Half a billion European birds pass through Israels skies on their way to and from Africa. While bird-lovers are delighted, pilots may encounter deadly surprises. A three-year birdwatching project has helped minimize the danger.
by Daniella Ashkenazy
A number of years ago, an apparently near-sighted eagle chose a rather large prey north of the Sea of Galilee. The mid-flight interception of a landing airliner tore off a wing of the bird, luckily landing the eagle in the hospital and the airplane safely on the ground. In a somewhat unusual move, an IDF pilot took the bird under his own wing, flying the injured eagle in an army Cessna to Tel Aviv for medical treatment, where doctors at the Zoological Gardens reattached the eagles wing.
The presence of 280 species of birds in one small country makes Israel a delight for ornithologists. Yet, some of the bird-watchers have serious business tracing the movement of flocks of larger birds like storks, pelicans and hawks. These constitute a hazard, primarily to military aircraft that fly fast at low altitudes. A seven-kilogram pelican hitting a jet fighter traveling at 900 km/hr will impact like 100 tons of force, and even birds weighing only one kilogram can put a motor out of commission - and claim lives.
To meet the problem head on, a three-year joint project was initiated by the Society for the Protection of Nature and the Israeli Air Force to map the behavior of the birds flying over Israel. For three years during the migration season, an army of ground-based volunteers from Israel and abroad operated 22 spotting stations spread out east to west in the areas where birds "enter Israeli air space." Recording a host of data, the spotters also noted the location of flocks at sundown. A manned glider and a pilotless scout aircraft intercepted flocks as they took off each morning following the birds in the air and recording the time, paths, speed and altitudes of different species as they passed over Israel.
The storks, for example, are the harbingers of spring in Israel: some 600,000 storks are the first species to cross Israeli airspace on their way back to Europe each year. It is now known that the average flying speed of storks is 35 km/hr, yet the birds can achieve an air speed of 80 km/hr when gliding. In the fall, when it is cool, the storks prefer to travel down the Jordan Valley. In the spring, however, the weather in Israels "natural hothouse" is too hot even for storks; they prefer a more westerly route for their return, flying over the Judean mountains. The storks which can arrive in flocks of 6,000 to 20,000 birds follow the same itinerary each spring and fall, with regular "lunching spots" they visit year after year.
The outcome of the three-year study was a comprehensive map of "bird-stricken zones" a take-off on the military term "missile-stricken zones." The map with different colors to mark different species tells pilots where they can expect flocks and what areas and altitudes to avoid at what time of the year. With the publication of the study, the number of mid-air collisions dropped by 88%.
The project prompted the publication of an illustrated book by Dr. Yossi Leshem the biologist and ornithologist who oversaw the project and spent untold hours in a two-man glider literally flying with the birds. Initially his "bird" was viewed with suspicion by flocks, but the birds rapidly learned to take the airborne intruder in stride. Published by the Ministry of Defense publishing house Maarachot and distributed by the Society for the Protection of Nature, To Fly With Birds documented the unique mission as well as providing a singular "birds eye view" of the world.
The map is backed up by real-time observation not only electronic measures like radar, but also an army of volunteer civilian spotters who, under the auspices of the Society for the Protection of Nature, create a "man-made radar network" every fall, tracking birds traveling south for the winter. In addition to the nature-enthusiasts, the IDF has special "bird units" that track the movements of flocks in and around airfields.
While many civilian and military airports around the world are equipped to keep birds off the runway, a pastoral airfield in the Jezreel Valley found itself twice in one month recently foundering in a multitude of dead fish. Several tons of fish rained down out of the sky without warning, putting the main runway out of commission for several hours. The bombardiers were a flock of pelicans that had dropped into nearby fish ponds for lunch. Startled in the middle of their mid-day meal apparently by angry farmers the pelicans took flight. Jettisoning excess baggage stored in their food pouches, they left to look for more hospitable lodgings.