What are ways that a supervisor can reward his/her employees to keep up morale?

Boy, that's a good one.

I had a boss who couldn't understand why her crew was always so unhappy and disjointed. She was just clueless. She always bragged about her management style, what a great manager she was, how great she was at team building, how many staff she had managed in the past, etc., and she was a nice lady, but . . . that didn't make matters any better.

The best way for a boss to make his crew feel appreciated is to show it.

It's not expensive to buy your crew pizzas on a Friday afternoon. It's not expensive to bring bagels and cream cheese or donuts or snacks in on a Monday morning. It costs nothing to stand up in the middle of the room and say, Hey, John, I really appreciate the job you did last week; keep up the good work - and mean it. John will walk around on cloud nine, and he will work all the harder for the public display of kudos again - and so will everyone else. (Those who don't and who are jealous that John got a good word and they didn't are not team players and don't belong on your team).

When you are close to a holiday weekend, whether it's Easter or Christmas or President's Day, you can take your crew to a nice restaurant for lunch, you know, on a day when you're going to have a long weekend or something like that. Most bosses get an expense account specifically for entertaining their crews. My boss did. She was given a budget of $3000 every year for doing nice things and rewarding her crew. She never spent a dime of it.

The next thing a boss should NEVER do is correct a member of his or her staff in front of another member of the staff. For starters, it's illegal. It's called creating a hostile work environment and it's a violation of the Civil Rights Act of 1964.

Secondly, your anger and frustration will pass, but your staff member's humiliation will last forever. It will poison everything he/she does from that moment forward and it will put such a strain on all his/her relationships that he/she will eventually quit/get fired over it. That kind of humiliation is almost impossible to overcome.

Thirdly, and most importantly, if one of your staff has a serious complaint about another member of staff, take it seriously. I complained to my boss - a woman! - that my coworker (male) was harrassing me and threatening my physical safety. Not only did she not take it seriously, she scolded me for telling my husband what was happening. I complained to HR over the young man and I nearly got fired over it. In the end, in order to "make me happy," they gave HIM a raise and a promotion. The whole crew fell apart after that. Morale was so low, everyone in the department was jumping ship as fast as they could.

Another important thing to do is if you get frustrated and lose your cool in front of the whole group, apologize in front of the whole group. This will make you look like a humble enough boss that you know you are not perfect and are capable of making mistakes, willing to be accountable for your actions and not pass the buck and blame your subordinates for your problems. This will breed loyalty like you won't believe.

One last thing. If you see that things are not working well, ask your crew in a group meeting to tell you where the holes are and how they can be shored up. If they feel that you are being sincere, they will tell you the truth. When they have a suggestion, if it's possible, follow through with it and don't just 'take it into consideration.'

Those few little things, nothing, really, will be the difference between people who will run through walls for you, or people who will want to run over you in the parking lot. Something like 74% of employees feel that they can do a better job than their boss can. That's serious and shows a serious chasm between the boss and his crew. Take it seriously and try to be the guy/gal in the 26% rather than the other way around.

Good luck.

bonus pay helps or having a little party will boost moral to perform well. Or saying Thanks to them.

well from what I hear the supervisors aren't supposed to no longer encourage their employees to become better people
because foreigners will work for less.

Buy a treat for the group and the supervisor should call the group together and tell them "Thanks for doing such an outstanding job."

why not try thanking them and letting them know when you feel a job is well done - we are ALL working for the paycheck, but a little appreciation goes a LONG way

Take them out to lunch, give them a bonus, take them out for Starbuck's coffee mid morning, just because, or just say, "Thanks for the great job you have been doing, I really appreciate all your effort." And then remember them at raise time.

Feedback is always good - if someone does something well, tell them, and be precise about what exactly they did - not just "Good work, well done!" but "You dealt really well with that irate customer, and calmed him down", or "That was good team-work, and helped us get the job done early". Then tell the head of the department how well the employee did and maybe let the employee know you are doing this.

I am assuming t as you mentioned "supervisor", that you did not mean "boss", and therefore that this person is not in a position to pay bonuses or give extra hours or days off. Obviously these would be good rewards if relevant. Some of the suggestions seem to contemplate the supervisor having to spend their own money on treats, but this would not really be a reasonable expectation, unless they are given the money to do this by those in control of the organization, or unless any increased output by their team would result in a sufficient financial gain to them to make it worth their while expending their own money on staff they are supervising.

Depends on the size of the team. Small teams generally get along better than larger ones where sub teams and severe pecking orders start to form if you don't keep alert. Make sure that everyone knows what they have to do for a given situation. There is nothing worse than a team unsure of it's final objective. Well directed teams are generally happy and the reward of the job well odne is often the driving factor.
Make sure you have meetings on Mondays, not Fridays! explain and present your expectations for the week. you can do the friday pizza run occasionally, but only if there has been a lot of late night working or an unusually heavy workload or tight dead line has been met. You don't want to be too chummy with your team as sooner or later you are going to have to winkle one or two out for a roasting or some stern guidance. Being too friendly can lead to a situation of familiarity which can be disastrous, especially in teams where the loyalty is less than forthcoming.

This is my personal experience of being in, and leading teams. Hope it helps.