NEST-BOXES

It is important to standardize nest boxes as much as possible across Golondrinas sites. This will reduce the number of potential confounding factors in comparative studies, especially those asking questions about physiology and energetics.

The box suggested here is a simple nest box with a side that swings out to facilitate checking the box contents and cleaning. All lumber is 1 inch lumber that is really about 0.75 in thick (1.9 cm). It is important to use rough-cut lumber, or at least lumber that is unfinished on one side (with the rough surface facing the box interior). The rough surface provides a purchase for the young swallows when they are ready to leave the nest box and for the adults in their hundreds of visits into and out of the box.

Nails or screws may be used for assembly–nails are a lot cheaper, but screws last better and make modifications of the box or replacement of some parts easier. If screws are used, it is best to use an uncommon head type–we use square drive screws in the states, as curious young humans are less likely to have a square-driver available. The box is mounted on a tree, fence post, or pole by threading wire through the holes drilled in the back, or by screwing the box directly onto the support.

If available lumber is thicker (or thinner) than suggested, the inside length and width (i.e. the floor dimensions) should be 5 x 5 in (or 12.7 x 12.7 cm).

The hinge for the swinging side is made with two aligned nails. Being careful that these nails are on the same line and perpendicular to the walls of the box insures that the side will swing out fully. The swinging side is held in place with a nail placed into an inclined drilled hole that goes through the front side and penetrates the swinging side (“keeper nail”). This hole should be drilled after the box is assembled, and when the “keeper” nail is installed, it is difficult to tell that the box is designed to open at all. This can be a real advantage in areas that have a lot of curious young humans about!

All boxes should be fitted with a simple ‘wig-wag’ trap, which greatly increases the efficiency of capturing adult breeding swallows for banding and experimental manipulations.

 

 

 

“Wigwag Trap” for Trapping Adults

A simple but effective nest box trap for breeding adults can be constructed using the design shown at left.

The advantage of this trap is that it can be installed on the box from the time the swallows first investigate the box. One can then trap the birds there without ever having to worry about them getting used to a new object near their box at trapping time.

The trap is activated by pulling on a long piece of monofilament fishing line attached to the ‘anchor’ staple by means of a snap-swivel. The line is attached only at the time of trapping, and may initially cause some hesitation by the birds. We typically watch from 15 – 20m away and vigorously pull on the fishing reel when the bird we are after enters the box. Note that there are two ‘keeper’ holes. When the trap is not in use, the right-most hole is used to hold the trap securely away from the hole. To set the trap the ‘keeper’ nail is moved to the left hole and the trap rests against this nail until pulled to capture the bird(s).

The ‘wigwag’ can be easily cut from standard lath material (roughly 1/4″-3/8″ thick x 1.5″ wide). The anchor staple and the trip line guide are heavy carpentry staples about 1cm long. For the pivot nail we use galvanized roofing nails that are short enough not to penetrate through to the inside of the box, with a large head that serves to stabilize the lath at its pivot. For the keeper nail we usually use “sinker nails” that are covered with heat-sensitive glue. We never generate any heat by pounding these in, but the glue coating keeps the nails from rusting. And for the ‘catch’ nail we use a very large galvanized finishing nail.

Install these traps in the following way:

1.            Hammer a staple onto the lath about 1/2 way along its length. Be sure not to go through the lath, otherwise the staple points will snag on the box front.

2.            Place the lath over the box hole and the spot for the pivot (dashed ‘footprint’ in diagram – note angle). Drill a hole through the lath and into the box at the pivot, placing the hole off center on the lath so that more of the lath is below the pivot than above it. This encourages the lath to fall away from the box hole if anything goes wrong. At the same time, drill a pilot hole for the ‘catch nail’, just slightly to the right side of the lath. This pilot hole should be parallel to the ground, not all the way through the front of the box, and not too close to the size of the nail.

3.            Pound in the roofing nail to pivot the lath–we sometimes add a washer between the head of the nail and the lath to ensure that the lath can turn freely on the pivot. In any case, do not pound the nail in very tightly!

4.            Drill two holes, inclined downward, for the keeper nail. Drill one hole through the lath (this will hold the lath when not in use), and one hole directly to the left of the lath. These holes should allow the keeper nail to be inserted and removed easily, and it helps if the hole is not drilled all the way through the box wall (it might catch the swinging side).

5.            Pound in the long catch nail securely, but not through the box front. Swing the lath up against the catch nail (check to be sure the hole is covered – if not, the pilot hole may need to be re-drilled) and, holding the lath securely, bend the catch nail to the left across the edge of the lath to make a latch.

6.            Finally, nail in the trip line guide. Only drive this staple in far enough to hold firmly in the wood–you want to leave enough room for the snap swivel of your fishing line to pass easily through when setting and removing the trap line.