By Rick Cruz and Terry Suchma

For many PM landlords and bluebird managers, European Starlings continue to be a scourge in our interest, decreasing the numbers of Purple Martins as well as other native, cavity-nesting birds. Starlings, not only foul grains and livestock water on farms, but they destroy many cavity nesting bird nests and kill Purple Martins and other managed songbirds (House Wrens, Nuthatches, chickadees, American Bluebirds, etc.). Most landlords in our interest, today, understand the impact of this unwanted non-native bird species from Europe.

In the recent Spring issue of The Scout Report (Vol. 6 (1), pp. 15-16 & 31), The PM Society provided a very interesting and enlightening article by PM Society member, John R. Consolini, of Redmond, WA. In this article, Mr. Consolini, a wildlife nuisance officer, provided informative text on why European Starlings are tremendous nuisances to the agricultural industry. Also, John generously furnished our readers with a detailed diagram on how to make a large-scale, starling trap, also known as an Australian Crow Trap, or V-Trap. The V-Trap is commonly used by wildlife nuisance officials like John Consolini, or by landlords that live on large parcels of land, usually in rural areas. Because of the large profile of such traps, V-traps are not typically used in city, or suburban, settings where housing and people are more densely packed.

Many, in the Purple Martin interest, are already familiar with the V-Trap from plans provided by Purple Martin Society member, Andrew M. Troyer, Conneautville, PA, through his wildlife catalog, Bird's Paradise. The V-Trap is one of the most effective bait traps for capturing House Sparrows and European Starlings.

For those who are unfamiliar with this unique trapping device, the typical V-Trap is a large, rectangular hardware cloth cage (6' H x 6' W x 8' L) with a V-shaped roof, or top. The inside of the trap is baited with bread products or apples. A small three-inch slot runs the length of the center of its V-shaped roof. Target species look down and see the bait inside, pass through this slot-opening, gaining access to the food. Once inside the V-Trap, the birds typically can not figure out how to get back out the slot through which they gained entrance. Ordinarily, a side-access door allows a person to get into the low slung trap (5-6 feet high) to remove unwanted birds and/or to clean it. The trap has no moving parts and does not need to be reset in any way. It is a continuously-working trap for targeted birds as long as there is food provided and a few others birds, or decoys, left inside. Basically, this is the premise on which the trap is supposed to work. But, from time to time, some starlings and House Sparrows do learn how to get out. If left inside long enough, a few wily birds figure out how to walk upside-down on the inside top section of chicken wire to the V-Trap funnel, gaining access to the three-inch slot opening at the top. Once one bird sees how it is done, it can easily be birdie see, birdie do with some of the other birds inside the cage trap. Soon, the whole lot of birds may follow and escape.

The trap is rather large as well as bulky. It requires a strong human back to move it from place to place. It was some of these problems that PMS member, Dennis Zwerenz, Hampshire, IL (see Scout Report article PM Wonder of the World, Vol6 (2)), wanted to eliminate. In past years, Zwerenz used two V-Traps with good results. It was from his observations from using the V-Trap that inspired him to improve this trap and make it more efficient. With these new improvements, a new trap name was needed.

The Z-Trap was born.

The Z-Trap

Close-Up of the Z-Funnel

Zwerenz envisioned a trap that could be easily moved without the help of others. In order to do this, the weight had to be reduced. Traditionally, the V-trap is made using 2 x 4's and covered in one-inch chicken wire. Plus, it typically has no solid floor and sits on the ground where it is placed.

The sheer size of it and the material use to construct V-Traps made it a formidable thing to move. So, the first improvement had to be in the materials used. Zwerenz would use more lightweight materials. Instead of 2 x 4's of wood, Zwerenz made the structure out of 2 x 4's of green fiberglass and covered it in 5/8" green galvanized wire with 5/8", or ½ " square mesh. Like other ingenious landlords, the fiberglass that Zwerenz used were scraps that he cleverly found. The fiberglass was similar to the fiberglass used in making fiberglass step-ladders. Understandably, one must be careful when working with fiberglass as it irritates the skin.

Fiberglass certainly reduced the weight, but if left permanently assembled, it would still be too bulky and heavy to move alone. So, Zwerenz met this challenge and built the trap to consist of eight large, individual removable panels. Four walls (sides), two roof sections, the specially designed Z-funnel, and a floor (also consisted of four smaller panels). Six-inch rubber wheels were installed on all side, or wall, panels so that the partitions could be wheeled easily during the trap's assembly. It must be noted that the wheels do not aid in moving the assembled trap at all. The separate partitions are mobile but not the assembled trap.

All panels can be quickly assembled, or disassembled, with the use of four special drawhasp latches (#V-35) ($6.00) secured by padlocks (Zwerenz uses #10 padlocks). Drawhasp latches and #10 padlocks are sold by National Hardware Co. and available almost anywhere in stores like Farm and Fleet, Sears Hardware and Home Depot stores. These latches clip on to each wall panel giving the trap its solid rectangular shape. After the drawhasp latches are installed, Zwerenz puts locks on them so that the latches do not pop off as well as for security against stealing or vandalism of the trap.

The most important feature of the trap is the Z-Funnel. This is the trap part that provides the access for the birds to gain entry into the trap but does not allow them to escape. The V-Trap designs includes a three-inch wide gap through which the birds just drop down, from the trap roof, to get to the bait down below. Typically, running the whole 7-8 foot length of the trap, this gap is situated in the middle of the two roof panels that are joined at a 25° angle. Once inside, the birds ordinarily cannot access the opening through which they came. Usually! But, sometimes, the birds figured it out, and the occupants climbed and fluttered or climbed their way along the underneath of the chicken wire roof until they reach the gap and headed for freedom.

Zwerenz set out to eliminate this frustrating escape problem. To do this, Zwerenz made the Z-funnel gap to measure 3" W x 4½ "D x 5' L. The gap is lined on both sides with clear acrylic plastic pieces that are 5'L x 4½"W.And, the clear acrylic plastic is key to stopping sparrow or starling escape. Then, he added three-inch dowel rods, screwed perpendicularly into the acrylic plastic every five inches and about 1" down from the top (all along five foot gap of the funnel). On top of the funnel and on the roof, Zwerenz made a fiberglass canopy, which can also be made from wood, PVC or metal, and runs above the Z-funnel gap along the length of the gap and is installed five inches above the Z-funnel entrance gap. If a bird chooses to enter the trap, the bird can not see the way from which it came due to this canopy. The canopy blocks the view of the sky, and freedom, from the birds inside. The dowels provide a convenient perch above that give potential occupants a bird's-eye view of the food inside while comforting the birds' unwillingness to enter. Once inside, if the occupant decides to climb upside-down and flutter to escape up through the funnel opening, it finds that its way is also thwarted by the 4 ½" clear acrylic plastic side pieces that lines the inside of the Z-funnel entrance. The birds cannot get a grip on the slip acrylic. The plastic actually hangs down an additional inch, or so, blocking escape like a shield. This modification alone has made the Z-Trap a benchmark trap.

Still, Zwerenz came up with a few more innovations to improve the Z- Trap's efficiency.

With the standard V-Trap, live decoys are essential to maintain a steady trapping rate. In order to do this, several birds must be kept alive inside the trap throughout the trapping season. This means that food, water and shelter must be provided. Food is not big issue here as the trap should be regularly baited every two days with food and a pan of clean water that is placed on green Astroturf® floor panels.

Times regularly occur when the trap has been tremendously successful and must be emptied of most of its decoys. The old way was for the landlord to enter the trap, through a side access door, and with a large net, to catch the birds, and a pillowcase in which to place the captured birds. This can draw attention from uneducated and nosey neighbors, is time-consuming and sometimes difficult. So, the perfected Z-Trap has two sheltered areas that are attached from the outside of the trap but are open to the inside. These also double as a bird-removal device.

The shelter areas, or bird removal devices, are called Shelter Boxes, and are located on each end of the trap. A 100-watt lightbulb, inside the Shelter Boxes, provides warmth during the cold winter. The trap occupants spend cold days and nights roosting inside these Shelter Boxes. Unknown to them, a door closes and traps them inside this roost/Shelter Box for removal. A small opening in the back promises freedom, but instead, it leads to a tube that drops down into a hardware cloth, collecting cage. This wire cage is then removed and its occupants can be disposed of in a humane manner. No backbreaking activity is needed to round up the trap contents in the low-slung trap.

The finishing touch on the Z-trap is its color. This may seem like a trivial thing, but Zwerenz's attention to details, makes this important. Here, in the greater Chicagoland area, great flocks of House Sparrows and starlings begin to congregate around the dumpsters of every restaurant as winter draws near. Once the insects of summer have been killed by frost, these dumpsters become their primary food sources. For the most part, the local dumpsters here are green in color. Knowing that birds have the ability to imprint on food sources, Zwerenz rightfully thought that the color, dumpster-green, would help increase his catch-ratio. So, the green fiberglass and plastic-coated fine metal mesh, along with green indoor/outdoor carpeting on the floor panels, put the finishing touch to the Z-Trap.

Last Fall, PM Society member, Harlow Fox, of Morris, IL, using a new and improved version of the Z-Trap captured more than 3000 starlings from October '98 to March '99. For those PM landlords who have a large starling problem with their Purple Martins and/or bluebirds and are living either on large farm tracts or suburban estate-type lots, this can be a very important addition to the management routine.
We are very pleased to present to our members The Z-Trap as designed by our valued member, Zwerenz. As you may remember, Zwerenz is also the engineer for The Purple Martin Tower profiled in our last issue.

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