Nestbox styles and pros and cons are subject to great debate. A box can open from the top (roof), side, front, or bottom. And when it does open, the door can be hinged on top edge or the bottom edge. While some of the opening styles may be easier to clean, they may not desirable from a routine monitoring standpoint.
Top hinge: easier to peek in, box contents contained
Bottom hinge: contents can fall out.
Top opening boxes: Stretch a 12″length, 3/4″ wide strip of elastic to its maximum, and then staple it (using galvanized staples) to the top and size of the box. Gilbertson boxes detach from the top when squeezed, so you have to be careful not to drop the bottom part when separated. Good for preventing and removing paper wasps, and for nestbox cams
Front opening: Adult may fly out in your face since that is how they are used to entering and exiting. Can be difficult to set up monofilament to deter house sparrows unless the fishing line is placed to the sides. Easier to set up on inbox traps. Not suitable for a Noel Guard or a cone added to the entrance.
Side opening: Can be tricky to set up inbox traps if box is too narrow.
Bottom Opening: World’s worst idea in my opinion.
|Fairly obvious what would happen when monitoring this box if there were an active nest inside. If it had TWO openings (one on the side/top, one on the bottom) it might work. This box could be easily cleaned by dumping contents into a bag. Nests should not be dumped on the ground when cleaning boxes, as the debris could attract predators.
|There is a hinge on the back of this box. If there were a loose, active nest inside, how would you keep it from falling apart? How can you see the top of the nest to ID or count eggs/nestlings ? If the nest slumps when opened, it will be difficult to re-close the box. It is not very stable, and the hinge can break off when opening.
|Obviously eggs or nestlings could fall out of this box when opened.
The student of Nature wonders the more and is astonished the less, the more conversant he becomes with her operations; but of all the perennial miracles she offers to his inspection, perhaps the most worthy of admiration is the development of a plant or of an animal from its embryo.
-Thomas Henry Huxley, British biologist and educator. Reflection #54, Aphorisms and Reflections, selected by Henrietta A. Huxley, Macmillan, 1907.