Crawlers and fliers – how to study forest insects

Studying insects is interesting yet challenging. Determining individuals to the species level

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The presence of birch bark beetles can be detected by their unique eating patterns. ©Stella Thompson

nearly always requires capturing them first, although some species, such as the birch bark beetle (Scolytus ratzeburgi), can be identified by the unique pattern they leave on tree trunks. However, it is almost always necessary to use various types of traps to capture individuals if identifying the insect species present at a certain site is the main objective of a study. For example, butterflies are trapped during the night using light traps, and the occurrence of certain protected species can be confirmed using feromone traps that use synthetic lures as bait. Traps can be dug into the ground, lifted high up into tree canopies, or attached to the insides of hollow tree trunks.

As my PhD research I am assessing how beavers affect forest beetle populations. I have several research questions:  do beaver-induced flood zones have different beetle species assemblages than other areas, do the increased moisture and sunlight conditions in the flood zone affect species assemblage, and do beaver areas advance or hinder potential forest pest or protected species. My research combines a game species with widespread effects on its surroundings and forest beetles, several species of which have become scarce and require protection. Beaver-induced flooding and the species’ habit of felling tree trunks may locally disturb forest owners, but my study is looking into whether beavers’ actions facilitate or disturb forest pests. Combining game and insect research is cool, and generates new information on which to base decision-making for future protection measures, beaver population management, and even for using beavers as a natural tool for restoring degraded wetlands and forests.

Window traps are widely used for determining the insect assemblages of sites. Window traps cannot be used to capture specific insect groups, because all sorts of invertebrates ranging from flies to pseudoscorpions and wasps to beetles creep or fly into them. Window traps are very simple: the trap is attached to a tree trunk or set to hang between two trees. Insects crawl or fly into the plastic plexiglas frame and then fall through the funnel into a liquid-filled container at the bottom. The container is filled halfway with water, dishwashing fluid, and salt. The dishwashing fluid prevents the insects from regaining flight, consequently drowning them. The salt helps preserve the insects until the trap is emptied out, which happens about once a month. I have 120 traps spread out at several sites, so every summer I collect about 600 samples.

Unfortunately other creatures may sometimes end up caught in the window traps. So far I have inadvertently captured a few common lizards and a bat. This is always disappointing, because an individual dying for nothing does not advance research or science in any way. In the same way it is frustrating if you unintentionally set up a trap on a tree trunk that an ant colony uses as its route. Hundreds or even thousands of ants may drown in the window trap. As my own study focuses on beetles, I cannot utilize the ants in any way. At least this does not happen very often.

After the trap container has been emptied the gathered sample is sifted through using tweezers and a microscope, to separate the insect groups that I am interest in. Next the individuals are determined to the necessary level. Sometimes determining the family level is enough, but if making conservation decisions or gaining new information on certain species is the goal, it is usually necessary to determine individual insects to the species level. How this is done depends on the order in question, e.g. beetles are often recognized by their ankles and genitals.

Occasionally you come across data deficient species, i.e. species that are not well known or understood. Species, genera, and families are determined using identification keys, which are sometimes incomplete. For example, currently the best key for identifying Finnish rove beetles is in German, and for several families the most complete keys are in Russian. So I’m currently kind of happy that I studied German in middle and high school. I guess next I should begin uncovering the secrets of Russian vocabulary.

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Let’s ban lead shot!

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

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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.

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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.

The beaver – our wetland rescuer

The beavers (Castor canadensis and Castor fiber) have recovered from near extinction, and come to the rescue of wetland biodiversity. Two major processes drive boreal wetland loss: the near extinction of beavers, and extensive draining (if we exclude the effects of the ever-expanding human population). Beaver dams have produced over 500 square kilometers of wetlands in Europe during the past 70 years.

 

The wetland creation of beavers begins with the flood. As floodwaters rise into the surrounding forest, soil and vegetation are washed into the water system. The amount of organic carbon increases in the wetland during the first three impoundment years, after which they gradually begin reverting back to initial levels. The increase in organic carbon facilitates the entire wetland food web in stages, beginning with plankton and invertebrates, and ending in frogs, birds and mammals.

The previous shoreline is very evident from an aerial photograph. Also the beaver flooded area shows clearly. © Antti Nykänen

The previous shoreline is very evident from an aerial photograph. Also the beaver flooded area shows clearly. © Antti Nykänen

Beaver-created wetlands truly become frog paradises. The wide shallow water area creates suitable spawning and rearing places. The shallow water warms up rapidly, and accelerates hatching and tadpole development. Beaver-created wetlands also ensure ample nutrition. The organic carbon increase raises the amounts of tadpole nutrition (plankton and protozoans) in the wetland, along with the nutriment of adult frogs (invertebrates). Furthermore, the abundant vegetation creates hiding places against predators for both tadpoles and adult frogs.

Beaver-created wetlands are perfect rearing places for frogs. The warm water accelerates hatching and the abundant aquatic vegetation gives cover against predators. © Mia Vehkaoja

Beaver-created wetlands are perfect rearing places for frogs. The warm water accelerates hatching and the abundant aquatic vegetation gives cover against predators. © Mia Vehkaoja

The flood and beaver foraging kill trees in the riparian zone. Deadwood is currently considered a vanishing resource. Finnish forests have an average 10 cubic meters of deadwood per hectare, whereas beavers produce over seven times more of the substrate into a landscape. Beaver-produced deadwood is additionally very versatile. Wind, fire and other natural disturbances mainly create two types of deadwood: coarse snags and downed logs. Beavers, on the other hand, produce both snags and downed logs of varying width, along with moderately rare deciduous deadwood. The more diverse the deadwood assortment is, the richer the deadwood-dependent species composition that develops in the landscape.

Beaver-created wetlands produce  especially standing deadwood. © Mia Vehkaoja

Beaver-created wetlands produce especially standing deadwood. © Mia Vehkaoja

Deadwood-dependent species are one of the most endangered species groups in the world. The group includes e.g. lichens, beetles and fungi. Currently there are 400 000 to a million deadwood-dependent species in the world. Over 7000 of these inhabit Finland. Pin lichens are lichens that often prefer snags as their living environment. Beaver actions produce large amounts of snags, which lead to diverse pin lichen communities. Snags standing in water provide suitable living conditions for pin lichens; a constant supply of water is available from the moist wood, and the supply of light is additionally limitless in the open and sunny beaver wetlands.

 

The return of beavers has helped the survival of many wetland and deadwood-associated species in Finland, Europe and North America. Only 1000 beavers inhabited Europe at the beginning of the 20th century. Now over a million beavers live in Europe. I argue that this increase has been a crucial factor benefitting the survival and recovery of wetland biodiversity. Finland and the other EU member states still have plenty of work to do to achieve the goals of the EU Water Framework Directive. Both the chemical conditions and the biodiversity of wetlands / inland waters affect the biological condition and quality of wetlands.

 

The whole research published here

Golden eagles deter foxes, facilitate forest grouse

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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.

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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.

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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.

Pin lichens — the tiny color blots on deadwood

Have you ever entered a forest and seen a person hugging a tree, peering up along the trunk? From this day onwards you can breathe freely again, because you have just encountered a pin lichen biologist at work, and not some bizarre tree-hugging ritual.

Pin lichen biologist peering up along the trunk. © Stella Thompson

Pin lichen biologist peering up along the trunk. © Stella Thompson

Pin lichens, or more formally known as Calicioids, are a diverse and monophyletic lichen group, which usually inhabits deadwood. As their name suggests, they resemble pins. They are tiny, approximately between one millimeter and five centimeters in size. The best way to observe them is to peer up along the trunk of a tree. The spores accumulate into a mazaedium (a cup-shaped part of the fungi), from which they can cling onto the hairs and feathers of animals, or passively disperse otherwise. The spores can be recognized as soot-like dust on your fingers.

Pin lichens growing on deadwood. This species Mycocalicium subtile can be identified with often paler infested area than the surrounding wood. © Mia Vehkaoja

Pin lichens growing on deadwood. This species Mycocalicium subtile can be identified with often paler infested area than the surrounding wood. © Mia Vehkaoja

Although it is relative easy to observe pin lichens with the bare eye, species identification is usually conducted using a loupe or microscope. Further observation opens an entire new world of colors. The algae parts of many pin lichen species are brightly colored in yellow, green, or red. On other species, the stalk of the fungal part forming the actual pin structure can also be quite colorful: white, green, yellow, or brown.

Rust-stained pin lichen (Chaenotheca ferruginea) thrives on conifers, and it is quite widely distributed in temperate to cool temperate areas of the Northern Hemisphere. © Mia Vehkaoja

Rust-stained pin lichen (Chaenotheca ferruginea) thrives on conifers, and it is quite widely distributed in temperate to cool temperate areas of the Northern Hemisphere. © Mia Vehkaoja

There are approximately 70 different pin lichen species in Finland, but unfortunately they are a very deficiently studied group. Some species are parasites. They sponge on e.g other pin lichen species or mosses. Even pin lichen fossils have been found within amber. Using these fossils we are able to model the tree structures of forests that grew over a million years ago. This tiny, yet fascinating, species group deserves to receive more attention. Furthermore, observing them is relatively easy, because they don’t move and make a run for it. All you need is a pair of sharp eyes.

The voice of an ecologist and nature conservationist has fallen silent – Professor Ilkka Hanski 1953-2016

Finnish nature research lost its best known voice after the passing of Ilkka Hanski. Hanski, who made a long and impressive career, contributed to population, evolution and nature conservation biology. The Metapopulation Research Centre, led by Hanski, is focused on studying the effects of fragmentation on species ecology and evolution. The Glanville fritillary butterfly (Melitaea cinxia) is the model species for this research, and lives in meadows and pastures of the Åland Islands in Finland. The butterfly research helps to understand how populations occupy and disappear from fragmented patches (pastures and meadows), and how this affects the features occurring in these populations. In addition to Åland, Hanski has ongoing studies in Madagascar and Borneo. These dung beetle studies have focused on speciation processes and the effects of forest loss on species viability. In his last years Hanski also studied the influence of natural biodiversity on human well-being. For example, biodiversity was found to affect the occurrence of asthma and allergies. Hanski was awarded several prizes for his career, the latest being the BBVA Foundation Frontiers of Knowledge award of Ecology and Conservation Biology earlier this year.

The Glanville fritillary butterfly acts as a model species for the metapopulation theory. The family groups of larvae spin silken webs for their protection. © Sari Holopainen

The Glanville fritillary butterfly acts as a model species for the metapopulation theory. The family groups of larvae spin silken webs for their protection. © Sari Holopainen