1960 年 2 巻 15 号 p. 89-98
The food habits of the following species of Herons in Saitama Prefecture were analyzed from their stomach contents: Egretta alba modesta, Egretta intermedia intermedia, Egretta garzetta garzetta, Bubulcus ibis coromandus, Nycticorax nycticorax nycticorax. Their common feeding grounds were rice fields but specific difference of food items were found, as shown below:
E. alba modesta Crustacea 63.5% Pisces 27%
E. i. intermedia Insecta 44.4% Pisces 23.2% Amphibia 18, 4%
E. g. garzetta Crustacea 41.8% Piscea 27.0% Insecta 26.5%
B. ibis coromandus Insecta 92.2%
N. n. nycticorax Pisces 56.0% Insecta 28.4% Amphibia 9.8%
Nearly all of their foods were animal matter, except a few crops of rice which were accidentally eaten. They thus have no immediate relation to the rice plants, but are beneficial, feeding on American crawfish, locust, mole-cricket and gadfly, etc, though the Night Heron is rather noxious much eating fishes and amphibia. Difference of food items was found compared with Ikeda's result obtained from a coastal area.