Table 1.

Number and percentage of helpers falling into different categories of pedigree relationship with breeders and coefficients of relatedness (r_pedigree) between helpers and the brood they care for calculated from pedigrees.

helper assisting	categories	rpedigree	number of cases	%
both parents	first-order relative	0.5	5	5.7
father or mother only		0.25	12	13.6
son or daughter		0.25	10	11.4
sibling		0.25	37	42.0
half-sibling	second-order relative	0.125	1	1.1
grandfather		0.125	1	1.1
aunt		0.125	2	2.3
non-relative	non-relative	0	20	22.7
total	—	—	88	100