Beavers facilitate Teals at different scales

Wetland ecology group_University of Helsinki_Teal

Teal broods utilize beaver ponds.

Blog text by Petri Nummi, Eeva-Maria Suontakanen, Sari Holopainen and Veli-Matti Väänänen “Beavers facilitate Teals at different scales” is now available on the Ibis website.

Advertisements

There and back again – a mire’s tale

In a remote country lived a rich mire species community. But that was once upon a time, when Finland was a land of mires. Nowadays, only fragmented pieces are left in the southern region, while large natural mires can still be found in Lapland. Nevertheless, only one third of historical levels remain. Most mireswere dried due to farming and forestry. Ditches were dug to gather water from ca. 6 million hectares of mires. This affected the hydrology and further the ecology of these wet ecosystems. Several plant and animal species are adapted to mires, and have thus suffered from habitat loss and fragmentation. For example, forest grouse and bean geese (Anser fabalis) utilize mires during their breeding period. Due to ditching, mires stop producing their ecosystem services, because berry production and game bird populations (these are cultural and provisioning ecosystem services), decrease, and thus the recreational values of the areas lessen.

Wetland ecology group_University of Helsinki_Mire_Cloudberry

Cloudberry (Rubus chamaemorus) grows on mires and benefits from restoration activities.

Finland has about 10 million hectares of dried mires, more than half of which have been utilized by forestry. However, about a fifth of this area does not produce wood well enough for it to be profitable. After several centuries of mire destruction,  a change is now in the air. Finnish mires are being restored with increasing effort. For example, in 2017 Metsähallitus (the Park and Forest Service) began an EU-funded project called Hydrology LIFE. The project aims to safeguard not just mires, but also small water bodies and important bird lakes in 103 Natura 2000 areas. The project restores and protects mires.

Wetland ecology group_University of Helsinki_duck_mire_restoration_hydrology

Mire hydrology can be restored by blocking ditches.

Hydrology is the most important issue to consider when restoring a mire. Blocking ditches leads to changes in water balance, and eventually to active peat formation, which is basically the definition of a mire. After the ditches are blocked, water levels normally rise rapidly to correspond with the natural situation. However, actual peatland processes return at a much slower speed. Forest vegetation is slowly replaced by mire vegetation, starting from the ditches. The processes take a long time, so whether or not the original mire ecosystem returns is yet to be seen. It is also possible that we are actually just creating new mire types.

Wetland ecology group_University of Helsinki_Elimyssalo_mire_peatland_forest reindeer

Elimyssalo nature conservation area in Eastern Finland consists of various peatland types. The area is an important calving place for wild forest reindeer (Rangifer tarandus fennicus).

Helping forest grouse

Wetland ecology group_University of Helsinki_hazel grouse

Forest grouse utilize peatland-forest ecotones. The hazel grouse (Tetrastes bonasia) population in Finland has suffered from peatland loss.

Peatland-forest ecotones are key environments for forest grouse, but unfortunately these areas are becoming very rare. The willow ptarmigan (Lagopus lagopus) has suffered from mire fragmentation in Finland. Ptarmigan habitats are fragmented especially in Southern Finland, and thus there are small populations living far from each other. Luckily, local people are usually interested in peatland restoration that helps species such as the willow ptarmigan. Several good examples exist of how ptarmigans have accepted restored peatlands. The Finnish Association for Nature Conservation has a project “SuoMaa”, which began in 2016, and targets protecting and restoring taiga nature. One of the aims is to restore peatlands to support and enlarge a ptarmigan breeding peatland network and create connections between strong and threatened populations.

 

Read more

Hydrologia-Life

Suomen metsäkanalintukantojen hoitosuunnitelma

Restoration of peatlands, Luke

 

Hawks for hunting

Falconry is a centuries-old form of hunting in numerous countries around the world. It is considered an integral aspect of many cultures, and was therefore added to the UNESCO Lists of Intangible Cultural Heritage as a living human heritage element in 2010.

Falconry involves a trained bird of prey that is instructed by a falconer to hunt its natural prey species. The birds can be falcons, hawks, or eagles: even a few owl species have successfully been used. The falconer releases his bird once he has seen a potential prey animal. The bird flies after the prey, and pins it to the ground. The falconer follows, kills the prey, and gives the hawk a compensatory food reward. Falconry can be practiced during regular hunting seasons.

Wetland ecology group_Stella Thompson_University of Helsinki_falconry

Several cultures utilize birds of prey for hunting. Lotta the goshawk hunts in Finland. ©Markku Kallinen

Falconry is practiced in many Arab nations, European countries (e.g. Great Britain and the Czech Republic), and in most US states, to name a few examples. The International Association for Falconry (IAF) carefully regulates falconry. The association’s objective is to advance the protection and conservation of birds of prey through falconry and awareness raising.

Despite conservation efforts, many people harbor negative feelings towards falconry. And true problems do exist; certain countries allow the crossbreeding of species. If hybrid hunting hawks manage to escape from captivity, they can weaken the genetic purity of local birds. Alien species are also used in certain areas. For example, Britain has imported Harris’s hawks (Parabuteo unicinctus) into the country for pheasant hunting, but escapees have been reported nesting in the wild. The ethics behind captive wild bird species and breeding them in captivity also remains an issue. On the other hand, falconry has also managed to lessen prejudices that people have harbored against birds of prey in many countries, and falconry organizations further the conservation of both birds of prey and other bird species by e.g. raising awareness and campaigning against illegal animal trafficking.

At one time, falconry was also popular in Finland, where the goshawk (Accipiter gentilis) was the bird of prey most used. Falconry is technically legal according to Finnish hunting legislation, but actually obtaining a hunting hawk is not easy in practice. Goshawks are protected in the country, so a native bird cannot be captured. Therefore a bird must be brought in from abroad. The bird cannot be an alien species, and individuals brought in must also be sterile, as goshawks in other countries are of different populations than in Finland.

Wetland ecology group_Stella Thompson_University of Helsinki_falconry

Markku and Lotta mainly hunt mountain hare. ©Pia Kallinen

However, Finland certifiably has one pair of hunting goshawk and falconer. Markku Kallinen and Lotta the goshawk uphold an old hunting tradition that disappeared during the 1960s. Markku and Lotta mainly hunt mountain hare (Lepus timidus). See a video of Lotta feeding, filmed by Pia Kallinen.

Lotta’s activities can be followed (in Finnish) at https://www.facebook.com/haukkametsastys/

Wetlands, the Earth’s kidneys

Wetlands are one of the world’s most important ecosystems. They are referred to as the “Earth’s kidneys” and that comparison could not be more accurate. Wetlands truly are as important to the planet as kidneys are to humans, with one exception: humans can survive with only one kidney, but the Earth cannot.

Kidneys are in charge of humans’ fluid balance. If we are dehydrated, our kidneys try to preserve as much water in our bodies as possible, and when we have excess water our bodies, our kidneys work to discharge the extra water. Wetlands work in the same way. They mitigate both floods and droughts by absorbing and recharging water.

A wetland photographed from a drone. © Antti Nykänen

In addition to fluid balance, kidneys are also responsible for removing unnecessary and hazardous substances, such as waste products and medical substances. In resemblance to our kidneys, wetlands purify our natural waters. They filter and remove nutrients and pollutants from our rain and floodwaters. Extra nutrients will sink to the bottom of the wetland and hence are available for wetland vegetation. Kidneys purify 1750 litres of blood every day, but the water purification ability of global wetlands is 30-fold. Wetlands purify 30 cubic litres of water daily.

Unfortunately, the world has lost approximately half of its wetlands, and Europe alone has destroyed and altered two-thirds of its wetlands. We need strong actions to retain the Earth’s functioning.

The value of wetlands is essential in urban environments, where nutrient and pollutant levels are manyfold compared to more natural environments. Urban wetlands should be seen as important and cheap tools to purify our stormwaters, along with maintaining biodiversity within cities.

A Moorhen (Gallinula chloropus) chick at a wetland in Finland. © Mia Vehkaoja

Luckily, the Ramsar Convention has acknowledged the importance of urban wetlands and themed this year’s World Wetland Day as “Wetlands for a Sustainable Urban Future”. Happy World Wetland Day 2018! Let’s appreciate the Earth’s vital organs.

Whooper swans don’t out-graze wigeons

A few decades ago the whoopers swan (Cygnus cygnus) was an endangered and rare species in Finland. It only bred in remote lakes and people rarely saw them. The population increase of whooper swans after protection is one of the success stories in Finnish nature conservation. Nowadays the swans can be heard gaggling all around Finland. The whooper swan is a large bird, and it thus consumes a lot of vegetation. Water horsetail (Equisetum fluviatile) is one of its favourites.

The whooper swan population has increased greatly, and their gaggling can be heard widely in Finland.

Certain other species also prefer water horsetails. For example, wigeon (Mareca penelope) broods forage within the horsetail growths searching for emerging invertebrates. A study published earlier this year showed that the water horsetail is disappearing from Finnish and Swedish lakes. The reasons for this pattern are unknown, but one possible explanation could be increased grazing pressure. Whooper swans effectively utilize horsetails, and swan grazing was therefore suspected to be influencing the disappearance of the horsetail. Wigeon populations have concurrently shown a worrying decrease.

A recently published study conducted of 60 Finnish and Swedish lakes utilized vegetation and waterbird data gathered in the early 1990s and in 2016. The study area widely covers the boreal, reaching from southern Sweden to Finnish Lapland. The whooper swan population increased strongly during the study period. Researchers studied whether whooper swans’ grazing on water horsetail is causing the negative trend in the wigeon population. Pair counts were used to indicate waterbird communities, and thus any changes caused during the brood time were not shown.

Whooper swans are grazers that have to consume a great deal of vegetation to survive.

The study showed that whooper swans strongly preferred lakes with horsetails during the 1990s, but this connections is not seen anymore. While the number of swan-occupied lakes has increased, the number of horsetail lakes has decreased dramatically. However, it appears that swans and disappearing horsetails do not associate, because the horsetail has also been from lakes where swans don’t occur. The horsetail has increased in some swan-occupied lakes.

The number of lakes used by wigeon has decreased, but swans are apparently not causing this. Wigeon loss has not been stronger on lakes occupied by swans. Quite the opposite, as wigeons and swans appear to positively correlate. Even though wigeons prefer horsetail lakes, their disappearance is not associated with the horsetail loss occurring in the study lakes, which suggests that wigeons can also utilize other lake types. On the other hand, the researchers note that this study  did not considered the critical brood time, when the foraging opportunities among the horsetail growths are especially important. Thus it may still be possible that wigeons are affected by horsetail loss, but this effect only appears during the brood time.

Read more:

Pöysä et al. 2017. Recovering Whooper Swans do not cause a decline in Eurasian Wigeon via their grazing impact on habitat. Journal of Ornithology.

Pöysä et al. 2017. Habitat associations and habitat change: seeking explanation for population decline in breeding Eurasian wigeon Anas penelope. Hydrobiologia.

Blog text: Vanishing wigeons and fading horsetails

Traffic flattens billions of frogs every year

Amphibians are run over by cars more often than other vertebrates. Per road kilometer, an average 250 amphibian individuals die every year because of traffic. According to this calculation, over 113.5 million frogs die annually on the Finnish road network (454 000 km). In Brazil, one of the world’s amphibian hot spots, traffic annually kills 9 420 frogs on each road kilometer. This means a total of over 16 billion frogs lost due to traffic.

 

Roads built near wetlands are the most significant cause of frog mortality on all continents, but particularly in Europe. No relief is in sight for this problem, because traffic amounts are increasing every year throughout the world.

 

Fast-moving frog species are somewhat fortunate because their traffic mortality is quite low on roads with little traffic (24–40 cars per hour). Up to 94% of fast-moving frogs survive when crossing a road. Slow-moving species, such as the common toad (Bufo bufo), are not that lucky. Only half of common toads survive to the other side of a road. On busier roads (60 cars in an hour) over 90% of common toads are run over by a car.

A dead common toad (Bufo bufo) hit by a car. © Mia Vehkaoja

Amphibians suffer from both direct and indirect negative effects of road networks and traffic. Mortality is a direct cause, whereas isolation is an indirect cause. Amphibians migrate according to seasons: during spring to their breeding grounds and during autumn to their wintering grounds. These migrations make amphibians vulnerable to traffic mortality. Season migrations occur particularly in the temperate zone, such as in Europe, where traffic has become the greatest threat to amphibian survival in certain places.

 

The traffic mortality of frogs decreases population sizes and reduces migration, which lead to a decreasing gene flow between populations and the disappearance of genetic diversity. Smaller populations are at greater risk of going extinct.

 

Historically thousands of kilometers of roads have been built through wetlands, which leads to the disappearance, isolation and depletion of wetland habitats. Roads also influence the cycle and function of water systems. Road construction has drained and polluted wetlands all over the world.

 

Conservation actions should concentrate not only on restricting road construction laws and regulations, but on preventing frogs from accessing roads by installing culverts and fences. According to a French study, the combination of culverts and fences is the most efficient way for saving frogs from traffic mortality. But this is just one study, and unfortunately we still know too little about which methods are best for amphibian conservation.

Increased geese populations occupy pastures and city lawns in Fennoscandia

Many geese populations in Fennoscandia are increasing rapidly, and geese have become more visible in human-inhabited landscapes. Currently geese utilize agricultural lands and even urban lawns. High geese brood densities have a significant impact on their environments due to increasing grazing pressure.

Greylag geese graze on pastures and hay lands, preferring short vegetation to high ones. Geese grazing also keeps vegetation short. Geese trimming a lawn in Reykjavik, the capital of Iceland.

Geese broods prefer pastures near shores

A newly published Swedish study revealed that greylag geese broods are rather picky when selecting farmland fields for grazing. The most used fields were pasturelands near water. Goslings preferred shorter vegetation, assumingly due to its higher quality and the open landscape views in case of predators. Grazing geese also keep the vegetation short.

Broods tend to prefer grazing areas near shores, from where they can easily reach the safety of water when threatened. Grazing geese broods are suggested to pose a fairly small risk of agricultural conflicts due to their preference for near-shore pastures (instead of crop fields for example). However, extremely high grazing pressure by geese can reduce plant biomass, thus affecting livestock grazing. In arctic areas, such as Greenland and Svalbard, geese grazing is observed to be the reason for decreased hay and decreased seed counts in soil.

In contrast to broods that prefer near-shore areas, non-breeding geese can cause conflicts with agriculture, due to their grazing in crop fields. Non-breeding birds that are able to fly can utilize areas further from water, and according to a Swedish study, they also graze also on crop and vegetable fields in addition to pastures. Large flocks preferred typically open and flat with no or few trees or shrubs.

The two differing patterns shown by broods and adults means that geese managers should consider the two behavioural strategies when planning geese management.

Barnacle geese grazing among Helsinki University research cattle. Breeding geese flocks have e.g. destroyed some the university’s research fields and caused high expenses.

City geese have found Helsinki’s shore lawns

The barnacle goose is a fairly new species in Helsinki. The species tends to breed in remote arctic areas, but after geese were released from the local zoo in the late 1980s, geese began breeding on the islands and islets of the Helsinki archipelago. The released geese are assumed to have returned to breed, and brought their offspring and other geese with them. Since then the goose population has been growing and occupying shore areas from the islands and mainland. Grazing geese are nowadays a visible element in the city of Helsinki, competing over space with citizens.

Geese densities are rather high on Helsinki shore lawns, where non-flying broods gather to graze. In August juvenile birds can move further from the shoreline to feed. The best seashore lawns tempt dozens of broods. In urban areas lawns are usually a nice buffet table for the geese: they typically prefer plant species used in lawns, and mowing sustains fresh vegetation. Compared to natural lawns, urban lawns can be better for broods.

This geese enclosure has very limited plant diversity, but Potentilla species not preferred by geese are flourishing.

 

However, geese grazing is affecting plant diversity by decreasing it. Few plant species tend to dominate in the grazed areas, while  the diversity and coverage of species is more balanced in areas with no geese grazing. Good quality lawns benefit broods, because they don’t need to move long distances while grazing. Geese population growth in the Helsinki area has been refracting after reaching ca. 1300 breeding pairs, and one reason is thought to be the limitation of good feeding habitats for broods. Geese already use almost all possible lawns in Helsinki. During dry summers with poor lawn growth geese may be greatly food-limited, which is reflected in the population size. Thus it seems that the barnacle goose population in Helsinki has reached its carrying capacity.

In the Helsinki archipelago barnacle geese nest commonly on rocky islands and islets, where food availability is highly limited. Well-managed city lawns are thus tempting for the broods.

Methods for preventing geese grazing were measured in Helsinki. One possibility is to use plant species that geese don’t prefer, instead of the current species mix that seems to be especially tempting for geese. Another possibility is to fence off areas were geese are not welcome. Goslings cannot fly, and thus cannot reach fenced areas, and they also avoid areas where they have limited visual contact to water.

 

Read more:

Olsson et al. 2017: Field preference of Greylag geese Anser anser during the breeding season. European Journal of Wildlife Research

Barnacle goose population declined in the Helsinki Metropolitan Area. 2016. Environment.fi

Barnacle goose population remains unchanged despite a good breeding year. 2013. Environment.fi

Niemi et al. 2007: Valkoposkihanhi pääkaupunkiseudulla. Suomen Ympäristö.

Valkoposkihanhien seuranta. 2016. Ymparisto.fi.