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Vol. 45 No. 2, 2006
Comparison of Three Common Methods for Studying the Diet of Nestlings in Two Accipiter Species
Kuang-Ying Huang1, Yao-Sung Lin1, and Lucia Liu Severinghaus2,*
1Institute of Ecology and Evolutionary Biology, National Taiwan University, Taipei, Taiwan 106. E-mail: kyhoung@ms8.hinet.net
2Research Center for Biodiversity, Academia Sinica, Taipei, Taiwan 11528
Kuang-Ying Huang, Yao-Sung Lin, and Lucia Liu Severinghaus (2006) Food provisioning to 4 Accipiter virgatus nests and 2 A. trivirgatus
nests was monitored during 1998 and 2000 in Yangmingshan National Park,
Taipei, Taiwan. We made direct observations of prey deliveries and
collected prey remains and pellets throughout the breeding seasons in
order to compare the effectiveness and efficiency of the different diet
analysis methods for these 2 raptor species. The method of using prey
remains worked best for A. virgatus
for all measurements, producing 45.23% of all prey items found, 45.23%
of all prey items identified to prey taxa, and 38.87% of all prey items
identified to species. The observation method worked best for A. trivirgatus,
providing 41.05% of all prey items and 18.95% of prey items identified
to species, but the proportion of prey items identified to prey taxa
was highest using the pellet method (37.37%). Time efficiency was
consistently the highest for the prey remains method in A. virgatus. In contrast, for A. trivirgatus,
the pellet method was most efficient for assessing the number of prey
items delivered and the number identified to prey taxa, but the prey
remains method worked best for identifying prey to species. Combining
the prey remains and pellet methods increased the prey taxa identified
to 81.63% for A. virgatus and 58.95% for A. trivirgatus.
Although the value of direct observation has been stressed by many
researchers, its effectiveness varied between these 2 species studied
in Taiwan.
Key words: Prey delivery, Prey remains, Pellet analysis, Accipiter, Diet analysis.
*Correspondence: E-mail: zobbowl@gate.sinica.edu.tw
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