Oberes Rhinluch nature reserve: Where are the cranes?

In the morning twilight, the Upper Rhinluch is still in semi-darkness. In the east, the cloud-covered sky slowly turns from a cool gray-blue to pink. Apart from the engines of the cars and vans that keep rushing past, you can barely hear anything, and the sky above the Am Wäldchen counting station is still empty.

The Rhin-Havelluch region near Kremmen northwest of Berlin is one of the largest crane resting areas in Western Europe. Every year, thousands of the large birds gather from mid-September to early November before continuing their journey to southern wintering areas.

The station on the country road between Linum and Hakenberg is one of the thirteen counting sectors in the crane roosting area. Every Tuesday, volunteers from the Oberes Rhinluch Landscape Development Association (LSV) take their position at sunrise. Equipped with a clipboard, tally sheet, pen and binoculars, they wait for the cranes to leave their roost in the morning to look for food in the surrounding fields.

This autumn, however, significantly fewer cranes were counted in the Oberes Rhinluch nature reserve than in previous years. On October 13th the number was 13,630 birds - at the same time last year it was 33,590 and in 2024 it was 72,400 birds.

The supposed absence of the cranes has been attracting attention for weeks and fueling speculation about the possible causes. Is it because of the bird flu that was rampant last year? Are the birds lacking food? Or are the hot late summer and persistent drought responsible for the low numbers?

Behavioral biologist and crane expert Kristina Hühn warns against drawing hasty conclusions. “You can see it either way,” she says. "Compared to last year, there are now significantly fewer. But nature is nature. It's different every year. We've been counting here since 1990. This year is an exception."

The numbers are currently lower elsewhere too, reports Hühn. However, the actual reasons for this cannot yet be clearly stated at this point in time. "What I'm observing now can end up being completely different. It's always a snapshot." Science is a process and hypotheses first have to be verified.

According to Hühn, it cannot be ruled out that many cranes will arrive later. Severe wind conditions may have delayed their journey. The current figures alone would therefore not allow a conclusive assessment of how the autumn migration is developing overall.

Bird flu as an explanation for the current low population in the Rhinluch excludes chicken. Last year's outbreak only affected a fraction of the total population. She also finds the assumption that there will suddenly be less food available in the fields unconvincing. The fact that modern harvesters leave less harvest residue and therefore less food for the cranes in the fields can hardly explain such an abrupt decline from one year to the next.

Hühn, on the other hand, sees drought as a decisive factor. The Upper Rhinluch is a former moor area that was drained during GDR times. Since 2001, meadow areas around the Linum ponds have been specifically irrigated to create suitable sleeping places for the cranes. This year, however, the required water from the Müritz region arrived late due to the drought. As a result, only about a fifth of the usual area could be irrigated.

“It’s because of the dryness – of course,” says Helga Müller-Wensky from the Oberes Rhinluch landscape development association. Due to the significantly smaller irrigated area, the cranes simply lack safe places to sleep. This may be why the birds moved to other bodies of water in the area. Their bank areas could have been more suitable for resting this year due to the dryness and the resulting low water level. However, since no counts take place elsewhere, this explanation remains a guess for the time being.

As the sky above the Am Wäldchen counting station is covered with rain clouds, it is gradually getting louder. First of all, the calls of the geese can be heard as they fly in flocks from the sleeping area. Then the characteristic, trumpet-like sound of the cranes is occasionally mixed in.

First two, then eight, then six birds. In between, larger groups keep passing by. The typical familial triple constellations of two parents with one young bird can often be seen. At the end of the morning there are 551 cranes on the station's tally sheet.

Most cranes are recorded at the Blackhen Damm and Linum Church counting points. Many of them fly south and southwest. At the Rhinbogen, helpers observe numerous cranes migrating north. Across all 13 counting sectors, the counting teams came to a total of 15,226 animals on this day.

“I expected more,” says Müller-Wensky when finally adding up the results. However, the massive deduction the day before must be taken into account. Thousands of cranes set out this Monday, favored by the weather conditions. During the day the birds were spotted, among other places, over the Taunus, near Göttingen and along the Elbe towards Magdeburg. Müller-Wensky assumes that more than 20,000 cranes were still in the area on Sunday evening.

How the situation in the Rhin-Havelluch crane region will develop in the long term is difficult to predict, according to Hühn's assessment. Climate change does not just mean drought, but also extreme weather conditions that would affect the migratory conditions of birds. In addition, there is a decline in insects. Young cranes in particular rely on protein-rich food from insects and worms during their growth. The fact that more and more cranes are apparently only raising one chick instead of two is one of the consequences that can already be observed.

What these developments mean specifically for the Upper Rhinluch cannot yet be said. Among other things, it remains to be seen whether there will be fewer cranes resting in the region in the future or whether their distribution will shift. One thing is certain, however: Sufficient water and undisturbed sleeping places are crucial prerequisites for the Rhinluch to maintain its importance as a resting area for the cranes. Anyone who would like to experience the natural spectacle despite the changed conditions should therefore find out in advance about the rules of conduct in the rest area and, if possible, take part in an officially offered guided tour.