eding ▁grounds ▁in ▁Sc and in avia ▁and ▁other ▁countries ▁near ▁the ▁Balt ic ▁Sea . ▁ ▁Sort ▁sol ▁takes ▁place ▁in ▁the ▁hours ▁just ▁after ▁sun set . ▁ ▁The ▁birds ▁gather ▁in ▁large ▁f lock s ▁and ▁form ▁huge ▁form ations ▁in ▁the ▁sky ▁just ▁before ▁they ▁decide ▁for ▁a ▁location ▁to ▁ro ost ▁for ▁the ▁night . ▁ ▁The ▁movements ▁of ▁the ▁form ations ▁have ▁been ▁li ken ed ▁to ▁kind ▁of ▁a ▁dance ▁or ▁bal let ▁and ▁the ▁birds ▁are ▁so ▁numerous ▁that ▁they ▁seem ▁to ▁ob liter ate ▁the ▁sun set , ▁hence ▁the ▁term ▁" sort ▁sol " ▁( Dan ish ▁for ▁" black ▁sun "). ▁ ▁Sort ▁sol ▁in ▁the ▁mar sh ▁near ▁T ø nder ▁can ▁occasionally ▁compr ise ▁a ▁formation ▁with ▁up ▁to ▁one ▁million ▁birds . ▁ ▁Usually ▁f lock s ▁break ▁up ▁when ▁the ▁number ▁of ▁individuals ▁exceed ▁about ▁half ▁a ▁million ▁birds ▁due ▁to ▁excess ive ▁internal ▁dist urban ces ▁in ▁the ▁f lock . ▁ ▁If ▁a ▁pred ator ▁bird ▁enters ▁the ▁f lock , ▁the ▁star lings ▁initi ate ▁a ▁ver itable ▁bomb ard ment ▁with ▁dro ppings ▁and ▁vom it ▁that ▁soil ▁the ▁fe athers ▁of ▁the ▁pred ator . ▁ ▁In ▁rare ▁cases ▁the ▁stick y ▁depos its ▁may ▁render ▁the ▁pred ator ▁unable ▁to ▁stay ▁air bor ne . ▁ ▁Over ▁ 2 0 ▁years , ▁there ▁have ▁been ▁two ▁confirmed ▁cases ▁of ▁young ▁northern ▁g osh aw ks ▁that ▁d rown ed ▁because ▁the ▁incident