats. They cut off vital spawning grounds for trout and blocked eels' migratory paths through the system. Habitats for other aquatic life have also been destroyed with reduced water affecting the integrity of the peatlands. Not only has this altered general ecosystem health, but it has increased carbon emissions as peatland conditions deteriorate and their carbon-storing powers diminish.

This project is an exciting opportunity to reverse some of the ecological damage in Mýrar by reconnecting freshwater habitats and reviving peatlands. Restoring these ancient wetlands not only supports local wildlife, it also provides crucial breeding and resting grounds for great migratory species, extending the impact far beyond Iceland.

In partnership with the Land and Forest Iceland, Fuglavernd/ BirdLife Iceland, the Marine and Freshwater Research Institute and the RSPB - Flyways Programme, we've identified these opportunities to improve the landscape. 

This project is the first phase of re-opening connectivity and restoring channels, lakes and peatlands in the wetland system. Our focus is on restoring two vital watersheds in the Mýrar region: Kálfalækur and Blöndulækur. Both areas have been heavily impacted by past land use, where peatlands were drained, streams were straightened, and fish migration routes were blocked.

Restore natural hydrological processes and flows to reconnect habitat for migratory freshwater species

Create and restore peatland habitat for more biodiversity, with a particular focus on breeding wader populations as an indicator of habitat function

If you want to see a lay of the land before reading our plans, view this 360° drone image.

In both watersheds, we’re restoring natural stream channels and removing barriers that prevent migratory freshwater fish from reaching spawning and feeding grounds. This will be done by removing four man-made barriers and regrading the watercourses. 

Beginning with Stream Bretalækur in the Kálfalækur watershed, two barriers are being removed and redesigned using a natural step-pool approach. This involves closing drainage ditches that were cut into natural streams, diverting flows and causing the build up of barriers in the streams. By closing these ditches and re-profiling the area into step-pools, we will allow the flow to reach Lake Bretavatn. In doing so, this opens up 30.6 ha of feeding grounds for trout, connecting them from spawning grounds in the stream. Other species, including birds, will also benefit from the restored habitat, with islets in the lakes also providing breeding areas. This phase will improve the freshwater connectivity of the system by another 4 km.

In the Blöndulækur watershed, we’re removing another two barriers to open access to two small restored lakes, which in turn will connect three lakes across the watershed. To do this, full channel realignments will replace artificial drainage ditches. For both barriers, we will close the channel and build more natural connections by redesigning the flow between lakes. Creating longer, more natural bends provides more habitat for aquatic organisms as well as helps prevent erosion, which could dramatically lead to the lakes draining again. By replicating natural and physical processes as much as possible, we are trying to ensure the re-opened watercourse is physically stable for the long-term.  

The restoration work in Blöndulækur will result in critically endangered eel gaining access to two more lakes, which is 21.6 ha of new habitat. With the lakes reconnecting to 6.3 km stream habitat, this benefits both resident and anadromous trout who also access more vital habitat. Once the final obstacle is removed, there will be an uninterrupted flow that extends 16 km from the headwaters out to sea.

As part of the restoration, any fish present will be carefully rescued using electrofishing to safely move trout and endangered eels upstream before barriers are removed. In parallel, we're studying fish populations in affected lakes by trapping, measuring, and tagging eel and trout. The data will help us estimate population sizes, track their movement between lakes and understand their age and growth through scale analysis.

In total, 3,362 meters of surrounding drainage ditches will be closed, allowing the peatlands to re-wet and the water table to rise. As natural flows are restored, the decomposition of organic matter will slow and reduce GHG emissions, and conditions for peatland vegetation will improve. Overall, these changes will boost ecosystem health, benefiting many species but especially vital for wading birds and waterfowls, which rely on these wetlands being intact and healthy habitats to breed.

This project also seeks to engage stakeholders like landowners in the process of restoring their lands. They will be supported and guided on how to track changes to the wetlands by being fully involved in the monitoring. Through active participation, our ambition is to demonstrate a new, more holistic model of wetland restoration— one which both biodiversity and people benefit.

Different angles of Mýrar's inland wetland ecosystem, including its inhabitants and species, the migration barriers and spectacular Icelandic scenery. 

To measure the impact of our actions, the project team monitors key indicators and compares outcomes to the baseline scenario. Some of the areas we’ll be looking to assess include changes in watercourse topology, peatland water table levels, wader populations, and where possible breeding densities recorded. Any relevant results that are gathered will be shared more widely through the RSPB Flyways Programme— a network of conservation sites aimed at protecting vital habitats for migratory birds along the East Atlantic Flyway.

Mossy Earth is providing €135,364 of the total budget of €157,483 to cover staffing, engineer contractors, equipment, travel and monitoring costs.

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Restoration of wetlands in Mýrar Management Plan.docx.pdf

Closing ditches and removing barriers to rewet peatland and reconnect crucial freshwater habitat in the inland wetlands of Mýrar, West Iceland.

Restoring Ancient Wetlands

Closing ditches and removing barriers to rewet peatland and reconnect crucial freshwater habitat

The inland wetland of Mýrar in West Iceland is an ancient freshwater ecosystem of international importance. Its expansive freshwater habitats are resting places for migratory birds, some of whose global populations rely on them as breeding grounds. Within its many lakes and streams, species like the critically endangered eel feed and grow during epic migrations. In two key catchments of the Mýrar wetlands, we’re supporting the first wetland restoration project of its kind in Iceland for freshwater species. The goals? To unblock migratory paths, rewet drained peatlands and restore flows that connect all the way out to sea.

Why we reintroduced these raptors from England to Spain

Red kites are scavengers and opportunistic predators that play a valuable ecological role by cleaning up carrion and small carcasses. This contributes to nutrient cycling and helps limit the spread of disease. In addition, red kites help control populations of small rodents, such as mice and rabbits, keeping their numbers in check and preventing them from becoming pests that could cause both ecological and economic damage.

As both scavengers and predators, red kites provide vital ecosystem services - roles that have earned them both praise and persecution throughout history. In medieval London, they were celebrated for helping to clean the streets of disease. However, in the centuries that followed, their fortunes reversed as they were hunted, their eggs collected, and they were poisoned to extinction across much of the UK.

The reintroduction of red kites, through translocation efforts from Sweden and Spain in the early 1990s, has brought the species back from the brink of extinction in the UK. Now, it’s time to return the favour.

Before we explore the specific action plan of this project, let’s take a closer look at the characteristics and behaviours of red kites.

Red kites are medium-large raptors endemic to Europe, recognized by their reddish-brown body, forked tail, and wingspan of up to 180 cm. They are skilled hunters, reaching speeds of 113 mph (180 kmh) when diving for prey, which includes small birds, mammals, carrion, earthworms, reptiles, and amphibians.

Although only previously thought to be an uplands species, we now know they are well adapted to lowlands too. Habitats such as open farmland, valleys or wetlands are where they can be found seeking food and in mature broadleaf woodlands to nest and roost. The global breeding population is estimated at about 32 to 38 thousand pairs distributed across 28 European countries.

Call for help: southernmost populations dive

The Iberian Peninsula, particularly Spain, has seen alarming declines, with fewer than 50 breeding pairs remaining. The red kite is now listed as endangered in this region, requiring urgent intervention.

The European Red Kite Action Plan identifies the main threats for this species:

Poisoning (direct and indirect) - the leading cause of mortality, especially from illegal baits and rodenticides. Between 1990-2005, poisoning is estimated to have killed 14,000 red kites in Spain alone.

Shooting and capture - especially in Spain.

Habitat loss - due to agricultural intensification.

Food availability issues, wind farms, electrocutions, and other contaminants. 

The project goals, proposed at the 2018 International Red Kite Symposium, aim to: ensure the long-term survival of breeding populations in Iberia; reinforce the species' global range; address key threats and improve habitat conditions.

A comprehensive feasibility study assessed a 660,000-hectare area in Spain, following guidelines of the International Union for Conservation of the Nature (IUCN), to evaluate:

Two external advisory committees, consisting of experts in red kite reintroductions and conservation, were then established, one of which reviewed the study and endorsed the project.

Establishing strategies and measures to protect against existing threats is key to the success of this project and was therefore a vital component of the feasibility study. The red kites in the project area face very similar threats to the species on a global scale. However, the study identified the following key threats, specific factors and protection measures on a local level.

Shooting prevention – Awareness campaigns for hunting associations, supported by wildlife authorities.

Anti-poisoning strategies – Specialised teams use trained dogs and rangers to detect poison and enforce wildlife crime laws.

Electrocution prevention – The local electricity company is repairing and maintaining dangerous electric pylons.

Wind farm risk – No wind farms exist in the project area nor are there plans to construct any.

Reintroducing red kites: from the UK to Spain

The project involves translocating 30 red kites from strong UK populations to Spain each year.

Young birds (6 weeks old) are collected by the RSPB, Natural England, and the Forestry Commission.

They undergo medical checks at AMUS Wildlife Rescue Centre in Spain.

After acclimatization, they are transferred to a private estate on the Spainish-Portuguese border, housed in aviaries before release.

GPS backpacks and wing tags are attached to track movement and identify potential threats.

The red kite release and monitoring area is in the southwest Iberian Peninsula, spanning Andalusia and Extremadura, and Portugal's Alentejo region. The landscape consists of rolling hills, farmland, and infrastructure like roads and power lines. This represents a difficult, yet key challenge, for rewilding projects alike - to integrate nature and people harmoniously. This is where we believe close monitoring through technology will play a big part.

Partners: The planning and delivery of this project draws on the expertise and dedication of our partners AMUS & the RSPB. The enthusiasm and commitment of the project’s manager, Afonso Godino of AMUS, deserves particular mention. He played a central role in getting this project off the ground after 4 years of hard work for a raptor he is passionate about protecting.

Stakeholders: Wildlife authorities from Spain and Portugal, local municipalities, livestock breeders, hunting societies, and landowners.

Funding: Primarily from the EU’s LIFE programme, supplemented by member donations to cover aviary, GPS, and release costs.

We’ve been eagerly awaiting data from our birds' GPS tags; it's now arrived with some interesting findings. We can share with you some maps and video footage of the red kites. View the gallery below for the maps and click on the links in this description below to watch the videos.

Image 1 shows red kites that are alive (white) and red kites that have unfortunately died (red).

Image 2 shows the last updates from two birds that flew to Morocco before their devices failed (yellow), therefore we are unable to confirm if they are alive or dead.

Image 3 shows the last updates from five birds in Spain before their devices failed (yellow), again we are unable to confirm if they are alive or dead (except for one - see more details below).

Image 4 shows the birds that are close to the release area.

This first video shows red kites and ravens feeding a feeding station close to the red kite release site.

This second video shows griffon vultures and ravens feasting at the same feeding station.

Some of the birds are roosting near to and feeding at a feeding station managed by AMUS in collaboration with local livestock breeders close to the release site. Camera trap footage from the feeding station shows they are healthy. In terms of the birds that died, we know two were predated by a Eurasian Owl, one was probably electrocuted, *and two are believed to have been poisoned but we are awaiting the toxicology report. The remaining red kites are spread across the West of Spain and GPS data suggests all is normal with the birds. Finally, one of the birds that lost GPS connection has been spotted alive in Spain by its wing tag!

*February 2023 Update: sadly, another red kite has died from direct poisoning in the South of Portugal. 

*April 2023 Update: Red kite no. 8 takes a day trip to the Portuguese coast!

Read our full updates of these events in your account or on our social media channels.

The first series of maps from our GPS tags show a mix of behaviour. The final map shows red kite no.8's journey.

Follow the effort to reinforce red kites through this series of vlogs.

The State of Raptor Poisonings in the Iberian Peninsula poisoning 

Why we're releasing more Red Kites in 2025

In this video, we discuss the issue of poisoning of reintroduced red kites with project partner Afonso Godino from AMUS.

Red kite reintroductions  - PROJECT DISCUSSION

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RedKiteReintroduction_RewildingManagementPlan.pdf

We are supporting a Eurokite LIFE Project to reinforce the red kite population in southern Spain. Learn how the UK's red kites are returning a favour to their Iberian relatives.

Red Kites Reintroductions in the Iberian Peninsula

Reinforcing raptor populations in their southernmost range

The red kite (Milvus milvus), an iconic, graceful raptor has had a turbulent relationship with people over the centuries, from once being praised to almost going extinct in the UK. Translocated Spanish red kites saved UK populations last century but now their Spanish cousins are in severe trouble. This project is reinforcing the southernmost populations through reintroducing 120-130 red kites from the UK to Extremadura in Spain, over a 4-year period.

Red Kite Reintroductions in the Iberian Peninsula

For our second Rewilding Impact Project we headed to our Native Oak Woodland Restoration project in the centre of Portugal. The first stage was to meet with our project partners Montis and discuss what the most beneficial rewilding actions would be for the project. After a lengthy brainstorming session, we arrived at the following three interventions that were then put to the vote: (1) A bio blitz, (2) a mapping drone and a (3) natural engineering workshop

A team of biologists would be invited for two days to assess the biodiversity of the plantation area and surrounding mountain sides. As well as identifying the flora and fauna in the area, the biologists would be there to train our forest engineers in carrying out such assessments in the future.

The second day would be open to the public to take part and help collect as much ecological information as possible. The data gathered would then be put on a collaborative platform for public and academic use. Throughout the two days there would be a particular focus on flora identification, bat behaviour and night butterflies.

A mapping drone is simple yet extremely useful tool for monitoring the results and evolution of the native oak woodland project. It can also be used to identify the most strategic areas for future interventions, e.g. areas with waterlines running through or sectors that have some existing oaks among the dense Portuguese Broom.

What’s more, our partners could begin systematically creating a custom cartography of the area and the work they have done to date, which would be put on a collaborative platform for academic use.

A Natural Engineer Specialist would be invited to the plantation area for a two-day workshop. Our team would receive an in-depth theory lesson on natural re-engineering techniques as well as a day and a half in the field building gabions and wooden dams along the waterlines of the property.

The gabions (large cylindrical cages or nets filled with rocks) and wooden dams (constructed from fallen trees and branches) would be installed at various points along the waterlines to slow the flow of water thus advancing the retention of sediments. By doing so, the various ‘dams’ would help prevent soil erosion, host habitats for small invertebrates and improve soil quality in the long term. Essentially it would mimic the natural behaviour of beavers that once roamed these streams.

It was a landslide victory (no pun intended) for the Natural Engineering Workshop, with the large majority of our members voting in its favour. The workshop took place on the weekend of the 4th & 5th of May 2019. We intervened in two water runoff lines, constructing 11 palistrades and 3 gabions.

Margarida Silva, Forest Engineer at Montis

By setting up these structures in the water courses (that in our case are not permanent all year round), will create areas of sediment retention, which will in turn decompose and fertilize the surrounding soil, instead of being washed way. In the last weeks we have already seen some sediment attached to the gabion nets and between the branches of the palistrades.

Building gabions & palistrades in waterlines slows the flow of water and advances the retention of sediments. Essentially mimicking the behaviour of beavers.

Natural Engineering

Why we're restoring these forgotten cave ecosystems

Over 10,000 caves and pits have been mapped out in Croatia’s vast network of underground caverns and passages. This figure, however, might just be scratching the surface with some cavers estimating there could be double this amount. This is Croatia’s largest water reserve and the location of a unique and precious ecosystem. In what seems to be an uninhabitable place due to the lack of light and nutrients, there are, in fact, species that thrive. 

The Predolac cave is located in the south of Croatia and is home to two distinct cave-dwelling species - Congeria kusceri and Marifugia cavatica. The former is a living fossil and relic from the Tertiary period (65 - 2.5 million years ago). As it is the only known underground bivalve that is found in caves, Congeria kusceri is anatomically adapted to have a colourless shell and tissue and few sense organs. A colony of Congeria kusceri was discovered in the Predolac cave in the mid 20th century and was deemed the first location (of 15 known locations in the Dinaric karst region) that had living underground Congeria shellfish in Croatia. Their uniqueness is accentuated by the fact that it is the last remaining species of its group which died out 5 million years ago. 

Marifugia cavatica is from the class of polychaetes, otherwise known as bristle or tube worms. This species is the only one of approximately 350 serpulid polychaetes that lives in freshwater. It forms complex tube-like structures on cave walls that it uses for protection and it filter feeds through feathery branches that it extends into the water column. Other species tend to be found in association with these tube structures, presumably because they provide shelter, and so it is considered a habitat forming species.

Both Congeria kusceri and Marifugia cavatica are examples of rare cave species that have specifically evolved within these special ecosystems. The way in which they have developed makes them more susceptible to changes to the environment.

Being as rare as they are, we had some trouble sourcing images of these species, but check out this link to see Marifugia cavatica and this for Congeria kusceri (credit: Ondřej Zicha, biolib.cz) and well as an article.

Unfortunately, waste disposal in karst caves has been a widespread problem in Croatia. For centuries, some cave entrances have been used as dumping grounds for litter. As a result, pollution has flowed into these sensitive ecosystems threatening vulnerable cave species. As a permeable environment, fast running water rushes through the bedrock without being purified in any way before reaching groundwater reserves. This is unlike surfaces outside of karst areas where toxic compounds can be cleansed through layers of soil containing microorganisms. To add to this, modern day waste is more likely to be made from slowly decomposing materials that can linger in cave systems for hundreds of years.

The Predolac cave has been severely impacted by this issue with large amounts of waste clogging its lakes. A major concern is that the cave’s water bodies connect to the River Neretva - the main source of water for the region. Located near the mouth of the cave is a visitors centre which attracts tourists to venture up close to the underground caverns. The centre’s visitors could represent another source of litter entering the cave. 

Although recent changes to waste management programmes and policy in Croatia are attempting to reduce the influx of waste, there is an immediate need to address the existing pollution. Failure to do so could result in the extinction of some of the precious flora and fauna that inhibit the karst ecosystem.

The main objective of this project is to remove all of the waste in the Predolac cave and in doing so, improve the environment for populations of Congeria kusceri and Marifugia cavatica.

The cleanup will require expert cave divers from our project partners BIOTA - a local team of biologists who are passionate about protecting the subterranean networks of Croatia. They are experienced in speleodiving i.e diving in submerged caves. The lack of a free surface on these technical dives makes them a challenging task that often requires decompression on ascent to the surface.

The full extent of the waste at the cave is not certain, however, we don’t expect there will be a need for more than one intervention. BIOTA will report on the state of the cave prior to and after the cleanup, taking photos to record the type of waste recovered from the site. 

As part of this effort, the team will also work with the manager of the visitors’ centre, who is also the landowner, to discuss prevention measures for future littering. Communication will continue in the years after the cleanup to receive updates on the cave’s condition. 

We would like to thank Mossy Earth members for funding the cost of the team’s time, travel expenses and diving equipment.

The outcomes of this project could positively impact several groups in the community. Firstly, tourists will benefit from an experience not stained by the sight of waste and better appreciate the natural beauty of the cave. With this in mind, the visitors’ centre should also stand to gain from an improvement to their tourist attraction. The project also provides an opportunity for the cave ecology specialists at BIOTA to advise the landowner on the best practices for managing this cave in a way that protects its unique inhabitants.  We also hope that those living in the nearby city of Metković will benefit from our intervention in the Predolac cave. The cave’s lakes are joined to other water bodies in the vicinity that eventually merge with the city’s main river. By clearing waste in this cave, we are preventing pollution downstream. 

More broadly, we also want to bring attention to an example of positive change in the region. A cave that was once seen as a dumping ground now provides an opportunity for ecotourism where people can enjoy its natural beauty and mystery.

If you want to see how a previous cave cleanup went, which included removing a fridge, head over to this project page.

Hear what project manager Tiago, has to say about this project in an interview with our community manager, Meija, below.

Cave clean up project discussion w/ Tiago & Meija

cave clean up map@4x.png

HR_002_CAVE_PREDOLAC_Management_Plan.docx.pdf

This is a project to remove waste from the water bodies of the Predolac cave in Croatia. Cave ecosystems contain uniquely adapted species which need our help.

Predolac Cave Cleanup

Ridding submerged caves of waste to protect distinct cave-dwelling species

For millions of years, water has run over the limestone and dolomite bedrocks of Croatia carving out a special subterranean world. In this mysterious underground terrain, uniquely adapted species have evolved in the dark, damp environments in what’s known as karst caves. Although we are no longer cave-dwelling species ourselves, our impact on these fragile ecosystems is still being felt. For decades, caves in Croatia have been used as dumping grounds for waste, which is threatening endemic cave species and polluting important sources of water. Supporting our partners BIOTA, we are attempting to undo some of the footprint by sending a team of technical divers into the Predolac cave to remove waste.

The lesser blind mole rat (Nannospalax leucodon) has some highly specialised physical adaptations. Unlike some mole rats belonging to the family of rodents called Spalacidae and despite its name, the lesser blind mole rat is not completely blind. Its tiny (1mm) eyes are sunken beneath its skin and fur that act as light sensors. Adults typically range from 11 to 16 cm in length but can grow as much as 27 cm. These characteristics along with its cylindrical tailless body, no external ears, fur coat and protruding incisor teeth, make it uniquely adapted to life underground. 

Being well equipped to spend most of its time burrowing beneath the surface, this rodent is capable of building impressive long tunnels. To do this, it prefers areas with a deep layer of loose, draining soil that can be easily dug. The mounds they create appear like molehills, only bigger, and are used for foraging, nesting and shelter. This particular species is found across Eastern European lowland meadows and pastures where there is a semi-steppe climate.

As a solitary species, lesser blind mole rats live separately in special corridor systems. They only encounter others during mating season (January and February) with a gestation period of about 3-4 weeks. After this time, females typically produce litters of 2-6 babies. Mole rats are mainly active during the night, when they emerge from their tunnels in search of food. Their diet predominantly consists of potatoes, onions, carrots, parsley and other tuberous shoots. Possessing strong incisors allows them to gnaw through an assortment of plant material.

Below ground behaviours impacting vegetation above

Burrowing animals are important ecosystem engineers of open habitats. In the case of the lesser blind mole rat, through their burrowing they shift large amounts of soil creating sparsely vegetated areas. Studies have found these patches often consist of different vegetation from the surrounding habitat. In this sense, the lesser blind mole rat is considered to engineer its environment to benefit biodiversity. Their impact on vegetation happens in the following ways:

By consuming below ground plant organs like bulbs and roots, they help reduce certain plant species abundance. Conversely, any leftover organs a mole rat doesn’t eat, can sprout later.

Mole rat mounds allow for areas of open soil surface which affects vegetation dynamics and can increase species diversity.

The presence of such underground species impacts soil structure and parameters.

From abundance to ‘extinction’ in Croatia

The story of the lesser blind mole rat’s demise is one of land use change and the resulting loss of its habitat.

Years of increasing agricultural intensification, urbanisation and infrastructure development, meant the species’ natural habitat of grasslands and pastures gradually gave way to other land uses. Mole rat populations withered as these habitats were ploughed and the animal began adapting to life on agricultural landscapes. It’s on these private fields of pastures, small crop-fields and orchards the mole rat caused damage and suffered persecution. Eventually, the species was declared extinct in Croatia in 1984. After almost three decades without a single sighting, the existence of a small population was confirmed in 2023 in Vučedol, near the banks of the Danube River. Being the only known population and recently discovered, there is little knowledge on their status and current threats.

There is a fear among conservationists from BIOTA that after the attention and excitement of discovering this new population settles, the species will be deemed a pest once more. It is therefore essential to gather information quickly to safeguard the species and avoid it slipping ‘back’ into extinction. Their survival would not only be of conservation value but they would also improve the landscape ecologically through the mole rat’s role as an ecosystem engineer.

The two key objectives of this project are:

to address the knowledge gap on this newly discovered population; 

to serve as a rapid response to prevent its potential extinction.

To achieve the first objective biologists from BIOTA intend to develop a non-invasive and cost-effective eDNA based approach to detect this secretive species. This involves identifying a sequence in the DNA of lesser blind mole rats that can be used to distinguish it from other species and then analysing soil from active tunnels to validate the method. We hope that by developing and validating this eDNA approach, we will make it faster and cheaper to assess the distribution of the species and that this will allow us (and anyone else working to conserve the species) to be more data-driven in our efforts to help this species bounce back.

The second objective will require the team to act quickly on several fronts involving:

assessing the status and threats to the newly detected population;

identifying appropriate solutions and conservation actions to tackle the threats and ensure the species’ pervaliance.

BIOTA will conduct an assessment of the species’ status and threats, including a survey at the site and suitable locations surrounding the confirmed sightings. One of the main aims is to evaluate the presence or absence of the species, which will involve checking the areas for large molehills. 

Discussions will also be initiated with local farmers and authorities to seek viable solutions for the coexistence of mole rats and farmers. Several actions can be explored, such as relocating the population or converting the surrounding available land into feedlots to reduce any potential damage to farmland.

We would like to thank our members for making it possible for us to set aside a budget of €5,000 to cover staff, equipment, materials and any urgent damage control measures that may be needed to facilitate the coexistence between the species and local people.

The future of this species is tightly linked to the way it is perceived by the people who interact with it day to day. Therefore we believe that any measures designed to help the species recover have to be co-designed with local people through healthy dialogue and collaboration if they are to have a long lasting impact. This is especially important because the lesser blind mole rat can cause damage to crops and this is something that cannot be ignored as we look for ways of finding space for the species in the landscape. 

Further benefits could also extend to these areas: 

Once developed and validated, the eDNA monitoring approach can be implemented by anyone that has the needed tools and skills. This could open the door for additional research and will also make it easier for the Public Institution for Management of Protected Areas of Nature in Vukovar-Srijem County to update the distribution of the species and make well informed management decisions.

By collecting baseline data and shedding light on the situation, we will be laying the foundation for additional work. The data we collect may help to attract more funding to support the recovery of the species. The successful recovery of the lesser blind mole rat could become a reason for pride among the local community and perhaps attract interest from tourists visiting the  City of Vukovar. 

This work should also generate momentum around this topic and facilitate the collaboration between different stakeholders including local landowners and public institutions.

Rewilding

How it works

Translocating European Ground Squirrels

Restoring Ancient Wetlands

Red Kite Reintroductions in the Iberian Peninsula

Natural Engineering

Predolac Cave Cleanup

Safeguarding the Lesser Blind Mole Rat

Rewilding:

An introduction