​​​​The adventures and dramas of birds: a story told by a camera trap and a GPS-tracker

Hi-tech equipment is helping our researchers gather valuable information about the endangered ​​​Greater ​​​Spotted ​​​Eagles. With the help of camera traps, we learn a lot about their behavior, diet and breeding, while GPS-trackers are revealing numerous patterns of the eagles’ migration. Ornithologist Valery Dombrovski has been researching Greater Spotted Eagles for decades. He knows how to systematize facts, numbers, graphs and trajectories… However, as a really sharp-sighted scientist, he can see whole stories behind this information. And here is one of those stories.

Male Greater Spotted Eagle Dzimon was captured and tagged with a GPS-tracker on the 9th of July 2020, in the eastern part of the Almany Mires in Polesia, not far from his nest. He wasn’t much different from other birds of the species: he hunted properly and raised a strong chick by autumn.

Dzimon and his chick in the nest.

​​But ​​​​​something strange began to happen with Dzimon following spring, after he had returned to Polesia from his wintering site near the border of Sudan, Ethiopia and South Sudan. Having arrived ​at​ his nest, Dzimon his female in ​the​​​ company of another male. The couple had already renewed the old nest with fresh branches and lined it with green leaves to make​ the​​​ eggs​’​ incubation more comfortable.

The new male in the nest. Dzimon hasn't arrived yet.

The female’s behavior was not at all strange. She never knows if her old partner will return, and therefore she accepts courtship from any male who likes her. Usually, the new male leaves the nest in case the female’s old partner returns. At first it seemed like that was happening. Dzimon and the female visited the nest together, and the alien disappeared. But this only lasted for a couple of weeks.

The last weeks of Dzimon's family life.

On the 27th of April, Dzimon flew to the edge of his hunting territory and stayed at the same place for three days in a row. Unfortunately, the camera trap at the nest was not working at that time, and we don’t know what happened ​​​i​n the nest right before he left. But the eagle was confused, it was noticeable in his behavior. It seemed that he didn’t know what to do next. So, three days later, he took to the air and left those places. He never returned to his female and the future chick.

Dzimon started wandering. At the beginning, he headed to the north to hunt in an agricultural area near the town of Turau/Turaw, which was rich in field mice. Well refreshed, the bird headed east in a week’s time, reaching the town of Pietrykaw 70 kilometers away. Then he flew back crossing the river Ubarc and the Almany Mires and found himself on the bank of the Jaselda river not far from the town of Pinsk. On the 16th of May, Dzimon surprisingly headed to the town of Pinsk and stayed there, in the urbanized area, for more than a month! It looks like he was hunting right in private gardens on the outskirts of the town. In late June, the eagle changed his location again and flew to the Belarusian-Ukrainian border, where he stayed until the beginning of the autumn migration.

The srack of Dzimon's wandering in summer 2021.

And what about the nest and the female? The new male that appeared in spring was still there. He spent the summer feeding the female and their chick that grew up and left the nest successfully in August. But why did Dzimon leave his nest? We can only guess. Maybe he lost the competition with a stronger and younger male, or maybe he guessed somehow that he would have to feed someone’s else chick… The bird’s thoughts will remain a secret.

During the spring migration of 2022, Dzimon arrived​ ​​in​ Polesia very late – on the 19th of April. It was one of the latest known dates for the return of a Greater Spotted Eagle. He rushed directly to his old nest. Perhaps he was still hoping for a happy family life? Apparently, no​ ​​o​ne was waiting for him at home. Having spent about 20 minutes there, he flew on into the depth of the Almany Mires. Over the next month, Dzimon tried to settle down there. But he didn’t succeed, since the area was already shared by other nesting birds. Gradually, they drove him out further south, to Ukraine, where the density of the species is not so high. He spent most of the season close to the village Stare Selo in Ukraine. On the 25th of July, Dzimon flew kilometers to the south-east, to​ the​ Zhytomyr region, where he died three days later. No​ o​ne knows what happened to him. The Ukrainian experts only found a tracker and the remains of Teflon straps that used to fix the device on the bird’s back. This was the end of Dzimon’s journey, during which he never found a new home.

The project “Polesia – Wilderness Without Borders” is part of the Endangered Landscapes & Seascapes Programme and is funded by Arcadia. The project is coordinated by Frankfurt Zoological Society (FZS).

This post is also available in BLR.