Eco-logic / Avian upheaval
Eagles are one of the many bird populations in Israel that are under threat, according to a new study.
What do members of the bustard family, the cream-colored courser and the Nubian nightjar have in common? These birds are becoming extinct in Israel, because their nests are being destroyed.
According to a new study conducted by Israeli scientists, 73 percent of nesting bird species here have undergone a major increase or decrease in number. Nineteen species have completely ceased to nest here; while 16 nesting species are new invaders from other mostly tropical countries that had never appeared here before, but have now begun to take over the environment. One of the most prominent examples is a common Indian bird that has spread all over the country.
This upheaval in population was documented by Professors Yoram Yom Tov and Eli Gefen of Tel Aviv University, and Ohad Hatsofeh, an Israel Nature and Parks Authority bird ecologist, for the American journal "Biological Conservation."
"We are witnessing the attrition of the bird world in Israel and the expectation is that it will be much less varied in the future," the study says. "Populations of dozens of species that can not acclimate themselves to change will continue to decrease and some will disappear completely. Most of these are large birds of prey.
"In contrast, tropical species or those which have adapted to human activities will continue to increase, aided by the increase in irrigated land, including that in the desert. Species that were common in the Mediterranean climate will spread to the desert, apparently at the expense of local species," say the researchers, who examined the fate of 227 species of nesting birds over the last 100 years, gathering and analyzing data from extensive observation of nesting birds by nature preservation and bird watching organizations over decades.
Eagles under threat
The main factors leading to changes in the number of birds are destruction of their nests, the displacement of local species by foreign invaders, and the use of poisons. The population of eagles as well as several other types of rare birds in Israel is in danger because of a series of poisoning incidents.
Many birds that nest on the ground are in danger of extinction in the Negev area and the Arava because of the spread of agriculture, and the growth of Bedouin communities that are unrecognized by Israeli authorities. Among the endangered birds are the chlamydotis of the bustard family, and the cream-colored courser in the northern and western Negev, of which only a few hundred remain.
Then there is the dire fate of the Nubian nightjar, a ground brooder whose nesting areas south of the Dead Sea have become agricultural land. According to a survey by Yoav Perlman of the Society for the Protection of Nature in Israel, the number of nesting nightjar couples has declined from 80 to 15 over the last 30 years. In contrast, there are species flourishing here due to an abundance of new and varied food sources supplied by human beings. For example, gray crows and jays have spread out in new areas, and in the case of the crows, they have begun to attack and eat other species.
In other areas of the world, only about half the number of nesting bird species have undergone significant changes in the size of their populations. The fact that there has been such an upheaval in the number of local nesting birds is a reflection of damage to the environment. Over the last 100 years, the human population between the Jordan River and the Mediterranean Sea has grown sixteen fold. Irrigated agricultural land has increased by a factor of 135, and, nonetheless, more than 90 percent of natural water sources (swamps and winter pools ) have dried up and disappeared. Twenty towns have been established in the Arava desert in the south of Israel, which was previously almost completely unpopulated.
"We will have a more homogenous natural world reflecting the fact that landscape vegetation has become more uniform, due to the way we irrigate," ecologist Hatsofeh, one of the authors of the study, said this week. "We don't know the exact ecological implications over the long term that will lead to the disappearance of more unusual species that cannot adapt to the conditions. But it is clear that the disappearance of biological variety influences not only wild life but also human beings who are dependent on nature."
The study offers various recommendations for reducing the threat to nature in Israel, including a prohibition on the import of birds likely to invade, limitations on the use of pesticides, and increased protection for natural nesting areas. In light of the expected trend of development, however, it is difficult to be optimistic. Building will increase significantly over the next 20 years; the population will continue to grow and consume natural resources. The new data only emphasize the urgent need to protect the little that remains.
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