Table 1. Summary of nest measurements.

	American Robin		Yellow Warbler		Carduelis		Savannah Sparrow
	Churchill	Elgin	Churchill	Elgin	Churchill	Elgin	Churchill	Elgin
Nest mass	246.1±45.2	163.8±40.0	9.6±2.1	5.7±1.4	16.6±3.3	9.7±2.2	8.6±3.4	10.6±3.1
Nest-wall thickness	17.3±3.6	14.0±2.8	11.9±0.9	8.1±1.0	15.9±2.7	12.0±0.5	9.2±4.6	10.8±3.0
Exterior nest diameter	124.2±4.6	113.2±4.0	71.7±3.8	63.1±1.5	78.5±6.1	73.3±1.0	83.1±9.9	79.8±10.2
Interior nest-cup diameter	93.9±4.0	86.7±6.5	49.9±1.8	48.7±1.8	49.8±3.4	48.6±1.0	70.5±6.9	60.9±2.9
Exterior nest depth	97.8±14.8	96.8±13.8	71.1±6.6	59.6±12.0	55.8±6.0	70.5±9.4	55.8±10.6	54.3±8.4
Interior nest- cup depth	59.6±5.1	50.0±3.8	31.1±4.9	33.9±2.2	29.0±2.2	33.7±4.1	33.2±4.5	43.4±2.5

Summary of nest measurements taken from nests for each species from our northern site near Churchill, Manitoba and our southern site near Elgin, Ontario. Measures of the outer and inner nest cup diameter are the average of the maximum and minimum diameters of the outer and inner cup. Outer nest depth is the distance from the top rim of the nest walls to the bottom of the nest's exterior. Inner cup depth is the distance from the top rim of the nest walls to the base of the interior nest cup (where eggs are placed). Nest dimensions are the average measurements (in g or mm) of five nests (± SD). N = 5 for all species except Carduelis in Elgin where N = 4.