As a long-time member of DOPPS (BirdLife Slovenia), I was invited this year to volunteer in the LIFE Trsca project, carried out by Notranjska Regional Park. The purpose of this invitation was to participate in bird monitoring on Lake Cerknica, an opportunity I gladly accepted.
Bird monitoring on Lake Cerknica takes place from January 1st to March 31st, with the period divided into ten-day intervals, meaning that we must conduct a census once every ten days. Our target groups include waterbirds (various duck species, swans, geese, shorebirds, etc.), as well as all species of raptors and corvids. The goal of the census is to count all species and individuals within these groups, enter the data into a database, and mark on a map where they were observed. This provides a comprehensive picture of where birds congregate the most and how they move across the Cerknica Plain.
For the census, we have pre-determined counting points—22 in total—that allow us to count birds most accurately and efficiently. These points are arranged to enable a circular route around the lake.
It is best to start the census in the early morning, as birds are most active at that time, making them easier to spot. The monitoring lasts about 6 to 7 hours, depending on the number of birds. Later in the day, birds often hide in the reed beds, making identification and counting more difficult. When this happens, the only thing you can hope for is that the white-tailed eagle (Haliaeetus albicilla) has not yet had its meal that day and decides to hunt right then, flushing all the hidden birds into the open. This is why ornithologists are generally in favor of early mornings.
Since our lake is the largest in Slovenia when at full water level, it is practically impossible to conduct a census without binoculars and a spotting scope—these are essential tools for the entire survey. The worst nightmare of an ornithologist is spotting a huge mixed flock of ducks or shorebirds in the middle of the lake while having only binoculars at hand. Most people probably cannot imagine the frustration and stress that birdwatchers experience in such moments.
Speaking of large flocks—this season has been quite good for various duck species. During the mid-winter waterbird census, we recorded as many as 1,300 mallards (Anas platyrhynchos), the most common duck species in Europe. Now, other, less common species are returning from their wintering grounds in significant numbers. In early February, I observed a single flock consisting of approximately 900 eurasian teals (Anas crecca), 700 northern pintails (Anas acuta), and over 150 gadwalls (Anas strepera). And migration is just beginning! If the water level remains high until March, we can expect even higher numbers.
This winter period has also brought two surprising duck species that have decided to overwinter in our region—the ferruginous duck (Aythya nyroca), target species in LIFE Trsca project, and its even rarer relative, the greater scaup (Aythya marila). The latter was recorded in record numbers—11 individuals. It may not sound like much, but for such a rare duck species, this is a remarkable count.
Beyond birds, it is worth mentioning other, less feathery and more furry representatives of biodiversity. Since we live in Notranjska, near a lake surrounded by forests, many other animals roam the area. During our surveys, I spot a brown bear (Ursus arctos) at least once a year, while otters (Lutra lutra) are a common sight in winter. With a bit of luck, I have even observed a wolf (Canis lupus) a few times.
For nature lovers, Lake Cerknica is an excellent destination. With a well-maintained educational trail, exploring is even easier and more informative. Bird enthusiasts will find something special here in every season. My personal favorite is spring, when birdlife is most vibrant, but with a little effort, interesting sightings can be made year-round.
Article was prepared by Anže Škoberne, a member of DOPPS, project partner in LIFE Trsca.