Abstract: Based on the theory of optimization on foraging,animal should make trade-offs between the energy obtained and the predation risk. Frugivores demonstrate various foraging strategies and food selection patterns. They may choose food according to fruit size,color,and smell. Using experiments of size-based food selection,we tested whether fruit size affected the foraging behavior of fulvous fruit bats (Rousettus leschenaulti)and short-nosed fruit bats (Cynopterus sphinx)that were commonly seen in Guangdong Province. Four sizes of apple cubes (1 cm,2 cm,2. 5 cm,and 3 cm)were prepared and numbered from I to IV. The quantity,frequency,and time spent of cube ingestion by bats were recorded by camera trapping. Results showed that bats ingested higher quantities of medium-size cubes (types Ⅱ and Ⅲ)than those of other types,but they chose small size cubes (type I)more frequently than they did other types. Furthermore,they spent more time ingesting cubes of large size (type Ⅳ)when cubes were provided separately. We found that the fruit bats tended to carry small and medium-sized cubes back to their stops for ingestion during foraging,however they stayed at the location of cubes when they ate large cubes. In conclusion,bats apply different strategies when dealing with food of different sizes. We propose that both species of bats prefer the ‘takeout’strategy under trade-off between foraging risk and net energy income.

Key words: Food selection, Food size, Foraging behavior, Foraging strategy, Fulvous fruit bat (Rousettus leschenaulti), Short nosed fruit bat (Cynopterus sphinx)

摘要： 按照最优化觅食理论,动物在取食时需在能量获取与捕食风险之间权衡。本文通过室内行为实验,研究两种旧大陆果蝠棕果蝠和犬蝠对食物大小的选择规律与取食策略。按体积由小到大将苹果分为Ⅰ型、Ⅱ型、Ⅲ型、Ⅳ型4 种类型的食物块,通过红外相机观察果蝠对不同大小食块的取食情况,并就其对各类型食块的取食率、取食次数和停留时间进行统计分析。结果表明:这两种果蝠对Ⅱ型和Ⅲ型食块的取食率显著高于Ⅰ型和Ⅳ型;对Ⅰ型食块的取食次数显著高于Ⅱ型和Ⅳ型;对Ⅳ型食块的停留时间显著高于Ⅰ型和Ⅱ型。它们在摄取体积较小的食块时,以取走后进食为主要取食方式,但摄取大体积食块时则主要在原地进食。取食过程中,果蝠优先选择大小适于搬运的食块,是捕食风险与能量收益权衡的结果。

关键词: 棕果蝠, 犬蝠, 取食行为, 食物大小, 食物选择, 取食策略