BIOTROPICA 41(1): 81–84 2009 10.1111/j.1744-7429.2008.00457.x
Experimental Study of Nest-site Selection in the Biscutate Swift (Streptoprocne
biscutata, Aves: Apodidae) in Southern Brazil
Mauro Pichorim1, James J. Roper, and Emygdio Leite de Arau´jo Monteiro Filho
Departamento de Zoologia, Universidade Federal do Parana´, Cx. P. 19020, Curitiba, PR, Brazil, 81531-990
ABSTRACT
Biscutate swift Streptoprocne biscutata nests are usually built on protected rocky cliff walls. Birds often renest at the same location. Remains of previous nests may offer
information about potential nests and quality of nest-sites. Here, we experimentally study nest-site selection to test the hypothesis that information from previous
nests is used in current nest-site selection. We placed old nest material at artificial nest-sites to test whether new nest-sites are chosen based on the presence of nesting
material. We also tested whether the use of natural nest-sites is influenced by nesting material by creating two types of natural sites: previously used natural nest-sites
with vestiges of old nests removed and never used natural nest-sites to which vestiges of old nests were added. In the first experiment, in 139 nest-use opportunities,
16 artificial nest-sites were used, all of which included vestiges. In the second experiment, in 91 nest-use opportunities, four nests were in previously unused but
natural locations to which vestiges had been added, 22 nests were in previously used sites without vestiges, and the remaining 65 nests remained unused. Two processes
are apparently in action: first, prior experience and memory; second, vestiges indicate where nesting has occurred, possibly useful for first breeding, or for imperfect
memory. Previous nesting information may explain why swifts use nesting locations for many years and why new nesting colonies seldom form. This transmission of
information suggests that swifts tend to be conservative and nest where previous nesting has occurred.
Abstract in Portuguese is available at http://www.blackwell-synergy.com/loi/btp.
Key words: artificial nest; avian reproduction experiment; swifts.
NESTS OF SWIFTS IN THE GENUS Streptoprocne are usually in hard-
to-reach places, caves or overhanging rocky cliff-faces, often behind
waterfalls protected from the elements (Lack 1956, Whitacre 1989,
Chantler 1999, Pichorim 2002). Predation avoidance is apparently
the best explanation for the evolution of this nest site selection
(Chantler & Driessens 1995). The biscutate swift, Streptoprocne
biscutata (Sclater, 1866), nests on horizontal substrates and rocks
(shelves) that protrude from vertical or nearly vertical and over-
hanging rock faces, usually in caves. These sites may also often
be limiting (Pichorim 2002). Nesting materials include a variety
of plant materials that birds ‘glue’ together on the substrate with
saliva. After reproduction, nests remain in situ and vestiges of nests
may stay in place long after their use, often providing a substrate on
which new nests are built (Pichorim 2002).
Remains of previously used nests may offer information about
adequate nest locations and may be important in the nest-site se-
lection process. A variety of bird species may reuse nests, possibly
with reduced costs of nest-site selection and construction, as well
as providing information about nest-site quality (Slagsvold 1985).
Reuse of nest sites is common in swifts (Mar´ın & Stiles 1993,
Thompson & Home 1993, Collins & Foerster 1995, Mar´ın 1997).
Reduced energetic costs may be important, since for some species of
swifts, nest construction is a considerable investment in energy and
time. Reuse would then provide an advantage in reduced time and
energy spent in nest construction that can then allow more rapid
nesting once birds arrive on the breeding ground. Here, we experi-
Received 26 February 2008; revision accepted 19 July 2008.
1Corresponding author; current address: Departamento de Botaˆnica, Ecolo-
gia e Zoologia, Centro de Biocieˆncias, Universidade Federal do Rio Grande
do Norte, Campus Universita´rio, Natal, RN, Brazil, 59072-970; e-mail:
mauropichorim@yahoo.com.br
mentally tested whether biscutate swift uses vestiges of old nests as
information about where to nest during the current reproductive
event.
METHODS
During the reproductive seasons of 1999–2002, nest site use was
studied in two swift colonies in the central eastern region of the state
of Parana´, in southern Brazil (25◦22′ S, 48◦58′ W and 25◦11′ S,
48◦51′ W, 1250 and 1050 m asl, respectively). This region is part of
the Atlantic Forest biome. Both colonies were in granite formations
with cave-like vertical rock faces that have been used for nesting for
many years (Pichorim 2002).
Artificial nesting substrates were built in the form of a half
cone (16 cm radius × 20 cm height), the base of which was directed
upwards to provide a plateau on which to nest (providing a platform
similar to those used by the birds; Pichorim 2002). They were made
of a combination of phenol-formaldehyde resin, marble and rock
powder, green pigment, and catalyst, and bolted to the rock wall
(Fig. 1).
The ‘artificial nest site experiment’ tested whether new nest-
sites are chosen based on the nesting material found at the potential
nest site. Old nest material was placed at a portion of the artificial
nest sites to provide the appearance of previously used nest sites.
Fourteen platforms were mounted in 1999, 39 in 2000, 47 in 2001,
39 in 2002, for a total of 139 artificial nest sites (86 with vestiges
of nests and 53 without vestiges).
The ‘natural nest site experiment’ tested memory versus in-
formation in nest site selection. If memory, birds should favor
previously used sites, regardless of nesting material. Alternatively,
C© 2008 The Author(s)
Journal compilation C© 2008 by The Association for Tropical Biology and Conservation
81
THE JOURNAL OF TROPICAL BIOLOGY AND CONSERVATION

82 Pichorim, Roper, and Monteiro Filho
FIGURE 1. Examples of artificial nest sites in place, showing a platform that was similar to those used by the birds. In the detail is one artificial platform with nest
and eggs.
if nesting material provides information, then birds should favor
locations with nesting material from previous nesting attempts. In
this experiment, previously used nest sites had old nesting material
removed. The material was then used in another site to simulate
previous use. Vestiges were removed from 62 natural nest sites (16
in 1999, 17 in 2000, 16 in 2001, 13 in 2002) and added to 29 new
natural sites (eight in 1999 and 2000, seven in 2001, six in 2002).
In practice, these two experiments occurred simultaneously,
and all experimental manipulation took place a minimum of
90 days prior to nest use by the birds. Nesting material that was
placed in the unused site was always from nests used during the
previous season. Contingency table analysis (G) was used to test
whether birds preferentially selected new sites with remains of old
nests, and to test whether natural nests with vestiges were preferred
to those without vestiges.
RESULTS
In the artificial nest site experiment, of 139 nesting opportunities,
16 were in artificial nest sites with vestiges of nests (in a total of 86
opportunities). Artificial nest sites without vestiges were never used
(N = 53 opportunities). This supports the prediction that birds
use nesting materials to help indicate where they should nest (G =
16.6, df = 1, P < 0.05).
In the natural nest site experiment, in 91 nesting opportuni-
ties, 22 were in historically used sites without vestiges. Four nests
were in previously unused but natural nest sites with vestiges. The
unused sites were distributed among 40 previously used sites with-
out vestiges and 25 unused sites with vestiges (G = 4.97, df = 1,
P < 0.05). This pattern was different than that of the artificial nest
site experiment in that the expected value for used sites with vestiges
was twice that of the observed value (Fig. 2). Thus, previously used
sites are more often reused than expected. Finally, even though there
were many more available sites than were used, the trend was for
birds to tend to use previously used sites: 18 percent (42 of 230)
of all nesting opportunities were used, of those, 11 percent were in
natural nest sites and 7 percent in artificial sites (G = 10.5, df = 1,
P < 0.05).
DISCUSSION
The artificial nest site experiment supports the hypothesis that the
biscutate swift uses nesting materials as information for nest site
choice. On the other hand, the natural nest site experiment supports
the hypothesis that memory influences nest site choice. If only
vestiges were important, the results of the natural site experiment
should have been similar to those of the artificial experiment. Thus,
the mixed results suggest that this swift apparently use two strategies
by which to decide where to nest: (1) vestiges of old nests; and
(2) memory of previous nesting attempts. Memory of previous
nesting attempts suggests reuse of sites by the same pair, which may
reduce energetic costs. Energetically, the saliva nests of Aerodramus
maximus and A. fuciphagus are costly to produce and when removed
(for bird’s-nest soup), result in reduced lipid reserves and reduced
reproductive success (Kang et al. 1991, Phach & Voisin 1998).
Apparently, biscutate swift uses saliva in nest construction since
fresh nesting material is wet and viscous and nests may require a
month for completion (Pichorim 2002), suggesting a relatively large

Nest-site Selection by Biscutate Swift 83
FIGURE 2. Comparison among treatments of the number of nesting opportunities in artificial and natural nest site experiments. In artificial nest sites (A), only
sites with vestiges of old nests were used (G = 16.6, df = 1, P< 0.05), and in natural nest sites (B), vestiges were unimportant in determining whether sites were used
(although the test was significant, but not in the predicted direction), suggesting that experienced birds remember prior nesting events. Note that a larger proportion
of nesting opportunities are used in natural nests.
cost to nest construction. Thus, a benefit to nesting for experienced
pairs would be simply to remember and use the nest of the previous
year. Also, if the nest was successful in the previous year, perhaps it
is a good predictor of current success.
Vestiges in nest sites may provide benefits, particularly for
naı¨ve, fist time nesting, birds: (1) location of a previously used, and
presumably acceptable, nest-site; and (2) reduction of energy spent
in nest construction, which may be even more important for first-
time nesters. Since only artificial nest sites with vestiges were used,
as contrasted with used nest sites, this portion of the nesting pairs
may be naı¨ve. If we assume that only naı¨ve birds used artificial sites,
then clearly, vestiges are important. To test these contrasting results
would require that birds, both old and young at nests, are captured
and marked, to be recaptured at nests in subsequent years.
Both of these trends,memory and information,may contribute
to understanding the long-term use of caves and cliff faces by these
birds. Reuse of nest sites may indicate risk averse behavior such that
birds tend to avoid the use of new locations, even if adequate, due to
the lack of nesting information. Other grottoes with potential nest
sites are near the study area and they were explored to search for
nesting colonies. While superficially very similar to the study site,
swifts apparently never used these locations. If birds are risk averse
and if nest sites are limited, then these birds would appear to be
self-limiting—that is, some pairs might forego reproduction despite
adequate and available nesting substrates. For example,A. fuciphagus
is apparently nest-site limited, yet new sites are not immediately used
when they become available (Langham 1980).While ‘potential’ nest
sites are difficult to quantify, substrates for nests are available and
common, which suggests that nest sites are not limiting. Yet, due to
this apparent risk averse behavior, birds appear to be self-limiting.
Perhaps predation is such a strong risk for adults as well as for their
reproductive attempt, that using a novel site is not adaptive.
In summary, biscutate swift nesting behavior suggests that birds
either use memory (experienced pairs) or evidence (naı¨ve pairs) as
information about where to nest and that novel sites are avoided
by both. Such behavior is a form of cultural transmission of infor-
mation from one season to the next and may explain geographic
patterns of nesting colonies. Also, such nest-site choice may appear
to be self-limiting, which in turn may appear to limit population
growth. Alternatively, swifts are long-lived birds and so perhaps
foregoing reproduction in any one year is better than to risk pre-
dation. Further study is recommended to better understand cul-
tural transmission of information regarding reproduction and how
microclimate or predation risk influence nesting success. Finally,
construction of nesting sites could be used as a conservation man-
agement tool. By providing additional sites in the midst of already
used sites, perhaps more and naı¨ve pairs may be induced to use these
new sites.
ACKNOWLEDGMENTS
The first author thanks the ConselhoNacional de Desenvolvimento
Cient´ıfico e Tecnolo´gico (CNPq) for financial support. We thank
theGraduate Program inZoology at the FederalUniversity of Parana
for institutional support. F. Cruz offered valuable help in the build-
ing and installation of the nesting platforms. We also thank A.
Lorenzetto, A. D. Ferreira, A. A. B. de Oliveira, D. A. Corne´lio,
C. A. F. R. Gatto and T. Monteiro for invaluable help in the
field.

84 Pichorim, Roper, and Monteiro Filho
LITERATURE CITED
CHANTLER, P. 1999. Family Apodidae (Swifts). In J. Del Hoyo, A. Elliott,
and J. Sargatal (Eds.). Handbook of the birds of the world, Vol 5,
Barn–owls to Hummingbirds, pp. 388–457. Lynx Editions, Barcelona,
Spain.
CHANTLER, P., AND G. DRIESSENS. 1995. Swifts, a guide to the swifts and tree
swifts of the world. Pica Press, Sussex, UK.
COLLINS, C. T., AND K. S. FOERSTER. 1995. Nest site fidelity and adult longevity
in the Black Swift (Cypseloides niger). N. Am. Bird Band. 20: 11–14.
KANG, N., C. J. HAILS, AND J. B. SIGURDSSON. 1991. Nest construction and egg
laying in Edible-Nest Swiftlets Aerodramus spp. and the implications for
harvesting. Ibis 133: 170–177.
LACK, D. 1956. A review of the genera and nesting habits of swifts. Auk 73:
1–32.
LANGHAM, N. 1980. Breeding biology of the Edible-Nest Swiftlet Aerodramus
fuciphagus. Ibis 122: 447–461.
MARI´N, A. M. 1997. Some aspects of the breeding biology of the Black Swift.
Wilson Bull. 109: 290–306.
MARI´N, A.M., AND F. G. STILES. 1993. Notes on the biology of the Spot-Fronted
Swift. Condor 95: 479–483.
PHACH, N. Q., AND J. F. VOISIN. 1998. Influence of cave structure, microclimate
and nest harvesting on the breeding of theWhite-Nest SwiftletCollocalia
fuciphaga germani in Vietnam. Ibis 140: 257–264.
PICHORIM, M. 2002. The breeding biology of the Biscutate-Swift (Streptoprocne
biscutata) in southern Brazil. Ornit. Neotrop. 13: 61–84.
SLAGSVOLD, T. 1985. Nest site selection. In B. Campbell, and E. Lack (Eds.).
A dictionary of birds, pp. 391–393. Buteo Books, Vermillion, South
Dakota.
THOMPSON, D. L., AND H. D. HOME. 1993. Long term changes in weather and
in the breeding schedule of Common Swifts (Apus apus). Avocetta 17:
199–202.
WHITACRE, D. F. 1989. Conditional use of nest structures by White-Naped and
White-Collared Swifts. Condor 91: 813–825.