Table 1.

Occurrence of aberrant behaviours, retreat migration and deaths of raptors during migration across the Sahara Desert, as recorded by satellite telemetry. For definitions of cat. 1–5, see §2. Figures show number of tracks, with number of individuals given in parentheses (several adult individuals were recorded on repeated autumn and spring migration).

agen tracks (birds)mean track direction (degrees)n without aberrationsn with aberrationscourse changeslow speedinterruptionretreatdeath
cat. 1–4cat. 1cat. 2cat. 3cat. 4cat. 5
autumn
ospreyadult24(14)20018(13)6(4)5(3)3(3)3(3)2(1)0
juv4(4)1912(2)2(2)2(2)1(1)01(1)1
honey buzzardadult6(6)1894(4)2(2)02(2)2(2)00
juv7(7)2004(4)3(3)1(1)3(3)2(2)01
marsh harrieradult16(9)2066(5)10(7)9(7)7(6)7(6)00
hobbyadult4(4)1973(3)1(1)1(1)1(1)000
juv2(2)2121(1)1(1)1(1)1(1)1(1)02
total autumn63(46)20038(32)25(20)19(15)18(17)15(14)3(2)4
spring
ospreyadult17(10)1712(9)5(4)3(3)2(2)1(1)00
marsh harrieradult15(8)117(4)8(6)6(5)7(5)6(5)2(2)2
total spring32(18)1419(13)13(10)9(8)9(7)7(6)2(2)2
total95(46)57(33)38(25)28(18)27(21)22(18)5(4)6