Line 45 ERROR UnicodeEncodeError: 'ascii' codec can't encode character u'\xe1' in position 16: ordinal not in range(128), has something to do with add

ERROR

Exception in thread Thread-2:
Traceback (most recent call last):
  File "/usr/lib64/python2.7/threading.py", line 804, in __bootstrap_inner
    self.run()
  File "/usr/lib64/python2.7/threading.py", line 757, in run
    self.__target(*self.__args, **self.__kwargs)
  File "redditbot.py", line 48, in poststream # GIST HAS DIFFERENT NUMBER OF LINES
    subredditra.contributor.add(author)
  File "/home/kenmr/.local/lib/python2.7/site-packages/praw/models/reddit/subreddit.py", line 1362, in add
    self.subreddit._reddit.post(url, data=data)
  File "/home/kenmr/.local/lib/python2.7/site-packages/praw/reddit.py", line 432, in post
    return self._objector.objectify(data)
  File "/home/kenmr/.local/lib/python2.7/site-packages/praw/objector.py", line 122, in objectify
    raise APIException(*errors[0])
  File "/home/kenmr/.local/lib/python2.7/site-packages/praw/exceptions.py", line 25, in __init__
    error_str = '{}: \'{}\''.format(error_type, message)
UnicodeEncodeError: 'ascii' codec can't encode character u'\xe1' in position 16: ordinal not in range(128)

redditbot.py

import praw
import re
import collections
import threading

reddit = praw.Reddit(client_id='XXXXX', client_secret="XXX",
                     password='X', user_agent='BOT',
                     username='X')

subredditra = reddit.subreddit("subreddit to get contributors list with mod permission")

contlist = []
for contributor in subredditra.contributor(limit=None):
    contlist.append(contributor.name)

wanted = ["wanted","words","in","comments","to","add","to","contributors"]

def commstream(subreddit):
    sub = reddit.subreddit(subreddit)
    for comment in sub.stream.comments():
        text = comment.body # Fetch body
        author = comment.author
        # print author
        cnt = collections.Counter()
        words = re.findall('\w+', text.lower())
        for word in words:
            if word in wanted:
                cnt[word] += 1
        cntsum = (sum(cnt.values()))
        if (not author in contlist) and (len (cnt) >= 2) :#and ((len cnt) >= 2):
            print author
            print text
            print cntsum
            print cnt
            subredditra.contributor.add(author)
            contlist.append(author)

def poststream(subreddit):
    sub = reddit.subreddit(subreddit)
    for submission in sub.stream.submissions():
        author = submission.author
        title = submission.title
        if (not author in contlist):
            print title
            print author
            subredditra.contributor.add(author) #ERROR
            contlist.append(author)

# qcp = Queue.Queue()
# qpc = Queue.Queue()
thread1 = threading.Thread(target=commstream,args=["subreddit to stream comments"])
thread2 = threading.Thread(target=poststream,args=["subreddit to stream post"])
thread1.start()
thread2.start()

# while True:
#     try:
#         commstream()
#     except praw.errors.HTTPException as error:
#         if error._raw.status_code == 503:
#             time.sleep(30)
#             print("503 ERROR")
#             continue
#         else:
#             raise SystemExit