7 5 , ▁per egr ine ▁fal cons ▁had ▁been ▁reduced ▁to ▁ 3 2 4 ▁pairs ▁in ▁North ▁America , ▁primarily ▁as ▁a ▁result ▁of ▁D DT , ▁a ▁widely ▁used ▁p estic ide . ▁D DT ▁lower ed ▁est ro gen ▁levels ▁in ▁female ▁per egr ines ▁and ▁in hib ited ▁the ▁production ▁of ▁calci um , ▁causing ▁eggs ▁to ▁thin ▁and ▁break ▁during ▁inc ub ation . ▁Rec overy ▁efforts ▁for ▁the ▁per egr ine ▁fal con ▁have ▁been ▁remark ably ▁successful : ▁agricult ural ▁D DT ▁was ▁b anned ▁by ▁the ▁U . S . ▁in ▁ 1 9 7 2 ▁and ▁efforts ▁to ▁bre ed ▁and ▁train ▁per egr ine ▁fal cons ▁in ▁capt ivity ▁to ▁later ▁release ▁to ▁the ▁wild ▁were ▁effective . ▁In ▁ 1 9 9 9 , ▁the ▁per egr ine ▁fal con ▁was ▁removed ▁from ▁the ▁U . S . ▁End anger ed ▁Species ▁list . ▁ ▁W ings ▁for ▁My ▁Fl ight ▁was ▁originally ▁published ▁in ▁hard cover ▁by ▁Add ison - W es ley ▁in ▁ 1 9 9 1 . ▁The ▁book ▁was ▁repub lished ▁in ▁ 1 9 9 9 ▁by ▁P ru ett ▁Publishing ▁with ▁a ▁for ew ord ▁by ▁Robert ▁Michael ▁P yle ▁and ▁a ▁new ▁pre face ▁and ▁ep ilog ue ▁by ▁Hou le . ▁The ▁book ▁was ▁updated ▁again ▁in ▁ 2 0 1 4 ▁and ▁repub lished ▁by ▁the ▁University ▁of ▁New ▁Mexico ▁Press ▁with ▁photograph s ▁and ▁a ▁pre face ▁by ▁Hou le