. Bulletin of the British Ornithologists' Club. mm. mm. mm. mm. mm. mm. first egg laid and the subsequent staggered hatching). This size difference is shown by the following measurements taken on recently hatched downy young on 29th March, 1969: Nestling 1 Culmen Tarsus Wing Nestling 2 Culmen Tarsus Wing At this stage the nestlings did not show fear to human intrusion, but only lifted their heads and emitted a continual hissing noise, probably a begging response. At a different nest older young were observed. The history of it is shown as: 9th January, 1969 C/3 28
. Bulletin of the British Ornithologists' Club. mm. mm. mm. mm. mm. mm. first egg laid and the subsequent staggered hatching). This size difference is shown by the following measurements taken on recently hatched downy young on 29th March, 1969: Nestling 1 Culmen Tarsus Wing Nestling 2 Culmen Tarsus Wing At this stage the nestlings did not show fear to human intrusion, but only lifted their heads and emitted a continual hissing noise, probably a begging response. At a different nest older young were observed. The history of it is shown as: 9th January, 1969 C/3 28th February, 1969 three well fledged young. 29th March, 1969 three young, one able to leave nest. 6th April, 1969 two young, both able to leave nest. Assuming that laying was completed on the first visit (an unlikely event) and accepting the incubation period of 24-30 days given in McLachlan & Liversidge (1957), then the nestling period for two young was a minimum of 58 days, a substantially longer period than the "less than six weeks" men- tioned in McLachlan & Liversidge (1957). Obviously further information is needed on this point. The reaction of well-feathered young to human intrusion was very differ- ent to that of the younger ones previously described. On the 28th February, 1969 on our approach the birds were unable to stand, and all displays were given from a squatting position with partially raised breast. When faced with an intrusion the birds lifted up their heads, and raised the feathers of the. Plate 1. Forward Display: A,gpHatbnestlings. 149. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original British Ornithologists' Club. London : British Ornithologists' Club
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