LOL! That it is weird, isn't it. I checked wiki's source for that info and found this: "With Nancy Wilson's addition following completion of College in 1974, the band was re-christened Heart and moved to Vancouver, British Columbia after manager Mike Fisher [actually 'Flicker', not Fisher] found out he was to be drafted by the United States Army."
http://jam.canoe.ca/Music/Pop_Encyclopedia/H/Heart.html
Also, someone, around the time of your reply, made a correction/clarification to the wiki article (I highlighted new addition in bold type). It now reads:
"By the mid-1970s the male band members were eligible to be drafted to Vietnam (The United States Left Vietnam in 1973 - Conscription ended in December 1972), so the band relocated to Vancouver, British Columbia, Canada.[3]
http://en.wikipedia.org/wiki/Heart_(band)#Success_.281975.E2.80.931982.29
Wiki just changed it again! I give up.
I'm the resident expert on the ending of the draft since I was the last guy drafted in my hometown. I unenthusiastically entered the Army as a left-leaning anti-war but somewhat loyal citizen December 1st, 1971. Nixon suspended the draft on Dec 7th ("a day that will live in infamy," I thought). The draft was reactivated at the beginning of 1972, but very few numbers were called. Vietnam ground comabat ended in April 1972, and the draft was shelved that same month. Trained as a medic (I was a I-A-O objector and not required to bear arms), by the time I got out of Medics training, everybody was being sent to Germany, where forces had grown thin. Two years later, half the Army was painting rocks just to keep everybody busy and we were all offered early drops for the thinnest of excuses.