Given the task definition and input, reply with output. In this task, you are given a paragraph in Chinese, and your task is to construct a question in Chinese from the given passage. Construct a question in such a way that (i) it is unambiguous, (ii) it is answerable from the passage, (iii) its answer is unique, and (iv) the answer is a continuous text span from the paragraph. Avoid creating questions that (i) can be answered correctly without actually understanding the paragraph and (ii) uses the same words or phrases given in the passage. 

寒鸦（学名：）为鸦科寒鸦属的鸟类，旧时归类于鸦属寒鸦亚属，别名慈鸟、小山老鸹。全球活动范围约为15,600,000平方千米。该物种的保护状况被评为无危。寒鸦的平均体重约为233.5克，体长可达35厘米；上体除颈后羽毛呈灰白色外，其余为黑色；胸和腹部为灰白色。分布于欧洲，西亚和北非各地。栖息地包括温带草原、牧草地、城市、亚热带或热带的旱林、耕地、亚热带或热带的（低地）干草原、海崖和多岩石的离岸岛屿和温带森林。一般栖息于戈壁荒漠有绿洲的树林中、亦见于河流两岸的峻峭岸壁上以及巢主要在石质或土质的洞穴或缝隙中；冬季常和秃鼻乌鸦混合成群。该物种的模式产地在瑞典。寒鸦包括四个认定的亚种 分布于欧洲的亚种混合交配：

寒鸦的全球活动范围是多大？