The Diets of Four Sympatric Raptors in Breeding Seasons at Yangmingshan
Date Issued
2004
Date
2004
Author(s)
Huang, Kuang-Ying
DOI
zh-TW
Abstract
Abstract
The diets of four sympatric raptors, i.e., Besra Sparrowhawk (Accipiter virgatus), Crested Goshawk (Accipiter trivirgatus), Serpent Eagle (Spilornis cheela), and Oriental Honey Buzzard (Pernis ptilorhynchus) in breeding seasons were studied from 1993 to 2002 in Yangmingshan area, northern Taiwan. Three approaches, including direct observation, food remain method and pellet method, were applied to study prey samples in nesting places. Prey types and frequency were recorded to measure prey biomass and food diversity. The prey compositions and food niche overlap among raptors were also quantified. As a result, food habits of the four sympatric raptors varied in food diversity, food evenness, and food niche breadth. The food resource partitioning among these four raptors included prey class, prey frequency composition and prey biomass composition. In a total of 871 prey items of Besra Sparrowhawk, 5 classes and 30 prey types were recorded. Birds were the major prey in both frequency (58.1%) and biomass (84.8%). The prey composition of Crested Goshawk in 621 prey items included 5 classes and 41 prey types. Birds (42.5% by frequency, 51.4% of total biomass) and mammals (19.2% by frequency, 45.4% of total biomass) were the major preys. In 86 prey items of Serpent Eagle’s diet, 5 classes and 21 prey types were verified. Reptiles (70.9% by frequency, 64.3% of total biomass) were the major food of this species. Three classes and 8 prey types were included in Oriental Honey Buzzard’s 123 prey items which insects (paper wasp) were the most important prey (78.9% by frequency, 83.5% of total biomass). Although the Besra Sparrowhawk and Crested Goshawk has a higher overlap in prey composition, their prey sizes are quite different. The Besra Sparrowhawk fed on smaller preys while Crested Goshawk on larger ones. During the breeding season, obvious prey shifts were found in Besra Sparrowhawk and Oriental Honey Buzzard. Besra Sparrowhawk shifted their prey from birds to insects (cicada) while the Oriental Honey Buzzard changed its role from an irregular frog and lizard forager to a wasp specialist. A comparison was made for the various methods applied in this study in terms of their effectiveness, efficiency, advantages, and disadvantages. The food remain method worked best for Besra Sparrowhawk. Direct Observation method worked best for Crested Goshawk. However, combining food remain and pellet methods not only improved the proportion of prey types and prey items identified, but also the efficiency per unit time.
Subjects
鳳頭蒼鷹
松雀鷹
陽明山
東方蜂鷹
猛禽
大冠鷲
食性
Raptor
Yangmingshan
Accipiter trivirgatus
Diet
Accipiter virgatus
Spilornis cheela
Pernis ptilohynchus
Type
other