A cardiagan is left by the side of a track in the fields between the Serbian and Croatian border, pictured during the night of September 17, 2015, near Tovarnik, Croatia.

A blanket is left by the side of a track in the fields between the Serbian and Croatian border, pictured during the night of September 17, 2015, near Tovarnik, Croatia.

A water bottle is left by the side of a track in the fields between the Serbian and Croatian border, pictured during the night of September 17, 2015, near Tovarnik, Croatia.

A jumper is left by the side of a track in the fields between the Serbian and Croatian border, pictured during the night of September 17, 2015, near Tovarnik, Croatia.

A baby's bib is left by the side of a track in the fields between the Serbian and Croatian border, pictured during the night of September 17, 2015, near Tovarnik, Croatia.

A discarded cigarette packet is left by the side of a track in the fields between the Serbian and Croatian border, pictured during the night of September 17, 2015, near Tovarnik, Croatia.

Clothes and foodstuffs left by the side of a track in the fields between the Serbian and Croatian border, pictured during the night of September 17, 2015, near Tovarnik, Croatia.

A child's shoe is left on the roadside near buses that are leaving the Croatian town of Tovarnik, during the night of September 17, 2015. Thousands of migrants and refugees had arrived in Tovarnik, and the people crowded to make it into trains and buses leaving for an unknown destination.

Shoes and garbage are left on railway tracks beside a train leaving the Croatian town of Tovarnik, on September 18, 2015. Thousands of migrants and refugees had arrived in Tovarnik, and the people crowded to make it into trains and buses leaving for an unknown destination.

A broken pair of sunglasses lay fallen on railway tracks beside a train leaving the Croatian town of Tovarnik, on September 18, 2015. Thousands of migrants and refugees had arrived in Tovarnik, and the people crowded to make it into trains and buses leaving for an unknown destination.

Shoes and garbage are left on railway tracks beside a train leaving the Croatian town of Tovarnik, on September 18, 2015. Thousands of migrants and refugees had arrived in Tovarnik, and the people crowded to make it into trains and buses leaving for an unknown destination.

A baby's buggy is discarded in a bush near the railway station in the Croatian town of Tovarnik, on September 18, 2015. Thousands of migrants and refugees had arrived in Tovarnik, waiting sometimes for days at the station, hoping to get on a bus or train onto northern Europe.

A pair of ladies boots lay on the ground by the roadside in the Croatian town of Tovarnik, on September 18, 2015. Thousands of migrants and refugees had arrived in Tovarnik, waiting sometimes for days at the station, hoping to get on a bus or train onto northern Europe.

A pair of jeans lay by the roadside at the Croatian-Hungarian border at Beremend, in eastern Croatia, on September 18, 2015. Having crossed into Croatia from Serbia, and being kept in the town of Tovarnik, people were put on buses and brought up to the town of Beli Manastir and on to the border, where Hungary would bus them through to Austria.

Clothes hang to dry on a tree in an orchard in the town of Tovarnik, Croatia, on September 19, 2015. Thousands of people were kept in Tovarnik whilst authorities struggled to organise buses and trains to take them onwards to the border in order to continue their journey towards northern Europe. People often lived with little or no access to basic services, including running water and toilets.

A discarded tent is pictured on the roadside in the town of Tovarnik, Croatia, on September 19, 2015. Thousands of people were kept in Tovarnik whilst authorities struggled to organise buses and trains to take them onwards to the border in order to continue their journey towards northern Europe. People often lived with little or no access to basic services, including running water and toilets.

Clothes, shoes, and a bag lay discarded in a bush by the roadside leading to the station in the town of Tovarnik, in eastern Croatia, on September 19, 2015. Having crossed into Croatia from Serbia, and being kept in the town of Tovarnik, people were put on buses and brought up to the town of Beli Manastir and on to the border, where Hungary would bus them through to Austria.

A tent, clothes and sleeping bag lay discarded by the side of the road in the town of Tovarnik, Croatia, on September 20, 2015. Thousands of people have come through Tovarnik en-route to northern Europe, and often stayed multiple nights. Some had shelter, sleeping in tents they had brought with them, but many slept outside. Some tents were left behind as people rushed to get on buses to travel onwards.

Clothes from a discarded bag lay by the roadside leading to the station in the town of Tovarnik, in eastern Croatia, on September 19, 2015. Having crossed into Croatia from Serbia, and being kept in the town of Tovarnik, people were put on buses and brought up to the town of Beli Manastir and on to the border, where Hungary would bus them through to Austria.

A faux fur coat lays discarded by the roadside leading to the station in the town of Tovarnik, in eastern Croatia, on September 20, 2015. Having crossed into Croatia from Serbia, and being kept in the town of Tovarnik, people were put on buses and brought up to the town of Beli Manastir and on to the border, where Hungary would bus them through to Austria.

A discarded tent lays by the side of the road in the town of Tovarnik, Croatia, on September 20, 2015. Thousands of people have come through Tovarnik en-route to northern Europe, and often stayed multiple nights. Some had shelter, sleeping in tents they had brought with them, but many slept outside. Some tents were left behind as people rushed to get on buses to travel onwards.

A pair of shoes lay discarded in the ashes of a fire outside a transit centre set-up by Croatian authorities outside the town of Opatovac, Croatia, on September 22, 2015. After thousands of migrants and refugees started passing through Croatia from Serbia, following the Hungarians closing the border between Serbia and Hungary, Croatia struggled to deal with the people crossing its borders. The temporary camp was built for 4000 people, but was quickly overwhelmed.

Shoes lay discarded next to a blanket given out by the United Nations Refugee Agency outside a transit centre set-up by Croatian authorities outside the town of Opatovac, Croatia, on September 23, 2015. After thousands of migrants and refugees started passing through Croatia from Serbia, following the Hungarians closing the border between Serbia and Hungary, Croatia struggled to deal with the people crossing its borders. The temporary camp was built for 4000 people, but was quickly overwhelmed.

A discarded tent and baby stroller stand by the side of the road in the town of Tovarnik, Croatia, on September 20, 2015. Thousands of people have come through Tovarnik en-route to northern Europe, and often stayed multiple nights. Some had shelter, sleeping in tents they had brought with them, but many slept outside. Some tents were left behind as people rushed to get on buses to travel onwards.

Clothes and sleeping materials lay discarded outside a transit centre set-up by Croatian authorities outside the town of Opatovac, Croatia, on September 23, 2015. After thousands of migrants and refugees started passing through Croatia from Serbia, following the Hungarians closing the border between Serbia and Hungary, Croatia struggled to deal with the people crossing its borders. The temporary camp was built for 4000 people, but was quickly overwhelmed.