by Daniel Walker
Once all fieldwork was obtained we had to listen to our acoustic samples in order to identify all the species we had recorded. It was really surprising how sensitive the recording equipment was, picking up bird song that we did not hear when in the field. Through our surveying we identified a total of 42 species, including; yellowhammer, wood warbler, golden oriole, goshawk and lesser spotted eagle.
We found that acoustic sampling was more effective in identifying species, simply because we were able to replay recordings again and again and therefore pick out every species, whereas with distance sampling we had to make a split second decision in the field which therefore meant it was easier to miss certain bird calls. However something that our study found is that it is better to use a combination of both acoustic and distance sampling because while acoustic sampling picked up vocal species that we did not see in the field, distance sampling allowed us to identify species that we did not hear call, such as the lesser spotted eagle and the white stork.
Having been interested in birds since a very young age, this trip to Poland was a perfect opportunity to see new species. My team and I decide to carry out avian surveys of three habitats in the Bialowieza forest area; Grassland, Mixed Forest and Conifer Plantation. We carried out surveys using both distance and acoustic sampling via point transects in the three habitat types. The aim of our project was to compare avian species richness between habitats and to test effectiveness of the techniques we were using. Since we were studying birds the best time for surveys was at first light, so that we could obtain our samples during the dawn chorus. So we carried out our transects over three days, one day per habitat, between the hours of 4am and 9am, this gave us the best opportunity to see and hear the greatest number of bird species. Once our bird data was collected we carried out vegetation surveys in each habitat in order to have a scientific basis for the habitat categories we have selected, this surveying involved working out the height, density and species of trees around our transect point, along with assessing ground vegetation using the DAFORA scale, whereby we classified different types of plants such as ferns and herbaceous plants in terms of their abundance.