Bird death
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Birds are considered to be predestined bioindicators because they have similar demands on habitat and food as humans . So one can conclude from a decline in biodiversity or biomass that the ecosystem is doing badly.
causes
Agribusiness
Pesticides, especially insecticides, not only cause great insect death , but also affect birds, mammals and amphibians. Insecticides mean that many insectivores, such as the hoopoe or the house martin, lose their nutritional basis. Other species also feed their young with the protein-rich insects in spring. However, if these are not available, the supply of the young birds cannot be guaranteed.
Global warming
Wind turbines
A very emotionally discussed topic among environmental and species conservationists is wind power plants. These, too, are increasingly being used due to global warming, because they generate almost no emissions after production. According to estimates, they kill around 100,000 birds a year in Germany, which are caught by the rotors or its suction when migrating or foraging. In order to compare this number with other factors such as the cat one has to pay attention to the following: the size of the affected birds and thus the eggs per brood or broods per year. So it is less dramatic if a winter golden chick falls victim to a cat, as they hatch up to ten eggs per brood. However, if a red kite is hit by a wind turbine, the consequences for the local population are much more fatal, because red kites hatch one or two eggs per year. Wind turbines also contribute to the scarcity of habitats because they have a certain disruptive factor for some bird species. These keep a distance of several hundred meters from the enclosures and thus lose important habitats, which can have a dramatic impact on the local breeding bird density.
Hunting and illegal pursuit
Invasive species
The house cat is also an invasive species that should not be underestimated. Although these can usually only be found in settlement areas, there are only around two million feral domestic cats in Germany that do not hunt just to pass the time. According to Peter Berthold, German domestic cats catch at least 30 million birds a year. But even with the mere presence of the cat in the garden, adult birds no longer feed their young birds or build their nests higher. The latter in turn leads to predators discovering and destroying the nest. There are a few solutions to the problem mentioned. Leaving cats outside in the early hours of the morning during the breeding season will protect the young birds that have just fledged. The greatest containment of the problem, however, would be the sterilization of all feral cats, as well as domestic cats with free range.
Bird strike
building
Buildings with large glazed areas pose a particular danger to birds. Birds fly against windows because they are either transparent or reflect the background. Various extrapolations of the number of victims per year come to results in the double-digit or even triple-digit million range. As early as 1990 Daniel Klem came to the conclusion that one should expect at least one bird per house. This would then be multiplied by the number of residential buildings in Germany 18 million. Recent calculations, which also take high-rise buildings and bus shelters into account, come to the result of more than 100 million dead birds in Germany.
traffic
The loss of birds in traffic is mainly due to the high speeds, but also due to the loss of habitat (associated with the expansion). Interestingly, if you compare the mortality rates of birds in road traffic with those in train traffic, it is noticeable that the rate in train traffic is significantly higher. The question arises why this is so, because the motor vehicle routes are used much more frequently. On the one hand, it is due to the fact that birds also have accidents on the overhead lines of the railway due to the unexpected flying up due to the approaching train. An investigation called "SCV" documented the collision victims on a railway line over a period of five years. She came to the result, which was extrapolated, that 20 - 50 birds perish per kilometer of the route. Especially owls were affected more than average. When searching for food, which is often done by hearing, they fly just above the ground and are caught by trains. In winter, the snow is carried away by the draft and the snow-free area offers a good source of food for birds of prey. The German road network is very well developed and therefore represents a major threat overall. Roads with hedges and bushes in particular pose a high risk for songbirds. A study in Radolfzell shows that around ten percent of the breeding pairs there lose a parent, after which the brooding is ended.
consequences
Like every living being, the bird in general has a role in the ecosystem. To illustrate one of these functions, one can look to China. Birds were systematically killed there under Mao, as they were said to have a negative impact on the harvest. Those who did not obey these orders faced the death penalty. A total of two billion birds were killed. This resulted in insect plagues that China has not yet got a grip on.
Individual evidence
- ↑ Peter Berthold: Our birds, page 122
- ↑ Peter Berthold: Our birds, page 131/132
- ↑ Lars Lachmann: Does the house cat threaten biodiversity? - NABU. NABU, July 8, 2020, accessed July 14, 2020 .
- ↑ https://www.bund-nrw.de/mektiven/detail/news/vogelschlag-an-glas-ueber-18-millionen-oder-100-millionen-was-stektiven/news-topic/vogelschlag/ , last visited on January 1, 2020
- ↑ http://www.naturschutzrecht.eu/wp-content/uploads/2008/05/EBA-Wirkungsprognose-11-2006.pdf , pages 37-48
- ↑ Peter Berthold: Our birds, page 118, 119