0     Fish     Trout
1     Fish  Pickerel
2     Fish      Pike
3     Bird     Goose
4     Bird      Duck

Num_Fish = np.random.randint(5, 45)
Num_Bird = np.random.randint(55, 95)

d = {'Bird': Num_Bird, 'Fish': Num_Fish}
data['Random'] = data['Category'].map(d)

0     Fish     Trout      22
1     Fish  Pickerel      22
2     Fish      Pike      22
3     Bird     Goose      53
4     Bird      Duck      53