Steward V B, Smith K G, Stephen F M
Department of Entomology, University of Arkansas, 72701, Fayetteville, AR, USA.
Department of Zoology, University of Arkansas, 72701, Fayetteville, AR, USA.
Oecologia. 1988 Aug;76(3):348-352. doi: 10.1007/BF00377028.
Predation by red-winged blackbirds Agelaius phoeniceus L. on 13-year periodical cicadas (Magicicada spp.) and reactions by periodical cicadas to predators were studied during emergence of Brood XIX during summer of 1985 in northwestern Arkansas (USA). Emergences of periodical cicadas are classic examples of predator satiation due to high local densities of cicadas and birds are the major predators of adult periodical cicadas. Reactions of periodical cicadas to predators were assessed by recording behaviors exhibited by cicadas when approached in trees by a human hand during the 3-week period of peak adult densitics. Most male cicadas made a noise in association with escape behaviors when approached, and 50% of the females, which are silent, attempted escape behaviors. Observations of predation attempts on cicadas by red-winged blackbirds were made during the period of peak predation pressure. Red-winged blackbirds spent less time searching for cicadas over that 2-week period of increasing predation pressure, and became increasingly efficient at capturing cicadas. Handling time of cicadas by red-winged blackbirds increased by about 20 seconds over that period, as blackbirds spent more time consuming female cicadas. The flysquawk response, used only by male cicadas, was effective in deterring red-winged blackbirds; only 5% of the attacks by blackbirds were successful when that behavior was exhibited. All cicadas that remained motionless and silent when approached by blackbirds were captured and consumed. Because females remained inactive when approached more often than did males, blackbirds may have consumed more female cicadas. Changes that appeared in reactions of preiodical cicadas to the model predator and to the attacks of blackbirds reflect both changes in the sex ratio of the cicada populations and changes in behaviors of cicadas associated with mating and egg laying. The loud noise made by male periodical cicadas at mating centers did not appear to deter predation by blackbirds. Changes in the behavior of blackbirds that appeared to be in association with greater predation on female periodical cicadas relates directly to aspects of foraging theory, particularly predictions concerning more selective foraging during periods of abundant food resources.
1985年夏天，在美国阿肯色州西北部，对红翅黑鹂（Agelaius phoeniceus L.）捕食13年周期蝉（魔蝉属Magicicada spp.）以及周期蝉对捕食者的反应进行了研究。周期蝉的羽化是捕食者饱和的经典例子，因为当地蝉的密度很高，而鸟类是成年周期蝉的主要捕食者。在成年蝉密度高峰期的3周内，通过记录当人手靠近树木时蝉所表现出的行为，来评估周期蝉对捕食者的反应。大多数雄蝉在被靠近时会发出与逃避行为相关的声音，而50%沉默的雌蝉会尝试逃避行为。在捕食压力高峰期对红翅黑鹂捕食蝉的尝试进行了观察。在捕食压力增加的那两周内，红翅黑鹂寻找蝉的时间减少，并且捕捉蝉的效率越来越高。在此期间，红翅黑鹂处理蝉的时间增加了约20秒，因为黑鹂花费更多时间取食雌蝉。只有雄蝉使用的蝇叫反应在威慑红翅黑鹂方面是有效的；当表现出这种行为时，黑鹂只有5%的攻击成功。当被黑鹂靠近时保持不动且沉默的所有蝉都被捕获并吃掉。因为雌蝉比雄蝉更常被靠近时保持不动，所以黑鹂可能吃掉了更多的雌蝉。周期蝉对模拟捕食者和黑鹂攻击的反应中出现的变化，既反映了蝉种群性别比例 的变化，也反映了与交配和产卵相关的蝉行为的变化。雄周期蝉在交配中心发出的巨大噪音似乎并不能威慑黑鹂的捕食。黑鹂行为的变化似乎与对雌周期蝉的更多捕食有关，这直接关系到觅食理论的各个方面，特别是关于在食物资源丰富时期更具选择性觅食的预测。
