Since the end of last August, thousands of birds began to appear dead in various parts of the southern United States. Many people found the carcasses in their yards and gardens, when they went for a walk in the countryside or simply on the sidewalks of the cities. No one knew the cause of the massive bird deaths, although there were some theories related to the fires that at that time were still raging in many parts of the country.
However, in order to know more, it was necessary to perform a necropsy on these animals. That is why scientists from the National Wildlife Health Center of the U.S. Geological Survey have studied the bodies of 40 of the 170 dead birds that were sent to their facilities. The result is that the only common factor that linked most of them is that they were in a high degree of starvation. They possibly died of starvation.
During the months of August and September, a total of 10,000 bird deaths in unknown conditions were reported. Of all those carcasses, 170 were sent to the U.S. Geological Survey’s National Wildlife Health Center. However, only 40 were in suitable post-mortem conditions for analysis.
Once the necropsy was performed, it was found that 32 of these specimens showed signs of starvation, such as an empty stomach or blood in the intestines. This showed that possibly the cause of the massive bird deaths had been hunger, but why?
This remains an unresolved question, although the authors of the research believe that it may be related to the intense drought that took place in summer. Moreover, as soon as autumn began, a cold wave hit the area, accompanied by an intense snowstorm. All of this together could make feeding difficult for the birds at two levels. On the one hand, the plants would generate fewer seeds. On the other hand, possibly the insects they normally feed on reproduced less.
It was initially thought that the smoke plumes from the fires in the United States might have been the cause of the mass deaths of birds. However, necropsies have shown that none of them had signs of poisoning. But they did detect other factors that could have led to a fire-related death from disorientation.
The chaos around them, along with the shortage of food, could have pushed them to migrate earlier, faster and further. This would lead them to fly longer, depleting their energy reserves. In fact, many of the corpses studied showed their depleted fat deposits, as well as shrinkage in the chest muscles that control the wings. They were exhausted.
Finally, it should be noted that this forced escape, in addition to the wind and cold, would cause them to become disoriented and end up crashing into the buildings. Some, when lost, would choose to go down to the frozen ground, where they could die of cold. Or they could be run over, as was shown by some of the bodies, according to a statement by those responsible for the necropsies.
Therefore, the cause of the massive bird deaths was most likely hunger. However, the reasons that led them not to eat enough to survive are much more varied. All of them equally sad.