Blue DF heads south

Over the past twenty years Roy Dennis has pioneered the use of satellite transmitters to follow UK ospreys on migration and to learn more about their movements on both the breeding and wintering grounds. Much of this data is in included in my recently completed PhD thesis. This autumn we are tracking a new adult male osprey on migration, Blue DF. This osprey is well known to wildlife photographers because it regularly fishes at both Rothiemurchus Fishery and also Aviemore Lochan – a quick Google search will reveal an array of stunning photos of the bird. He was originally ringed as a chick at nest A18 by Roy Dennis in 2010 and this spring took over from another well-known osprey, Red 8T, at nest A10 in Strathspey. He successfully reared two chicks with an unringed female and by Wednesday evening last week, when we caught him under licence at Rothiemurchus Fishery, his family were already heading south. Blue DF was also ready for migration: he weighed over 2kg having put on around 500g of fat in preparation for his long journey south.

Blue DF is regularly seen fishing at both Rothiemurchus Fishery and Aviemore Lochan (photo by Mike Crutch)

Sure enough when we received the first data from his transmitter at 11:30am on Friday morning he was already in the Scottish borders, 10 km south-east of Kelso. Over the course of the next five hours he made steady progress south-east and at 16:40 he was just east of York at an altitude of 668 metres. An hour later he passed to the west of the Humber estuary and he finally settled to roost for the night in the corner of a deciduous woodland 15 km north-west of Lincoln.

At 09:54 next morning Blue DF had flown over the western part of Lincoln and was migrating south-east, in a strong westerly wind. Three hours later, despite heavy squally showers, he had flown 96 kilomteres from his overnight roost and was heading over Peterborough at an altitude of 682 metres. He maintained a constant south-easterly course through Cambridgeshire and then Essex, crossing the Isle of Sheppey soon after 16:00. He eventually settled to roost for the night in a wood midway between Tunbridge Wells and Folkestone in southern Kent after a day’s flight of 282 km.

Sunday morning dawned sunny and clear on the south coast and DF was obviously keen to press on because at 06:12 he was already 20 km south of Hastings, crossing the English Channel at an altitude of 124 metres. The 117 km crossing took three-and-a-half hours with Blue DF making landfall to the west of Dieppe soon after 09:00. He then continued on a southerly heading through Upper Normandy, at a relatively low altitude (maximum 392 metres) before settling to roost in a forested area near the village of La Saucelle, some 100 km west of Paris after a day’s flight of 277 km.

Blue DF made a 3.5 hour, 117 km crossing of the English Channel between Hastings and Dieppe on Sunday morning. Times and altitude above sea level shown on map

The satellite data suggested that DF hadn’t fed since leaving Scotland but at 09:01 this morning he was fishing in small lake 31 km south-west of his overnight roost. He was obviously successful because the next two GPS fixes (separated by 30 minutes) show he was perched nearby, presumably tucking into breakfast. He didn’t linger for long however because at 10:39, the last GPS fix of this batch, he was 12 km to the south-west migrating onwards at an altitude of 311 metres.  We’ll update you on his progress later in the week. You can also check out Blue DF’s migration on our interactive map. It will be fascinating to see where this experienced adult osprey spends the winter.

Blue DF stopped to fish at a series of small lakes near the town of Nogent-le-Rotrou on Monday morning

Blue DF’s migration from Strathspey to Lower Normandy, 7-11 September