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BRAW Informational Packet:

Attracting Eastern Bluebirds & Other Cavity Nesters (26 pages),
by Kent Hall, Ph. D. and Pat Ready (Editor)

This booklet pulls together the collective experiences of people who work especially in the interest of bluebirds, particularly those persons who record and summarize their nest box data and whom we term monitors.

CONTENT of the INFO PACKET

Cover: Life cycle of the Eastern Bluebird (Photos by Pat Ready)

GUIDELINES FOR SUCCESSFUL MONITORING OF EASTERN BLUEBIRD NEST BOXES By Kent D. Hall, Ph.D.

  • Why Monitor Eastern Bluebird Nest Boxes?
  • History of Bluebird Production in Wisconsin by BRAW Monitors.
  • Breeding Bird Survey (BBS) data – bluebirds are increasing
  • Comparison of Eastern Bluebird and Tree Swallow fledglings in 2005-12 time period
  • Number of fledgling Eastern Bluebirds & Tree Swallows, and number of active nest-boxes, in the 1994 to 2012 time period. Note that most BRAW monitors dropped paired boxes by 1997 and most dropped crowded single boxes by 2002.
  • Breeding Bird Survey (BBS) data – bluebirds per route
  • Relative Abundance of cavity nesting songbirds in 2006 and 2010.
  • BRAW management practices that are thought to have improved Eastern Bluebird production on the Audubon and other Bluebird Trails.
  • Location, Location, Location
  • Relocation
  • Box Style/Dimensions
  • Spacing
  • Nest, Egg & Chick Removal for bluebirds, chickadees, Tree Swallows (1,2,3,4) and House Wrens (4): Procedures approved by USFWS in Dec., 2006
  • Common Predators of Bluebirds: Raccoons, House Sparrows and Black Flies, Woodpeckers
  • Direction of Opening
  • Common Myths Associated With Bluebird Monitoring.
  • Natural History Information for Cavity Nesting Songbirds: 2002-2012
  • What kind of nest box should I use for a bluebird trail?
  • Monitoring Instructions. (p. 10)
  • Nest Guide to Cavity Nesters by Patrick Ready/BRAW
  • Individual Nestbox Weekly Field Record / Bluebird Restoration Association of Wisconsin, Inc.
  • Fence post mounting system
  • 3/4” Conduit Mounting System
  • NABS style Bluebird Box, plan
  • Peterson Nest Box (Unvented), plan
  • The “K” Bluebird Nest Box, plan
  • Resources for bluebirders:
  • County Coordinators are Ready to Help You
  • School and Youth Outreach
  • Recommended Reading
  • Bluebird chick development– first 14 days by Jack Bartholmai
  • ANNUAL BIRD NESTING SURVEY SUMMARY
    Etc.

Helpful Tips (by Kent Hall)

What are the best Locations for a Bluebird Trail

Location, Location, Location:

Ideal sites: short, sparse grass with interspersed trees: cemeteries, golf courses, parks, business parks, bike trails, Rail Road tracks

What are the best Perch Sites?

One or more trees (10’ ideal) within 100’ (preferably closer) to the front or to one side of nest box (most hunting starts on a perch and these trees are vital for use as survival perches when chicks first fledge)
Fences (barbed, electric, wooden)
Electrical wires (no more than 30’ high preferred), clothes lines

Boxes should be totally exposed to sun-light from sunrise until noon; thereafter, shading is permissible

Need a territorial forage area of 1-3 acres of predominantly open habitat
Noisy sites okay (interstates, other roadways, railroads, temporary air shows, church picnics)

Roadways with limited traffic can be ideal nest box sites and adults and young chicks are rarely killed by traffic.

How close should the boxes be?

Space no closer than 100-200 yards (1-3 acre territories needed); encourages Tree Swallow occupation if boxes are placed closer than this.

Pairing reduces bluebird and increases swallow production/box

When should you relocate the boxes?

Change the nest box position if there has been no bluebird nesting attempt in a season
OR
Change by the end of the following April (75-90% of nest boxes have been occupied by bluebirds by then); if no nesting has occurred by the end of April your 2nd nesting season, it is sign that your site is unappealing to bluebirds. But moving the to better nest sites still gives you a 50:50 chance of occupancy for the season.

What are the best Box Styles and Dimensions?

Box Style/Dimensions:

In “the wild”, bluebirds prefer to occupy old woodpecker holes that are not usually very large or deep

Shallow, narrow boxes work best:
4-5” below the bottom of the hole as maximum depth
4 x 4”, 4 x 5” nesting platform (inside dimensions)

No vents or keep vents closed until June 1 to prevent wind chill from killing eggs and/or chicks. The summer of 2012 showed that high temperatures can kill chicks in nest boxes. But cold weather has still proven to be more damaging than heat.

Since it is likely that the changing climate assures high summer temperatures in the future, we recommend monitors consider making their boxes “convertible” by dropping side doors in the summer and replacing them at the end of the season.

For Peterson boxes, holes can be drilled at the top of one side and a piece of “lathe board” placed over them until June 1. A single or pair of screws can be used to seal the openings during spring. The main thing to do here is to produce air circulation to prevent heat buildup as in an attic.

On the other hand, in the southwestern part of the state where black flies are a problem, screens should be placed over the openings to prevent ease of black fly entry.

Oval hole small enough to keep out starlings & cowbirds

Don’t use predator guards on box fronts (too thick for bluebirds) or perches on boxes (used by predator birds such as sparrows & kestrels). Instead, use a predator guard on your mounting post or make the mounting post your predator guard (3/4” electrical
conduit preferred).

See detailed plans.

In which direction should the boxes be?

Keep away from prevailing westerly winds (cools boxes)

Use the same direction for all boxes.

Cornell University has determined that directing the opening of a nest box to the north-east, east or southeast improves the fledging rate of Eastern Bluebirds in northern latitudes. Apparently, boxes pointed in that direction, heat up more quickly in the mornings in cold weather but do not collect as much heat from a southern exposure in summer.

What are the nest boxes recommended by BRAW?

BRAW recommends using nest boxes that have proven to be highly attractive to bluebirds. These boxes are shallow (4-5” from  bottom of hole to nesting platform), narrow (4” x 4” nesting platforms), have oval openings (1 3/8” x 2 ¼”) and are unvented  (vents can be opened after June 1 in areas where black flies are not prevalent). Any box that meets these specifications is  recommended by BRAW. Read more…