There is no clear reason. Some wind vanes (weathercocks) have other shapes on them, ships, for example.
It has been suggested that the Church (St Peter was the first Pope) encouraged the placing of weathercocks on churches as the cock was the emblem of St Peter. Remember "Before the cock crows thrice …"
because it tells the chicken where to go
Ceiliog gwynt is wind vane.
I used a wind vane to see what direction was the wind blowing to
wind vane
It is measured using an anemometer.
well there can be alot of stuff on a wind vane but it is usually a rooster and helps animals feel comfortable around home.
A wind vane typically consists of a flat or arrow-shaped piece of metal attached to a vertical pole. The metal piece rotates freely, pointing in the direction of the wind. This allows observers to easily determine the wind direction.
A weather vane is only used to measure the velocity of the wind. Below a metal rooster is a fixated X with letters on the end, indicated N (north) W (west) E (east) and S (south). Which ever way the rooster is facing is the direction of the wind, i.e., if it is facing the way above N, the wind is blowing north.
A wind vane is a mechanical way of telling which way the wind is blowing. Some can be just a windsock that fills with air when the wind blows. Another might be iron, cast in the form of an animal like a rooster, that is set onto a spindle that lets the rooster turn easily.
The wind direction vane is spinning like a top!
Wind vane
Weather vane is for direction and anemometer is for speed
The word vane could be in a sentence like, "i have a big vane"
because it tells the chicken where to go
Ceiliog gwynt is wind vane.
I used a wind vane to see what direction was the wind blowing to
The wind vane is in the barn.