Welcome to the community!
Since your problem is to check whether three is a significant difference between the number or Migrants and the number of Residents over different time periods of spring, I think you may do ANOVA here, provided the assumptions hold good.
You can compute Migrant_Resident_count_difference as the difference of Migrant Count and Resident Count. Then, you can do ANOVA on these differences with respect to Time Period.
Hope this helps.
PS
I should emphasise that though ANOVA can be used, it's debatable whether you should use it or not. You've count data, so surely the assumption of normality will fail. If there are "large" number of observations, then data can be assumed to have come from a Normal distribution (saisfying conditions of Normal approximation to Poisson / Negative Binomial), and then you can use it, otherwise you should not.