Migrants crowd as they wait to cross the Croatian border near the village of Berkasovo, Serbia October 19, 2015. Thousands of migrants clamoured to enter European Union member Croatia from Serbia on Monday after a night spent in the cold and mud of no-man's land, their passage west slowed by a Slovenian effort to impose limits on the flow to western Europe. (Photo by Marko Djurica/Reuters)





Migrants protect themselves from the rain as they wait to cross the Croatian border near the village of Berkasovo, Serbia October 19, 2015. (Photo by Marko Djurica/Reuters)





A migrant feeds an infant as she waits among others to cross the Croatian border near the village of Berkasovo, Serbia October 19, 2015. (Photo by Marko Djurica/Reuters)





A migrant on a wheelchair protects himself from the rain near the border crossing with Croatia, near the village of Berkasovo, Serbia October 19, 2015. (Photo by Marko Djurica/Reuters)





Migrants rest as they wait covered with blankets to cross the border with Croatia near the village of Berkasovo, Serbia, October 19, 2015. (Photo by Marko Djurica/Reuters)





Migrants walk through a field close to the border with Croatia near the village of Berkasovo, Serbia October 19, 2015. (Photo by Marko Djurica/Reuters)





Migrants camp in the no man's land as they wait to enter Slovenia from Trnovec, Croatia October 19, 2015. The Balkans faced a growing backlog of migrants on Monday, thousands building up on cold, wet borders after the closure of Hungary's southern frontier diverted them to Slovenia. (Photo by Srdjan Zivulovic/Reuters)





A migrant's child sleeps as it is seen in a rain cover at the border crossing from Slovenia in Trnovec, Croatia October 19, 2015. (Photo by Antonio Bronic/Reuters)





Migrants protect themselves from the rain as they wait to cross the border with Croatia near the village of Berkasovo, Serbia, October 19, 2015. (Photo by Marko Djurica/Reuters)





Migrants warm up by a fire as they wait to cross the Croatian border near the village of Berkasovo, Serbia October 19, 2015. (Photo by Marko Djurica/Reuters)





A migrant smokes a cigarette as he waits among others to cross the Croatian border near the village of Berkasovo, Serbia October 19, 2015. (Photo by Marko Djurica/Reuters)





Migrants queue at the border crossing with Croatia near the village of Berkasovo, Serbia October 19, 2015. (Photo by Marko Djurica/Reuters)





A child sleeps as migrants wait at the border crossing with Croatia near the village of Berkasovo, Serbia October 19, 2015. (Photo by Marko Djurica/Reuters)





Migrants queue at the border crossing with Croatia near the village of Berkasovo, Serbia October 19, 2015. (Photo by Marko Djurica/Reuters)





Migrants ride on a tractor's trailers as they travel to the border with Croatia near the village of Berkasovo, Serbia October 19, 2015. (Photo by Marko Djurica/Reuters)





Migrants rest on the ground as they wait to cross the border with Croatia near the village of Berkasovo, Serbia, October 19, 2015. (Photo by Marko Djurica/Reuters)





Migrants protect themselves from the rain as they walk through a field close to the border with Croatia near the village of Berkasovo, Serbia, October 19, 2015. (Photo by Marko Djurica/Reuters)





Migrants rest as they wait to enter Slovenia from Trnovec, Croatia October 19, 2015. (Photo by Srdjan Zivulovic/Reuters)





Migrants sit in trailers as they travel to the border with Croatia near the village of Berkasovo, Serbia, October 19, 2015. (Photo by Marko Djurica/Reuters)





An EU sign is seen as migrants wait in the no man's land to cross the border to Slovenia from Trnovec, Croatia, October 19, 2015. (Photo by Srdjan Zivulovic/Reuters)





A migrant covers his head with a cardboard box as he waits in no man's land to cross the border to Slovenia from Trnovec, Croatia, October 19, 2015. (Photo by Srdjan Zivulovic/Reuters)





Migrants look on as they wait to enter Slovenia from Trnovec, Croatia October 19, 2015. (Photo by Srdjan Zivulovic/Reuters)





A child looks on as migrants walk into Slovenia from Trnovec, Croatia, October 19, 2015. Some 5,000 migrants reached Slovenia on Monday from Croatia, with another 1,200 on their way by train, the Slovenian interior ministry said, accusing Croatia of ignoring efforts to contain the flow. (Photo by Srdjan Zivulovic/Reuters)





Migrants cover themselves with a blanket as they walk into Slovenia from Trnovec, Croatia, October 19, 2015. (Photo by Srdjan Zivulovic/Reuters)





A man is lifted over a fence by Slovenian policemen as migrants attempt to cross the border near Trnovec, Croatia October 19, 2015. (Photo by Antonio Bronic/Reuters)





Migrants walk along a road close to the border with Croatia near the village of Berkasovo, Serbia October 19, 2015. The Balkans struggled with a growing backlog of migrants on Monday after Hungary sealed its southern border and Slovenia tried to impose a limit, leaving thousands stranded on cold, wet borders where tempers frayed. More than 10,000 were stranded in Serbia, the United Nations refugee agency (UNHCR) said, with more on the way but nowhere to go. (Photo by Marko Djurica/Reuters)





Migrants covered with a space blanket wait to cross the border with Croatia near the village of Berkasovo, Serbia October 19, 2015. (Photo by Marko Djurica/Reuters)





Slovenian policemen keep order as migrants attempt to board the first bus after opening the border with Slovenia in Trnovec, Croatia October 19, 2015. Some 5,000 migrants reached Slovenia on Monday from Croatia, with another 1,200 on their way by train, the Slovenian interior ministry said, accusing Croatia of ignoring efforts to contain the flow. (Photo by Antonio Bronic/Reuters)