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.
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.
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.
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/
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.
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.
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.
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).
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.
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.
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
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.
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.
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.
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.
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.
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.
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.
This is a mallard (Anas platyrhynchos). It is your basic duck, familiar from park wetlands. A mallard quack is also the classic duck sound.
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.
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.
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.
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.
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
It looks like a duck
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.
Ducks Unlimited: Waterfowl Hybrids
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.
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.
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.