Krebs investigated experimental plots in Canada's Yukon territory that contained hare populations.
克雷布斯调查了加拿大育空地区含有野兔种群的试验田。
Krebs has discovered that great blue herons look up more often when in smaller flocks than when in larger ones, solely as a consequence of poor feeding conditions.
克雷布斯发现,大蓝鹭在较小的群体中比在较大的群体中更容易抬头,这完全是由于恶劣的饲养条件造成的。
Krebs hypothesizes that the herons in smaller flocks are watching for herons that they might follow to better feeding pools, which usually attract larger numbers of the birds.