It's a plane... It's a drone... It's birds!

IAF flight controllers figured out they were dealing with a different kind of intruder large flocks of migratory birds heading for water bodies in Gujarat. (AP)

For several weeks earlier this year, the IAF carried out fighter sorties along the border in Gujarat after radar signals indicated that unmanned aircraft were heading towards Indian territory.
What surprised the IAF was that the "enemy" knew exactly what it was up to. As soon as fighters scrambled from Jamnagar would vector in to intercept the source of the radar contact, the signal would mysteriously disappear from the screen, only to reappear once the fighters left the area.
The cat-and-mouse game continued for weeks before IAF flight controllers figured out they were dealing with a different kind of intruder large flocks of migratory birds heading for water bodies in Gujarat, flying at incredible speeds with the help of strong tail winds.
The force, however, is not clear what kind of migratory birds these were.
A report on the incidents says that between December and February, radars placed them as "slow-moving tracks of variable heights of 4 to 6 km and variable speed from 100 to 250 kmph".
As their profile matched the profile of UAVs, repeated tactical action was initiated by scrambling fighter aircraft as well as homing in local flying aircraft to the area, it says.
The probability of the intruders being birds was reinforced when the IAF got in touch with the Nalsarovar and Thol bird sanctuaries and authorities said the possible route and flight profile of the tracks matched those of birds migrating to Gujarat.
The report says the IAF will now put into practice the lessons it has learnt and map out migratory patterns and the months in which birds cross over from across the border.