Large Pied Wagtail

Like you rightly guessed, this family of birds gets its name 'Wagtail' because of the constant motion of its tail. The bird has a prominent white eyebrow and are generally found in pairs. The female is the one with duller brown colour. The bird has a pleasant singing note and is pretty comfortable with humans. This one came as close as two feet from me.
Photographed this bird near Sultan Battery in Mangalore.
Camera Sony H-7 ; 1.7x telephoto ; f/8

White Wagtail

The Wagtail prefers bare areas for feeding, where it can see and pursue its prey. This bird was foraging on my ship's deck for the entire day and never let me photograph it. Because of its constant movement, I had to keep moving with the bird and after pursuing it for hours, I finally gave up. Late in the evening, when the cold Persian gulf wind began blowing, this little bird came close to where I was standing to take shelter from the cold wind. It's is at this time that I set up my tripod and finally managed to photograph it. Mission accomplished.
f/4.5 , 1/10 sec