Table Of Content126 THE WILSON JOURNAL OF ORNITHOLOGY • Vol. 119, No. 1, March 2007
forest of western Madagascar. Journal of Avian Rand, A. L. 1954. Social feeding behavior of birds.
Biology 29:17-24. Fieldiana-Zoology 36:1-71.
Kushlan,J. a. 1978. Commensalism inthe Little Blue Robbins, M. B. 1981. Two cases of commensal feed-
Heron. Auk 95:677-681. ing between passerines. Wilson Bulletin 93:391-
Maxson, J. anda. D. Maxson. 1981. Commensalfor- 392.
aging between Hairy and Pileated woodpeckers. Willis, E. O. 1972. The behaviorofSpotted Antbirds.
Journal of Field Ornithology 52:62-63. Ornithological Monographs 10.
The Wilson Journal ofOrnithology 1 19(1):126-128, 2007
Interspecific Egg-dumping by a Violet-green Swallow in an Active
Western Bluebird Nest
Danika Kleiber,' ^’^ Jenne Turner,'’"* Amber E. Budden,’’*^ and Janis L. Dickinson‘s^
—
ABSTRACT. We observed a Violet-green Swal- olet-green Swallow {Tachycineta thalassina)
low (Tachycineta thalassina) laying an egg in an ac- laying an egg in an active Western Bluebird
tive Western Bluebird (Sialia mexicana) nest. The {Sialia mexicana) nest containing nine-day-
Western Bluebird male and not the female, was ag-
gressive to the Violet-green Swallow but the swallow old nestlings at Hastings Natural History Res-
remained to lay the egg. This is the first documented ervation, Carmel Valley, California (36° 22' N,
incidence of which we are aware involving altricial 121° 34' W). Nest boxes have been monitored
interspecific egg-laying during the nestling phase. We at Hastings and nearby ranches as part of a
suggest the timing of this event was more consistent long-term study of Western Bluebirds since
with incidental egg deposition, or egg-dumping, than 1983 (Dickinson et al. 1996). Western Blue-
brood parasitism or nest usurpation. Received 13 De-
cember 2005. Accepted 24 July 2006. birds are the primary box-nesting species at
this study site, but other secondary cavity
nesters use nest boxes at lower frequencies,
including Ash-throated Flycatchers {Myiar-
Observations of birds laying eggs in nests chiis cinerascens). Oak Titmice {Baeolophiis
of other species are of interest because this inornatns). House Wrens {Troglodytesaedon),
behavior, when timed appropriately and di- Bewick’s Wren {Thryomanes hewickii) and
rected at nests where parents fail to recognize Violet-green Swallows (Table 1).
foreign eggs and offspring, may be the start- We conducted a study of parental feeding
ing point for evolution of interspecihc brood behaviors during spring 2005 using video to
parasitism. Other explanations for this behav- identify patterns of resource allocation within
ior are nest usurpation and egg-dumping,
which is the deposition of an egg into another
species’ nest without any specific adaptive
function. We collected video footage of a Vi- TABLE 1. Frequency of nest box use by second-
ary cavity-nesting species at Hastings Natural History
Reservation, Carmel Valley, California, from 1983 to
' Hastings Natural History Reservation, 38601 E. 2004.
Carmel Valley Rd., Carmel Valley, CA 93924, USA.
- University of British Columbia, Department of Species Nests(/!) Totaluse(%)
Forest Sciences, Forest Sciences Centre, 2424 Main
Mall, Vancouver, BC V6T 1Z4, Canada. Western Bluebird 1,860 69
1420Walnut St., Ste. 650, Philadelphia, PA 19102, OAsahk-tThirtomaotuedseFlycatcher 220984 118
USA.
House Wren 175 7
Department ofZoology, University ofToronto, 25
Harbord St., Toronto, ON M5S 3G5, Canada. VBieowliectk-’gsreWenreSnwallow 1222 <15
Cornell Laboratory ofOrnithology. 159 Sapsucker
Woods Rd., Ithaca, NY 14850, USA. Total nesting attempts (at least
one egg) 2,661 100
^Corresponding author; e-mail: [email protected]
SHORT COMMUNICATIONS 127
the nest. The day before himing we replaced let-green Swallow left the nest box, leaving a
the natal nest box and nest material with a box white egg on the outer rim of the nest cup
of the same dimensions containing a Western where she had been sitting. During the after-
Bluebird nest, but with a Plexiglas side to ac- noon the video nest box and nest were re-
commodate the camera. A video camera and placed with the natal nest box and nest; the
small LED light were positioned within a Violet-green Swallow egg was also trans-
sleeve connected to the nest box on the morn- ferred. When we returned to the nest the fol-
ing of filming, which began at approximately lowing day the Violet-green Swallow egg was
0530 hrs PST. Tapes were set on short play lying broken in the bottom of the nest. There
and recorded for a period of 120 min. During was no second Violet-green Swallow egg.
the first recording an experimenter collected
DISCUSSION
simultaneous observational data on parental
m
activity from a blind approximately 30 Three hypotheses are possible explanations
away. Following tape completion, a second for our observations: nest usurpation, brood
tape was inserted to record an additional 120 parasitism, and interspecific egg-dumping.
min ofnestling provisioning observations. No Nest usurpation is a possible explanation giv-
additional observational data on parental ac- en that Western Bluebirds and Violet-green
tivity were collected from outside the nest. Swallows are both secondary cavity nesters
whose breeding times overlap (Brown et al.
OBSERVATIONS
1992, Guinan et al. 2000). However, in this
We collected video data on 27 May 2005 instance, timing of egg-laying and the ob-
from a Western Bluebird nest containing five served behavior of the Violet-green swallow
nine-day-old nestlings and a single unhatched was not consistent with nest usurpation. Vio-
Western Bluebird egg. In this instance, the let-green Swallows in our population use nest
time stamp on the video unit failed, and ob- boxes at a low frequency (Table 1), but are
servations were timed using the video counter common and presumably use natural cavities
and calibrated using the corresponding obser- as nesting sites. Previously described nest
vational data. The video nest watch began at usurpation interactions between Violet-green
0520:00 hrs. At 071 1:53 hrs, a female Violet- Swallows and Western Bluebirds do not match
green Swallow entered the nest box and sat in the behavior we observed. In Arizona, Brawn
the far left corner at the top of the nest cup. (1990) observed large groups of Violet-green
At 0712:46, the Western Bluebird male en- Swallows taking over a nest box defended by
tered the box and proceeded to peck at the a Western Bluebird, but a single Violet-green
Violet-green Swallow’s head six times before Swallow, such as we observed, was not suc-
leaving the nest box at 0713:03. The Violet- cessful in displacing Western Bluebirds. Suc-
green Swallow responded to the pecking at- cessful use of a Western Bluebird box by a
tack by tucking her head down and remaining single pair of Violet-green Swallows has been
still. After 5 sec, the female Western Bluebird observed, but was preceded by interspecific
fed a nestling from the box entrance. She ap- provisioning of the bluebird’s young (Eltzroth
peared to ignore the Violet-green Swallow and and Robinson 1984).
entered the box only to turn around, leaving Brood parasitism can also be ruled out due
1 1 sec after arrival. The adult male and female to improper timing of laying. We found no
Western Bluebirds fed the nestlings twice record of either intra- or interspecific brood
more while the swallow was in the nest box, parasitism by Violet-green Swallows in the lit-
but did so without entering the nest. At 0721: erature (Brown et al. 1992). The placement of
41, the first video tape ended and the second the egg outside the nest cup would be incon-
was inserted. We estimated the time from the sistent with brood parasitism behavior.
ending of the first tape and beginning of the It is more likely the Violet-green Swallow
second to be approximately 30 sec, and added laid the egg because she was physiologically
that time to our calculations. The Western committed to do so but was unable to lay in
Bluebird adults did not enter the box again her original nest, a behavior known as “egg-
while the Violet-green Swallow female was dumping” (Wiens 1971). There are many doc-
present. At approximately 0733 hrs, the Vio- umented cases ofinterspecific egg-dumping in
128 THE WILSON JOURNAL OF ORNITHOLOGY • Vol. 119, No. 1, March 2007
avian species not known for brood parasitic Brawn, J. D. 1990. Interspecific competition and so-
behavior (Bailey 1886, Holcomb 1967, Wiens cial behavior in Violet-green Swallows. Auk 107:
1971, Gustafson 1975, Canned and Harring- 606-608.
ton 1984, Littlefield 1984, Carter 1987, Sealy Brown, C. R., A. M. Knott,andE.J. Damrose. 1992.
Violet-green Swallow (Tachycineta thalassina).
1989). Females may lay in another cavity be- The birds of North America. Number 14.
cause they are unable to approach their own Cannell, R F. and B. a. Harrington. 1984. Interspe-
cavity at the time of laying, due to the pres- cific egg dumping by a Great Egret and Black-
ence of a predator, nest usurpation, or other crowned Night Herons. Auk 101:889-891.
disturbance. Based on monitoring ofnest box- Carter, M. D. 1987. An incident ofbrood parasitism
es at Hastings Reservation, 11.2% of 98 Vi- by the Verdin. Wilson Bulletin 99:136.
olet-green Swallow nests with at least one egg Dickinson, J. L., W. D. Koenig, and F. A. Pitelka.
failed before hatching from 1983 through 1996. Fitnessconsequencesofhelpingbehaviorin
the Western Bluebird. Behavioral Ecology 7:168-
2005. This small incidence ofnest failure dur-
177.
ing laying and incubation is only partially at- Eltzroth, E. K. and S. R. Robinson. 1984. Violet-
tributable to predation, but indicates that in- green Swallows help Western Bluebirds at the
frequent nest predation or disturbance during nest. Journal ofField Ornithology 55:259-261.
laying could account for the behavior we ob- Guinan, j. a., P. a. Gowaty, and E. K. Eltzroth.
served. Although there are no data on conspe- 2000. Western Bluebird (Sialia rnexicana). The
cific nest usurpation in Violet-green Swal- birds of North America. Number 510.
lows, nest usurpation has been well docu- Gustafson, J. R. 1975. A Sage Sparrow egg in a
Black-throated Sparrow nest. Auk 92:805-806.
mented in Tree Swallows (Tcichycineta bicol- Holcomb, L. C. 1967. Mourning Dove egg in nest of
or) (Leffelaar 1985). catbird and robin. Wilson Bulletin 79:450-451.
ACKNOWLEDGMENTS Leffelaar, D. and R. J. Robertson. 1985. Nest usur-
We thank Wendy Fair and Caitlin Stern for helpful pation and female competition for breeding op-
portunities by Tree Swallows. Wilson Bulletin 97:
comments and Cachagua General Store forgastronom-
ical support. This research was funded by NSF grant 221-224.
lBN-009702toJLD. Editedvideofootagemaybeviewed Littlefield, C. D. 1984. Sandhill Crane incubates a
Canada Goose egg. Wilson Bulletin 96:719.
at: http://www.birds.comell.edu/birdhouse/nestboxcam/
movies_home/vgsw_in_webl courtesy of Cornell Labo- Sealy, S. G. 1989. Incidental “egg dumping” by the
ratory of Ornithology’s “The Birdhouse Network.” House Wren in a Yellow Warbler nest. Wilson
Bulletin 101:491-493.
LITERATURE CITED
Wiens, J. A. 1971. “Egg-dumping” by the Grasshop-
Bailey, H. B. 1886. The Brown Thrush laying in the per Sparrow in a Savannah Sparrow nest. Auk 88:
nest of the Wood Thrush. Auk 4:78. 185-186.
The Wilson Journal ofOrnithology 1 19(1):128—129, 2007
Western Bluebird Captures a Western Fence Lizard
Caitlin A. Stern'•“
—
ABSTRACT. 1 observed a male Western Bluebird there is one previous report ofa Western Bluebirdcar-
(Sialia nie.xicana) capture a western fence lizard rying an unidentified lizard in the manner of a prey
loporus occidentalis). the first reported incidence of item, and a few reports ofpredation on vertebrates by
vertebrate-directed raptorial behavior in the Western the congeneric Eastern Bluebird {Sialia sialis). Re-
Bluebird. There are no previously published reportsof ceived 9 January 2006. Accepted 28 June 2006.
Western Bluebirds capturing vertebrate prey, although
Western Bluebirds {Sialia rnexicana) are
Car'mHealstiVnagllseyNaRtdu.r,alCaHrimsetlorVyalRleeys,erCvaAti9on3,9243,86U0S1A.E. primarily insectivorous during the breeding
-Current address: Department ofNeurobiology and season, and rely upon berry crops during win-
Behavior, Cornell University, Ithaca, NY 14853, USA; ter (Guinan et al. 2000). Individual Eastern
e-mail: [email protected] Bluebirds (Sialia sialis), a congeneric species.
