Cause of mass deaths of starlings in the Hague identified

Written by Seringe S.T. Touray

Autumn was in full swing in The Hague last year, the last residues of summer fading, parks filled with people, tree leaves falling. Suddenly, a massive number of deaths took place among starlings, a mystery that soon had numerous experts and research organizations in the Netherlands investigating. Was it poison or genetic? Was it man-made or natural? Today, experts put all worry and speculation to rest by revealing the actual reason behind the death of more than 350 of the birds – and the answer is not what experts initially thought.

The mystery occurred in the Huijgenspark, close to Hollands Spoor station in The Hague. The surroundings and trees in this part of the city are an important gathering spot for starlings. Initial speculations in Autumn, when the sudden massive deaths occurred, pointed towards possible intentional poisoning of the birds, which, as history shows, is at least worthy of consideration. Other speculations pointed to the possible contamination of the natural waters in which flocks of starlings indulge, and to the testing of a new 5G cell phone tower, believed to have a negative environmental impact. The 5G mast is visible from the site where the flocks of birds died, which didn’t help its case. In the thick of the speculation, some dogowners also claimed that their dogs might have been affected by an illness connected to the sudden death of the birds. According to them, their pets grew sick after they had walked them near the spot where the birds died, resulting in vomiting and other symptoms of illness. As a result of these reports, police were forced to fence off the site of these strange occurrences temporarily.

When research into the death of the starlings began, bird rescue centre Vogelopvang de Wulp in The Hague revealed its preliminary thoughts, stating that the cause of death might have been the result of ingested poison, specifically a toxic substance called taxus found in yew berries. The problem with this theory was that starlings have feasted on yew berries for years, avoiding the harmful effects of the poison, found only in the seeds of the berries. Such seeds are generally consumed and excreted without any harm. As such, the chances of yew berry poisoning were slim, leading researchers to look for other answers. Despite further investigation, experts including the Dutch Wildlife Health Centre and the Wageningen Bioveterinary Research Laboratory (WBVR), became more confident that taxus was the cause of the sudden death of the starlings. The institutes concluded that the birds were almost certainly killed by the poison obtained from the yew plant. Moreover, the researchers actually found toxins from the taxus in the dead starlings’ organs. Although it is unusual for this toxin could be fatal to the birds, the institutes maintained their theory, but admitted that they couldn’t determine how the starlings absorbed the harmful toxins in the seeds of the yew berries. By now, they had hoped for answers. Instead, further research disproved the death-by-taxus-theory.

Researchers at the National History Museum in Rotterdam performed a necropsy on at least fifteen birds to determine the cause of death and shed light on the mystery. Kees Moeliker, director of the museum, and Erwin Kompanje, a senior researcher, discovered extreme internal bleeding in all examined birds, as a result of ruptured livers. The dead birds had also suffered severe damage to the blood vessels, lungs and heart. But this solved only one part of the mystery. The researchers concluded in Straatgras, the National History Museum magazine, that the starlings must have forcefully flown towards and collided with the ground in a sudden fit of panic, upon arrival or departure from their resting places, and that these impacts were fatal. The WBVR laboratory in Lelystad joined the National History Museum in its conclusion, putting all speculation to rest and eliminating the possibility of human error or experiment, harmful viruses or diseases. As of this moment, the assumed cause of death is that the birds collided with deadly force with each other, with tree branches or with the ground due to being panicked and disoriented.