A Couple of Wrens

This pair of House Wrens seems to be building a new nest in the box that is hung on an old utility pole near the old bar.

Typically, it’s impossible to tell the male and female apart, as the species is not sexually dimorphic. But, one of these two has many missing feathers around the rump. I’m no expert in Wren anatomy, however based on one photo where I can see the rear vent, I think it’s the female that has endured the trauma.

At AllAboutBirds.com, I read, “As the season progresses their nests can become infested with mites and other parasites that feed on the wren nestlings. Perhaps to fight this problem, wrens often add spider egg sacs into the materials they build their nests from. In lab studies, once the spiders hatched, they helped the wrens by devouring the nest parasites.” I am wondering if this cream colored, soft and stringy looking item in the male’s beak might be a spider’s egg sac.