The Squacco- /Indian Pond Heron complex Ardeola ralloides/grayii
 

From The UAE Checklist:

Squacco Heron Ardeola ralloides
Fairly common spring and autumn migrant, rare other times.

Indian Pond Heron Ardeola grayii
Common winter visitor to the Khor Kalba mangroves on the East Coast from mid August to May, rare other months and other sites.