It flew over to the protected cool of the spruce where its "offspring" awaited.
I didn't think the calls I were hearing were those of a small sparrow and sure enough, a hulking flying target was sullenly waiting in the cool.
It re-doubled its begging when it heard the Chipping Sparrows calls...
The plump parasite was soon rewarded. Sibley lists an average cowbird weight of 44 grams and the sparrow at 12. Couple that with juveniles being fed up to build up fat reserves for their initial inefficient foraging and I'll bet the weight ratio is closer to 5:1.