▁are ▁mig rat ory ▁and ▁winter ▁along ▁the ▁eastern ▁and ▁western ▁coast s ▁of ▁North ▁America , ▁on ▁the ▁Great ▁L akes , ▁coast al ▁northern ▁Europe ▁and ▁Asia , ▁with ▁st rag gl ers ▁to ▁the ▁Black ▁Sea . ▁The ▁most ▁important ▁winter ing ▁area ▁is ▁the ▁Balt ic ▁Sea , ▁where ▁a ▁total ▁of ▁about ▁ 4 . 5 ▁million ▁gather . ▁ ▁The ▁long - ta iled ▁du ck ▁is ▁gre g ari ous , ▁forming ▁large ▁f lock s ▁in ▁winter ▁and ▁during ▁migration . ▁They ▁feed ▁by ▁div ing ▁for ▁m oll us ks , ▁cr ust ace ans ▁and ▁some ▁small ▁fish . ▁Although ▁they ▁usually ▁feed ▁close ▁to ▁the ▁surface , ▁they ▁are ▁capable ▁of ▁div ing ▁to ▁depth s ▁of ▁. ▁According ▁to ▁the ▁Aud ub on ▁Society ▁Field ▁Guide ▁to ▁North ▁American ▁Bird s ▁they ▁can ▁d ive ▁to ▁ 8 0 ▁f ath oms ▁( 1 4 6 ▁meters ▁or ▁ 4 8 0 ▁feet ). ▁They ▁are ▁the ▁only ▁du cks ▁that ▁use ▁their ▁wings ▁to ▁d ive , ▁which ▁gives ▁them ▁the ▁ability ▁to ▁d ive ▁much ▁deeper ▁than ▁other ▁du cks . ▁ ▁Name ▁In ▁North ▁American ▁English ▁it ▁is ▁sometimes ▁called ▁old squ aw , ▁though ▁this ▁name ▁has ▁fallen ▁out ▁of ▁favour ▁under ▁influence ▁of ▁negative ▁con not ations ▁of ▁the ▁word ▁squ aw ▁in ▁English ▁usage . ▁Some ▁bi olog ists ▁have ▁also ▁fe ared ▁that ▁this ▁name ▁would ▁be ▁off ensive ▁to ▁some ▁Native ▁American ▁tribes