Table 1.

Least square means (±s.e.m) and differences between cold (−10 °C: C) and thermoneutral (27 °C: T) treatments for body composition variables in black-capped chickadees.

Variable	Cold	Thermoneutral	F (df)	P	% difference (C relative to T)
Food intake	3.86 ± 0.09	2.69 ± 0.08	96.4 (1,45)	<0.0001	43.5
Mass and fat
Body mass	11.96 ± 0.16	12.25 ± 0.16	1.5 (1,47)	0.2	−2.4
Total organ fat mass	0.88 ± 0.07	1.25 ± 0.06	16.1 (1,35)	<0.001	−29.6
Furcular fat mass	0.11 ± 0.01	0.15 ± 0.01	5.7 (1,35)	<0.05	−26.7
Muscles
LD pectoralis	0.41 ± 0.01	0.39 ± 0.01	0.97 (1,34)	0.33	5.1
LD legsa	0.23 ± 0.005	0.25 ± 0.004	9.2 (1,33)	<0.01	−8.0
LD carcassa	1.21 ± 0.02	1.24 ± 0.02	0.83 (1,33)	0.37	2.4
LD total musclesa	1.86 ± 0.04	1.85 ± 0.04	0.0005 (1,33)	0.98	0.5
Cardio pulmonary
Heart	0.16 ± 0.004	0.14 ± 0.004	12.0 (1,34)	<0.001	14.3
LD lungs	0.025 ± 0.001	0.028 ± 0.001	6.4 (1,35)	<0.05	−10.7
Digestive and excretory
LD gizzard	0.087 ± 0.005	0.079 ± 0.005	1.35 (1,35)	0.25	10.1
LD intestine	0.039 ± 0.002	0.036 ± 0.002	1.6 (1,34)	0.22	8.3
LD liver	0.078 ± 0.004	0.066 ± 0.004	2.0 (1,25)	0.17	18.2
LD pancreas	0.0094 ± 0.0007	0.0048 ± 0.0007	23.6 (1,32)	<0.0001	95.8
LD kidneys	0.030 ± 0.001	0.029 ± 0.001	0.21 (1,35)	0.65	3.4
Other
LD skina	0.11 ± 0.003	0.11 ± 0.003	0.01 (1,33)	0.91	0.0
LD brain	0.10 ± 0.001	0.11 ± 0.001	0.78 (1,35)	0.38	−9.1
Total LD body massa	2.33 ± 0.05	2.30 ± 0.04	0.18 (1,33)	0.67	1.3

Units are in grams except for food intake (g/day).

^aIncludes bone mass and controls for structural body size (see text for details).