Utility Pole Bluebirding

Dean E. Sheldon, Jr.

Introduction

Our family comes from a long line of birders and we've been birding for a long time. But Eastern Bluebirds (Sialia sialis) have been a part of that "long time" for only 13 years or since we moved to the farm. We first saw five birds on a dying black walnut tree in the pasture during a walk on a balmy Sunday afternoon in October 1981 and that changed our lives. We listened and read and talked to bluebirders. We went to workshops and joined bluebird groups and read almost everything relating to bluebirds that we could find. And, we put up our first boxes in the spring of 1982. From then on, we were committed-really committed--to bluebirding as an extraordinary conservation experience.

Scientific Studies

Dr. Wayne H. Davis is a faculty member of the School of Biological Sciences at the University of Kentucky and a member of the Ohio Bluebird Society. Dr. Davis is, perhaps, best known for his Kentucky slot-box and his research into anti-sparrow nest boxes for bluebirds. We have corresponded, informally, about utility pole locations for bluebird boxes since the fall of 1991.

In the course of our discussions, he cited the existence) of two studies indicating that bluebirds do not take to nest box sites on or near utility poles or power lines. That proposition was of great interest to us.

Munro and Rounds, writing in the Journal of Wildlife Management in 1985, concluded, among other things, that nest box trails for Eastern Bluebirds should be placed in open wooded pastures away from roads and utility lines. "Data indicate a strong association between sites used by Eastern Bluebirds and the absence of utility lines." The authors suggested that bluebirds tend to avoid using nest boxes below utility lines because of the presence of American Kestrels (Falco sparverius) as predators in these locations. In 1991, Steve Parren of the Vermont Fish and Wildlife Department, suggested in the Wildlife Society Bulletin that bluebirds seem to prefer nest box sites away from high perches (including utility lines) because of the use of these vantage points by kestrels.

While we have no quarrel with the research presented, our observations (its presented below) simply do not agree with the findings made. Our observations tend to be almost directly opposite from this published research. On the basis of our work, we believe that utility poles represent a preferred nest box site of the Eastern Bluebird.

Our Experience

Our bluebirding has been long in the practical and, admittedly, short in the scientific. We do no banding, but our record-keeping has been accurate, consistent, and complete from the outset.

In the spring of 1982 we first began placing boxes on the utility poles surrounding our farm fields. We subsequently placed boxes on the right-of-way fence along U.S. 30 near Hayesville in central Ashland County with extraordinary nesting results. From there, we began more utility pole box placements here in Ripley Township, Huron County--again, with amazing productivity. The Ripley trail has been expanded twice. We also have a trail in northern Richland County. Our third trail traverses parts of all three of the abovementioned counties. A total of 109 utility pole-mounted boxes were monitored on these trails during 1994. The remaining 42 boxes are post-mounted in fields and meadows in various locations.

We have recently begun a fourth utility pole trail of 25-30 boxes near Havana and Steuben in west central Huron County. We are also adding a few additional boxes to our other trails. When this work is completed, we will have 150 utility pole-mounted box sites in three counties covering more than 248 square miles (95.7 km2 in north central Ohio. This amounts to 1.65 box sites per square mile (.64 box sites per km2) throughout the area.

Because of our interest in the nesting success at utility pole sites, we have summarized our data for the last four nesting seasons in Table 1.

Obviously, there are numerous mathematical and theoretical conclusions which could be developed from this data. Our interest, however, is of a more practical nature--we simply want to produce more bluebirds from the nest boxes on our trails. We believe that these simple statistics show, conclusively, that the best place to accomplish this is on utility poles.

Criteria for Selecting Locations

As Wayne Davis points out "...it is common knowledge among experienced bluebirders that power poles and power lines make excellent sites (for nest boxes) and are a big plus as a part of bluebird nesting territory" (pers. comm.). The transmission wires themselves, cross arms, guy wires, bracing poles, and other appurtenances make excellent perches from which the birds conduct their predatorial flights. Road signs, sign posts, fences, fence posts and an almost endless variety of other fixtures found within road rights-of-way make for absolutely prime bluebird habitat. A closely-mowed berm is also a plus. But not just any old pole will do. Pole locations should be selected carefully. Generally speaking, the poles should be located in the following way:

away from farm barns and outbuildings, abandoned sheds, lean-tos and corn cribs, silos, feedlots, old machinery, etc.;

along or near a fence or fence post for perching before entering the box and for preening;

near a large tree which provides cover and roosting for the male while his mate is occupied in the box; o as far as possible away from House Wren (Troglodytes aedon) territory;

near a watercourse, if possible;

near a neat, tidy home with tight, closed outbuildings and a big, well-mowed yard which provides excellent foraging opportunities;

near or adjacent to pastures/meadows with animals grazing on a regular basis (but not near feedlots);

on back country roads with little traffic.

Table 1. Eastern Bluebird Nest Box Locations in Relation to Fledging, 1991 through 1994

Number of Boxes and Box Locations

1991 1992 1993 1994

Utility Pole-Mounted 50 (43%) 72 (53%) 94 (67%) 109 (72%)

Post-Mounted Fields 67(57%) 63 (47%) 47 (33%) 42 (28%)

Total Box Locations 117 135 141 151

Fledgings

From Utility Poles 129 (71%) 227 (78%) 312 (92%) 481 (95%)

From Post Mounts 54 (29%) 64 (22%) 28 (8%) 24 (5%)

Total Fledgings 183 291 340 505

Some additional considerations:

we have experienced very little vandalism over the years which may be due, in part, to box placement on low volume, rural roadways. The risk of vandalism can be reduced by not putting boxes at intersections;

it is important to be alert to the workings of the power company in relation to the replacement of poles, either individually or the reconstruction of an entire section. Usually, the poles are marked for this purpose well in advance of the actual work allowing plenty of time for box relocation. Bluebird nest boxes do not interfere with the maintenance of power lines which is done from hydraulic "bucket" trucks;

we mount boxes on the poles by using double-headed framing nails making withdrawal of the nails easy when relocation is required;

collisions between birds and vehicles can best be avoided by mounting boxes so that the entrance hole does not face the roadway.

Bluebirds tend not to be attracted to nest box sites on poles which are next to large, unbroken expanses of cultivated land (i.e., corn, soybeans, wheat, etc.). Pole sites with trees, fences, signposts, streams, and other varied land forms seem to be preferred as nesting locations.

Advantages of Utility Pole Placement

There are any number of advantages to the placement of nest boxes on utility poles. They include the following:

the opportunity for box placement in a wide variety of optimum habitats (see Criteria for Selecting Locations above) preferred by bluebirds;

better control over nuisance predators, especially raccoons (Procyon lotor). Bird on Utility pole Because boxes are located some considerable distance from one another, the animals simply do not have a scent trail to follow so as to be able to investigate all of the nest boxes in a given area. In 12 years, we've only had to place.. 'coon guards" or grease poles three times to prevent predation. During that time, we have had only five nest disturbances attributable to raccoons or cats. With proper habitat selection and by spreading the boxes out, we have dramatically reduced the House Sparrow (Passer domesticus) and House Wren problems on our trails;

ease of box movement/relocation. When we encounter persistent sparrow/wren problems, we simply remove that box and -place it in an entirely new location making appropriate changes on the trail map. We move boxes at the first sign of telltale scratch marks or muddy paw prints left by raccoons or cats. Occasionally, when conditions change at a box site (i.e., new building construction, heavier traffic volumes, traffic rerouting, vandalism, etc.), we simply move the box. In short, we are not committed to a box site on a particular post in a given field. Utility pole bluebirding has lots of flexibility built into it;

exposing birds to a greater variety of food sources;

boxes spread over a wider geographic area make more people aware of the presence of bluebirds and bluebirding;

continuous search for new, prime nest box locations over a larger land area while keeping an inventory of potential box sites for later possible use;

this kind of bluebirding is readily adaptable to the urban/suburban landscape;

utility poles make excellent mounting sites for heavy nest boxes, especially the Peterson box;

no posts to pound, pull, or grease; no nuts, bolts, washers, or wires needed for mounting;

ease of monitoring. Our boxes are all placed where they are easily accessible from the roadside without walking long distances over rough terrain. We avoid pole sites with steep slopes, deep ditches, and heavy infestations of poison ivy.

Kestrels

Our experience and the statistics make it extremely hard to understand the findings made in the two academic studies cited above indicating some sort of adversarial relationship between bluebirds and kestrels at nest sites.

We have been putting up kestrel nest boxes for more than 40 years and when we moved here to the farm, we put up three kestrel boxes (one in a tree; two on utility poles) directly next to the fields where, in 1993, we fledged 111 Tree Swallows (Iridoprocne bicolor) from post-mounted boxes. We have had bluebirds nesting in post-mounted boxes less than 75 feet (22.86 m) from an active kestrel nest box. In neither case, has there been any evidence of kestrel predation.

One of our utility pole trails has four bluebird nest boxes mounted on poles on the north and east sides of a large field. During the years 1991 through 1994, these boxes produced 49 bluebirds and 14 Tree Swallows. While no kestrel nest box is present, the falcons hunt from this same pole line all day long but always from 4:00 p.m. to 6:00 p.m. Our observation of these kestrels has shown no bluebird predation at all over this four year period. In fact, the kestrels hunt from the very poles on which the bluebird nest boxes are mounted.

Based on our observations, there is absolutely no correlation between the location of bluebird nest boxes on utility poles or adjacent to utility pole lines and the predation of bluebirds by kestrels.

Make no mistake about it--kestrels are superb aerial predators, We watch them feast on Red-winged Blackbird (Agelaius phoeniceus) and Common Grackle Quiscalus quiscula) nestlings which they take directly from the nest after having observed the dutiful parents carrying food to the nest for their young.

Beyond this, kestrels make great use of post-mounted nest boxes as hunting perches in their endless search for other nestling birds, mice, meadow voles (Microtus pennsylvanicus), crickets, grasshoppers, and other insects--but bluebirds as significant prey? No.

Special Equipment

"Safety first" must be the guideline for this special kind of bluebirding, all of which is done from a vehicle along traveled roadways. Some suggestions based on our experience:

we work out of a pickup truck which is equipped with a yellow strobe light and a slow-moving vehicle emblem. Both of these safety Items are available at auto supply or farm stores. We use the four way flashers at every monitoring stop. A neon orange bicycle flag is also helpful-anything to attract motorists' attention to your stopped position on the roadway;

we keep a complete set of county highway maps showing (in pencil) each of the box locations on our trails;

our gear is stored in a large, waterproof tackle box which is kept in the bed of the truck all season. We carry an extra nest box for emergency replacements. A plastic bag in the cab contains abandoned nests and dry grass for nest replacements or re-building;

a milk crate makes a handy container for recyclables picked up along the trail.

Conclusion

None of this would be possible without the thoughtful cooperation which we have had from the utility companies and their workers in the field.

This is obviously not a scholarly treatise--nor is it meant to be anything other than a collection of informal statistics and observations on one method of bluebirding which has worked for us and which appears to be effective.

Acknowledgments

Special thanks to Wayne Davis for his insistent encouragement. Thanks, also, to John Blakeman for his input on kestrels. Thanks to Carol and Bert for listening and to Thomas for his patient help in the preparation of the text.

Literature Cited

Munro, H.L. and R.C. Rounds. 1985. Selection of artificial nest sites by five sympatric passerines. J. Wildl. Manage. 49:264-276.

Parren, S.G. 1991. Evaluation of nest-box sites selected by Eastern Bluebirds, Tree Swallows and House Wrens. Wildl. Soc. Bull. 19:277-286.

4569 Greenwich-Milan Townline Ad.
Greenwich, OH 44837

Reprinted, with permission, from the author Dean Sheldon Jr. and "Sialia/Bluebird" Journal of the North American Bluebird Society. NABS is a membership organization for persons interested in bluebirds and other North American birds which use cavities for nesting. For membership information, send a message to nabluebird@aol.com or go to the NABS web site at http://www.nabluebirdsociety.org/