The Effect of Temperature on Northwest Crow Flocking Behaviour

Abstract

The flocking behaviour of northwest crows (Corvus caurinus) is an important mechanism for crows to protect themselves from predators and to keep warm (Goodenough et al, 2017). The objective of this study is to determine whether temperature affects the flocking behaviour, i.e., size of crow flocks and number of flocks, of northwest crows in Vancouver, BC, as winter approaches. It is hypothesized that as temperature decreases, crows will flock in larger flocks. To perform this experiment, the number of crow flocks as well as the approximate size of the flocks (grouped into categories to approximate the number of crows per flock: 2-5, 6-20, 21-50, 51-100, >100) was tallied for a ten-minute period prior to sunset daily for 2 weeks (n=14) in the same location. The temperature at the time of data collection was recorded. A linear regression was performed on the number of crow flocks and temperature to determine whether there is a correlation. It was determined that there is a negative correlation between total number of flocks and temperature as the beta-coefficient is -0.79 and with a statistically significant p-value of 0.0073 (<0.05). Separate linear regressions were performed for individual categories of the sizes of the flocks which found that only flocks with less than five crows had statistically significant correlations with temperature. Therefore, the study fails to reject the null hypothesis that temperature has no effect on crow flocking behaviour and thus concludes that temperature does not impact northwest crow flocking behaviour.