What Mean the Flies?

I'm worried about my nestling house wrens. The parents still come and go, ducking inside to carry off fecal sacs after almost every morsel delivery, but several changes in today's observation are cause for concern, whether real or imagined: 1) The time between deliveries seems longer, 2) The cries of the nestlings sound thinner, 3) The skinny adult (the mother?) entered the house at one point and stayed long with no squawking from the babies, and 4) Flies are buzzing around the house.

I've grown fond of these infants, and fear for their good health.

The mugginess of the morning, the pastel of the sky, the weakness of the clouds, the heaviness of the air, the forecast of heat for the day---the whole of the picture contributes to a prevailing sense of doom for my young family. dkm