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Attracting Bluebirds and Other Cavity
Nesting Songbirds in North Dakota

Other Songbirds Utilizing Bluebird Trails

Several other species make use of the same boxes utilized by bluebirds. The three primary ones include the tree swallow, house wren, and house sparrow. It is also possible to attract a black-capped chickadee or nuthatch, both cavity nesters.

This section will help you both identify the bird species and the nests and eggs of each through use of color photographs. A chart further describing nest, egg and other characteristics can be found at the end of this section.

Tree Swallow

A bird scientifically named for its dual bright colors of iridescent blue-gray and white, this beneficial insect eater also makes use of cavities targeted for bluebirds. Both the male and female are similar in appearance. They are found in areas near water and wood lines where abundant insect populations thrive. Tree swallows are distributed throughout the state excluding the extreme southwestern portion. Tree swallows are approachable birds and can be quite tolerable of humans. Their nests are characterized by being made of grasses and lined with feathers. Tree swallow eggs are pure white.

GIF - Tree swallow nest
Tree swallow nest. Materials used include grasses with a lining of featehrs.
GIF - Tree swallow on box
An adult tree swallow stakes claim to a nest box on the Henderson WMA. Adult tree swallow males and females are similar in appearance and use the same nest boxes as bluebirds.

House Wren

This small, mostly brown cavity nester can be found statewide along the edges of deciduous forests, shelterbelts, city parks and backyards. Wrens are beneficial because they are insect eaters and are entertaining to watch. They will, however, out compete the bluebird for nesting space so avoid placing nest boxes too close to wooded habitat unless you are specifically attempting to lure wrens in.

Wrens are characterized by their small size and tail which is often held straight up in the air at a ninety degree angle to the body. Their nests are made entirely of twigs and their eggs are about one-third the size of bluebirds and tree swallows. Male and female house wrens are similar in appearance.

GIF - House wren nest
A house wren nest shown tipped toward you to allow viewing of eggs. House wrens use twigs, often filling the entire nest box to the top. Eggs are about the size of small jelly beans and vary in color from light pinkish to brown.
GIF - House wren
House wrens are beneficial birds that eat insects and provide hours of entertainment. They compete with bluebirds for nesting space when nest boxes are placed too close to tree rows or other woody plantings.

House Sparrow

The exotic house sparrow, introduced to America from Europe in 1850, has all but taken over many habitats once occupied by native species. It is an aggressive bird and will kill adults and young of other beneficial species as well as remove eggs from nest boxes being utilized by bluebirds. The house sparrow is not protected by law and should be eliminated whenever possible. Its nests are constructed of coarse grasses, weeds, feathers, sticks and a variety of other trash. Its eggs can easily be identified from other species because they are speckled much like the wren but substantially larger.

GIF - Male house wren GIF - Female house wren
The house sparrow male (left) and female (right) are species which were introduced to this country from Europe and have flourished in many habitats once occupied by only native birds. These birds attack and kill bluebird and tree swallow adults and young, and compete ferociously for their nesting space. They are most common in urban areas and farmsteads where they rely upon humans for providing waste grain and discarded food. House sparrows are not protected by law and can be taken by any legal means.

Cavity Nesting Songbird Nest and Egg Data

Nesting Activity
Tree Swallow
House Wrens
House Sparrows
Dates: Arrival Mid March Mid to Late April Early May Permanent Resident
Nest Building: Location of Nest (in natural cavities) Open country with scattered trees, near mowed or sparsely covered ground (prairie and farmland) Partly open country with old or dead trees, often near water Open woodland & wood borders, shrubland, farmland, suburbs, up to 200' from cover Hole or crevice anywhere, especially by buildings and urban areas
Male Claims Nest With Grass (1-6 weeks before nest building) Curved white feathers Twigs Grass or by sitting in hole
Materials Dry grass & weed stems (occasionally fine rootlets or twigs), lined with finer grass (occas, hair or feathers) Dry grass (occasionally straw) or cattails, lined with feathers (often white) Twigs and stems, leaves, & fibers. Lined with fine grass, feathers, hair, bark strips Long coarse grass stems with seed heads, weeds, feathers, trash
Size & Shape Loosely built with 2-3" cup Loosely woven with large shallow cup, feathers upright curving over eggs Bulky nest of twigs nearly filling box Large untidy dome with side entrance to deep space with little or no bottom
Days to Build and Builder 4-11 days by F, (2-14 days possible + possibly 1+ week before first egg laid) 14-21 days by F (7-30 days possible) M: 8-10 days (base)+
F: 4 days (lining)+
possibly 2 days before 1st egg laid
1+ days, by M
Eggs: Color Blue and occasionally white White Light pink to white with rust specks Off-white to bluish green with gray brown spots
Total Number Laid 4-6 eggs
(3-7 possible)
5-6 eggs
(4-8 possible)
5-8 eggs
(to 12 possible)
4-6 eggs
(3-8 possible)
Incubation Period 12-14 days
(12-18 days possible)
14-15 days
(13-16 days possible)
13 days
(12-15 days possible)
12 days
(10-14 days possible)
Hatch Timing Synchronous Synchronous Synchronous Synchronous
DO NOT DISTURB after: (Age when nestings could prematurely fledge) 12 days 15 days 9 days Remove eggs before they hatch!!
Total Time in Nest: 17-18 days usually (15-20 is possible) 20-21 days usually (16-24 possible) 16-17 days usually (12-18 possible) 15-16 days usually (14-17 possible)
Number of Broods: 2 broods
(sometimes 3)
1 brood
(rarely 2)
1-2 broods
(rarely 3)
2-3 broods
(sometimes 4)

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