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.  

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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

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

Finland is a developing country when it comes to its fishing policy

Almost all of Finland’s migrant fish are threatened. At the moment the endangered fish species of Finland have no protection; they are like outlaws. For example the Finnish landlocked salmon (Salmon’s subspieces Salmo salar m. sebago only lives in inland waters) is more endangered than the Saimaa ringed seal (Pusa hispida saimensis). A study shows that only 0.04 % of the smolts survive and reach sexual maturity. This means that only one individual in 2500 smolts will spawn.

Almost all of Finland’s migrant fish are threatened. Luckily, the trout (Salmon trutta) is not yet one of them. © Mikael Kraft

Almost all of Finland’s migrant fish are threatened. Luckily, the trout (Salmon trutta) is not yet one of them. © Mikael Kraft

Additionally, the sea trout parr (Salmo trutta trutta) is critically endangered in Finland. Hydro-electric power plants previously destroyed the robust populations of the sea trout, but nowadays the main problem is fishing nets. Finland is probably the only civilised state where anybody can fish using nets. In other parts of the world fishing with nets is strongly regulated or banned completely. All the endangered species living in the inland waters of Finland, even the Saimaa ringed seal, face the same threat: fishing nets (both professional and free-time fishermen). The main problem with fishing nets is that they catch almost all the smolts, leaving no fish to spawn.

Finland is also the only nation in the world that allows fishermen to fish using massive trawls in inland waters. Finnish researchers are unanimous: our fishing policy is unsustainable. Policymakers don’t listen. Rather, they are against every positive development. In today’s world with the EU and other institutions, how is it possible that no one outside Finland is not reacting. If Finnish policymakers are this blind or spineless, maybe the EU could invoke for example the Habitats Directive (more formally known as Council Directive 92/43/EEC on the Conservation of natural habitats and of wild fauna and flora), and force Finland to alter its fishing policy. We have some successful example (the Przewalski’s horse returning to Mongolia, deforestation in Madagascar) of how pressure / help from the outside world has contributed to the preservation of species or ecosystems in developing countries. At least the EU should wake up now and prevent the local extinction of several fish species.

Further reading:
Salmi P, Auvinen H, Jurvelius J, Sipponen M (2000) Finnish lake fisheries and conservation of biodiversity: coexistence or conflict? Fisheries Management & Ecology 7: 127–138. DOI: 10.1046/j.1365-2400.2000.00183.x

Auvinen H, Jurvelius J, Koskela J, Sipilä T (2005) Comparative use of vendace by humans and Saimaa ringed seal in Lake Pihlajavesi, Finland. Biological Conservation 125(3): 381–389. doi:10.1016/j.biocon.2005.04.008