. Bulletin of the British Ornithologists' Club. Birds. 57 [ 105(2)} 113 skins from India, Nepal, Sri Lanka, Burma, Thailand, Vietnam, Java and the Malay Peninsula were analysed for taxonomic evidence. 4 topotypes of Tyto alba stertens from lowland Assam, plus 38 others from all parts of India, Nepal and Sri Lanka were examined. Similarly 14 topotypes of javanica from Java were compared with 21 specimens from the Malay Peninsula, 20 from Thailand, 8 from Burma and 8 from Vietnam. The following parameters were measured: 1. Wing length — maximum flattened chord. 2. Tail
. Bulletin of the British Ornithologists' Club. Birds. 57 [ 105(2)} 113 skins from India, Nepal, Sri Lanka, Burma, Thailand, Vietnam, Java and the Malay Peninsula were analysed for taxonomic evidence. 4 topotypes of Tyto alba stertens from lowland Assam, plus 38 others from all parts of India, Nepal and Sri Lanka were examined. Similarly 14 topotypes of javanica from Java were compared with 21 specimens from the Malay Peninsula, 20 from Thailand, 8 from Burma and 8 from Vietnam. The following parameters were measured: 1. Wing length — maximum flattened chord. 2. Tail length — maximum flattened length. 3. Number of dark bars on central tail feathers and distance between centre points of bars. 4. Breast dot density and breast dot size. 5. Size of apical dot of sixth primary feather. 6. Bill width at nares. 7. Left claw lengths. Differentiation between populations from the north and south was apparent with 3 parameters — breast dot size and density and the apical dot size of the 6th primary feather. All 3 varied parallel with each other and the mean breast dot size was investigated in more detail. Only some breast feathers have dots and these vary in size from feather to feather. Mean breast dot size and dot density were estimated by curving a cardboard quadrat 50 x 50 mm onto the breast region and making a total count of all dots within the quadrat. The 10 most central dots were then measured to estimate mean dot size. Dot sizes for regional samples were then pooled and a mean calculated. Fig. 2 shows mean figures and variation in dot size for the 2 topotypes and associated populations. A more detailed exposition of breast dot size appears in Fig. 3 where the values for local populations within the main sample regions are displayed. 1-75 ±0-42 1-83*0-74 2-10±0-88 1-61*0-54 1 59i040. "fes oo . 2-87i0-82 Figure 3. Detail of breast dot size in Tyto alba for various regions of Asia. Confidence limits are given to one standard deviati
Size: 2165px × 1154px
Photo credit: © Book Worm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1800, bookdecade1890, booksubjectbirds, bookyear1893
