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Use of Nest Boxes in Ponderosa Pine Forests1
2
jeffrey D. Brawn and Russell P. Balda3
Abstract. Use of nest boxes by secondary cavity nesting
birds was assessed on 3 study plots in northern Arizona's ponderosa
pine forests from 1980 to 1982. Sixty boxes were installed on each
of the 8.0 ha plots. Box use as nest sites increased, overall, from
5% to 31% during the 3 breeding seasons. Differences in % use
between plots were related to the availability of natural nest sites
in snags. To date, 6 species have nested in the boxes. Nest
attempts were 73% successful. The employment of nest boxes as a
management tool may become more viable if current trends in land
use practices persist.
The objective of alleviating the negative impact
of certain silvicultural practices on cavity nesters has
generated several management options. These options
include: (1) retention of a certain density of suitable
(i.e. large enough) snags on a managed stand (Balda
1975, Scott 1978); (2) letting a certain amount of a
stand mature to or remain in old growth conditions
(Hardin and Evans 1977); (3) creation of snags by either
routing out holes (Carey and Sanderson 1981), killing
. trees (Bull et al. 1980), or fungal innoculation; and
(4) installation of nest boxes.
INTRODUCTION
All organisms have certain requirements that must
be satisfied in order to survive and reproduce. The
habitat requirements of non-game birds have received
considerable attention with much recent work focusing
on the interaction between timber management and avian
habitat needs (e.g. USDA For. Serv. 1980).
An especially lar~e amount of research has been
devoted to cavity nesting birds and their relationships
with snags, i.e. dead or dying trees. Such research
is abundant because: (1) cavity nesters are a diverse
~roup of birds; (2) many aspects of cavity nester habitat
needs are relatively specific and easily quantified; and
(3) the reliance of cavity nesters on snags renders them
vulnerable to certain land use practices. Investigations
of many aspects of cavity nesting bird biology have been
performed including; types of snags used for nesting
(Connor and Adkisson 1977, Scott 1978, Cunningham
et al. 1980); densities of snags suitable for support of
viable populations (Balda 1975, Scott 1979); and use of
snags as foraging substrates (Brawn et al. 1982).
These studies have clearly demonstrated, by either
experimental or descriptive analyses, the critical
importance of snags to cavity nesters. Moreover,
virtually all research has supported the notion that
strict silvicultural management of forests is selective
against snags, and that density of snags and/or nest
holes is a ~ood predictor of cavity nester densities.
The first two of the above options are likely the
best in terms of a holistic approach to the maintenance
of cavity nester populations; however, certain factors
are becoming increasingly serious which may,
unfortunately, mitigate their use in the future.
Projected demands for wood fiber and resources (i.e.
land) available to meet these demands are likely to
result in an increasingly intense level of silvicultural
management on many forests (Gould 1980). In addition,
and perhaps as important, the ever increasing public
demand for fuelwood is having a dramatic impact on the
"life expectancy" and density of snags (Scott et al.
1980).
Interestingly, most research on cavity nesters
has dealt with primary cavity nesters (PCNs); i.e.
species which are able to excavate their own nest and
roost holes. A tacit assumption of such studies has
been that if PCNs are provided for, then the species
which are unable to excavate, or secondary cavity
nesters (SCNs), will also be accommodated. Whereas
this assumption in intuitively sound, it has resulted in
a general avoidance of research on the last of the
aforementioned management options for cavity nesters,
i.e. nest boxes.
1
Paper presented at the snag habitat management
symposium. [Northern Arizona University, Flagstaff,
june 7-9, 19831. .
2
jeffrey D. Brawn is a Research Assistant at the
Department of Biological Sciences, Northern Arizona
University, Flagstaff, Ariz.
3 Russell P. Balda is a Professor of Biology,
Nest boxes have been widely used in Europe for
much of the 20th century (Bruns 1960, von Haartman
1971). Boxes have generally maintained populations of
SCN s in habitat which would otherwise be unsuitable.
In certain instances the results have been dramatic,
and many-fold increases in SCN breeding densities have
Department of Biological Sciences, Northern Arizona
University, Flagstaff, Ariz.
159
,
been recorded (von Haartman 1956, 1971). Commercial
forests in much of Europe are intensively managed and
it is likely that the presence of boxes has prevented
local extirpations of many SCNs.
Inside Height - 21 em
3
The volume of each box was approximately 1900 em •
Boxes were installed by hanging them on metal-wood
holders which had been nailed to tree trunks.
In North America, nest boxes have been employed
on a relatively small scale. Generally, their use has
been limited to ~arne species or selected non-~ame
species such as Eastern Bluebirds (Sialia. sialis)
(Pinkowski 1977). Certain workers have, oddly,
resisted the idea of nest boxes as a management option
in North America (Miller and Miller 1980). A typical
objection to boxes is that they furnish only one of the
resources which snags offer, i.e. unused holes for
SCN s. This consideration is valid but does not diminish
the utility of boxes as part of the solution to effective
cavity nester management.
Sixty boxes were installed on each plot; thus, a
total of 180 boxes were used for this study at a density
of about 7 boxes/ha. Boxes were installed during the
spring of 1980.
Four types of boxes were installed on each plot;
large-hole (38 mm) and small-hole (32 mm) with and
without. sawdust. Hole size is important because SCNs
usually prefer to use nests with holes just large
enough for them to pass through. The hole sizes we
selected accommodate all potential avian inhabitants of
the boxes in northern Arizona (raptors were not within
the scope of this study). Sawdust was provided for
those species which are known to partially excavate
nest holes in snags and/or modify old woodpecker holes.
If boxes are to be used as an effective management
tool in North America it will be necessary to have
baseline data concerning their use. Prior to the
present study, no large-scale nest box programs for
non-game birds have been conducted in western
coniferous forests (Smith 1980). This paper will report
on some of the results of a study designed to assess the
efficacy of nest boxes in ponderosa pine forests. The
objectives of this study were:
(1) to determine if SCNs will utilize nest boxes
in ponderosa pine forests;
(2) to monitor the success of SCNs that breed in
boxes; and
(3) to determine the cost of a nest box program.
Other aspects of this study such as effects of boxes on
SCN populations, SCN habitat selection, and management recommendations will be reported on elsewhere.
Boxes were spaced evenly throughout the plots
using grid-markers as guides. The distribution of
boxes on WS-17 was, necessarily, somewhat uneven
due to the limited availability of trees suitable for
hanging boxes.
Assessment of Box Use and Breeding Success
Each box was checked at least twice during each
breeding period from 1980 to 1982. Boxes found to be
in use were checked more frequently.
Nesting success of box occupants was closely
monitored. All boxes used during the breeding period
were cleaned out during the following fall.
METHODS AND MATERIALS
Field work was conducted on 3 study plots, all
located within the USFS Beaver Creek Watershed
Project located south of Flagstaff in the Coconino
National Forest, Coconino County, Arizona. Each
plot covered 8-8. 5 ha •
RESULTS AND DISCUSSION
Use of Boxes--Overall Response
The number of boxes used for nesting increased
over six-fold between 1980 and 1982 (table 2). The
greatest response to the boxes occurred on WS-8
where an average 22% contained active nests each year.
The smallest response occurred on WS-13 which had
only an average 7% nesting use. The use of boxes on
all three plots, however, has increased each successive
year. Within each plot the largest increases were
between the 1980 and 1981 breeding seasons.
All plots consisted of ponderosa pine (Pinus
ponderosa) dominated stands with varying densities of
gam bel oak (Quercus gambeli). Elevation of the plots
varied from 2100 to 2300 m. Average annual precipitation and temperature on the Beaver Creek Watershed
are approximately 64 em and 7.2°, r~spectively.
The three plots differed in silvicultural histories:
one plot (WS-13) was uncut for approximately 60 years;
one plot (WS-8) was moderately thinned in 1974; and one
plot (WS-17) was severely thinned in 1969. Silvicultural
profiles of the plots are shown in table 1. Importantly,
snag densities on the WS-13, WS-8, and WS-17 plots
were high, medium, and low, respectively.
The build-up of box use on all plots resulted from
two trends: (1) within a given species more pairs
nested in boxes each year; and (2) more species used
the boxes each year. For example, on WS-8 in 1980,
2 Western Bluebird (Sialia mexicana) and 2 Pygmy
Nuthatch (Sitta pygmaealnests were found, whereas in
1982 we found 9 Western Bluebird, 5 Pygmy Nuthatch,
9 Violet-green Swallow (Tachycineta thallassina), 1
Mountain Chickadee (Parus gambeli), and 1 Whitebreasted Nuthatch (Sitta carolinensis) nests.
Type and Installation of Boxes
Boxes used in this study were made from a mixture
of concrete and wood chips and were purchased in W.
Germany. The boxes were cylindrical with the following
dimensions:
Total Height - 25 em
Distance from Hole to Bottom - 17 em
Outside Radius - 10 em
Use of Boxes by Species
To date, 6 species have nested in the boxes
(.table 3). Mountain Bluebirds (Sialia currucoides),
160
Table 1. Sil vicultural Profiles of Study Plots
Criterion
Relative
Density
Relative
Dominance
Relative
Frequency
Importance
Value
Absolute
Density
(trees/ha)
Number of
Sna~s
Plot
Tree Species
WS-17
~.
:eonderosa
gambeli
81
19
87
13
69
31
237
63
57
12
7
~.
:eonderosa
gambeli
68
32
65
35
62
38
198
102
52
21
9
~.
:eonderosa
gambeli
92
8
94
6
82
18
268
32
209
16
21
g.
~.
:eonderosa
gambeli
89
79
21
259
41
217
19
18
~.
:eonderosa
90
8
2
91
9
86
8
6
77
19
4
253
36
583
54
9
39
WS-17C
WS-8
WS-8C
WS-13
g.
g.
g.
g. gambeli
l· de:e:eeana
11
Purple Martins (Progne subis), and Red-breasted
Nuthatches (Sitta canade""il'SS'S) are the only local SCNs
which have yet to use the boxes. Considerable interspecific variation with regard to box use has been
found. Western Bluebirds have utilized the boxes most
readily on all three plots. Violet-~reen Swallows
be~an to use the boxes in low numbers during 1981 on
WS-8 and WS-13. In 1982 swallows nested in the
boxes on WS-8 and WS-17 in relatively hi~h densities.
Bluebirds and swallows are both migratory species.
Amon~ permanent residents, box usage has been
~rea test with Pygmy Nuthatches, followed by Mountain
Chickadees and least with White breasted Nuthatches
and House Wrens (Troglodytes aedon). Based on
preliminary data from 1983, however, White-breasted
Nuthatch use of the boxes is increasing.
has found that adverse winter conditions can have a
distinct negative effect on bird populations (Balda et al.
this volume). Finally, a period of "adjustment" may
be required before all the SCNs recognize the boxes
as potential nest sites. A type of social facilitation is
possibly involved; that is, birds observe use of boxes
by other birds and subsequently learn that the boxes are
an exploitable resource. Studies concerning box use
by Wood Ducks (Aix sponsa) have also noted a ~radual
increase through time in the proportion of boxes used
(Doty and Kuse 1972).
The overall pisparate response to the boxes on
the plots is likely due, in part, to the availability of
natural nest sites. The number of boxes divided by the
number of excavated holes counted on snags within the
plots were: WS-13, 1.2; WS-8, 1.9; and WS-17, 8.57.
A correlation between these ratios and the % of SCN
nests found in boxes indicated a significant positive
relationship (r = .67, df = 7, P < 0.05). This indicates
that availability of snags and box usage are mutually
dependant. If box usage continues to increase on
WS-13 as it did between 1981 and 1982, however, this
relationship will become less distinct. These data
indicate that availability of snags may precipitate a la~
in box usage but that boxes will eventually be utilized.
Further research will be required to properly evaluate
this matter. The question of why certain species
re.spond to boxes more than others wi ll be considered
elsewhere (Brawn and Balda, in prep.).
The relatively meager overall response on all
three treatment plots in 1980 has several potential
explanations. On WS-8 and, especially, WS-13, the
boxes were installed rather late in relation to timing
of SCN breeding due to snow conditions. In addition,
the winter previous to the 1980 breeding period was,
even by local standards, quite severe. Another,
on~oin~ study on avian communities in northern Arizona
Table 2. Number of boxes with nests on treatment plots
from 1980 to 1982 •
Number of Boxes Used (%)*
Plot
1980
WS-17
WS-8
WS-13
Overall
Usa~e
1981
11
Nesting Success of Birds Using Boxes
1982
3 (5)
6 (10)
0
13 (22)
22 (37)
4 (7)
24 (40)
24 (40)
8 (13)
9 (5)
39 (22)
56 (31)
Overall, 73% of the nesting attempts in boxes ~re
successful; that is, at least one nestling fledged (table 4).
This success rate agrees favorably with what has been
found for cavity nesters and/or temperate passerines
(Nice 1957, Rickleffs 1969). Thus, it does not appear
that the boxes used in this study present any particular
liability to breeding birds.
*Boxes with two nests in one season are counted once.
161
Table 3. Use of boxes for nests by various SCNs between 1980
and 1982.
Number of Boxes Used
WS-8
WS-17
1980
Species
Violet-~reen Swallow
Mountain Chickadee
White-breasted Nuthatch
Py~my Nuthatch
House Wren
Western Bluebird*
0
0
0
0
0
3
1981
1982
1980
5
0
0
0
3
0
3
0
0
0
2
1
10
1
1
2
0
15
1981
4
2
0
5
0
11
WS-13
1982
1980
1981
1982
9
1
0
0
0
0
0
0
1
1
0
0
0
2
1
2
0
2
0
3
1
5
0
9
*Boxes used twice for first and second broods are counted only once.
Considerable variation between species was
found in nestin~ success. Py~my nuthatche.s had the
highest nest success whereas Western Bluebird
second nests were the least successful. Nestin~
success was approximately equal on the three plots but
did vary between years. For example, overall Violet~reen Swallow success was about 35% lower in 1982
than 1981. Such variation appears to be due to annual
differences in sprin~-summer precipitation and
temperature and breed in~ phenolo~y (Brawn and Balda,
in prep.).
Nest parasites were not found to be an important
source of nesting failure. The only nests in which we
found parasites were second nests of Western Bluetirds
(N = 9, 39%). The parasites were blowfly larvae of
Apaulina (formerly Protocalliphora). We found no
relationship between incidence of parasitism and
probability of nest success or nesting mortality
(P > 0.05, x2).
The primary cause of nesting failure was
abandonment of either unhatched eggs or nestlin~s.
It is unlikely that predation on breeding adults was
responsible for these abandonments since, in the cases
where birds were color marked, breeding adults were
subsequently observed on the plots.
Non-avian use of the boxes by vertebrates was
limited. Between 1980 and 1982 we found direct evidence
of only 1 mammal nest; the species was unidentified.
During fall cleanout of boxes we did find several
instances of leaves placed on top of old bird nests, but
no animals were found. Importantly, mammalian use of
the boxes has had very little effect on avian use. Other
box projects, designed for birds, have had considerable
mammalian use of boxes, particularly flyin~ squirrels
(Glaucomys spp.) (Brawn 1979)4.
Non-Avian Use of Boxes
Predation on e~gs or nestlings occurred in only
4 out of the 110 nests (4%). This rate of predation is
much lower than that reported for many cavity nesters
(Rickleffs 1969). We are not certain of the identity of
the predator but, based on conditions of the nests, we
consider ~opher snakes (Pituophis melanoleucus) a
possibility. All the predation losses occurred on
Western Bluebird second nests in 1981. Thus, no
"build-up" of predation pressure has occurred on any
of the plots.
Cost of Boxes
The cash outlay and labor necessary to start and
maintain the box project have been reasonably low
(table 5). The boxes, including shipping from W. Germany,
cost less than $10.00 each. The only equipment
necessary to install the boxes were a ladder and hammer.
Labor needed to maintain the boxes was not
excessive. To date, after 540 box-years, 2 boxes,
which were struck by lightening, have had to be replaced.
One other box was removed from its han~er by persons
unknown and was replaced. Boxes used for nesting
were cleaned out after the breed in~ period. Cleaning
required about 1 man-hour /box.
Table 4. Overall nesting success of SCNs in nest boxes.
Species
Violet-green Swallow
Mountain Chickadee
White-breasted Nuthatch
Pygmy Nuthatch
House Wren
Western Bluebird
First Nests
Second Nests
Totals
Number of
Nest
Attempts
Number of
Successful
Nests (%)
21
7
2
18
1
12 (57)
6 (86)
1 (50)
17 (94)
1 (100)
38
...R
30 (79)
13 (43)
110
80 (73)
Other workers have recommended against nest box
For example,
pro~rams because of prohibitive costs.
4
Brawn, J.D. 1979. The relationship of cavity nesting
birds to snags in the oak-hickory forest. Unpub. Misters
Thesis. Univ. of Missouri-Columbia, Columbia,
Missouri.
162
McComb 0979~ with regards to southeastern forest~,
reports 4 to 14 cavities must be .Presen~ ~efore one 15
used by a cavity-dependant spec1es. C:lt.mg a cost of
$25.00/box it was determined that a m1mmum of
$100.00 was necessary for each active box.
Table 5. Cost and labor for nest box project.
Our findings, however, indicate that such caution
is unwarranted in ponderosa pine forests. Our data
clearly demonstrate that the costs/active box are
considerably less. For example, by 1982 we found
that about 1 box in 3 (on WS-8 and WS-17) were used·
This does not indicate, however, that 3 boxes are
needed for every one used by SCNs. Differences in
territorial behavior (between species), yearly
fluctuations in density of prospective breeders, climate,
and habitat type are likely most responsible fo7 f!luch
of the variation in box usage. Moreover, prehmmary
analysis of the 1983 breeding season ~ndicates that box
usage will again increase; thus lowermg the expense of
boxes in terms of cost/active nests.
Boxes, hangers, and
shipping
Installation
(transport of boxes to plot,
selection of box trees, and
installation)
Maintenance
(cleaning 1 time/year)
Item
Cash Outlay and/or Labor
$9.30/box
2 man-hours/box
1 man-hour/box
ACKNOWLEDGEMENTS
We thank the Federal Timber Purchaser's
Association, the National Forest Product's Association,
Northern Arizona University, and the Frank M. Chapman
Fund for supporting various aspects of this study.
CONCLUSIONS
The results of this study demonstrate that boxes
are a viable management option for SCNs in ponderosa
pine habitat but that extant snag-density will maf'kedly
effect how often and what uses boxes. On stands such
as WS-13 it is clear that the installation of boxes .is
unnecessary. On stands with few snags, boxes wlll be
used but the response is also mitigated by structure of
live vegetation. For example, we found t~at very open
areas, like WS-17, will support fewer fohage gleaners,
such as Pygmy Nuthatches, than areas like WS-8 which
have higher foliage volume.
LITERATURE CITED
Balda, R. P. 1975. The relationship of secondary
cavity nesting birds to snag densities in western
coniferous forests. USDA For. Serv.,
Southwest Region Wildl. Hab. Tech. Bull. 1. 37 p.
Brawn, J.D., W.H. Elder, and K.E. Evans. 1982.
Winter foraging by cavity nesting birds in an
oak-hickory forest. Wildl. Soc. Bull. 10:217-275.
Bruns, H. 1960. The economic importance of birds in
the forest. Bird Study 7:298-301 .
Bull, E .L., A.D. Twomby, and T. M. Quigley. 1980.
Perpetuating snags in managed mixed conifer
forests of the Blue Mountains, Oregon. In
Management of western forests and. grasslands for
nongame birds. R. M. DeGraff, Tech. Coord. ,
p. 325-336. USDA For. Serv. Gen. Tech. Rep.
I NT -86. I ntermt. For. and Range Exp. Sta.;
Ogden, Utah.
Carey, A.B. and H. R. Sanderson. 1981 • Routing to
accelerate tree-cavity formation. Wildl. Soc.
Bull. 9:14-21.
Conner, R.N. , and C. S. Adkisson. 1977. Principal
component analysis of woodpecker nesting habitat.
Wilson Bull. 89:122-129.
Cunningham, J. B., R. P. Balda, and W. S. Gaud. 1980.
Selection and use of snags by secondary cavity
nesting birds of the ponderosa pine forest. USDA
For. Serv. Res. Paper RM-222. 15 p.
Doty, H. A. and A.D. Kruse. 1972. Techniques for
establishing local breeding populations of Wood
Ducks. J • Wildl. Manage. 36:428-435.
Gould , N . E . 1980. U. S • timber needs and prospects
for bird habitats. In Management of western
forests and grasslands for nongame birds. R .M.
DeGraff, Tech. Coord., p. 295-301. USDA For.
Serv. Gen. Tech. Rep. INT-86. Intermt. For.
and Range Exp. Sta.; Ogden, Utah.
Hardin, K.I. and K.E. Evans. 1977. Cavity nesti~
bird habitat in the oak-hickory forest ..• a review.
USDA For. Serv. Gen. Tech. Rep. NC-30. 23 p.
Miller, E. and D.R. Miller. 1980. Snag use by birds.
In Management of western forests and grasslands
for nongame birds. R . M. DeGraff, Tech. Coord.
Maintenance of densities of snags sufficient to
locally maintain cavity-dependant species of wildlife
has been recommended by many workers. We stress
that snags will always be needed. in ponderosa pine
forests. Many species that requ1re snags do not use
nest boxes. Boxes cannot be considered as a complete
substitute for snags but should be considered as part
of the solution to maintaining snag-dependant fauna.
No management plan for cavity nesters should depend
on only one technique or policy. An integrated
approach will in the long term likely be the most
effective.
Finally, our data show that many oft-cited re~sons
for not using boxes can be irrelevant. We found ne1ther
predation or parasitism were ~actors that should
prohibit use of boxes. Costs m ~:mr studr we.re not
prohibitive: however, expense wlll be qUlte h~ely
variable depending on such aspects as box ~es1gn used
and scale of the project. We suggest that pllot box
programs be initiated in other habitat types so that the
efficacy of such an approach can be as.sessed. In the
ponderosa pine forests of northern Ar1zona, boxes
work and cannot be ignored as an effective management
option.
5McComb, W.C. 1979. Nest box and natural
cavity use by wildlife in mid-South hardwoods as related
to physical and microclimatic characteristics. Ph.D.
Thesis, Louisiana State Univ., Baton Rouge, LA.
163
p. 337-356. USDA For. Serv. Gen. Tech . Rep .
I NT -86. I ntermt. For. and Ran~e Exp. Sta.;
Ogden, Utah.
Pinkowski , B . C. 1977. Blowfly parasiti s m of eastern
bluebirds in natural and artificia l nest site s . J.
Wi ldl. Ma nage . 41 :272-276 .
Rickleffs, R.E. 1969 . An analysis of nest ing mortality
in birds. Smith . Contrib . Zool. 9:1-48.
Scott, V.E. 1978. Characteristics of pond e r osa pine
snags used by cavity nesting bird s in Arizona.
J. For. 76:26-28.
____ . 1979. Bird response to s nag r e moval in
ponderosa pine . j . For. 77:26-28.
- --,..--' J . A. Whelan, and P .L. Svoboda . 1980.
Cavity nesting birds and for est management.
.!..!!_Management or wester n fore s t s and grasslands
for nongame bird s . R . M. DeGraff, Tech. Coord .
p. 311-324. USDA For. Serv . Gen. Tech. Rep.
I NT -86. I ntermt. For . and Range Exp. Sta. :
Ogden , Utah .
Smith, K. G. 1980. Nongame bird s of the Rocky
Mountain s pruce-fir forests and their management. In Management or western forests and
g ra ss lands for nongame birds . R. M. DeGraff,
Tech. Coord . , p . 258-279. USDA For. Serv.
Gen . Tech. Rep . INT-86. Intermt. For. and
Range Ex p. Sta. ; Ogden, Utah .
USDA For. Serv . 1980. Workshop proceeding s:
Management of weste r n forests and grassland s
for nongame bird s . USDA For. Serv. Gen. Tech.
Rep. INT-86. 535 p. Intermt. For. and Range
Exp . Sta .; Ogden, Utah.
von Haartman, L. 1956 . Territory in the Pied
Flycatcher, Muscicapa hypoleuca. Ibi s 86:460-475 .
1 64