Measurements

Male larger than female in body length and bill length; these differences are apparent when the 2 are seen together (Hancock et al. 1992). In Texas males, mean, in cm (range): wing length 35.1 (34.1–36.9); bill width 5.4 (4.9–5.9); culmen length 16.8 (15.4–17.9); tarsus length 11.4 (10.7–12.3); tail length 9.8 (9.3–10.3); length of middle toe without claw 8.0 (7.6–8.6). In Texas females, wing length 33.5 (32.2–35.2); bill width 4.9 (4.5–5.3); culmen length 15.6 (15.1–16.2); tarsus length 10.4 (9.7–10.7); tail length 9.4 (8.5–10.0); length of middle toe without claw 7.4 (7.0–7.9; sample sizes for both sexes unknown; Oberholser 1974). On average, male slightly larger than female in wing length (13–15.8 mm, 3.8–4.7%), culmen from base (9–11.9 mm, 5.7–7.6%), and tarsus (4.9–9.9 mm, 4.7–10%); less difference in tail (2–4.1 mm, 2–4.3%; Oberholser 1974, Blake 1977). Average width of bill at spoon 10% greater in male; length of middle toe without claw 7.8% greater in male (Oberholser 1974). Geographic variation cannot be evaluated because measurements from U.S. and South America are combined (Blake 1977, Wetmore 1981) and the sources of measurements are not always clear.

Too few body mass data to compare male and female. Mean mass from Florida 1.49 kg ± 0.17 SD (range 1.23–1.8, n = 27 nesting adults; Bjork and Powell 1994); 1.58 kg (no sample sizes; Palmer 1962, Oberholser 1974); 1.43 kg in males (n = 3), 1.52 kg in females (n = 2; Haverschmidt and Mees 1994).