rocks
Bluebirds sometimes build more than one nest, as a diversion to predators.
Adellie penguins use pebbles to build nests.
The doctor bird uses silk from the spider web to build their nest.
the penguins love stones for nesting because in the wild they would use stones to nest on the coast
Yes, penguins use rocks in their mating rituals to build nests and attract mates.
The owl likely used tree branches (abiotic component) to build a safe nest in its ecosystem.
mud and saliva
No they build a new nest for each brood. However they may use the same nest site year after year.
Squirrels nest in trees or on the ground, using materials like twigs, leaves, moss, and fur to build their nests.
No. They make a new one for each brood but if you take out the old nest after the young have left the nest they may make a new in that birdhouse.
No. They build a new nest each year because of safety, health, and instinct reasons.
They pick anything they can find which is suitable.