Consistency of animal personality traits is expected. Mounting evidence suggests that animal personalities will change with time and major life events. Research into this phenomenon is often limited to span only short periods of time in the animals’ life or have few measures across their life. We measured Exploration, Activity and Boldness of litters of meadow voles, Microtus pennsylvanicus, in a pair of novel object tests six times over a year, representing a large proportion of the lifespan of the vole. Our null hypothesis was that the personality traits would not change, and our first alternative hypothesis was that personality traits would change equally for all individuals as they aged. Neither was supported. The data support our third hypothesis that traits would change and change unequally. Activity and Boldness were consistent across time. However, Exploratory behaviour increased with the vole's age. The supported models show that personality traits change consistently for related individuals, but the litters differ in their change with age. This suggests that meadow vole life history affects how personality traits develop, but not necessarily their magnitudes. We also tested the repeatability of traits across the testing intervals. We discovered that the repeatability of these three personality traits varied across time, depending on the trait. Activity was repeatable equally across ages. Exploration became more repeatable and Boldness became less so. Thus, personality traits may be more malleable than supposed, especially over long periods of time.

中文翻译：

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草地田鼠三个人格特征的长期可重复性和稳定性

预期动物人格特征的一致性。越来越多的证据表明，动物的性格会随着时间和重大生命事件而改变。对这种现象的研究通常仅限于动物生命中的很短时间，或者整个生命中很少采取任何措施。我们测量了草地田鼠（Microtus pennsylvanicus）凋落物的探查，活动和粗大度，在一年中进行的六次新颖的物体测试中，代表了田鼠寿命的很大一部分。我们的零假设是人格特质不会改变，而我们的第一个替代假设是，所有个体随着年龄的增长，人格特质都会同样地变化。都没有得到支持。数据支持了我们的第三个假设，即性状会不断变化和不平等地变化。活动和大胆在整个时间都是一致的。然而，探索行为随着田鼠的年龄而增加。支持的模型表明，相关个体的性格特征不断变化，但同窝仔随年龄的变化也不同。这表明草地田鼠的生活史会影响人格特质的发展，但不一定会影响其特质。我们还测试了整个测试间隔中性状的可重复性。我们发现，这三个人格特质的可重复性随时间的变化而变化，具体取决于特质。各个年龄段的活动均可以重复。探索变得更加可重复，大胆变得不那么容易。因此，人格特质可能比预期的更具延展性，尤其是在长时间内。