2015

Osprey hatchlings to soar soon

July is the time when osprey hatchlings have matured, and are ready to soar in their first flight, which is why researchers go on a bird watch to count, weigh, and put rings on them. About 80 percent of Latvia's osprey population nests in territories managed by JSC "Latvian State Forests" (LVM).

LVM environment specialist Aigars Kalvans says that nests that are situated in the company's territory are being studied in order to determine nesting success. Last year, all nests had a precise location, making it easier to find them using GPS this year. A total of 123 active nests were established this year, 7 of which were new nests. Over the last couple of years, the number of ospreys has been growing in all of Europe, including Latvia.

"We also perform ringing on ospreys in order to gather information about their behavior and main migration routes. I am doing my best to capture photos of the old birds, as then it is possible to track whether any of the hatchlings, which I have ringed, has returned to form couples here. So far, I have met about twenty individuals. However, there often are birds who have traveled very far, even 200 kilometers," according to Aigars Kalvans.

Ospreys are girdled with colored rings. Namely, one ring is made of aluminum, and contains a number and state, while another has a color. This is to eliminate the need to catch the birds upon recognition – the rings can be spotted by their color from distance, using a telescope or a camera.

Upon choosing a nesting place, the male settles on a tree top, which is at the vicinity's highest point. "Osprey nests can be reached only by experienced climbers, using special equipment – climbing spurs and special harnesses," says the skilled ornithologist.

Ospreys live in marshes, mostly on islets or the edge of the bog. A number of nests are also found in young forest plantations, clearings – ecological trees, beaver dams, and grandfather forests. The largest number of osprey couples in Latvia lives near Lubans and Usma lakes.

For the most part, the nest is made on top of a pine-tree, as the tree's dense crown provides stability. The nests are huge – the building process involves use of comparatively long and rough twigs. The interior is covered with moss, lichen, seaweed, and hay. In summer, when it is hot, ospreys use wet sphagnum moss due to its refreshening properties.

Unfortunately, there are cases when the nest is downed by strong wind. This is why ornithologists come assist the bird and build artificial platforms. "At the moment, half of osprey population is nesting on these platforms. Artificial platforms have another positive aspect – we are attracting the birds to a specific location. We provide these territories with protection, as ospreys usually return to their old nesting places, and the hatchlings, too, build nests near their birthplace in a 10-20 km radius," according to LVM osprey expert A. Kalvans.

The male is the one who picks a place for nesting and takes care of the food, while the female's task is to protect the nest. Osprey is also known as fish eagle, indicating the bird's menu – various fish, in Latvia mostly carp, pike, bream – fish that dwell near the surface of the water. In order to keep the meal close, the nesting place is built near (5-7 km) the feeding place.

As part of the nesting population watch, the activities include checking the known territories and searching for new nesting territories. The known nesting territories are checked 1 to 3 times per nesting season. The first check-up was conducted in May – June, when the territory's density of population was assessed; the second time – in July, when nesting success was evaluated. Territories are checked on warm days without precipitation and strong wind.

The eagle watch began in the 1980s, when the territory of Latvia was populated by about 100 couples. The watch ended in the mid-1990s, and was resumed after a long pause in 2007. At the moment, 200 couples have built their homes here, thus, the population of birds has doubled during these years.

The largest threat to fish eagles once was poisoning with pesticides, such as DDT. Another cause for the falling number of birds in Europe was hunting – fish eagles were killed, as people thought them to be competitors who ate up all the fish.