Nestbox Pairing (Part 1)

In addition to Messages that have appeared in the Bluebird Mailing Lists on this topic, the following are on the Audubon Society of Omaha website: 

• Observations on Pairing Bluebird Nestboxes by Kevin Berner
• To Pair or Not to Pair by Steve Eno
• Pairing Revisited
• Pairing houses: How do you do the math? by Linda Janilla

Subj: Re: BRAW Dropping Box-pairing, Breaking Records.
Date: 2/10/99 2:11:18 PM Central Standard Time
From: pea1"at"cornell.edu (Paul E. Allen)

...

You might need to closely examine the weather patterns in Wisconsin in 1998 to figure out if they had much to do with the relatively poor Tree Swallow production. In the Northeast, we had an extremely cold period at a critical time in the tree swallow season (during early chick-rearing) that caused massive chick dieoff. Bluebirds generally weren't as affected by the cold since the chicks were older (and they aren't affected by cold as much in the first place).

Is it possible that a cold snap during the season also caused a tree swallow chick dieoff in Wisconsin?

----------------------------------
Paul E. Allen

Cornell Lab of Ornithology
Nestbox Network paul_allen"at"cornell.edu
159 Sapsucker Woods Road (607) 254-2480
Ithaca, NY 14850 (607) 254-2415 FAX
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Subj: Re: Box "pairing"
Date: 2/11/99 6:05:53 PM Central Standard Time
From: scriv001"at"tc.umn.edu (Dorene Scriven)

Over the past three years we have seriously disagreed with the interpretation  of Wisconsin statistics presented by J. O'Halloran, particularly in regard to TRUE pairing. We regret that Mr. O'Halloran has chosen to use BLUEBIRD-L for his forum, because once again we believe his conclusions are flawed.

A 1997 poll of pairing recommendations of other bluebird organizations and individuals across the country, conducted by the President of Bluebirds Across Nebraska, revealed Mr. O'Halloran is not supported elsewhere in his conclusions. California recommends pairing at no more than 15 feet between boxes; bluebirders in the Northwest , with both competing tree swallow and violet-green swallows, often use triple boxing successfully. According to Minnesota studies of pairing starting in 1983 with 500 annual reports, the most successful balancing of bluebirds and tree swallows in the Midwest is between 15 and 25 feet. NO OTHER ORGANIZATION considers pairing to be "up to 100 feet."

While this year Mr. O'Halloran cites an example of 15 to 25 feet, the majority of his "paired" boxes were between 50 and 100 feet in 1997, according to the BRAW newsletter. We consider this the major flaw in his statistics. In addition, he does not allow for variations in: natural population swings; in weather (1998 was extremely benevolent to bluebirds across the Midwest, while a cold snap may have hit adversely at tree swallow nesting times.); in topography (the proximity to water); in distances between "pairs", in the many factors which may influence statistics.

Furthermore, while we are familiar with Dr. Dunn's graduate work under Dr. Raleigh Robertson of Ontario, Canada, the research we have seen does not support excessive polygamy in tree swallows. Carol & Dave Fiedler, with graduate degrees in tree swallows and bluebirds, have done research for 30 years. In a seven-year study of banded tree swallows (10,000 banded over the entire period), only one male tree swallow had two females at the same time.

Lastly, we do not believe in eliminating the beneficial tree swallow from bluebird trails. Nature has provided for both to survive, first by the single nesting of the tree swallow which normally occurs between the two nesting periods of the bluebird, and secondly, by the difference in feeding areas and prey. Tree swallows have often been witnessed defending both the bluebird box and its own against predators. Once again, our recommendation, based on 16 years of success, is that WHEN well-spaced single bluebird boxes become occupied more than 50% by tree swallows, TRY putting two boxes anywhere between 10 and 30 feet apart.. This does not necessarily mean ADDING boxes; it can be done simply by pulling two single boxes closer together, and leaving the distance thus created to the next box or next pair of boxes.

-Dorene Scriven, Chair, Bluebird Recovery Program of Minnesota

Subj: Dorene Scrivens Comment on Box Pairing
Date: 2/12/99 4:15:58 AM Central Standard Time
From: JOEOHALLOR"at"aol.com

I want this to be a civil answer to Dorene Scriven’s attack on my posting of “BRAW IS DROPPING BOX PAIRING, AND IS BREAKING RECORDS.”

In it I reported that the computer tally of BRAW monitors’ reports showed they fledged more than 10,000 bluebirds in 1998, up from 6,000 in 1997 from about the same number of boxes. The tally also showed that the BRAW monitors were dropping paired boxes in droves.

What’s so complicated or hard to understand about that? That’s not exactly "conclusions" from "statistics."

And we raised the question about the impact of the weather. Dorene Scriven did not respond to that question. The posting stated, “The summer of 1998 no doubt had excellent weather. But was Wisconsin’s weather any different from our neighboring States? Did their bluebird production increase by 65% in 1998?” If it did, we might attribute Wisconsin’s record bluebird production to the weather. If it didn’t, Wisconsin’s bluebird fledge probably soared because so many BRAW monitors chose to drop the paired boxes. So it would be helpful to know Minnesota’s, or other midwest States’ bluebird production for 1997 and 1998, along with the number of boxes used in those years. Is that not an appropriate kind of question for BLUEBIRD-L? Did Dorene Scriven purposely chose not to provide the information about Minnesota's fledge in her response?

Thruout her response, Dorene Scriven inferred that there was some kind of a mother lode of scientific data behind her well known, decade old position on box pairing. The implication I have been facing for years is that it hits the fan if one questions the box-pairing gospel. Yet, sometime around 1994-96, I asked for the data upon which Dorene Scriven relied to generate the box-pairing hypothesis. I got no data that I believed showed that box-pairing was good for bluebird production. As I recall, some of the tallies were based on “trails” rather than boxes, for example. Three 5-box trails should out vote one 100-box trail by three to one? Not hardly a good procedure, I don’t think. I also got from Dorene Scriven a number of copies of letters of recommendation written by upstanding citizens in favor of box pairing. I don’t regard tallies of such letters to be data. Perhaps Dorene Scriven would care to share with the readers of BLUEBIRD-L the data which she thought should have convinced me.

We in BRAW resolved at that time to slightly revise our monitors data summary form so we could obtain bluebird and tree swallow production data from singles and paired boxes of each of the reported box types. Whether it confirmed or refuted the box pairing hypothesis, we didn’t care.

I reported that BRAW has now 12,000 box years of data at hand, 4,000 boxes for three years, comparing bluebird and tree swallow production from singles and paired boxes. Yet Dorene Scriven states that she “regrets” that we used the Cornell BLUEBIRD-L as a forum to share it with the bluebirding community. I can imagine reasons why people who have been promoting box pairing for years in publications, books, etc. might “regret” the publication of such data. And I don’t intend any disrespect for any person who advances a hypothesis which is later proven to be incorrect. But doesn’t the 12,000 box-year Wisconsin study have just as much right to appear on Cornell’s BLUEBIRD-L as the pro-pairing allegations of the Chair of the Bluebird Recovery Program of Minnesota, Dorene Scriven?

In her response, Dorene Scriven states that a 1997 poll conducted by the President of BAN “revealed Mr. O’Halloran is not supported elsewhere in his conclusions.” Many of the recently successful BRAW monitors would probably get a big laugh at that statement. It seems the only big gun in Dorene Scriven’s response that’s supposed to blow away Wisconsin’s 12,000 box years of data, and Wisconsin’s fledge of over 10,000 bluebirds is just a Nebraska popularity poll. My posting related to bluebird production. Why does Dorene Scriven's response talk about politics and spin a popularity poll?

In her attempt to discredit me and the BRAW study, Dorene Scriven stated that that poll was a poll of "other bluebird organizations and individuals across the country..." Sound impressive? It involved less than 20 responses, as I recall.

And about that poll: I don’t recall seeing anything in any of those 17, or so, informal letters, which were tallied and published for that BAN poll, that
indicated that those letters were the result of the action of the boards of any associations. I don’t recall seeing anything in any of those letters that
the correspondents had studied or delved into the BRAW-reported bluebird production from singles and paired boxes. It is my recollection that at least one of the letters stated the correspondent had no opinion about box pairing because he or she had seen no data. Is it appropriate, or even polite, to publicly slash and trash my reputation and my report of the results from a three year, 12,000 box-year study, by spinning and puffing an informal
popularity poll involving what I recall to be less than 20 responses? Huff and puff away! It doesn't become you, Dorene Scriven.

Dorene Scriven attacked our definition of “paired boxes.” For the purpose of the BRAW study, we defined a paired box as any box within 100 feet of another nesting box. I think the American “100 feet” is pretty close to the international “30 meters.” Thirty meters is the distance within which the male tree swallow tends to reserve second boxes for second mates, according to reports in professional ornithological literature. As reported earlier, BRAW asked those of its monitors who reported paired boxes to specify whether they paired their boxes at distances of 0 to 15 feet, 15 to 25 feet, 25 to 50 feet, or 50 to 100 feet. According to the BRAW data, in the high tree swallow East zone of Wisconsin not one of these paired box distance categories was better in producing bluebirds than the singles boxes in the same area. The data revealed no “magic” distance.

I am pleased that Dorene Scriven found our definition of box pairing to be “the major flaw” in our study.

Later in her comments, Dorene Scriven gives me the impression that she also thought she could further discredit our report of Wisconsin’s production of over 10,000 bluebirds by citing banding studies involving 10,000 bandings. It seems she cites the banding studies in an attempt to convince people that male tree swallows are essentially not polygynous. I’m afraid that the new fangled thing called DNA won’t support anyone’s pathetic attempt to deny male tree swallow polygyny.

The 12,000 box-year BRAW box pairing study is just as big and is just as real as was that iceberg out there in front of the Titanic. And it ain’t gonna go away. I would suggest that it be approached with respect. Those who mock it may well have in store for themselves a chilling shock to their own
credibility. The Wisconsin BRAW monitors have shown that they do indeed respect the results of their own work. And, as a result, they have produced record breaking results.

Subj: Re: Box Pairing (long)
Date: 2/13/99 10:05:10 AM Central Standard Time
From: james-walters"at"uiowa.edu (James P. Walters)

Hatch Graham posts:

No scientist should shirk from peer review.

I can only second this view, but would also add it should apply to bluebirders, nestbox hobbyists, or whatever we choose to call ourselves.

You don't have to go far back in the history of this movement to see people attacked for challenging a dominant (or popular) idea. When I started bluebirding, it was an article of faith (among many) that bluebirds were monogamous. You don't hear much of that anymore. When Steve Gilbertson introduced the PVC house, the idea wasn't just attacked, Steve was, too. Now the PVC house is moving to be the predominant model-and for good reasons.

Joe O'Halloran, and the Bluebird Restoration Association of Wisconsin (BRAW), have moved the question of pairing from the personal and anecdotal level, to the state-wide, statistical level. As questions on their methodology have been raised, they have attempted to answer or incorporate them into the model Whether they have answered these challenges successfully are the questions that need to be asked.

Somewhere, lurking in the background of all this, is the question of what a "bluebird trail" is for? Years ago, there was little doubt about the answer to that question-conservation. Most people were involved in bluebirding out of a personal commitment to overcoming the perceived (and real) threats to the species. While current bluebirders are still "contributing" to a conservation effort, any real threats to the species are pretty much non-existant.

So the question "what is a bluebird trail supposed to do," now has many more answers than simply, "produce as many bluebirds as possible." I would submit that most trails are simply for the enjoyment and edification of the individuals and groups that run them. At some point, my "bluebird" trails ceased to be bluebird trails per se, and just became "nestbox trails"-with lots of different houses, and lots of different species. Occasionally, I leave mice, wasps, wrens, and even (please don't shoot me) House sparrows and starlings, in my boxes. I always leave bluebirds, chickadees, nuthatches, tree swallows, martins, kestrels, flycatchers, wood ducks, and others. And I hope to attract prothonotaries in the near future.

In other words, my trails will never have the "problem" that pairing seeks to address.

Once, in the late 80s I think, I challenged the late Harry Kruger on a particular question of "monitoring." Mr. Kruger (who monitored his trail on a DAILY basis) wrote politely back to tell me that my "approach" to monitoring was no better, or worse, than two of his old farmer friends who simply put up houses and cleaned 'em out once in the spring. A moment's reflection took me back to my first bluebird trail-in the early 60s-and the realization that that was exactly how I ran my trail then.

BRAW has a wonderful disclaimer (Bluebirding is NOT an Exact Science. . .) which they run with every issue of their newsletter. It's probably also worth reminding ourselves that it is not a religion, either. There is no true faith, and no need to excommunicate those who disagree with us.

I know that most of you are anxious for spring (and bluebirds). It would probably surprise you know that I (as a groundskeeper, with the months of Nov-March off work) want winter to go on and on-since this is my time to sit by the fire, read books, think, enjoy four or five cups of tea, and actually read all the morning papers (right down to the want ads, Dear Abby, and the horrorscopes). Winter never lasts long enough for me.

Best wishes,

Jim Walters james-walters"at"uiowa.edu
Johnson County Songbird Project
1033 E. Washington
Iowa City, IA 52240-5248

Subj: Pairing
Date: 2/15/99 8:47:56 PM Central Standard Time
From: scriv001"at"tc.umn.edu (Dorene Scriven)

Last week I posted to this network a determination to not carry further the oft-unpleasant debate between Mr. O'Halloran and the Bluebird Recovery Program of Minnesota, of which I am currently Chair. His definitions of pairing are quite different than ours, and as far as I can determine, most other bluebird organizations and individuals.

I thank those who privately e-mailed me in support. However, several national bluebirders (for example, Hatch Graham, Jim Walters, Jim McLochlin, Keith and Sandy Kridler) whom I know and whose opinions I respect, "wrote" otherwise and felt the issue should be resolved, and we all could come up with a definite recommendation about pairing. Others inquired whether there had been a strong increase in bluebirds elsewhere in 1998, and another wondered about how close bluebirds will nest.

It may seem a 'cop-out' to answer that every trail, [even just two boxes in a small yard] is unique. No two trails are exactly alike, the same proximity to  water, to good forage for bluebirds or for tree swallows, to perches, etc., and even if they were, there are annual population swings in both species, partly determined by climate and weather fluctuations on the wintering ranges and on the breeding ranges. Our recommendation, for trying true pairing as a management technique when tree swallows come to predominate, started out around 1983 when many people reporting to us felt overwhelmed by tree swallows.

Most of us had trails laid out in what was then the traditional manner - 100 yards or 300 feet apart. This had been the norm in most parts of the country for decades. In 1976 Dr. Lawrence Zeleny, founder of the North American Buebird Society, wrote: "Bluebirds usually will not nest closer than about a hundred yards from other bluebirds. Not much is gained, therefore, in placing nesting boxes closer to one another than that -- unless it is desired to provide nesting sites for other desirable species of cavity-nesting birds such as tree swallows, chickadees, and titmice. There is no actual harm done by situating the boxes closer than one hundred yards apart."

With artificial nest boxes came a re-blossoming of the bluebird, and tree swallows soon benefitted, too. Around 1982 tree swallows hit one of their cyclical upswings in population and BBRP received a lot of requests for help. (There were not many other state organizations at that time. Our national
membership was then 3300 .) Two gentlemen reported they had tried putting boxes about 25 feet apart and had good luck with both bluebirds and tree swallows. We suggested people try the next year, and indicate on their yearly report form what success they had. (In those days we had an optional back page for all sortsof extra information - type of terrain, type of box, distance to next box, distance to water, soil type, cover type, distance to buildings - you name it - everything we could think of that might make a difference. Dave Ahlgren did a statistical analysis (I'm beginning to hate those words!) of what reporters considered the most successful distance between boxes used by both bluebirds and tree swallows. There was a wide swing in the answers, but most fell in the range between 10 and 30 feet, with an average of 22 feet between boxes. Our report forms got simpler, but we still asked members if they paired,at what distance, and how many successful pairs of tree swallows and bluebirds they had. Over the years that average distance held pretty true, and we stopped asking for the distance. In fact in the early part of this decade, tree swallow numbers seemed down, and we suggested people might want to move their boxes further apart for a while. Two years ago the balance favored tree swallows again, and our 1998 form asked for numbers and best pairing distances. The 10 to 30 foot distance, with 300 feet or more to the next pair seemed to be working again. To be honest, we are just now tallying the1998 number of tree swallow successful nestings, against bluebird successful nestings, against pairing,  simply because it seemed so obvious that it can work, that we didn't bother to rack up statistics again.

This is a long-winded defense of pairing, but perhaps it helps explain our position. To answer the other two questions: It is not common, but bluebirds
have nested 100 feet apart at the same time.

If there is no visibility between nestboxes, e.g. front and back yards, with a house between, they may nest 50 feet or less apart. (See Marion Liles's
comments tonight) Merlin Lehman of Indiana had three eastern bluebirds nesting less than 100 feet apart, in a triangle, with two sides of the triangle 95 and 75 feet long. Each pair's territory was outside the triangle, in different directions. More often a female bluebird will start her second nest in the other box of a pair, especially if the first nest has not been cleaned out. Tree swallows may have used the second box, , and it cleared out, or it may have remained empty.

Were there other areas where bluebird numbers were exceptionally high this year? Bill Read from Ontario, Canada bluebird trails reported a 50% increase over the 40-year average, with "reproductive success of eastern bluebirds exceptional in 1998". Don Stiles's compilation of Calgary (Alberta) trails showed an increase in mountain bluebirds from 3778 fledged in 1997 to 8036 in 1998. 30% of their trails are paired. Nebraska had an increase in reported bluebirds fledged from 1606 in 1993 to 8728 paired boxes in 1998, a 543% increase. One large trail in Michigan had a 47% increase in successfully fledged bluebirds over 1997 (all boxes paired). A couple in Indiana added 15 boxes to the 44 in 1997 and fledged bluebird numbers doubled, to 207 in 1998. They have few tree swallows, do not pair boxes.

To conclude, and hopefully sign off once more on this pairing issue, we hope that all bluebirders are willing to move your boxes, singles or pairs, according to your own trail conditions, who you welcome in your nestboxes, what works FOR YOU. For me, personally, I like the statement of a distinquished Indiana bluebirder, "All my boxes are paired (20' apart) and many times I will have both Bluebirds and Tree swallows nesting in each group. Also, where maybe just a bluebird is nesting, I do have an empty box then, but I would much rather have occasional empty boxes and know that every bluebird looking for a cavity found one, versus looking and can't find."

-Dorene Scriven

Subj: PAIRING WORKS! (?) THE SINGLE BOX WORKS BETTER FOR BLUEBIRDS.
Date: 2/27/99 3:00:06 PM Central Standard Time
From: JOEOHALLOR"at"aol.com

Note: If you don’t have tree swallows or other polygamous cavity nesters such as wrens in your area, you may not be interested in the following memo.

PAIRING WORKS! (?) THE SINGLE BOX WORKS BETTER FOR BLUEBIRDS.

Among the replies to my earlier posting on box-pairing, several people encouraged continued discussion in the hope that the issue could be resolved.  I would hope so too. In my last memo, I pointed out that the goal of BRAW’s pairing study was to compare the bird production from closely spaced (paired) boxes to the bird production from widely spaced (singles) boxes. I pointed out that even within BRAW some people focused on an entirely different question, namely what distance is the best distance for separating paired boxes. I pointed out that unless the data gathered in a pairing study allowed comparison of the bird production from paired boxes to the bird production from widely spaced boxes, the most important first question could never be answered. Two entirely different questions. And they give two entirely different kinds of information. I hope that the earlier posting helped to clarify the issues. I hope this posting provides another step towards resolution.

People who only use paired boxes might think that “Pairing Works” (a) because they do indeed get bluebirds from paired boxes, and (b) because for a decade they have been assured by some people, including BRAW up to 1996, that “Pairing Works.” People have been assured that if the tree swallow population is high, they should try box-pairing. If valid, this advice would apply, for example, to people in the high tree swallow areas, like the East half of Wisconsin. But do paired boxes really “work” better than singles? The data says “Indeed, not! Neither in high tree swallow conditions, nor in low tree swallow conditions.” Let’s get down to brass tacks. Let’s compare the bird production from closely spaced (paired) boxes to the bird production from widely-spaced (singles) boxes in the same areas.

In the BRAW study, we define closely spaced (paired) boxes as boxes within (less than) 100 feet of each other, for example boxes spaced 15-25 feet apart. The recommended separation between widely spaced (singles) boxes is 100 yards or more.

Each year, the BRAW monitors report numbers of bluebirds fledged, and tree swallows fledged, etc. from specific numbers of specific boxes, for specific locations, etc. from closely spaced boxes (100 feet apart), and from widely spaced boxes spaced 100 feet apart, e.g. 100 yards or more.

So the resulting BRAW monitors’ data base allows one to compare, for example, the bird production from singles vs. paired boxes in the high-bluebird low tree swallow West half of Wisconsin, and in the high tree swallow low bluebird East half of Wisconsin. (Note the oft repeated inverse relationship between bluebird and tree swallow numbers.)

We call the combined production of bluebirds and tree swallows from an area, or from a box-type, or from a group of singles boxes, or from a group of paired boxes, “The Crop.”

For example, in 1998, in the high tree swallow East zone of Wisconsin, the crop from paired boxes was 35% bluebirds (65% tree swallows). If a person using all paired boxes in the East zone of Wisconsin does not know any better, and had been assured for a decade that pairing boxes is good practice in a high tree swallow area, that person might be very happy with 35% bluebirds in their crop. But in fact, the people using widely spaced (singles) boxes in the same East zone got a crop with 50% bluebirds from their singles boxes. There was a 41% better bluebird crop content from widely spaced (single) boxes than from the closely spaced (paired) boxes in the area with high tree swallow pressure. No wonder the paired-box users might feel they have been misled!

The same kind of pattern was observed in 1996 thru 1998 in the high tree swallow East Wisconsin zone. Single boxes produced larger crops, and crops with substantially higher bluebird contents (from about 25% to about 41% more bluebirds) than the crops from closely-spaced (paired) boxes in that zone. Clearly, singles boxes worked much better for bluebirds than paired boxes.!

And,what about under low tree swallow conditions? In 1996, in the high-bluebird low-tree swallow West zone of Wisconsin, the people who used paired boxes got a crop with 47% bluebirds. Wow! That’s fantastic! Again, if they didn’t know any better, and because they had been assured for a decade that “pairing works,” they would probably be pretty happy with 47% bluebirds in their crop. However, in fact, the people in the same area who used widely spaced (single) boxes got a larger per-box crop, and that larger crop from the singles boxes had 71% bluebirds. So the crop from singles boxes had a 52% higher content of bluebirds than the crop from the closely spaced (paired) boxes in the same zone under low three swallow pressure. No wonder the paired box users might feel they have been misled.

The same kind of pattern was observed in 1996 thru 1998 in the high bluebird low-tree swallow West zone of Wisconsin. Single boxes produced larger crops, and the crops from singles boxes had substantially higher bluebird contents (from about 21% to about 52% higher bluebird contents) than the crops from paired boxes. Clearly, singles boxes worked much better for bluebirds than paired boxes!

Please keep in mind that in every year, in both the West and East zones, the crops (bluebirds fledged plus tree swallows fledged) from closely spaced
(paired) boxes were smaller than the crops from widely-spaced (singles) boxes, on a crop per box basis.

Clearly, the data shows that there is much more bluebird production in both low and high tree swallow pressure conditions from widely spaced (singles) boxes than from closely spaced (paired) boxes. To my eye, which box-spacing is best for paired boxes is a trivial, virtually irrelevant question, in view of the big reality that widely spaced boxes produce bluebirds far better than paired boxes. The data showed that to be true in both low and high tree swallow areas.

After the first reports of the BRAW studies, some folks made allegations that there was some magic distance of paired box-separation which BRAW had not looked into, implying that, at the magic distance, the use of paired boxes was better than the use of singles. I would ask any person alleging some magic distance for paired box separation to show the BLUEBIRD-L members his or her data showing the bird production data from the paired boxes separated by the magic distance, and the bird production data from singles in the same area, upon which they relied to make the “magic distance” allegations to start with.

But because of the magic distance allegations, though not supported by data to our knowledge, we did ask our monitors who reported paired boxes to check off one of four categories of specific distance between their paired boxes. The resulting bird production data provided no support for a”magic distance” hypothesis.

The source of the data which allowed the above realities to be learned is the BRAW 12,000 box-year study. That study involved 4,000 monitored boxes for each of three years, 1996 thru 1998. The data compared here involves bluebird production and tree swallow production data. Wrens, chickadees, and house-sparrows, and a few other species also use bluebird boxes in Wisconsin, but we have no fledge data on them --only box-usage data.

Thanks to the help of two university ornithologists, in about 1995 we were pleased to discover that the data generated in each year of the BRAW study is consistant with the picture in the professional ornithology literature. Namely, in an area with at least some tree swallows, putting up second boxes close to respective first boxes (within 30 meters, about 100 feet) is just made to order for increasing the reproductive efficiency of the would-be
polygamous male tree swallows. For example, the BRAW bird production data clearly shows that putting up second nearby boxes (box-pairing) is just made to order for increasing the tree swallow content of the crop, and is made to order for decreasing the bluebird content of the crop, under both low and high tree swallow conditions. So to sum up, use of paired boxes “works” for increasing the tree swallow fledge, and use of singles boxes “works” for increasing the bluebird fledge.

Another word of caution about “depairing.”

In 1996, the BRAW data revealed that there was virtually no difference between the extremely low bluebird production in singles and paired DEEP boxes used in the high tree swallow East zone of Wisconsin. Deep boxes such as the Hill Lake became virtual tree swallow boxes. They gave disasterously low bluebird numbers in high tree swallow conditions, whether they were presented as singles or in pairs. For example, whether used as singles or in pairs, there would sometimes be about one bluebird occupancy in 20 or so deep boxes. Because of this, it became clear that converting paired DEEP boxes to singles in high tree swallow areas should be expected to provide no substantial improvement in bluebird production. I believe that the BRAW report about this resulted in the abrupt and widespread decline in the use of the deep boxes (to about half of what it had been) in Wisconsin. It also resulted in the Peterson box-type surging well into the lead in Wisconsin, to a number equal to the sum of the second and third place box-types combined. No doubt, the large decrease in the number of deep boxes, along with the widespread shift from paired to singles boxes, along with the widespread increase in Peterson boxes, and along with the good weather, all contributed to the 65% increase in bluebird fledge reported by BRAW monitors for the 1998 season.

Anyone interested in obtaining the reports on the BRAW pairing studies from the Spring 1999 issue of The Wisconsin Bluebird, or from past issues, can contact BRAW c/o Don Bragg, at donbragg"at"juno.com

Best of luck to us all in our preparations for the fast-approaching 1999 bluebirding season.

Joe O’Halloran
Chair, Data Analysis Committee
Bluebird Restoration Association of Wisconsin (BRAW)
February 27, 1999

Subj: Re: Pairing revisited.
Date: 7/4/99 5:52:39 PM Central Daylight Time
From: birdsfly"at"innercite.com (Hatch Graham)

Bruce Burdett wrote:
My experience here in SW New Hampshire has taught me that paired
boxes more than 15' apart are more likely to cause BOTH to be taken by the
TRSW. Reports on this Network tend to corroborate (sp?) this notion. I've
NEVER had a situation where boxes spaced 15' or less were both occupied by
the swallows. On the other hand, I've had MANY cases where BBs and TRSWs
lived 15' apart in peace and harmony. They're seem curious about each other,
but there's never anything even resembling strife. And I'm sure you're all
tired of hearing me reiterate that they join forces, often, to chase away
intruders of all kinds.

And I have experienced 3 nestings this year of House Wrens paired with TRES and WEBLs without the usual HOWR depredation. This works out with the study I reported on earlier that indicates the HOWR will not attack eggs in boxes very close to its own nest (perhaps for an inherent fear of making a mistake and pecking its own). At any rate, the author, S.Pribil, says there is no predation at less than 16 feet. The 10 swallows and 6 bluebirds fledged were
12, 14, and 15 feet from an active wren nest. The wrens fledged 20.
--
Hatch Graham, Editor, Bluebirds Fly! California Bluebird
Recovery Program
El Dorado County "at" 3100 ft, Lat 38°37'43"N, Long 120°37'47"W
-------------------------------------------------------------------------
for the encouragement and conservation of cavity nesters -especially bluebirds- anywhere in the West

Subj: Re: double boxes/trapped humming birds
Date: 9/12/99 8:19:28 AM Central Daylight Time
From: kridler"at"1Starnet.com (Keith & Sandy Kridler)

Good post Brenda! Thanks....In your area when you place a nest box can you look at the location and say, "This is perfect for bluebirds" and not have to worry about swallows? Or do they use any and all locations??? In the past I could place a box and say "no sparrow will use that one!" But now I have seen them anywhere along my trail in any and all types of boxes, I can exclude the chickadees and titmice by box location & even bluebirds (I don't) if I wanted too but was wondering if swallows are not adapting as more and more boxes are placed. I have seen House Sparrows expand their range and nesting times and figure that as more and more boxes are placed that other species will take advantage of weather patterns and try to be the "early bird gets the nest location".

Data collected in the early 80's is now 20 generations of bluebirds obsolete. Quite a bit of adaptation can be made in a species in 20 generations! (Look at humans!) From the time the Pilgrim's landed at Plymouth till the formation of NABS in the late 70's only a handful of nestbox trails were in existence. Not until the mid 80's did NABS style trails start making a widespread impact on bird species. Nearly everything we routinely quote is from the early pioneer's in bluebirding who observed and recorded this over 50 generations of bluebirds ago!!! If there are still going to be bluebirds and swallows after fifty more of their generations, we need to be more observant and question everything we already know and keep better records of what we see. We need to be quicker to embrace new ideas and experiment with more boxes each year. Just because something worked 15 years ago doesn't mean it will continue to work...We need to adapt as box builders and trail monitors as fast as the birds are or we will fall out of touch with them as we did in the 1950's. Best regards, Keith Kridler

I wrote this for Brenda but thought I should send to the whole list. KK

http://www.rbchs.pvt.k12.nj.us/science.htm

This is a web site containing a bluebird project at a school. They have bluebird trails in parks, and said that they have paired nest boxes on a single pole, back to back, to cut down on competition. Just about everything I've read has said to put nest boxes about 15 feet apart. Has anybody had any experience with two bird boxes back to back on a single pole? If so, would you please share your experiences? Thank you very much.

Julie Clark
Lewiston, Idaho

Joanne, et al,

If a bluebirder has no Tree (or Violet-green) Swallow competition in his area of the continent, then there is probably no real need to pair houses, as we must up here. You be the judge. I suppose there's no HARM in pairing some anyway. It might be interesting.

Bruce Burdett, NH Bluebird Conspiracy, Sunapee NH (Live Free or Die, etc.etc. etc.)

Bruce, Gary Springer and I talked about those pair of boxes. We thought it would be interesting if Carolina Wrens took one and BBs took the other. I'm waiting to see what happens. It looked like they were both fighting over the same box. But then yesterday I saw a BB sitting on top of the OTHER box. So, I'm crossing my fingers that BBs will take over at least one of them, and I won't care if the Carolina Wrens take over the other. I have no English Sparrow problem out here. Yippee.

Joanne Cox
Monroe, GA

Hi, all:

This is my first post. I read somewhere that if you put two nest boxes about 20-30 feet apart (assuming you're in an area that has swallows) the two will tolerate each other and the swallows will more vigorously defend the whole area against wrens and other "house pirates." This is assuming there are a reasonable number of suitable nesting sites in the area and the two species are not desperately fighting over the very last one. I have tried that with 3 pairs of boxes and, so far, it has worked well. I have other boxes scattered along the stream near my house and they are about 250-300 feet apart. Mostly, they seemed to be used by Tree Swallows although there are a couple of small houses mounted very near (and on) my house that were used by VG Swallows last year. There are only 4-5 next boxes that are used every year by Western Bluebirds and the rest are taken by Tree Swallows (which are lovely birds, anyway). Has anyone on the list tried pairing the houses? What was the success or failure of that kind of pairing? I would be very interested in hearing from others as I was thinking of increasing my "box-pairing" setup but wasn't sure if the ones I have are successful just because of the specific location, or just used by more tolerant members of the two species, or ??.

Regards, Joanne
Reardan (Spokane) WA
mailto: jhpowell"at"iea.com

I'm forwarding this to the List as an afterthought. - B. Burdett

-----Original Message-----

From: Bruce Burdett blueburd"at"srnet.com
To: jhpowell"at"iea.com jhpowell"at"iea.com
Date: Saturday, March 18, 2000 2:38 PM
Subject: 20'-30'

Joanne, et al,
In my book, - and in my area of the country.- boxes as far apart as
20'-30' are NOT paired. Any paired boxes farther apart than 20' MAX run the
risk of having BOTH taken by Tree Swallows, since our area is Tree
Swallow-rich and Bluebird-poor. None of my paired houses (and all my houses
are paired) are farther apart than 15', and some are as close as 10'. Often,
Bluebirds take one and Tree Swallows take the other, and they get along
GREAT. (I know that some of you are tired of hearing me say all this, but
Joanne is a new contributor.) I am looking at this moment at a picture of a
pair of my houses with a Bluebird on top of one and a Tree Swallow on top of
the other. When I snapped the picture they were getting ready to attack a
Bluejay who'd gotten too close to their houses, in their opinion. They
frequently made war together on a common enemy, but never bothered each
other even slightly.
And regarding Bluebird territoriality, I have never had Bluebirds
nest closer than a quarter-mile from other Bluebirds, and I've given them
plenty of opportunity. Tree Swallows, on the other hand, have one nest, and
one only, in EVERY ONE of my house-pairs (sites). Apparently Tree Swallow
territories are much smaller, perhaps because there are more of them per
square mile where I am. How dense they are where Joanne is I have no idea.
In my opinion, territory size is at least to some extent a function of local
population densities.
I gather we all agree on this List that Tree Swallows are great
birds, - both useful and beautiful. Usefulness and Beauty, as I recall, were
Plato's two most prized philosophical criteria, and he was no fool.

Bruce Burdett, NH Bluebird Conspiracy, Sunapee NH
blueburd"at"srnet.com

Laurie,

Have you tried pairing your nest boxes, that is putting the second nestbox within 10 feet of the first box? I have even heard of people (I have not seen it) who mounted the boxes back to back on the same mounting post. Since there two species eat different insects, they cohabit well. The Tree Swallow is more agressive so it aids the bluebird in defending the territory around the nest boxes. My sister who lives south of Valentine, Ne has gobs of tree swallows. We are trying a new style box (Bitner) that requires the bird to enter by walking over a block. The entryway is located up under the eaves on the sides of the box.

Last year out of 5 pairs of boxes, she had 5 tree swallow nests and all the other boxes had dummy tree swallow nests. No bluebirds. She likes the TSWA because she lives about 1/4 mile from a small pond that is infested with mosquitoes. The TSWA love the flying insects so she loves the TSWA!!! We do hope this year she will also get blubirds (eastern).  We can have Westerns also but have not had any nest in the nestboxes.  They are in the old cottonwood trees along the creeks. We are blessed since we do not have house sparrows and Eu starlings.

Carolyn Hall, Sandhills Bluebird Lady, Bassett, NE where it is 21* with a 20 mph N wind. We had a spat of small hail and a skiff of snow overnight. This is what is so tough on spring plants and baby animals.  Warm one day and back to winter the nest. I'm predicting a very poor hatch on my early nestings.

If you are plagued with "hordes of tree Swallows", PLEASE give pairing a try! It has worked like a charm for me, here in SW New Hampshire. All my houses are in pairs, 10 to 15 feet apart (no MORE than 15) and the "hordes of Tree Swallows" are never a problem. They get along just fine, with the Bluebirds in one house and the swallows in the other. They even work TOGETHER to chase away intruders of all kinds. Not many intruders will stand up to FOUR determined parent birds strafing them. Don't cheat on the 15 feet max. Houses 20 or 30 feet apart are NOT paired, in my book.

Bruce Burdett, NH Bluebird Conspiracy, Sunapee NH
blueburd"at"srnet.com

Dear Byron:

I suggest you put your nestboxes up in pairs about 12-15 feet apart, each on its own pole. Then one will more than likely be taken by bluebirds and the other by swallows. They tolerate each other that close, but will drive off their own kind.

I tried to send this earlier and there seems to have been a glitch. If you did already get it, forgive the repeat.

Randy Jones
Allentown PA

Yesterday evening the Blues (Eastern) were finally showing signs of building their nest in the box I put up about a month ago, and they entered for the first time last week. Much to my surprise, swallows were hanging around an harassing...I thought I only had barn swallows here, had not seen a tree swallow in the 4 years I've been here.

I checked the Stokes guide and it described EXACTLY what was going on at the box. The Swallows were ganging up on the Blues.

This morning, I purchased and put up a second box, as described in the Stokes' Bluebird book. Hopefully I'll get the Blues and the swallows to
nest... So far, the reaction is:

* Papa Blue has checked out the new box.
* The tree Swallows have only observed from a distance of about 40 yards.
* Papa Blue is swooping at my favourite male Robin--away from the box/nest area--whose nest is about 20 yards from the Blue boxes. I think he's a little annoyed about the 2nd box going up and is letting off some steam?

Any and all comments welcomed!

Nicholas
Holly, Michigan
42nd Parallel

Date: Thu, 27 Apr 2000 12:45:10 EDT
From: Nuts4bb"at"aol.com
Subject: Re: Competition Cometh

*From Terrie in Mt. Blanchard, OH (NW) Sunny 60* Beautiful Day!

Nicolas, Don't be alarmed, sounds like you're doing everything right! The Bluebirds can take awhile to decide on a house. The female is the one to make the final decision on which house to use (as it should be!). Just when you are sure they have chosen one house in particular, they will change their mind. Very frustrating for us bluebirders! The tree swallows can also take some time in their selection. Both can co-habitate beautifully and will even help each other in warding off House Sparrows! You didn't mention how far apart you placed the houses. Usually 15 feet is the closest you want them to each other. I've found a little more distance is better. I try to keep them at least 40-50 feet apart.
Have a great day with your birds!

Date: Thu, 27 Apr 2000 12:53:26 -0400
From: "Bruce Burdett" blueburd"at"srnet.com
Subject: Re: Competition Cometh

Nick, et al,
I've been trying and trying for more than a year now to tell you all how well PAIRING has worked for me, here in SW New Hampshire. And when I say 'pairing', I mean 10' to 15' apart, not 20', or 30', or 50'. It's been, for all practical purposes, infallible. All serious Tree Swallow competition in
my spread has ENDED. I often end up with the swallows in one house and Bluebirds in the other, and they get along just fine. If anything, the
Bluebirds pester the swallows a little, but only mildly. More important, interlopers get attacked by four adult birds rather than two, and most of us
know that Tree Swallows can be impressive 'strafers'. Every one of my pairs of houses last year had one swallow nest, never two. Houses not taken by Bluebirds either remained empty, or occasionally they were taken by chickadees. Incidentally, Nick, I also got the pairing idea from the Stokes' book, back in 1991, after my very first single-box set-up failed because of Tree Swallows. I'm grateful to the Stokes for that vital suggestion. Without pairing, I believe I'd have NO Bluebirds.
Bruce Burdett, NH Bluebird Conspiracy, Sunapee NH
blueburd"at"srnet.com
... 

Date: Thu, 27 Apr 2000 15:08:10 -0700
From: "Nicholas A. Zbiciak" nzbiciak"at"gfn.orgu
Subject: RE: Competition Cometh

Thanks Bruce.

I set the 2nd box about 13 feet from the original. So far, papa Blue is raoming in each, and I just saw a Swallow enter the original.

This is neat.

Nicholas

... 

Date: Thu, 27 Apr 2000 15:05:05 -0700
From: "Nicholas A. Zbiciak" nzbiciak"at"gfn.org
Subject: RE: Competition Cometh

Thanks.

They're about 12-15 feet apart.

... 

Nestbox Pairing (Part 2)

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