ISSN : 2287-8327
We investigated the foraging habitat preferences of heronsand egrets in an agricultural area inAsan city, Chungcheongnam-do, Korea. In the study area, rice fields were the most abundant habitat ype (86.8%)and total suitable feding habitat was greater in the northern area (59.0%) than the southern area (2.5%) ofthe colony. Most feding herons and egrets were located in the northern area of the colony. The number offeding individuals in a given area was related to the availa ble feding area (Pearson corelation, r=0.73,p< 0.01 for field habitats;r=0.901, p< 0.01 for freshwater habitats). Feding habitat preferences difered amongspecies. Grey herons (Ardea cinerea ), great egrets (Egreta lba ), and black-crowned night herons (Nycticoraxnycticorax) used reservoirs and itches. However, intermediate gret s (E.intermedia ) and catle grets ( Bubulcusibis ) were dependent on rice fields. The litle gret ( E. garzeta ) was a habitat generalist using al types ofhabitats. The two largest species, grey herons and great egrets, fed at deper site than litle grets and foragedin deper sites in reservoirs than in ditches (.2-test,.23=26.6 and p< 0.01 for grey herons, .23 =17.5 andp< 0.01 for great egrets). Al species displayed seasonal changes in feding habitat use and these changes wererelated with changes in availability of eding habitats.
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(2007) Received May 29 Accepted July 25,