Are there any preventive measures against bird strikes while in flight?
Airports engage in a number of strategies to reduce the number of birds nearby that might cause strikes. This has been addressed in a previous question: What are the ways to keep the birds away from airfields?

Avian Radar also exists: 


  Avian radar[44] is an important tool for aiding in bird strike mitigation as part of overall safety management systems at civilian and military airfields. Properly designed and equipped avian radars can track thousands of birds simultaneously in real-time, night and day, through 360° of coverage, out to ranges of 10 km and beyond for flocks, updating every target's position (longitude, latitude, altitude), speed, heading, and size every 2–3 seconds. Data from these systems can be used to generate information products ranging from real-time threat alerts to historical analyses of bird activity patterns in both time and space. 


https://en.wikipedia.org/wiki/Bird_strike#Flight_path


  Installations include civil applications at New York/John F Kennedy International Airport, Chicago/O'Hare International Airport and Seattle-Tacoma although the majority of both deployment and development activity is still focussed (sic) on military air movements. 


https://www.skybrary.aero/index.php/Detection_of_Bird_Activity_Using_Radar


  MERLIN Avian Radar System technology...is used...to detect and monitor hazardous bird activity on and around airfields for bird-aircraft strike hazard management. 


https://detect-inc.com/bird-control-radar-systems/