Maidens mares are those that have never been exposed to a stallion. That being the case, she could not be pregnant.
If you mean a mare who is having their first foal she will generally relax over the rump and the tail will become flaccid. Her udder may or may not be enlarged
but if it is her milk color will change from clear/golden to white.
First time mares are somewhat less predictable than mares that have had several foals, for this reason it is advisable to be more vigilant than with mares
who have a foaling history.
She will cock her tail to side or swish it violently to the side, urinate small amounts frequently and squeal; usually at the same time.
RGW
Well I think that they hold up their tail, at least that's what my horse riding instructer's horse does
The approximate gestation of a horse is 340 days.
Yes
a mare gives birth to the foal eleven months after conception
Mares do not reject their foals, and they will fight to protect them. In any case where the mare does reject her foal, it is because she deems it is physically damaged at birth or it is not 'normal'. A mare having her first foal is known as a maiden mare, whereas others are known as broodmares.
a broodmare is a female horse or pony used for breeding
yep
To give birth to a foal (baby horse) by a mare (mother horse).
mate a donkey mare with a donkey stallion
It takes 6 days of playing on howrse.com for a mare to give birth on Howrse.com. This is very close to being equivalent to the 11 months that a real mare would take to give birth.
You might find the following link helpful.
The udders will be swolen and the mare will drip milk. The mare will be restless and will lay down after a while. Also she will pie right before she is going to give birth.
A mare is pregnant for 340 to 342 days. The actual birth is very fast and normally takes 30 minutes as in the wild a mare would be in danger from predators so has to give birth fast.