If placed along a highway, a bluebird house should open parallel to, or away from, the road so the birds will not be hit entering or leaving their nests. Also, the openings should face toward a tree or shrub within 100 feet so young bluebirds have a place of safety for their first flight. Convenience. Bluebird houses should face open areas with few trees and low vegetation. This lets the birds see and capture insects.
leftover - a small part or portion that remains after the main part no longer exists remnant remainder, residual, residuum, rest, residue, balance - something left after other parts have been taken away; there was no remainder; he threw away the rest; he took what he wanted and I got the balance
Imagine digesting food in the body is like burning it. The leftover ash is what is referred to as acidic or alkaline. This is what causes the blood pH balance to change, resulting in a host of possible diseases since the body's ability to absorb and use nutrients from food is reduced in a highly acidic environment.