To calculate the mean number of birds the bird watcher saw in one day, we first need to sum the total number of birds observed and then divide by the number of days.
Here are the data points:
- Monday: 31
- Tuesday: 33
- Wednesday: 44
- Thursday: 29
- Friday: 88
- Saturday: 34
- Sunday: 30
Now, let's sum these values:
\[ 31 + 33 + 44 + 29 + 88 + 34 + 30 = 319 \]
Next, we divide the total by the number of days (which is 7):
\[ \text{Mean} = \frac{319}{7} \approx 45.5714 \]
Rounding to the nearest whole number, the mean number of birds the bird watcher saw in one day is:
\[ \boxed{46} \]