Rändlindudele ohtlikud hooned Tallinnas

Mõni sajand tagasi algas maailmas urbaniseerumine ehk linnastumine, mis kestab tänapäevani. Linnastumise tõttu hakkasid logistiliselt paremas kohas olevad asulad rahvaarvu suurenemise tõttu järjest laienema. Hooneid ehitati ja ehitatakse siiani juurde ümbritseva looduskeskkonna arvelt. See aga tähendab seda, et ka loomad ja linnud on pidanud kohanema inimese läheduse ja inimmõjudega. Osad looma- ja linnuliigid on küll kohanenud inimestega, eluga linnades ning seal varitsevate ohtudega, kuid teised mitte. Käesolev lõputöö käsitleb ühte suurt linnades tekkinud probleemi, milleks on lindude kokkupõrked hoonetega. See on aina kasvav probleem, kuna tänapäeval ehitatakse linnadesse järjest kõrghooneid juurde. Samuti kasutatakse nüüdses arhitektuuris palju klaaselemente, et ruumidesse rohkem valgust tuua, võimalikult hästi ümbritsevat vaadet nautida ning et hoone välimusele põnevust juurde anda. Peale selle on linnadesse ja hoonete ümbrusesse silmailu ning väiksemate lindude ja loomade elupaigaks mõeldud rohealasid, puid jmt hakatud uuesti rajama. Iseenesest on see idee hea ja pealtnäha loodussõbralik, kuid näiteks lindude jaoks võib olla see hoopis pöörvõrdelise tulemusega. Nimelt, kui mõne roheala, puuderivi või muu linnule atraktiivse paiga läheduses on rohkete klaaselementidega hoone, võib see linnu jaoks surmavalt lõppeda. Nii nagu inimesedki, ei näe linnud klaasi. Inimesed aga oskavad oma kogemuste ja loogilise mõtlemise kaudu eristada, kas meie ja eelistatud sihtkoha vahel on nö nähtamatu takistus või mitte. Linnud aga ei oska eristada klaasi muust ümbritsevast. Näiteks kui klaas on peegeldavate omadustega ning seal peegelduvad hoone ümber olevad puud, siis linnu jaoks on need peegelduses olevad puud sama moodi reaalsus nagu päris puudki ning ta võib nende poole lennates hoopis klaasiga kokku põrgata. Selliste kokkupõrgete läbi hukkub ainuüksi USA-s sadu miljoneid linde aastas. Kui antud probleemile tähelepanu ei pöörata, võib see viia paljude linnuliikide väljasuremiseni, seega on oluline selle probleemiga tegeleda. Maailmas, eriti Põhja-Ameerikas, on juba vastavaid uuringuid läbi viidud, et probleemi põhjuseid teada saada ning leevendusmeetmeid leida. Eestis sellekohased uuringud puuduvad, kuid probleemi on ka siin täheldatud pea igal kevadel ja sügisel, kui toimuvad lindude massilised ränded. Just rändeperioodidel suureneb lindude hukkumiste ja vigastuste arv hoonetega kokku põrgates. Käesolev lõputöö uuris rändlindude kokkupõrkeid hoonetega Tallinna linnas. Selleks selgitati kõigepealt teaduskirjanduse põhjal välja täpsemad parameetrid, mille põhjal Tallinnas riskipiirkondi otsida ning millise metoodika alusel hoonetele riskihinnangut sooritada. Selgus, et põhiliselt põhjustavad lindude kokkupõrkeid hoonetega hoonete klaasist elemendid ning öine valgustus. Töös uuriti põhjalikumalt parameetreid, milleks olid klaasi osakaal hoone välisseina materjalist, hoone kõrgus, haljastuse kaugus hoonest ning haljastuse osakaal hoone ümbruses. Välja toodud parameetrite järgi filtreeriti Quantum GIS programmi abil kõigepealt välja hooned, mis on alla 15 m kõrged, kuna rändlindude kokkupõrkeid hoonetega mõjutavad pigem üle 15 m kõrgused hooned. Seejärel filtreeriti välja hooned, mille välisseina kattematerjalis on klaasi osakaal alla 50%, kuna lindude kokkupõrked selliste hoonetega on väiksema tõenäosusega. Peale selle moodustati kõigi sõelale jäänud hoonete ümber 50 m ning 250 m puhvervööndid, mis aitasid paremini visualiseerida, kui kaugel on haljastus hoonest. Moodustatud puhvervööndite abil oli võimalik määrata ka haljastuse osakaalu puhvervööndis. See on oluline, kuna mida rohkem on lindudele atraktiivseid rohealasid ja muud haljastust hoone ümber, seda suurem on ka kokkupõrgete tõenäosus. Seega võeti töös aluseks, et hooned, mis on üle 15 m kõrged, mille välisseina kattematerjalis on 50% või rohkem klaasi ning mille 50 m ja 250 m puhvervööndites on haljasalasid üle 50%, on potentsiaalselt suurema ohutasemega. Tulemusena selgus, et taolisi hooneid on Tallinnas 20, mis kanti Quantum GIS programmi kaardikihile ning millest moodustati ka tabel koos aadressidega. Lisaks kaardile ning tabelisse kantud hoonete andmetele, anti ka soovitusi, milliseid piirkondi Tallinnas antud teema uurimisel rohkem kontrollida ning mis oleks töös käsitletava probleemi leevendusmeetmed. Antud lõputöö tulemused on mõeldud edaspidiseks kasutamiseks, kuna see on mõeldud aluseks tulevastele töödele lindude hukkumise kaardistamiseks Tallinnas.

Urbanization began a few centuries ago and it continues to this day. Due to the urbanization and increase in population in the cities, settlements that were in a logistically better place, began to expand. Buildings were built – and are still being built – at the expense of the surrounding natural environment. This means, however, that animals and birds have also had to adapt to human proximity and human influences. Some animal and bird species have adapted to humans, urban life and the dangers in the urban environment, but others have not. The given thesis, Dangerous Buildings for Migratory Birds in Tallinn, addresses one of the major problems that has arisen in cities, which is bird-building collisions. This is a growing probleem, as more and more high-rise buildings are being built in cities today. Also, many glass elements are used in modern architecture to bring more light into the rooms, to enjoy the surrounding view as well as possible, and to make the building visually more interesting from the outside. In addition, green spaces, trees, etc. have been re-established to cities and the surrounding of buildings to create habitats for smaller birds and animals and to bring humans closer to nature again. In itself, the idea is good and seemingly eco-friendly, but for birds, for example, it can be quite inverse. Namely, if there is a building with lots of glass elements near a green area, a row of trees or another place that is attractive to birds, it can be deadly for the birds. Like humans, birds can’t see glass. People, on the ohter hand, are able to distinguish through their experiences and logical thinking whether or not there is an invisible obstacle between them and their preferred destination. Birds, however, cannot distinguish glass from ohter surroundings. For example, if the glass has reflective properties and the trees around the building are reflected there, then for the bird these trees in reflection are as real as the real trees near the building, and the bird may collide with the glass as it flies towards the reflections. Such collisions kill hundreds of millions of birds a year in the United States alone. If this probleem is not addressed, it can lead to the extinction of many bird species. Therefore, it is important to address this issue. In the world, especially in North America, studies have already been carried out to find out the causes of the problem and to find mitigation measures. There are no studies on this topic in Estonia, but the problem has also been noticed here almost every spring and autumn, when mass migrations of birds take place. It is during migration periods that the number of bird deaths and injuries when colliding with buildings increases. The given thesis investigated the collisions of migratory birds with buildings in Tallinn. The main goal was to find the buildings in Tallinn that pose the greatest potential threat to migratory birds and to map them. In order to achieve the main goal, specific parameters were first identified on the basis of scientific literatuure. This was important for searching for risk areas in Tallinn and for doing a risk analysis on buildings. It turned out that the bird-building collisions are mainly caused by glass elements of the buildings and night lighting of the buildings and cities. In this thesis the parameters that were studied in more detail were the following: the proportion of glass in the the external wall of the building, the height of the building, the distance of the landscaping from the building and the proportion of the landscaping around the building. According to the parameters outlined, buildings less than 15 m high were first filtered out using the Quantum GIS program, as collisions with migratory birds are rather affected by buildings higher than 15 m. Subsequently, buildings with less than 50% of the glass in the external wall of the building were filtered out, since birds are less likely to collide with such buildings. In addition, buffer zones of 50 m and 250 m were formed around all the buildings that were left from the filtering. This helped to better visualize how far the landscaping and greenery is from the building. With the help of the formed buffer zones, it was also possible to determine the share of landscaping and greenery in the buffer zones. This is important because the more trees and other greenery that are attractive to birds around the buildings, the greater the likelihood of collisions. Thus, this thesis took as a basis that buildings higher than 15 m, with 50% or more glass in the covering material of the external wall and with more than 50% greenery in the 50 m and 250 m buffer zones have a potentially higher risk level of bird-building collisions. As a result, it turned out that there are 20 such buildings in Tallinn. All these buildings were added in the map layer of the Quantum GIS program. Also, a table with the addresses of the buildings was created based on the results. In addition to the data of the buildings on the map, recommendations were made on which areas in Tallinn should be inspected more in further studies of this topic and what would be the mitigation measures for the given problem. The results of this thesis are intended for future use, as it is intended as a basis for future works on mapping bird mortality in Tallinn.