Data on growth and development of young Brown-headed Nuthatches, summarized from a more complete table in Norris 1958 . Data given as means of average of 2–3 birds measured per age category (day). Mass in g; all other measures in mm.


	Hatching	Fledging	Post-fledging
	0 d	18 d	42 d
Mass	1.2	10.1	10.0
Bill	1.5	6.8	8.7
Forearm	5.0	19.2	19.0
Tarsus	5.3	15.5	15.0
P6		36.3	53.7
P6-covert		14.7(1)	16.1
Capital tract (crown)		7.7(1)	7.7
Spinal tract (dorsal region)		15.5(1)	19.5
Ventral tract (sternal region)		11.2(1)	13.7
Rectrices (average from central)		17.5	29.7

1
(1)Fledging values for P6, capital tract, spinal tract, and ventral tract are averages of values for 16 d and 21 d, because values for 18 d were not provided.