The Effect of Temperature on Northwest Crow Flocking Behaviour


  • Sarah Ghoul


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