What are the dark animals called?
The animals are birds.
    src        edge_attr  dst
0     0   to the left of    6
1     0  to the right of    5
2     0  to the right of   19
3     1  to the right of   19
4     1  to the right of    5
5     3   to the left of   14
6     3   to the left of   10
7     3   to the left of   17
8     5   to the left of    9
9     5   to the left of    1
10    5   to the left of   12
11    5   to the left of    0
12    6  to the right of    0
13    6  to the right of   14
14    6   to the left of   11
15    7  to the right of    8
16    8  to the right of   12
17    8   to the left of    7
18    8  to the right of   17
19    9  to the right of    5
20    9  to the right of   19
21   10  to the right of    3
22   11  to the right of    6
23   11  to the right of   14
24   12   to the left of    8
25   12  to the right of   19
26   12  to the right of    5
27   14   to the left of   20
28   14   to the left of   11
29   14   to the left of    6
30   14  to the right of    3
31   16   to the left of   21
32   16   to the left of   18
33   17   to the left of   21
34   17   to the left of    8
35   17  to the right of    3
36   18  to the right of   16
37   19   to the left of    1
38   19   to the left of    9
39   19               of    5
40   19   to the left of    0
41   19   to the left of   12
42   20  to the right of   14
43   21  to the right of   16
44   21  to the right of   17