stack	nfemales	stack_size	nclutch
3	2	4	21
4	2	5	15
5	2	5	22
6	3	5	29
8	4	6	28
9	2	6	17
10	4	8	25
11	3	7	21
12	3	7	29
13	2	8	14
14	3	8	17
16	4	9	23
17	5	9	22
18	6	9	37
19	6	10	22
20	7	10	20
21	7	11	35
22	5	11	25
23	7	11	33
24	4	11	18
26	8	12	40
27	7	12	32
28	7	13	29
29	4	13	21
30	8	13	37