Curious Finnish fireman rings 16 000 goldeneyes and Danish farmer rings 12 000 starlings – the most amazing examples of citizen science

 

Pentti Runko ringing a small goldeneye duckling.

While scientist struggle with short-term funding periods, the curiosity for nature that the general public shows, can unearth mechanisms that can only be found with long-term datasets. The persistent and systematic observations made by nature enthusts enables research about climate change or life history traits over several generations. Both are issues that require long-term research – and a lot of time and effort. Below are some examples of remarkable work done by citizen scientists curious about nature.

16 000 ringed goldeneyes have passed through the hands of a Finnish fireman

Finnish fireman Pentti Runko has collected systematic data of goldeneyes for several scientific studies. After starting his work in 1984, by 2017 Runko has ringed an amazing 16 000 goldeneyes and checked several hundreds of nest boxes every year.

In a recently published study, the authors utilized data concerning 14 000 of these goldeneyes ringed by Runko between the years 1984-2014. Among these goldeneyes were 141 females that were ringed as ducklings and recaptured later in the area. Based on these data it was possible to follow the recruit females’ lives from hatching to breeding. Thus the early life circumstances of these females are known, and the circumstances can be used to study their effects later on in life. In some cases early life circumstances have severe results on subsequent life, for example on breeding performance (duckling video).

Goldeneyes lay eggs in the nest boxes (video), which Runko checks for eggs several time during the season, to evaluate the hatching dates (video), to catch females and to ring ducklings.

The study was able to show deviations between individuals during the first breeding years and how circumstances during early life affected the breeding statistics of these females. Most females began breeding at the age of 2, but 44% delayed the start of breeding. Winter severity of the first two years affected the timing of breeding, but did not affect which year the females began breeding. As a conclusion, it appears that certain traits buffer the effects that the severity of the first weeks have, so the breeding parameters of females are not affected.  The research also showed that first-time breeders tend to begin breeding later than the yearly specific averages.

After ringing ducklings get back to the nest box.

The authors of another study used a set of 405 females and their offspring’s ringed by Runko, and found that the females’ condition matters when it comes to breeding success. Older, early-nesting females with good body condition and larger broods were able to produce more female recruits for the local population. The later the females bred, the less recruits they produced. The study also showed that females tend to adjust their breeding according to the ice-out dates of lakes. However, differences were observed between the flexibility of the females. Because early-breeding goldeneyes succeed better, the authors conclude that selection favours early-breeding individuals.

The lives and breeding habits of goldeneye females are closely followed at Maaninka (video).

Climate change effects can also be observed from goldeneye phenology. Runko showed that during the last 30 years goldeneyes have advanced their egg-laying dates by 12 days.

45 years of starling surveys in a farmer’s backyard reveal climate warming

Starlings are becoming scarce in Europe.

The Danish Ornithological Society Journal recently published a study that utilized data gathered by a Danish farmer, who ringed starlings for 45 years. Dairy farmer Peder V. Thellesen ringed ca. 12 000 starlings nesting in 27 nest boxes, and measured their phenology systematically. The data showed that during the study period starlings advanced their egg-laying dates by more than 9 days. This advance was observed in both first and second clutches. The result reflects the increase in April temperatures. Another important observation was that while no change was observed in clutch size and hatching rate, nest box occupancy has fallen dramatically in recent years. Starlings used to be common in Europe, but now they have decreased widely in Europe, also in Denmark. Changes in agricultural land use, especially decreased cattle grazing, are suspected as one example affecting starling populations. Loss of cattle-grazed land means less insect-rich foraging lands for the birds.

 

Read more:

Fox, T. and Heldbjerg, H. 2017. Ornithology: Danish dairy farmer delivers data coup. Nature.

Pöysä, H., Clark, R. G., Paasivaara, A. and Runko, P. 2017. Do environmental conditions experienced in early life affect recruitment age and performance at first breeding in common goldeneye females? Journal of Avian Biology.

Clark, R. G., Pöysä, H., Runko, P. and Paasivaara, A. 2014. Spring phenology and timing of breeding in short-distance migrant birds: phenotypic responses and offspring recruitment patterns in common goldeneyes. Journal of Avian Biology.

Kari S. Maattinen Youtube videos about goldeneyes

Thellesen, P.V. Common Starling Sturnus vulgaris clutch size, brood size and timing of breeding during 1971-2015 in Southwest Jutland, Denmark. The Danish Ornithological Society Journal.

YLE 2016: Lintuharrastaja on uhrannut kevätlomansa telkänpoikasille jo 30 vuoden ajan – “Se voisi olla Suomen kansallislintu”. In Finnish.

YLE 2013: Linnut pesivät nyt viikkoja aikaisemmin kuin 1980-luvulla

 

Advertisements

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.

It walks and quacks like a mallard, but does it look like one?

This is a mallard (Anas platyrhynchos). It is your basic duck, familiar from park wetlands. A mallard quack is also the classic duck sound.

Wetland ecology group_University of Helsinki_duck_mallard

A wintering mallard flock is quite colourful: males have green heads with yellow beaks and both sexes have blue wing spots.

Age and season affect plumages

But mallards do not always look like those in the picture above. Males do not always have green heads, nor are females always brownish grey. Depending on the season, and the age and genes of an individual, mallards can look a little different. Downy ducklings resemble the ducklings of all other dabbling duck species. However, they rapidly develop species-specific characters, and young drakes for example develop a hint of green on their head even before all the down has disappeared. In the summertime males briefly change into summer (eclipse) plumage that looks like female plumage. Except that a male beak is still yellow.

Wetland ecology group_University of Helsinki_duck_mallard male_sinisorsa

A young male mallard still has down on his back, while some green is already glittering on his head. Both female and male mallards are brown during summer and autumn. The yellow beak reveals that this individual is a male. © Sari Holopainen

Beak reveals sex

In addition to normal changes in plumages caused by seasons or growth, weird looking mallards can also be found. Their plumages might be different due to changes in their genes or hormones.

Wetland ecology group_University of Helsinki_duck_mallard female_sinisorsa

Light female mallard.

Various phenotypes are rather typical among animal species. These variations are common in mallards, and peculiar individuals can be found especially in cities. For example, females might be light due to mutations. Mutations can work in several ways causing changes in pigment production or in its appearance traits. Lightly coloured mallards produce pigments, but their colour appearance has changed. If an individual does not produce melanin pigments at all, it becomes a completely white albino.

Colour variations are thought to be typical in mallards in city environments, where predator pressure is lower and thus exceptional individuals survive better. On the other hand, mallard farming has potentially produced weird-looking individuals that have escaped and spread their genes to natural populations.

Wetland ecology group_University of Helsinki_duck_mallard_intersexual

Wetland ecology group_University of Helsinki_duck_mallard_intersexual_male_female

These peculiar mallard males in wintering flocks are actually females. The pictures show intersexual females together with two normal males and a female. Moulting males changing their eclipse plumage into nuptial plumage can look similar, but their beak colour once again reveals the actual sex. These pictures were also taken in the middle of winter, when males have already changed to their nuptial plumage.

The beak has an important role in identifying mallard sexes because males have yellow beaks and females have orange-spotted beaks around the year. The beak can also reveal intersexual females. They are individuals that express both female and male outfit. This can be caused by disturbances in female hormone production, or then an individual has both female and male features. Hormones regulate the outfit, and if large quantities of testosterone are produced, male plumage may result. Beak colouration is not as sensitive to hormonal changes and even though a female displays male characteristics, it will still have a female beak.

Hybrid ducks

Wetland ecology group_University of Helsinki_duck_mallard_teal_sinisorsa_tavi

This common teal x mallard hybrid male was coupled with a normal mallard female and defended it against clearly larger mallard males.

Mallard flocks may also have hybrid individuals. Duck species are close relatives, and can thus mix rather easily. Various species mixes are known, for example mallards can mix with common teals, Eurasian wigeons, northern pintails and black ducks. However, hybrids are quite rare, because each duck species have specific behaviours and characteristics that prevent hybridization. But sometimes these barriers collapse, and hybrid individuals are born. Hybrid individuals express characteristics from both original species. Their habits and characteristics typically do not interest individuals from the original species and therefore might not breed successfully.

Hybridization can cause several problems, which in the worst-case scenario can lead to the extinction of the original species. The hybridizations of mallard and black ducks in North America is becoming more common after shifts in their distribution. Hybridization is now threating black duck populations. Alien mallards can also cause a serious risk for endemic duck species and to their gene pool. For example, the Hawaiian duck (Anas wyvilliana) is unfortunately going extinct because of non-native mallards. Survival of the species now depends on protection actions that target the extirpation of all mallards and hybrids from the islands

Wetland ecology group_University of Helsinki_duck_mallard_intersexual_male_female_sinisorsa

Four naturally different mallards wintering in southern Finland. The normal type male was coupled with a normal female. An intersexual and a light female are in the upper part of the picture.

It looks like a duck

This white domestic duck is a descendant of a mallard. © Sari Holopainen

This white domestic duck is a descendant of a mallard. © Sari Holopainen

Mallards are commonly farmed, and several different colour variations exist among the domestic breeds. A white duck known by everyone is also a mallard variant. Farmed mallards have sometimes escaped, and now breed with natural mallards. Extraordinary ducks, resembling mallards more or less, are a fairly common sight in Southern and Central European parks. Alien genes in the natural mallard population become more rare in the northern parts of Europe.

Extraordinary ducks in European parks are probably related to mallards: Switzerland, Germany and Sweden. © Sari Holopainen

Extraordinary ducks in European parks are probably related to mallards: Switzerland, Germany and Sweden. © Sari Holopainen

Read more:

Pär Söderquist: Large-Scale Releases of Native Species: the Mallard as a Predictive Model System

Pictures by Harry J. Lehto, intersexual mallards

Pictures by Pekka Sarvela, colour variations

Ducks Unlimited: Waterfowl Hybrids

Vanishing wigeons and fading horsetails

Over 20 years ago Finnish and Swedish duck researchers began the “Northern Project” and conducted vegetation measurements on 60 Finnish and Swedish lakes while also counting their duck populations. The study lakes were located from southern Sweden and Finland to Lapland in both countries. Researchers found that the water horsetail (Equisetum fluviatile) grew abundantly on many of the study lakes. Breeding Eurasian wigeons (Anas penelope) were also abundant according to the study.

The water horsetail prefers eutrophic lakes and wetlands. Horsetails are an ancient plant group that has existed for over 100 million years. They are thus living fossils.

Wigeons also utilize eutrophic lakes during the breeding season. Adults are vegetarians, but wigeon ducklings also consume invertebrates, a common trait in young birds.

Wigeon brood foraging within water horsetails at Lofoten. © Sari Holopainen

Wigeon brood foraging within water horsetails at Lofoten. © Sari Holopainen

The vegetation mappings and duck surveys connected to the Northern Project were repeated in 2013–2014. The researchers wished to find reasons for the deep decline in breeding wigeon numbers. They observed that wigeons had disappeared from several lakes where they were found on 20 years ago. When the habitat use of wigeon pairs was studied, the pairs were observed to particularly prefer lakes with water horsetails. In Evo, southern Finland, the feeding habitats of wigeon broods were followed over a period of 20 years. Broods were found to forage significantly more often within water horsetails than in other vegetation.

Wigeons therefore prefer lakes with water horsetail present throughout their breeding season. However, the long-term research by the Northern Project has shown that water horsetail has declined and even disappeared from many lakes in Sweden and Finland: this is a large-scale phenomenon. The wigeon is suspected to suffer due to vanishing water horsetail populations. Also, Finnish pair surveys in addition to reproduction monitoring show negative trends for the wigeon.

Health water horsetail at Lofoten © Sari Holopainen

Health water horsetail at Lofoten © Sari Holopainen

The reasons behind diminishing water horsetail numbers are not known. Impact from alien species can be suspected locally. Glyceria maxima, an alien species in Finland, appears to be growing in areas were water horsetail has traditionally grown. Grazing by the muskrat (Ondatra zibethicus) could also be a reason, but the species does not occur in southern Sweden. The whooper swan (Cygnus cygnus) could be another potential grazer, and the species’ populations have rapidly increased during the last decades. But these species can only have local effects, which do no not apply to the whole study area. Researchers cannot exclude other possible explanations, for example diseases or changes in water ecosystems. Despite water horsetail having commonly existed in boreal lakes, their influence in the water ecosystem is poorly understood. This study suggests that the water horsetail has an important role, and its disappearance will be reflected in the food web.

 

Read more: Pöysä, H., Elmberg, J., Gunnarsson, G., Holopainen, S., Nummi, P. & Sjöberg, K. Habitat associations and habitat change: seeking explanation for population decline in breeding wigeon Anas penelope. Hydrobiologia.  

Let’s ban lead shot!

The use of lead shot and sinks is a global phenomenon. Only the past decades has

wetland-ecology-group_university-of-helsinki_blog_hazel grouse

Grouse species also suffer from the harmful effects of lead shot. ©Stella Thompson

increased our understanding of the negative effects that toxic lead shot inflicts on ecosystems. As an example, birds die of lead poisoning after eating lead shot. They mistake the ammunition for sand or grit, which they use to aid their digestion. The birds’ gizzards and stomach acids dissolve the shot, causing lead to accumulate in their bones. As little as two lead shots is enough to directly cause the death of a mallard-sized animal.

During the 1980s, the US Fish and Wildlife Service (USFWS) conducted a study on the effects of lead exposure on water birds such as waterfowl. Diving ducks were found to be most susceptible, but lead shot was also commonly found in dabbling ducks, geese, and swans. Long-term monitoring by the USFWS also uncovered negative effects on bald eagle (Haliaeetus leucocephalus) populations, and since then, several studies have found harmful effects to numerous animal groups around the world, e.g. bears, deer, predatory birds, doves, loons, and frogs. International studies also associate lead shot with increased lead concentrations in people who regularly consume game.

A federal ban on using lead shot for waterfowl hunting was issued in 1991 in the US. Since then, 34 states have decreed tighter state-wide bans, e.g. California completely banned the use of lead shots in the home ranges of the California condor (Gymnogyps californianus), and by July 2019 California will completely ban lead shot in all forms of hunting, the first state to do so.

But what is the European Union’s game plan concerning lead shot? A total ban has been proposed, but the motion is currently only a thought, and we are still miles away from actual progress. Several countries in the EU have issued various types of bans, e.g. the lead shot has been prohibited in wildfowl hunting in Finland since 1996. The US also seems far from a federal ban.

So what’s the big deal, why are we not stepping up and pushing forward?

Not everyone has been satisfied with the disappearance of affordable, high quality, and gun-safe lead shot. The lead shot ban has caused a great deal of debate and criticism over the years. Many are hoping to weaken the ban in waterfowl hunting to only concern certain shallow wetlands or very important rest areas along migration routes. Those opposing the ban have based their arguments on several propositions formed in the 1990s, which have since been scientifically proven incorrect:

 

Claim 1: Lead shot is not dangerous, because it is believed to rapidly sink to the bottom of wetlands, where waterfowl cannot reach it.

After initiating the partial lead shot ban in 1991, the USFWS began long-term monitoring of its affects. Lead shot –induced mortality in mallards dropped by 64% in the six years following the ban. And this is a dabbling duck species, which according to studies should not even suffer the most from lead poisoning. The impacts that the ban has had on diving duck populations, which find their nutrition from the bottom mud layer of wetlands, or on small duck species are probably even more pronounced. Lead poisoning additionally causes e.g. reproductive problems, which can lead to long-term population declines even without directly killing all individuals. For example, a French research group found that female teals carry shot in their gizzards more frequently than males do, wherefore females had worse survival rates than males. A study in the US relates 17–46% of the mortality of loons directly to lead shot, while the same estimates for swans and bald eagles are 31% and 12%, respectively. The lead shot ban is estimated to annually save 1.4 million waterfowl in the States alone. In Canada, the lead concentrations found in the bones of water birds lessened by 50–70% following a ban. An although loons are not hunted as game, their population declines due to lead shot and sinks should be taken in to consideration when considering the fate of toxic lead shot.

wetland-ecology-group_university-of-helsinki_blog_teal_mallard

Both teal and mallards suffer from lead poisoning, which besides causing death also causes behavioural abnormalities. This makes individuals more susceptible to hunting. ©Veli-Matti Väänänen.

Claim 2: Alternative shot types (mainly steel, vismuth, and zinc) are inefficient and expensive.

A 2015 study in the US compared the effectiveness of lead shot and two types of steel shot in the hunting of mourning doves (Zenaida macroura). No differences were found in aim, the number of injured escapees, hunter satisfaction, or realized quarry numbers. Necropsies of shot doves revealed no differences in the numbers of through-body shots or average strike depths. Steel shot was therefore found to be accurate enough for dove hunting. A poll study found nearly 80% of US hunters to prefer steel to lead shot, or at least consider the two equally effective. Initially the steel shot sold in several countries tried to mimic the qualities of lead shot. The resulting low muzzle velocities and large ammunition size led to poor hunting success. Higher quality steel shot is currently widely available, but the damage caused by poor shot quality was immediate, and is the only reason why steel shot still carries a bad reputation. Many people tested steel shot once or twice, and returned to illegally using lead shot despite the bans.

Steel shot was additionally about four times as expensive as lead shot when the ban was issued in the US, but rising demand has caused their prices to drop significantly. The same would probably occur in many European countries, where demand to increase.

 

Claim 3: Hunting with alternative ammunition increases the numbers of wounded animals. This has been suggested to happen because of the ineffectiveness of non-lead shot and hunters being unaccustomed to lighter weight ammunition.

The USFWS annually conducts a poll inventorying e.g. the numbers of total hunted quarry and injured escapees. During the 1950s and ‘60s, the number of injured escapees was about 20%, but initially grew to about 24% after the partial led shot ban. However, a few years later numbers dropped down to initial levels, as hunters became used to the new shot. During the last years the level has dropped to 14%. The study conducted on mourning dove hunting success also did not reveal any differences in the numbers of injured escapees. So if European hunters are still performing worse after lead shot bans in their countries, they should perhaps consider looking in the mirror and wondering what’s wrong with their aim.

 

Claim 4: The lead shot ban has decreased realized duck quarries, e.g. because hunting and hunting success have lessened.

To date, there is no scientific proof to back either of these claims. But on the contrary, waterfowl populations have decreased markedly during this same time period due to disagreeable habitat change. Could this, by any chance, be the actual reason for diminishing quarry sizes? Especially as assessments and research show that hunters have in fact not obeyed the lead shot ban very widely. For example, 90% of Finnish hunters are still estimated to use lead shot in waterfowl hunting. About 70% of the ducks shot in Britain carry lead shot in their bodies. This means that the use of steel shot cannot have decreased duck quarries, because steel shot simply isn’t being used.

However, one actual problem is that steel shot cannot be used in certain older shotguns. This has probably slightly lessened the duck hunting enthusiasm of some elderly hunters.

 

Unfortunately, the European Commission wants to focus on only lessening the amounts of lead found in wetlands. The EU has ratified the UN’s Convention on the Conservation of Migratory Species of Wild Animals, so we should be rid of lead shots within three years. Therefore it is fairly questionable that a total ban is currently not being discussed in more detail. A few EU nations, e.g. Denmark and Holland, have executed a total ban, thus preventing the use of lead shot in any forms of hunting. Nothing appears to be happening in the US either. Despite the encouraging results on the number of lead poisoning incidents dropping dramatically, the effectiveness of partial bans is just too weak. An overview from 2015 by the University of Oxford estimates that 50 000 to 100 000 birds die annually from lead poisoning in Britain alone. According to the Finnish Food Safety Authority and the Finnish Museum of Natural History, every third white-tailed sea eagle (Haliaeetus albicilla) death is directly related to lead poisoning. Partial bans are ineffective and their execution cannot be properly monitored. A total ban would also create pressure to develop shot that would work well with older shotguns. Now is the time to finally completely ban lead shots.

 

Additional information

on lead poisoning occurring in several bird species

http://link.springer.com/article/10.1007/BF00119051

http://www.nwhc.usgs.gov/disease_information/lead_poisoning/

 

on the mourning dove study

http://onlinelibrary.wiley.com/doi/10.1002/wsb.504/full

 

on the effects of lead on teals

http://www.sciencedirect.com/science/article/pii/S0006320707001346

What if species conservation leads to conflict?

The rise of nature conservation during the last century was a response to the weak environmental situation. Many animal species were declining, and conservationists strove to save them from extinction. Protection has worked for several species and population numbers have grown. This is obviously a good thing for the species, but can conservation offer an answer, if protection leads to conflict?

© Sari Holopainen

Barnacle geese have damaged e.g. Helsinki university research fields © Sari Holopainen

Big bird conflicts

Geese were the first group that I encountered this problem with. Many geese species have been strictly conserved due to population decreases. For some species conservation has worked so well that population increases have exceeded the tolerance limits of farmers. I read a text discussing the flexibility of conservation and management: if conservation targets are achieved, are we able to modify conservation-based management, if this is possible?  Geese-induced crop damages in particular have increased, and now geese also cause problems in cities. The populations of whooper swans and cranes have also increased in Finland, and they have caused crop damage. The conflicts between birds and farmers have been solved by paying farmers compensations, but other arrangements should also be utilized in the long term. One method is to attract for example cranes to certain fields, where they do not cause uncontrollable damage. When it comes to game species, the relationship between conservation and hunting should be considered. For example, legalizing the hunting of barnacle geese has been suggested in Finland, but is currently not realized. On the contrary, barnacle geese can be hunted to prevent crop damages in neighboring Estonia.

Eider breeding is in trouble © Sari Holopainen

Eider breeding is in trouble © Sari Holopainen

Even a protected predator eats meat

The dilemma becomes especially difficult when the protection of one species leads to a conflict in the protection of another species. Such a situation can evolve for example between a prey and its predator. Saving the white-tailed eagle from extinction in Finland is one of the great success stories of Finnish nature conservation. However, according to new research, eagles are one reason why eider populations have declined in the Finnish archipelago. Due to predation some islands have effectively lost their entire nesting eider populations. Eagles also utilize eider broods swimming at sea. However, the effect of the eagle is not so simple: on the other hand eagles control the American mink, which is an extremely harmful alien species destroying eider nests. In addition to eagles, eiders are also threatened by the eutrophication of the Baltic Sea and ecosystem changes connected to salt rate changes. If the eider population continues to decline, managers must evaluate the hunting possibilities of this traditional game species, although it might be not enough to solve the complicated problems facing the species.

A conflict situation has also appeared between the wolf and Finnish forest reindeer, both endangered species. There are only two populations of forest reindeers in Finland occurring in Kainuu and Suomenselkä. The growth of the Kainuu population has ceased after an increase of the wolf population in the area. Calf production has dropped, some of the traditional production areas are now empty, and the most important reason for the death of collared female forest reindeer is wolves. But as with the eider, changes have also occurred in the environment of the forest reindeers. Due to forest industry, forests are becoming younger, which has a positive effect on the moose, thus supporting dense wolf populations. As a result the forest reindeer suffers:  younger forests are not an optimal habitat for the species, and they suffer more from predation because moose is the more common species.

Calf mortality is observed to be worryingly high in Kainuu forest reindeer population. Calf  in Korkeasaari Zoo in Helsinki © Sari Holopainen

Calf mortality is observed to be worryingly high in Kainuu forest reindeer population. Calf in Korkeasaari Zoo in Helsinki © Sari Holopainen

Trees form a forest

These are good examples of how the protection of one species can be surrounded by complicated ecological impacts, not even to mention human dimensions. These connections should be considered when planning conservation. The question becomes especially timely if protection is successful. The conversation around conservation issues (at least for me) fairly often appears as straightforward, where risks and threats are recognized, but these complicated impacts could be more underlined. What to do if one species begins threatening another, or when a population increase causes damages? Are we able to understand the entire situation and work with the whole palette of tools available to reach the best conclusion, or do we just slide into polarized debate with no constructive solutions to offer? One example of such creative management issues occurs in Finland, where wolf hunting is currently allowed to increase the value of the wolf as a game animal. Concurrently it is hoped that attitudes towards the wolf will become better and wolf poaching will decrease. We are currently waiting for the results of this experiment.

Golden eagles deter foxes, facilitate forest grouse

Wetland ecology group_University of Helsinki_golden eagle

Top predators can have surprising effects on ecosystems. Golden eagle @Sari Holopainen

The effects of top and mesopredators on lower levels of food webs have been researched from many perspectives, but less focus has been given to the roles that avian top predators play on mid-sized mammalian predators. The cascade effects of raptors, which concurrently affect several trofic levels, have also gained little attention. However, researchers at the University of Turku have observed how the golden eagle (Aquila chysaetos) affects pine marten (Martes martes) and red fox (Vulpes vulpes) populations, along with the cascade affects induced on black grouse (Tetrao tetrix) and hazel grouse (Tetrastes bonasia) populations.

Golden eagles hunt black grouse, red foxes, and pine martens. When the opportunity arises they will also catch hazel grouse, but because of their smaller size and habitat preferences (thick forests), hazel grouse are better protected from golden eagles, which prefer open territory when hunting. The researchers initially hypothesized that the golden eagle would locally lessen the numbers of red foxes and pine martens, thereby causing a positive affect on the two grouse species.

However, the truth is not quite as simple. Pine marten and red fox densities actually increase in areas with large numbers of golden eagle. One possible reason behind this surprising result could be the large prey populations available for all three predators in these areas, along with the partially overlapping habitat preferences of pine marten and golden eagle. On the other hand, pine martens avoid open territory, possibly because of the non-lethal deterrent effect that golden eagles exert on pine marten.

Wetland_ecology_group_University_of Helsinki_hazel grouse

Top predators can have surprising effects on ecosystems. Golden eagle @Sari Holopainen

But the story doesn’t end here: high densities of golden eagles still does have an effect, as larger numbers of young hazer grouse and black grouse are present at these sites. The golden eagle may therefore facilitate the grouse by lessening the numbers of mesopredators in their territories through the deterrent effect. This would lead to less predation and egg eating by the pine marten and red fox. In other words, red fox and pine marten avoid golden eagles so effectively, that the two grouse species benefit from their weakened predation performance. A similar protective effect has also been observed with the goshawk (Accipiter gentilis).

Increasing golden eagle territory and offspring densities cause decreasing numbers of black grouse, but this does not occur with hazel grouse. The small size of the hazel grouse most likely protects it from golden eagle predation. The black grouse, on the other hand, favors open territory. Golden eagles therefore appear to have a protective effect on juvenile hazel and black grouse individuals, while threatening adult black grouse.

Wetland_ecology_group_University_of Helsinki_black grouse

Black grouse lekking @Stella Thompson

The cascade effects directed at these grouse species do not appear to change with fluctuating pine marten and red fox densities. The presence of other mesopredators, e.g. raccoon dogs (Nyctereutes procyonoides) and the American mink (Neovison vison), has been suggested as the reason for this. The effects of these other mesopredators were not assessed during the study.

The golden eagle affects mesopredator behavior without affecting their population densities. A similar deterrent effect has previously been observed from white-tailed sea eagles (Haliaeetus albicilla) on the American mink, and golden eagles most probably also deter minks and raccoon dogs. The eagles additionally deter the movements of other potential egg thieves such as corvids.