. Bonner zoologische Beiträge : Herausgeber: Zoologisches Forschungsinstitut und Museum Alexander Koenig, Bonn. Biology; Zoology. Figure 1. The Black Bittern at the peak of its display to the Brown Goshawk (see text). bill, took a small step forward and became motionless (fig. 1). During this time the goshawk, with its wings still held outward, turned to keep facing the bittern, then moved its wings slowly up and down, snapped its bill and erected feathers on its crown and neck. After the bittern became motionless, the goshawk relaxed its stance and in a matter of moments turned away and flew
. Bonner zoologische Beiträge : Herausgeber: Zoologisches Forschungsinstitut und Museum Alexander Koenig, Bonn. Biology; Zoology. Figure 1. The Black Bittern at the peak of its display to the Brown Goshawk (see text). bill, took a small step forward and became motionless (fig. 1). During this time the goshawk, with its wings still held outward, turned to keep facing the bittern, then moved its wings slowly up and down, snapped its bill and erected feathers on its crown and neck. After the bittern became motionless, the goshawk relaxed its stance and in a matter of moments turned away and flew out of view. The bittern then relaxed its posture and hopped back to its original position on the fallen tree, where it paused, stretched out its neck and shook itself (body shake: McKinney 1965) before flying further down the river. No vocalizations were made by either the bittern or the goshawk. The same posture has been observed many times in the Least Bittern (Ixobrychus exilis) (D. W. Mock, pers. comm.) and a similar display is illustrated for the Little Bittern (I. minutus) by Bauer and Glutz (1966: 374). The display termed „Pfahlstellung" by Portielje (1926) for the European Bittern (Botaurus stellaris) is also similar. Regarding the attack by the goshawk, Errington (1967: 222) has shown that potential predators can be discouraged from attacking if the prospective prey displays alertness to danger. Ludwig (1971) also pointed out that "the result may depend more on the relative sizes of predator and prey". Although the Brown Goshawk is very aggressive (Brown and Amadon 1968: 501), the size of the Black Bit- tern and its alertness to the goshawk's presence obviously made it an all too risky prey item, particularly for an immature and presumably inexperienced 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 perfect
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