Brown J L, Li S H, Bhagabati N
Department of Biological Sciences, State University of New York, Albany, NY 12222, USA.
Proc Natl Acad Sci U S A. 1999 May 11;96(10):5565-9. doi: 10.1073/pnas.96.10.5565.
In regions with severe winters, global warming may be expected to cause earlier onset of breeding in most animals, yet no documentation of such a trend exists in North America. In a study of marked individuals of the Mexican jay (Aphelocoma ultramarina) in southeastern Arizona, from 1971 to 1998, the mean Julian date of first clutch in the population declined significantly by 10.1 days. The date of the first nest in the population also became earlier, by 10.8 days. These changes were associated with significant trends toward increased monthly minimum temperatures on the study area, traits that are associated with the onset of breeding in this population. Significant trends from 1971 to 1997 toward warmer minimum temperatures in the months before and during the initiation of breeding were observed. These trends parallel changes in minimum temperatures and community composition in a recent study of grassland ecology in the western United States. Together, they suggest that more attention should be given to the possible ecological importance of global change in minimum temperatures.
在冬季严寒的地区，预计全球变暖会使大多数动物的繁殖期提前开始，但在北美尚无这种趋势的记录。在一项对1971年至1998年亚利桑那州东南部有标记的墨西哥松鸦（Aphelocoma ultramarina）个体的研究中，该种群首次产卵的平均儒略日显著提前了10.1天。种群中首个鸟巢出现的日期也提前了10.8天。这些变化与研究区域月最低气温上升的显著趋势相关，而这些特征与该种群繁殖期的开始有关。观察到1971年至1997年繁殖开始前及期间的几个月里最低气温呈变暖的显著趋势。这些趋势与美国西部最近一项草原生态学研究中最低气温和群落组成的变化相似。综合来看，它们表明应更多关注最低气温全球变化可能具有的生态重要性。
