1 The desert at Zait Bay, Egypt: a bird migration bottleneck of global importance GUDRUN HILGERLOH Supplementary material Supplementary material 1. Coordinates of the observation sites. The observations were performed in the desert at Zait Bay in the time period between the February 20 and May 6 2007. E N site (degrees) (degrees) M01 33,44 27,70 M02 33,45 27,73 M03 33,43 27,78 M04 33,40 27,81 M05 33,37 27,82 M06 33,35 27,89 M07 33,32 27,93 M08 33,29 27,97 M09 33,26 28,00 M10 33,23 28,04 M11 33,21 28,09 M12 33,19 28,13 M13 33,15 28,17 S01 33,49 27,69 S02 33,51 27,73 S03 33,48 27,78 S04 33,46 27,81 S05 33,44 27,85 S06 33,41 27,89 S07 33,33 27,93 S08 33,36 27,96 S09 33,32 28,00 S10 33,29 28,04 S11 33,26 28,07 S12 33,25 28,12 S13 33,23 28,16 2 Supplementary material 2. The number of days and of hours per day the extrapolation for each species is based on. The multiplication factor is the factor by which the bird frequency is multiplied to extrapolate the number of birds per season. The observations were performed in the desert at Zait Bay in the time period between the February 20 and May 6 2007. Species Hours per Number Multiplication factor day of days White Pelican 9 33 297 White Stork 8 47 376 Black Stork 8 53 424 Black Kite 10 37 370 Egyptian Vulture 9 65 585 Montagu’s Harrier 11 39 429 Pallid Harrier 11 63 693 Marsh Harrier 11 42 462 Levant Sparrowhawk 8 12 96 Honey Buzzard 9 10 90 Steppe Buzzard 9 48 432 Long-legged Buzzard 9 48 432 Steppe Eagle 9 55 495 Lesser Spotted Eagle 9 63 567 Booted Eagle 9 36 324 Short-toed Eagle 9 50 450 Kestrel 9 58 522 Lesser Kestrel 9 45 405 Common Crane 8 12 96 Bee-eater 9 22 198 3 Supplementary material 3. observation hours during migration days and hours of each species (n), the median number of birds per hour (frequency) and the range of migration frequencies. The observations were performed in the desert at Zait Bay in the time period between the February 20 and May 6 2007. Median Range Species (n) (frequency) (frequency) White Pelican 525 0 250 White Stork 521 0 25025 Black Stork 460 0 130 Black Kite 512 0 171 Egyptian Vulture 413 0 8 Pallid Harrier 13 0 2 Levant Sparrowhawk 203 0 3000 Honey Buzzard 106 0 11 Steppe Buzzard 535 0 1103 Long-legged Buzzard 385 0 13 Steppe Eagle 446 0 138 Spotted Eagle 9 0 2 Lesser Spotted Eagle 535 0 11 Booted Eagle 400 0 10 Short-toed Eagle 462 0 8 Lesser Kestrel 20 0 2 Common Crane 349 0 1197 4 Supplementary material 4. Mean and confidence interval of average migration magnitude at the different sites. The observations were performed in the desert at Zait Bay in the time period between the February 20 and May 6 2007. Species M01 M02 M03 M04 M05 M06 M07 M08 M09 M10 M11 M12 M13 White Pelican n 20 20 18 15 16 16 16 19 16 21 22 24 22 mean 0.1 5.0 12.5 10.8 conf. -95 -0.1 -5.7 -14.1 -9.6 conf.+95 0.2 15.7 39.1 31.2 White Stork n 20 20 18 15 16 16 16 19 16 21 22 23 21 mean 5.0 174.1 44.9 225.1 1.8 127.5 229.6 52.1 25.0 27.1 4.0 0.0 43.3 conf. -95 -5.5 -84.2 -48.8 -30.0 -1.4 -26.3 -224.9 -39.5 -11.4 -12.2 -4.4 -15.6 conf.+95 15.5 432.3 138.7 480.3 4.9 281.3 684.1 143.7 61.4 66.5 12.5 102.2 Black Stork n 17 17 16 14 15 14 14 19 15 16 19 20 19 mean 0.2 3.4 3.4 2.6 0.1 2.5 3.1 0.3 0.2 1.2 1.0 conf. -95 -0.1 -3.5 -2.3 -2.6 -0.2 -1.2 -2.2 -0.3 -0.1 -1.0 -0.9 conf.+95 0.4 10.2 9.2 7.9 0.4 6.2 8.5 1.0 0.5 3.4 2.9 Black Kite n 20 19 17 15 17 16 18 19 16 20 21 23 21 mean 3.0 1.0 4.2 1.7 5.5 3.6 1.4 1.1 1.8 1.7 1.1 4.0 3.2 conf. -95 -1.1 -0.7 -3.9 -0.6 -0.9 -2.4 -0.6 -0.2 0.2 -0.4 -0.5 -4.0 -3.1 conf.+95 7.1 2.7 12.3 4.1 12.0 9.5 3.4 2.3 3.5 3.8 2.7 11.9 9.6 Egyptian Vulture n 16 15 15 13 15 14 13 17 13 16 16 17 15 mean 0.1 0.1 0.3 0.4 0.7 0.2 0.2 0.1 0.2 0.2 0.4 conf. -95 -0.2 -0.1 -0.2 -0.1 -0.6 -0.2 -0.1 -0.1 -0.2 -0.2 -0.2 conf.+95 0.4 0.2 0.7 0.8 2.0 0.6 0.6 0.4 0.6 0.6 1.0 Pallid Harrier n 17 16 15 13 15 15 13 17 13 20 19 21 18 mean 0.1 0.1 0.1 conf. -95 -0.1 -0.1 -0.1 conf.+95 0.2 0.2 0.2 Levant Sparrowhawk n 8 5 8 7 8 5 6 8 7 6 7 9 8 mean 1.1 0.3 0.5 10.0 500.0 221.8 114.4 0.1 5 conf. -95 -0.7 -0.4 -0.7 -17.8 -785.3 -302.6 -165.2 -0.2 conf.+95 3.0 1.0 1.7 37.8 1785.3 746.1 394.0 0.4 Honey Buzzard n 5 5 7 5 4 3 4 3 6 4 6 6 5 mean 0.2 1.4 2.0 1.3 1.0 2.5 0.7 0.3 1.8 1.4 conf. -95 -0.4 -1.0 -2.9 -2.7 -3.3 -2.4 -2.2 -0.5 -2.9 -2.5 conf.+95 0.8 3.8 6.9 5.2 5.3 7.4 -2.2 1.2 6.5 5.3 Steppe Buzzard n 21 21 18 16 17 17 16 20 17 21 22 24 22 mean 12.8 4.8 59.3 3.0 65.5 21.6 5.4 1.6 6.8 1.2 32.6 0.1 5.0 conf. -95 -3.8 -2.5 -64.3 -1.2 -72.0 -6.3 -1.1 0.0 -4.0 -0.7 -33.6 0.0 -3.8 conf.+95 29.3 12.1 182.9 7.2 202.9 49.6 12.0 3.1 17.6 3.1 98.8 0.3 13.8 Long-legged Buzzard n 14 14 14 11 13 14 13 16 13 15 16 17 16 mean 0.1 0.1 0.1 0.6 0.1 0.2 0.4 0.1 conf. -95 -0.2 -0.1 -0.1 -0.2 -0.1 -0.2 -0.5 -0.1 conf.+95 0.5 0.2 0.4 1.4 0.2 0.5 1.4 0.2 Steppe Eagle n 18 18 17 14 17 17 13 19 14 16 17 20 18 mean 0.4 0.6 2.1 1.4 4.6 1.5 5.7 0.6 1.8 0.7 1.6 7.8 7.2 conf. -95 -0.1 0.0 0.3 -0.2 -0.2 -0.1 -1.1 -0.1 0.2 0.2 -0.7 -4.0 -1.7 conf.+95 1.0 1.2 3.8 2.9 9.4 3.0 12.4 1.2 3.4 1.2 3.9 19.5 -1.7 Spotted Eagle n 9 6 7 6 7 8 6 9 8 9 8 8 8 mean 0.1 0.1 0.1 0.1 conf. -95 -0.2 -0.2 -0.2 -0.2 conf.+95 0.5 0.4 0.4 0.4 Lesser Spotted Eagle n 21 22 19 15 19 20 18 18 18 21 21 22 22 mean 0.1 0.1 0.3 0.1 0.3 0.2 0.5 0.2 0.1 0.1 0.5 0.2 conf. -95 0.0 -0.1 0.0 -0.1 0.0 0.0 -0.1 -0.1 0.0 -0.1 -0.5 -0.1 conf.+95 0.2 0.3 0.6 0.2 0.5 0.4 1.1 0.4 0.2 0.3 1.5 0.5 Short-toed Eagle n 18 18 16 13 16 16 15 18 14 20 18 21 18 mean 0.2 0.2 0.1 0.1 0.2 0.3 0.1 0.1 0.3 0.1 0.4 conf.