Drones conquer biological research

For centuries, biologists have been known for their good fieldwork competence and persistence in data collection. But new technology has now arrived to weaken the strong constitution of biologists, though fortunately not our persistence.

Drones a.k.a. Unmanned Aerial Vehicles (= UAV) have been a hot topic for a while now. Previously talk has mainly concentrated on how drones can be used to deliver mail or pizza, or even used for military purposes. But recently researchers have also begun acknowledging the possibilities that drones offer.

Drones or UAVs are remote-controlled or autopiloted to fly a certain route. © Mia Vehkaoja

Drones or UAVs are remote-controlled or autopiloted to fly a certain route. © Mia Vehkaoja

Drones are, as their more professional name implies, unmanned light aircrafts that usually resemble either planes or helicopters. They are either remote-controlled or can be programmed to automatically fly a predetermined route. UAVs can be used to collect aerial photographs and videos, from which orthophotos and terrain and 3D models can be produced. The National Land Survey of Finland uses laser scanning photos that deliver an accuracy of 50 cm, whereas aerial photographs from drones can provide an accuracy of 1–10 cm. With such accuracies we can almost identify and count individual plant specimens.

An aerial photograph of a beaver wetland taken with a drone. © Antti Nykänen

An aerial photograph of a beaver wetland taken with a drone. © Antti Nykänen

Drone orthophotos make it possible for example to calculate the vegetation and open water cover percentages of a water system, and define the vegetation categories of an area. UAV-produced photos open up new horizons for defining vegetation classes. These classes have previously been categorized pretty roughly e.g. tree stand, bushes and brushwood. But now we can identify vegetation to the family or even genus level.

An orthophoto produced from the aerial photos taken with a drone. © Antti Nykänen

An orthophoto produced from the aerial photos taken with a drone. © Antti Nykänen

UAVs can also be utilized in game animal calculations. For example, they are an easier and faster way to calculate the ducks or geese in a certain area. On the other hand, they also make it possible to observe the nests of raptors from the air, which is considerably safer and faster (no tree-climbing involved) for the researcher, and a stress-free method for the bird. Heat cameras can additionally be attached onto the drone, making it possible to calculate the mammals, such as deer, in dense canopy landscapes. USA and Germany have already used drones to calculate mammal populations. UAVs are best suited for at least hare-sized animals.

Drones are here to stay and their use in research will increase and diversify in the future.  Researchers just need to hold on to their seats and let their imaginations fly.

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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.  

Crawlers and fliers – how to study forest insects

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

wetland-ecology-group_university-of-helsinki_birchbarkbeetle

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.