Daurian Shrike versus Turkestan Shrike
From The UAE Checklist:
Isabelline Shrike Lanius isabellinus isabellinus
This subspecies is called Isabelline Shrike (Daurian).
Common migrant and winter visitor, October to April, scarce other months.
Birds of the subspecies-group Isabelline Shrike (Chinese)·L. (isabellinus) arenarius/tsaidamensis could occur, but not reliably reported.
Turkestan Shrike Lanius phoenicuroides
Common migrant, March to early May and September to mid-November; scarce or absent other months. Recorded July.
Let's look at female and immature red-tailed Shrikes in the UAE: